<?php
/**
 * SeekQuarry/Yioop --
 * Open Source Pure PHP Search Engine, Crawler, and Indexer
 *
 * Copyright (C) 2009 - 2026  Chris Pollett chris@pollett.org
 *
 * LICENSE:
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 *
 * END LICENSE
 *
 * @author Chris Pollett chris@pollett.org
 * @license https://www.gnu.org/licenses/ GPL3
 * @link https://www.seekquarry.com/
 * @copyright 2009 - 2026
 * @filesource
 */
namespace seekquarry\yioop\executables;

use seekquarry\yioop\configs as C;
use seekquarry\yioop\library as L;
use seekquarry\yioop\library\CrawlConstants;
use seekquarry\yioop\library\CrawlDaemon;
use seekquarry\yioop\library\storage_formats\IndexShard;
use seekquarry\yioop\library\storage_formats\IndexDocumentBundle;
use seekquarry\yioop\library\processors\PageProcessor;
use seekquarry\yioop\library\storage_formats\DoubleIndexBundle;
use seekquarry\yioop\library\UrlParser;
use seekquarry\yioop\library\storage_formats\CrawlQueueBundle;
use seekquarry\yioop\library\storage_formats\MessagesBundle;

if (!defined("seekquarry\\yioop\\configs\\UNIT_TEST_MODE")) {
    if (php_sapi_name() != 'cli' ||
        defined("seekquarry\\yioop\\configs\\IS_OWN_WEB_SERVER")) {
        echo "BAD REQUEST"; exit();
    }
}
/**  For crawlHash function and Yioop constants */
require_once __DIR__ . "/../library/Utility.php";
if (!C\PROFILE) {
    echo "Please configure the search engine instance ".
        "by visiting its web interface on localhost.\n";
    exit();
}
ini_set("memory_limit", C\QUEUE_SERVER_MEMORY_LIMIT);
/*
 * We'll set up multi-byte string handling to use UTF-8
 */
mb_internal_encoding("UTF-8");
mb_regex_encoding("UTF-8");
/**
 * Command line program responsible for managing Yioop crawls.
 *
 * It maintains a queue of urls that are going to be scheduled to be seen.
 * It also keeps track of what has been seen and robots.txt info.
 * Its last responsibility is to create and populate the IndexDocumentBundle
 * that is used by the search front end.
 *
 * @author Chris Pollett
 */
class QueueServer implements CrawlConstants
{
    /**
     * Reference to a database object. Used since has directory manipulation
     * functions
     * @var object
     */
    public $db;
    /**
     * Web-sites that crawler can crawl. If used, ONLY these will be crawled
     * @var array
     */
    public $allowed_sites;
    /**
     * Web-sites that the crawler must not crawl
     * @var array
     */
    public $disallowed_sites;
    /**
     * Microtime used to look up cache $allowed_sites and $disallowed_sites
     * filtering data structures
     * @var int
     */
    public $allow_disallow_cache_time;
    /**
     * name of file used to hold statistic about current crawl
     * @var string
     */
    public $crawl_status_file_name;
    /**
     * Timestamp of lst time download from site quotas were cleared
     * @var int
     */
    public $quota_clear_time;
    /**
     * Web-sites that have an hourly crawl quota
     * @var array
     */
    public $quota_sites;
    /**
     * Cache of array_keys of $quota_sites
     * @var array
     */
    public $quota_sites_keys;
    /**
     * Channel that queue server listens to messages for
     * @var int
     */
    public $channel;
    /**
     * Controls whether a repeating crawl (negative man no) is being done
     * and if so its frequency in second
     * @var int
     */
    public $repeat_type;
    /**
     * If a crawl quiescent period is being used with the crawl, then
     * this stores the time of day at which that period starts
     * @var string
     */
    public $sleep_start;
    /**
     * If a crawl quiescent period is being used with the crawl, then
     * this sproperty will be positive and indicate the number of seconds
     * duration for the quiescent period.
     * @var string
     */
    public $sleep_duration;
    /**
     * Constant saying the method used to order the priority queue for the crawl
     * @var string
     */
    public $crawl_order;
    /**
     * Constant saying the depth from the seeds crawl can go to
     * @var string
     */
    public $max_depth;
    /**
     * One of a fixed set of values which are used to control to what extent
     * Yioop follows robots.txt files: ALWAYS_FOLLOW_ROBOTS,
     * ALLOW_LANDING_ROBOTS, IGNORE_ROBOTS
     * @var int
     */
    public $robots_txt;
    /**
     * Stores the name of the summarizer used for crawling.
     * Possible values are Basic and Centroid
     * @var string
     */
    public $summarizer_option;
    /**
     * Maximum number of bytes to download of a webpage
     * @var int
     */
    public $page_range_request;
    /**
     * Max number of chars to extract for description from a page to index.
     * Only words in the description are indexed.
     * @var int
     */
    public $max_description_len;
    /**
     * Maximum number of urls to extract from a single document
     * @var int
     */
    public $max_links_to_extract;
    /**
     * Number of days between resets of the page url filter
     * If nonpositive, then never reset filter
     * @var int
     */
    public $page_recrawl_frequency;
    /**
     * Indicates the kind of crawl being performed: self::WEB_CRAWL indicates
     * a new crawl of the web; self::ARCHIVE_CRAWL indicates a crawl of an
     * existing web archive
     * @var string
     */
    public $crawl_type;
    /**
     * If the crawl_type is self::ARCHIVE_CRAWL, then crawl_index is the
     * timestamp of the existing archive to crawl
     * @var string
     */
    public $crawl_index;
    /**
     * Says whether the $allowed_sites array is being used or not
     * @var bool
     */
    public $restrict_sites_by_url;
    /**
     * List of file extensions supported for the crawl
     * @var array
     */
    public $indexed_file_types;
    /**
     * List of all known file extensions including those not used for crawl
     * @var array
     */
    public $all_file_types;
    /**
     * Used in schedules to tell the fetcher whether or not to cache pages
     * @var bool
     */
    public $cache_pages;
    /**
     * Used to add page rules to be applied to downloaded pages to schedules
     * that the fetcher will use (and hence apply the page )
     * @var array
     */
    public $page_rules;
    /**
     * Holds the CrawlQueueBundle for the crawl. This bundle encapsulates
     * the queue of urls that specifies what to crawl next
     * @var object
     */
    public $crawl_queue;
    /**
     * Hold the MessagesBundle to be used for the crawl.  This bundle
     * is used to store data that is sent between the QueueServer and Fetcher
     * that has yet to be processed.
     * @var object
     */
    public $messages_bundle;
    /**
     * Maximum number of to_crawl schedules that can waiting to be returned
     * in the sequence they were sent out. I.e, if crawl results for
     * fetch batch x have not been returned then fetch batch x + $window_size
     * cannot be created from the queue.
     * @var int
     */
    public $window_size;
    /**
     * Holds the IndexDocumentBundle for the current crawl. This encapsulates
     * the inverted index word-->documents for the crawls as well as document
     * summaries of each document.
     * @var object
     */
    public $index_archive;
    /**
     * The timestamp of the current active crawl
     * @var int
     */
    public $crawl_time;
    /**
     * IP address as a string of the fetcher that most recently spoke with the
     * queue server.
     * @var string
     */
    public $most_recent_fetcher;
    /**
     * Last time index was saved to disk
     * @var int
     */
    public $last_index_save_time;
    /**
     * flags for whether the index has data to be written to disk
     * @var int
     */
     public $index_dirty;
    /**
     * This keeps track of the time the current archive info was last modified
     * This way the queue server knows if the user has changed the crawl
     * parameters during the crawl.
     * @var int
     */
    public $archive_modified_time;
    /**
     * This is a list of indexing_plugins which might do
     * post processing after the crawl. The plugins postProcessing function
     * is called if it is selected in the crawl options page.
     * @var array
     */
    public $indexing_plugins;
    /**
     * This is a array of crawl parameters for indexing_plugins which might do
     * post processing after the crawl.
     * @var array
     */
    public $indexing_plugins_data;
    /**
     * This is a list of hourly (timestamp, number_of_urls_crawled) statistics
     * @var array
     */
    public $hourly_crawl_data;
    /**
     * Used to say what kind of queue server this is (one of BOTH, INDEXER,
     * SCHEDULER)
     * @var mixed
     */
    public $server_type;
    /**
     * String used to describe this kind of queue server (Indexer, Scheduler,
     * etc. in the log files.
     * @var string
     */
    public $server_name;
    /**
     * String used for naming log files and for naming the processes which run
     * related to the queue server
     * @var string
     */
    public $process_name;
    /**
     * Holds the value of a debug message that might have been sent from
     * the command line during the current execution of loop();
     * @var string
     */
    public $debug;
    /**
     * Holds the int value of the previous partition in index
     * @var int
     */
    public $last_next_partition_to_add;
    /**
     * Keeps track of the time needed for the dictionary updater to add the
     * current partition contents to index
     * @var int
     */
    public $start_dictionary_time;
    /**
     * A mapping between class field names and parameters which might
     * be sent to a queue server via an info associative array.
     * @var array
     */
    public static $info_parameter_map = [
        "crawl_order" => self::CRAWL_ORDER,
        "crawl_type" => self::CRAWL_TYPE,
        "crawl_index" => self::CRAWL_INDEX,
        "cache_pages" => self::CACHE_PAGES,
        "page_range_request" => self::PAGE_RANGE_REQUEST,
        "max_depth" => self::MAX_DEPTH,
        "repeat_type" => self::REPEAT_TYPE,
        "sleep_start" => self::SLEEP_START,
        "sleep_duration" => self::SLEEP_DURATION,
        "robots_txt" => self::ROBOTS_TXT,
        "max_description_len" => self::MAX_DESCRIPTION_LEN,
        "max_links_to_extract" => self::MAX_LINKS_TO_EXTRACT,
        "page_recrawl_frequency" => self::PAGE_RECRAWL_FREQUENCY,
        "indexed_file_types" => self::INDEXED_FILE_TYPES,
        "restrict_sites_by_url" => self::RESTRICT_SITES_BY_URL,
        "allowed_sites" => self::ALLOWED_SITES,
        "disallowed_sites" => self::DISALLOWED_SITES,
        "page_rules" => self::PAGE_RULES,
        "indexing_plugins" => self::INDEXING_PLUGINS,
        "indexing_plugins_data" => self::INDEXING_PLUGINS_DATA,
    ];
    /**
     * Creates a Queue Server Daemon
     */
    public function __construct()
    {
        PageProcessor::initializeIndexedFileTypes();
        $db_class = C\NS_DATASOURCES . ucfirst(C\p('DBMS')) . "Manager";
        $this->db = new $db_class();
        $this->indexed_file_types = PageProcessor::$indexed_file_types;
        $this->all_file_types = PageProcessor::$indexed_file_types;
        $this->most_recent_fetcher = "No Fetcher has spoken with me";
        //the next values will be set for real in startCrawl
        $this->crawl_order = self::HOST_BUDGETING;
        $this->summarizer_option = self::CENTROID_SUMMARIZER;
        $this->restrict_sites_by_url = true;
        $this->allowed_sites = [];
        $this->disallowed_sites = [];
        $this->allow_disallow_cache_time = microtime(true);
        $this->quota_sites = [];
        $this->quota_sites_keys = [];
        $this->quota_clear_time = time();
        $this->page_rules = [];
        $this->last_index_save_time = 0;
        $this->index_dirty = false;
        $this->hourly_crawl_data = [];
        $this->archive_modified_time = 0;
        $this->crawl_time = 0;
        $this->channel = 0;
        $this->repeat_type = -1;
        $this->sleep_start = "00:00";
        $this->sleep_duration = "-1";
        $this->robots_txt = C\ALWAYS_FOLLOW_ROBOTS;
        $this->cache_pages = true;
        $this->page_recrawl_frequency = C\PAGE_RECRAWL_FREQUENCY;
        $this->page_range_request = C\PAGE_RANGE_REQUEST;
        $this->max_description_len = C\MAX_DESCRIPTION_LEN;
        $this->max_links_to_extract = C\MAX_LINKS_TO_EXTRACT;
        $this->server_type = self::BOTH;
        $this->index_archive = null;
        $this->crawl_queue = null;
        $this->messages_bundle = null;
        $this->indexing_plugins = [];
        $this->indexing_plugins_data = [];
        $this->server_name = "IndexerAndScheduler";
        $this->process_name = "0-QueueServer";
        $this->crawl_status_file_name =
            C\SCHEDULES_DIR . "/{$this->channel}-" . self::crawl_status_file;
        $this->debug = "";
    }
    /**
     * This is the function that should be called to get the queue server
     * to start. Calls init to handle the command line arguments then enters
     * the queue server's main loop
     */
    public function start()
    {
        global $argv;
        if (isset($argv[1]) && $argv[1] == "start") {
            if (isset($argv[2]) && in_array($argv[2],
                [self::INDEXER, self::SCHEDULER]) ) {
                $this->channel = (empty($argv[3])) ? 0 : min(C\MAX_CHANNELS,
                    abs(intval($argv[3])));
                $argv[3] = $argv[2];
                $argv[2] = $this->channel;
                // 3 indicates force start
                CrawlDaemon::init($argv, "QueueServer", 3);
            } else {
                $this->channel = (empty($argv[2])) ? 0 : min(C\MAX_CHANNELS,
                    abs(intval($argv[2])));
                $argv[2] = $this->channel;
                $argv[3] = self::INDEXER;
                CrawlDaemon::init($argv, "QueueServer", 0);
                $argv[3] = self::SCHEDULER;
                CrawlDaemon::init($argv, "QueueServer", 2);
            }
        } else {
            $this->channel = (empty($argv[2])) ? 0 : min(C\MAX_CHANNELS,
                abs(intval($argv[2])));
            CrawlDaemon::init($argv, "QueueServer", "{$this->channel}");
        }
        $this->process_name = $this->channel . "-QueueServer";
        $this->crawl_status_file_name =
            C\SCHEDULES_DIR . "/{$this->channel}-" . self::crawl_status_file;
        L\crawlLog("\n\nInitialize logger..", $this->process_name, true);
        $this->server_name = "IndexerAndScheduler";
        if (isset($argv[3]) && $argv[1] == "child" &&
            in_array($argv[3], [self::INDEXER, self::SCHEDULER])) {
            $this->server_type = $argv[3];
            $this->server_name = $argv[3];
            L\crawlLog($this->server_name . " logging started.");
        }
        L\crawlLog($this->server_name . " using channel " . $this->channel);
        $remove = false;
        $old_message_names = ["QueueServerMessages.txt",
            self::crawl_status_file, "ScheduleStatus.txt"];
        foreach ($old_message_names as $name) {
            if (file_exists(C\SCHEDULES_DIR . "/{$this->channel}-$name")) {
                @unlink(C\SCHEDULES_DIR . "/{$this->channel}-$name");
                $remove = true;
            }
            if (file_exists(C\SCHEDULES_DIR . "/$name")) {
                @unlink(C\SCHEDULES_DIR . "/$name");
                $remove = true;
            }
        }
        if ($remove == true) {
            L\crawlLog("Remove old messages..", $this->process_name);
        }
        $this->loop();
    }
    /**
     * Main runtime loop of the queue server.
     *
     * Loops until a stop message received, check for start, stop, resume
     * crawl messages, deletes any CrawlQueueBundle for which an
     * IndexDocumentBundle does not exist. Processes
     */
    public function loop()
    {
        static $total_idle_time = 0;
        static $total_idle_previous_hour = 0;
        static $total_idle_two_hours = 0;
        static $oldest_record_time = 0;
        static $last_record_time = 0;
        $info = [self::STATUS => self::WAITING_START_MESSAGE_STATE];
        L\crawlLog("In queue loop!! {$this->server_name}", $this->process_name);
        if ($this->isAIndexer()) {
            $this->deleteOrphanedBundles();
        }
        $method_statistics_file = C\LOG_DIR . "/" . $this->server_name .
            "Stats.log";
        L\measureCall(null, $method_statistics_file);
        L\crawlLog("Profiling info will be sent to: " .
            $method_statistics_file);
        L\crawlLog("PHP Version in use: " . phpversion());
        while (CrawlDaemon::processHandler()) {
            L\measureObject($GLOBALS, "", "GLOBALS");
            L\measureObject($this);
            if ($this->isAIndexer()) {
                L\measureObject($this->index_archive, "",
                    "IndexDocumentBundle");
            }
            if ($this->isAScheduler()) {
                L\measureObject($this->crawl_queue, "", "CrawlQueueBundle");
            }
            if ($this->isOnlyIndexer()) {
                $_SERVER["NO_ROTATE_LOGS"] = ((floor(time() / 30) % 2) == 0) ?
                    true : false;
            }
            if ($this->isOnlyScheduler()) {
                $_SERVER["NO_ROTATE_LOGS"] = ((floor(time() / 30) % 2) == 0) ?
                    false : true;
            }
            L\crawlLog("{$this->server_name} current memory usage: " .
                memory_get_usage() .
                " (Peak:" . memory_get_peak_usage().")!!");
            $record_time = time();
            $diff_hours = ($record_time - $oldest_record_time)/C\ONE_HOUR;
            $diff_hours = ($diff_hours <= 0) ? 1 : $diff_hours;
            $idle_per_hour =
                ($total_idle_time - $total_idle_two_hours) /
                $diff_hours;
            L\crawlLog("{$this->server_name} percent idle time per hour: " .
                number_format($idle_per_hour * 100, 2) ."%");
            if ($record_time > $last_record_time + C\ONE_HOUR) {
                $total_idle_two_hours = $total_idle_previous_hour;
                $total_idle_previous_hour = $total_idle_time;
                $oldest_record_time = $last_record_time;
                if ($oldest_record_time == 0) {
                    $oldest_record_time = $record_time;
                }
                $last_record_time = $record_time;
            }
            $info = $this->handleAdminMessages($info);
            $this->checkBothProcessesRunning($info);
            if (!empty($info[self::STATUS])) {
                if ($info[self::STATUS] == self::WAITING_START_MESSAGE_STATE) {
                    L\crawlLog("{$this->server_name} is waiting".
                        " for start message\n");
                    L\interruptibleSleep(C\QUEUE_SLEEP_TIME, 1,
                        function () {
                            return !CrawlDaemon::processHandler(true);
                        });
                    $total_idle_time += C\QUEUE_SLEEP_TIME/C\ONE_HOUR;
                    continue;
                }
                if ($info[self::STATUS] == self::STOP_STATE) {
                    continue;
                }
            }
            L\crawlLog("{$this->server_name} active crawl is ".
                "{$this->crawl_time}.");
            if ($this->isAScheduler() && $this->crawl_type == self::WEB_CRAWL) {
                if (($wake_up =
                    L\checkTimeInterval($this->sleep_start,
                    $this->sleep_duration)) > 0) {
                    L\crawlLog("SM: Scheduler message!!");
                    L\crawlLog("SM: CRAWL IN QUIESCENT/SLEEP MODE!!");
                    L\crawlLog("SM: Will continue processing crawl data, but");
                    L\crawlLog("SM: fetchers will stop downloading.");
                    L\crawlLog("SM: Touching crawl_status file to keep crawl ".
                        "from timing our due to fetcher inactivity.");
                    if (file_exists($this->crawl_status_file_name)) {
                        touch($this->crawl_status_file_name, time());
                    }
                    L\crawlLog("SM: Current time is: " . date('r'));
                    L\crawlLog("SM: Will wake up at " . date('r', $wake_up));
                }
            }
            $start_loop_time = time();
            //check and update if necessary the crawl params of current crawl
            $this->checkUpdateCrawlParameters();
            /* if doing a crawl that repeats, check to see if we should swap
              between active and last crawl
             */
            $this->checkRepeatingCrawlSwap();
            L\measureCall($this, "updateMostRecentFetcher");
            $this->processCrawlData();
            $time_diff = time() - $start_loop_time;
            if ($time_diff < C\QUEUE_SLEEP_TIME) {
                L\crawlLog("Sleeping...");
                L\interruptibleSleep(C\QUEUE_SLEEP_TIME - $time_diff,
                    1, function () {
                        return !CrawlDaemon::processHandler(true);
                    });
                $total_idle_time += (C\QUEUE_SLEEP_TIME - $time_diff) /
                    C\ONE_HOUR;
            }
        }
        L\crawlLog("{$this->server_name} shutting down!!");
    }
    /**
     * Checks to make sure both the indexer process and the scheduler
     * processes are running and if not restart the stopped process
     * @param array $info information about queue server state used to
     *      determine if a crawl is active.
     */
    public function checkBothProcessesRunning($info)
    {
        /* This function doesn't do anything if this process
            is both an indexex and a scheduler as then the fact
            that we're here means both processes running
         */
        if ($this->isOnlyScheduler()) {
            $this->checkProcessRunning(self::INDEXER, $info);
        } else if ($this->isOnlyIndexer()) {
            $this->checkProcessRunning(self::SCHEDULER, $info);
        }
    }
    /**
     * Checks to make sure the given process (either Indexer or Scheduler) is
     * running.
     * @param string $process should be either self::INDEXER or self::SCHEDULER
     * @param array $info information about queue server state used to
     *      determine if a crawl is active.
     */
    public function checkProcessRunning($process, $info)
    {
        static $first_check;
        static $last_check;
        $time = time();
        if ($this->debug != "NOT_RUNNING") {
            if (!isset($first_check)) {
                $first_check = $time;
                $last_check = $time;
            }
            if ($time - $last_check < C\LOG_TIMEOUT ||
                $time - $first_check < C\PROCESS_TIMEOUT ) {
                return;
            }
        }
        $last_check = $time;
        L\crawlLog("Checking if both processes still running ...");
        $lines_to_check = C\LOG_LINES_TO_RESTART;
            //about 20-30 minutes of log data
        $lines = L\tail(C\LOG_DIR . "/" . $this->process_name . ".log",
            $lines_to_check);
        $time = time(); // just in case took time to compute lines
        L\crawlLog("...Got " . count($lines) . " lines from " .
            $this->process_name . ".log");
        if ($this->debug != "NOT_RUNNING" && count($lines) < $lines_to_check) {
            L\crawlLog("...Too few log lines to check if both processes " .
                "running.  Assume still running.");
            return;
        }
        $filters = ($process == self::INDEXER) ? [self::INDEXER] :
            [self::SCHEDULER];
        $initial = ($process == self::INDEXER) ? "I" : "S";
        $process_lines = L\lineFilter($lines, $filters, false);
        $num_lines = count($process_lines);
        L\crawlLog("...Filtered " . $this->process_name . ".log lines ".
            "looking for $initial process. Found $num_lines lines associated ".
            "with process.");
        // err on the side of caution in assuming process dead
        $last_process_timestamp = $time;
        if (isset($process_lines[$num_lines - 1])) {
            $timestamp =
                L\logLineTimestamp($process_lines[$num_lines - 1]);
            L\crawlLog("...Timestamp of last processed line: ".
                $timestamp);
            if (!empty($timestamp) &&
                is_numeric($timestamp) && $time > $timestamp) {
                /*
                   Note if 0 then we have seen LOG_LINES_TO_RESTART lines
                   with no message from other process
                 */
                $last_process_timestamp = $timestamp;
                L\crawlLog("...seems to be a valid timestep, so using.");
            } else { //hopefully doesn't occur, maybe log file garbled
                L\crawlLog("...calculated from line: " .
                    $process_lines[$num_lines - 1]);
                L\crawlLog("...invalid timestep, so using current time.");
            }
        }
        L\crawlLog("...difference last timestamp and current time ".
            ($time - $last_process_timestamp));
        if ($this->debug != "NOT_RUNNING" &&
            $time - $last_process_timestamp < C\PROCESS_TIMEOUT ) {
            L\crawlLog("...done check. Both processes still running.");
            return;
        }
        $this->debug = "";
        L\crawlLog( "$process seems to have died...");
        $process_lines = array_slice($process_lines, -10);
        $time_string = L\makeTimestamp();
        $out_msg = "$time_string $process died. Last log lines were:\n";
        foreach ($process_lines as $line) {
            $out_msg .= "$time_string !!!!$line\n";
        }
        if (empty($process_lines)) {
            $out_msg .= "$time_string !!!!No messages seen this log file!\n";
            $out_msg .= "$time_string !!!!$process must have died before: " .
                L\logLineTimestamp($lines[0]);
        }
        $error_log = C\CRASH_LOG_NAME;
        L\crawlLog( "!!!!Writing to $error_log " .
            "crash message about $process...");
        if (!file_exists($error_log) || filesize($error_log) >
            C\MAX_LOG_FILE_SIZE) {
            file_put_contents($error_log, $out_msg);
        } else {
            file_put_contents($error_log, $out_msg, FILE_APPEND);
        }
        L\crawlLog( "!!!!Writing to $error_log ".
            "crash message about $process...");
    }
    /**
     * Check for a repeating crawl whether it is time to swap between
     * the active and search crawls.
     *
     * @return bool true if the time to swap has come
     */
    public function checkRepeatingCrawlSwap()
    {
        L\crawlLog("Repeating Crawl Check for Swap...");
        if (empty($this->repeat_type) || $this->repeat_type <= 0) {
            L\crawlLog("SW...not a repeating crawl, no swap needed," .
                "continuing crawl.");
            return;
        }
        $crawl_time = $this->crawl_time;
        $start_swap_file = C\SCHEDULES_DIR . "/StartSwap" .
            $this->crawl_time . ".txt";
        $finish_swap_file = C\SCHEDULES_DIR . "/FinishSwap" .
            $this->crawl_time . ".txt";
        if ($this->isAScheduler() && file_exists($start_swap_file) &&
            !file_exists($finish_swap_file)) {
            L\crawlLog("SW...performing scheduler swap activities.");
            // Delete everything associated with the queue
            $delete_files = [
                C\CACHE_DIR . "/" . self::network_base_name .
                    "$crawl_time.txt",
                C\CACHE_DIR . "/" . self::statistics_base_name .
                    "$crawl_time.txt"
            ];
            foreach ($delete_files as $delete_file) {
                if (file_exists($delete_file)) {
                    unlink($delete_file);
                }
            }
            $delete_dirs = [
                C\CACHE_DIR . "/" . self::queue_base_name . $crawl_time,
                C\SCHEDULES_DIR . "/" . self::messages_data_base_name .
                    $crawl_time,
                C\SCHEDULES_DIR . "/" . self::name_archive_iterator .
                    $crawl_time,
            ];
            foreach ($delete_dirs as $delete_dir) {
                if (file_exists($delete_dir)) {
                    $this->db->unlinkRecursive($delete_dir, true);
                }
            }
            $save_point_files = glob(C\SCHEDULES_DIR . "/" .
                self::save_point . $crawl_time . "*.txt");
            foreach ($save_point_files as $save_point_file) {
                @unlink($save_point_file);
            }
            $this->initializeCrawlQueue();
            $dir_name = C\CACHE_DIR . "/" . self::double_index_base_name .
                $this->crawl_time;
            DoubleIndexBundle::getStartSchedule($dir_name, $this->channel);
            file_put_contents($finish_swap_file, time());
            unlink($start_swap_file);
            L\crawlLog("SW...done scheduler swap activities!!");
            return;
        }
        if ($this->isAIndexer() && (($this->index_archive->repeat_time +
            $this->index_archive->repeat_frequency < time())
            || $this->debug == 'FORCE_SWAP')) {
            if (!file_exists($start_swap_file) &&
                !file_exists($finish_swap_file)) {
                L\crawlLog("SW...swapping live and search crawl!!");
                L\crawlLog("SW...writing StartSwap file for scheduler !!");
                L\crawlLog("SW...indexer waits for scheduler to do swap");
                file_put_contents($start_swap_file, time());
            }
            if (!file_exists($start_swap_file) &&
                file_exists($finish_swap_file)) {
                L\crawlLog("SW...indexer performing swap activities");
                $this->index_archive->swapActiveBundle();
                $this->last_index_save_time = 0;
                unlink($finish_swap_file);
                    L\crawlLog("SW...done indexer swap activities!!");
            }
            if ($this->debug == 'FORCE_SWAP') {
                $this->debug = "";
            }
            return;
        }
        L\crawlLog("...no swap needed continuing current crawl");
    }
    /**
     * Main body of queue server loop where indexing, scheduling,
     * robot file processing is done.
     */
    public function processCrawlData()
    {
        L\crawlLog("{$this->server_name} Entering Process Crawl Data Method ");
        if ($this->isAIndexer()) {
            /* check for orphaned queue bundles
               also check to make sure indexes closed properly for stopped
               crawls
             */
            $this->deleteOrphanedBundles();
            $this->processIndexData();
            $info = $this->index_archive->getArchiveInfo(
                $this->index_archive->dir_name);
            $count = (empty($info)) ? 0 :
                ($info['COUNT'] ?? 0) + ($info['ACTIVE_COUNT'] ?? 0);
            if (time() - $this->last_index_save_time > C\FORCE_SAVE_TIME
                && $count > 0 && $this->index_archive->documents->parameters[
                    "SAVE_PARTITION"] < 2) {
                L\crawlLog("Periodic Index Save... \n");
                $start_time = microtime(true);
                $this->indexSave();
                L\crawlLog("... Save time" . L\changeInMicrotime($start_time));
            }
        }
        if ($this->isAScheduler()) {
            $info = [];
            $info[self::TYPE] = $this->server_type;
            $info[self::MEMORY_USAGE] = memory_get_peak_usage();
            file_put_contents(C\SCHEDULES_DIR .
                "/{$this->channel}-ScheduleStatus.txt",
                serialize($info));
        }
        switch ($this->crawl_type) {
            case self::WEB_CRAWL:
                if ($this->isOnlyIndexer()) {
                    return;
                }
                //so isScheduler true here
                L\measureCall($this, "processRobotUrls");
                if (C\USE_ETAG_EXPIRES) {
                    L\measureCall($this, "processEtagExpires");
                }
                L\measureCall($this, "processToCrawlUrls");
                L\measureCall($this, "processReceivedRobotTxtUrls");
                $this->messages_bundle->window_size = $this->window_size;
                $this->messages_bundle->initWindows();
                if(!$this->messages_bundle->isSendFull()) {
                    L\measureCall($this, "produceFetchBatch");
                } else {
                    L\crawlLog("Sender window full: Next schedule will " .
                        "be produced when current schedules are acknowledged");
                }
                break;
            case self::ARCHIVE_CRAWL:
                if ($this->isAIndexer()) {
                    L\measureCall($this, "processRecrawlRobotUrls");
                    if (!file_exists(C\SCHEDULES_DIR . "/" .
                        self::schedule_name . $this->crawl_time . ".txt")) {
                        $this->writeArchiveCrawlInfo();
                    }
                }
                break;
        }
    }
    /**
     * Used to check if the current queue server process is acting a
     * url scheduler for fetchers
     *
     * @return bool whether it is or not
     */
    public function isAScheduler()
    {
        return strcmp($this->server_type, self::SCHEDULER) == 0 ||
            strcmp($this->server_type, self::BOTH) == 0;
    }
    /**
     * Used to check if the current queue server process is acting a
     * indexer of data coming from fetchers
     *
     * @return bool whether it is or not
     */
    public function isAIndexer()
    {
        return strcmp($this->server_type, self::INDEXER) == 0 ||
            strcmp($this->server_type, self::BOTH) == 0;
    }
    /**
     * Used to check if the current queue server process is acting only as a
     * indexer of data coming from fetchers (and not some other activity
     * like scheduler as well)
     *
     * @return bool whether it is or not
     */
    public function isOnlyIndexer()
    {
        return strcmp($this->server_type, self::INDEXER) == 0;
    }
    /**
     * Used to check if the current queue server process is acting only as a
     * indexer of data coming from fetchers (and not some other activity
     * like indexer as well)
     *
     * @return bool whether it is or not
     */
    public function isOnlyScheduler()
    {
        return strcmp($this->server_type, self::SCHEDULER) == 0;
    }
    /**
     * Used to write info about the current recrawl to file as well as to
     * process any recrawl data files received
     */
    public function writeArchiveCrawlInfo()
    {
        $schedule_time = time();
        $first_line = $this->calculateScheduleMetaInfo($schedule_time);
        $fh = fopen(C\SCHEDULES_DIR . "/" . self::schedule_name .
            $this->crawl_time . ".txt", "wb");
        fwrite($fh, $first_line);
        fclose($fh);
        if (is_object($this->messages_bundle)) {
            $sites =
                $this->messages_bundle->nextMessages(
                    MessagesBundle::SCHEDULES_FOLDER);
            $this->writeCrawlStatus($sites[self::RECENT_URLS] ?? []);
        }
    }
    /**
     * Even during a recrawl the fetcher may send robot data to the
     * queue server. This function prints a log message and calls another
     * function to delete this useless robot file.
     */
    public function processRecrawlRobotUrls()
    {
        L\crawlLog("Checking for robots.txt files to process...");
        if (is_object($this->messages_bundle)) {
            $this->messages_bundle->nextMessages(MessagesBundle::ROBOTS_FOLDER);
        }
        L\crawlLog("done. ");
    }
    /**
     * Handles messages passed via files to the QueueServer.
     *
     * These files are typically written by the CrawlDaemon::init()
     * when QueueServer is run using command-line argument
     *
     * @param array $info associative array with info about current state of
     *     queue server
     * @return array an updates version $info reflecting changes that occurred
     *     during the handling of the admin messages files.
     */
    public function handleAdminMessages($info)
    {
        $old_info = $info;
        $is_scheduler = $this->isOnlyScheduler();
        $message_file = CrawlDaemon::getMessageFileName(
            "QueueServer", $this->channel);
        L\crawlLog("{$this->server_type} is checking for queue server ".
            "messages in $message_file ...");
        if (file_exists($message_file)) {
            $info = unserialize(file_get_contents($message_file));
            if (empty($info)) {
                L\crawlLog("{$this->server_type}:\n" .
                    "...$message_file unserializable or empty, unlinking!");
                unlink($message_file);
                return $old_info;
            }
            if (isset($info[self::DEBUG])) {
                $this->debug = $info[self::DEBUG];
                L\crawlLog("The following debug message found: ". $this->debug);
                unlink($message_file);
                return $old_info;
            }
            if (empty($info[$this->server_type])) {
                $info[$this->server_type] = 1;
                if ($this->server_type == self::BOTH ||
                  (isset($info[self::INDEXER]) && isset($info[self::SCHEDULER]))
                  ) {
                    L\crawlLog("{$this->server_type}: Both process have seen\n".
                        "...$message_file so unlinking.");
                    // both processes have seen message so unlink and unmark
                    unlink($message_file);
                } else {
                    // write that current process has seen message
                    $num_bytes =
                        file_put_contents($message_file, serialize($info),
                        LOCK_EX);
                    if (empty($num_bytes)) {
                        return $old_info;
                    }
                }
            } else {
                // already seen the message waiting for other process to see
                return $old_info;
            }
            if (isset($info[self::FETCHER_QUEUE_SERVER_RATIO])) {
                $this->window_size =
                    C\FETCHER_NUM_WINDOW_SCALE *
                    max($info[self::FETCHER_QUEUE_SERVER_RATIO], 1);
                L\crawlLog("{$this->server_type} set current window size to " .
                    $this->window_size);
            }
            switch ($info[self::STATUS])
            {
                case "NEW_CRAWL":
                    if ($info[$this->server_type] > 1) {
                        break;
                    }
                    $info[$this->server_type] = 2;
                    if ($old_info[self::STATUS] == self::CONTINUE_STATE) {
                        if (!$is_scheduler) {
                            L\crawlLog("Stopping previous crawl before start".
                                " new crawl!");
                        } else {
                            L\crawlLog(
                                "Scheduler stopping for previous crawl before".
                                " new crawl!");
                        }
                        $this->stopCrawl();
                    }
                    $this->startCrawl($info);
                    $info[self::STATUS] = self::CONTINUE_STATE;
                    if (!$is_scheduler) {
                        L\crawlLog("Starting new crawl. Timestamp:" .
                            $this->crawl_time);
                        if ($this->crawl_type == self::WEB_CRAWL) {
                            L\crawlLog("Performing a web crawl!");
                            L\crawlLog("robots.txt behavior is: ");
                            if ($this->robots_txt == C\ALWAYS_FOLLOW_ROBOTS) {
                                L\crawlLog("  Always follow robots.txt");
                            } else if ($this->robots_txt ==
                                C\ALLOW_LANDING_ROBOTS) {
                                L\crawlLog("  Allow landing pages.");
                            } else {
                                L\crawlLog("  Ignore robots.txt.");
                            }
                        } else {
                            L\crawlLog("Performing an archive crawl of " .
                                "archive with timestamp " .
                                $this->crawl_index);
                        }
                        // write the crawl status file not queue server messages
                        $this->writeAdminMessage("BEGIN_CRAWL");
                    } else {
                        L\crawlLog("Scheduler started for new crawl");
                    }
                break;
                case "STOP_CRAWL":
                    if (!$is_scheduler) {
                        L\crawlLog(
                            "Stopping crawl !! This involves multiple steps!");
                    } else {
                        L\crawlLog("Scheduler received stop message!");
                    }
                    $this->stopCrawl();
                    if (file_exists($this->crawl_status_file_name)) {
                        unlink($this->crawl_status_file_name);
                    }
                    $info[self::STATUS] = self::WAITING_START_MESSAGE_STATE;
                    if (!$is_scheduler) {
                        L\crawlLog("Crawl has been successfully stopped!!");
                    } else {
                        L\crawlLog("Scheduler has been successfully stopped!!");
                    }
                break;
                case "RESUME_CRAWL":
                    if ($info[$this->server_type] > 1) {
                        break;
                    }
                    $info[$this->server_type] = 2;
                    if (isset($info[self::CRAWL_TIME]) &&
                        (file_exists(C\CACHE_DIR . "/" .
                        self::queue_base_name . $info[self::CRAWL_TIME]) ||
                        $info[self::CRAWL_TYPE] == self::ARCHIVE_CRAWL) ) {
                        if ($old_info[self::STATUS] == self::CONTINUE_STATE) {
                            if (!$is_scheduler) {
                                L\crawlLog("Resuming old crawl...".
                                    " Stopping current crawl first!");
                            } else {
                                L\crawlLog("Scheduler resuming old crawl...".
                                    " Stopping scheduling current first!");
                            }
                            $this->stopCrawl();
                        }
                        $this->startCrawl($info);
                        $info[self::STATUS] = self::CONTINUE_STATE;
                        if (!$is_scheduler) {
                            L\crawlLog("Resuming crawl");
                            $this->writeAdminMessage("RESUME_CRAWL");
                        } else {
                            L\crawlLog("Scheduler Resuming crawl");
                        }
                    } else if (!$is_scheduler) {
                        $msg = "Restart failed!!!  ";
                        if (!isset($info[self::CRAWL_TIME])) {
                            $msg .=
                                "crawl time of crawl to restart not given\n";
                        }
                        if (!file_exists(C\CACHE_DIR . "/" .
                            self::queue_base_name . $info[self::CRAWL_TIME])) {
                            $msg .= "bundle for crawl restart doesn't exist\n";
                        }
                        $info["MESSAGE"] = $msg;
                        $this->writeAdminMessage($msg);
                        L\crawlLog($msg);
                        $info[self::STATUS] = self::WAITING_START_MESSAGE_STATE;
                    }
                break;
            }
        } else {
            L\crawlLog("... No message file found.");
        }
        return $info;
    }
    /**
     * Used to stop the currently running crawl gracefully so that it can
     * be restarted. This involved writing the queue's contents back to
     * schedules, making the crawl's dictionary all the same tier and running
     * any indexing_plugins.
     */
    public function stopCrawl()
    {
        if ($this->isAScheduler()) {
            $this->crawl_queue = null;
        }
        if ($this->isAIndexer()) {
            $this->shutdownDictionary();
            //Calling post processing function if the processor is
            //selected in the crawl options page.
            $this->runPostProcessingPlugins();
            $this->index_archive = null;
        }
        $close_file = C\SCHEDULES_DIR . "/" . self::index_closed_name .
            $this->crawl_time . ".txt";
        if (!file_exists($close_file) &&
            strcmp($this->server_type, self::BOTH) != 0) {
            file_put_contents($close_file, "2");
            $start_time = microtime(true);
            do {
                if ($this->isAIndexer()) {
                    L\crawlLog("Indexer waiting for Scheduler to stop.");
                } else {
                    L\crawlLog("Scheduler waiting for Indexer to stop.");
                }
                sleep(C\QUEUE_SLEEP_TIME);
                $contents = trim(file_get_contents($close_file));
            } while(file_exists($close_file) && strcmp($contents, "1") != 0 );
        } else {
            file_put_contents($close_file, "1");
        }
    }
    /**
     * Used to write an admin crawl status message during a start or stop
     * crawl.
     *
     * @param string $message to write into crawl_status.txt this will show
     *     up in the web crawl status element.
     */
    public function writeAdminMessage($message)
    {
        $crawl_status = [];
        $crawl_status['MOST_RECENT_FETCHER'] = "";
        $crawl_status['MOST_RECENT_URLS_SEEN'] = [];
        $crawl_status['CRAWL_TIME'] = $this->crawl_time;
        $crawl_status['REPEAT_TYPE'] = $this->repeat_type ?? -1;
        $crawl_status['SLEEP_START'] = $this->sleep_start ?? "00:00";
        $crawl_status['SLEEP_DURATION'] = $this->sleep_duration ?? "-1";
        //value might be 0 so don't use empty use !isset
        $crawl_status['MAX_DEPTH'] = $this->max_depth ?? -1;
        $crawl_status['ROBOTS_TXT'] = $this->robots_txt ??
            C\ALWAYS_FOLLOW_ROBOTS;
        $crawl_status['COUNT'] = 0;
        $crawl_status['ACTIVE_COUNT'] = 0;
        $crawl_status['DESCRIPTION'] = $message;
        file_put_contents($this->crawl_status_file_name,
            serialize($crawl_status));
        chmod($this->crawl_status_file_name, 0777);
    }
    /**
     * During crawl shutdown, this function is called to do a final save and
     * merge of the crawl dictionary, so that it is ready to serve queries.
     */
    public function shutdownDictionary()
    {
        $this->writeAdminMessage("SHUTDOWN_DICTIONARY");
        $is_double_index = L\generalIsA($this->index_archive,
            C\NS_LIB . "storage_formats\\DoubleIndexBundle");
        if (is_object($this->index_archive)) {
            $this->index_archive->stopIndexing();
        }
        $base_name = ($is_double_index) ? self::double_index_base_name :
            self::index_data_base_name;
        $this->db->setWorldPermissionsRecursive(C\CACHE_DIR . "/" .
            $base_name . $this->crawl_time);
    }
    /**
     * During crawl shutdown this is called to run any post processing plugins
     */
    public function runPostProcessingPlugins()
    {
        if (isset($this->indexing_plugins)) {
            L\crawlLog("Post Processing....");
            $this->writeAdminMessage("SHUTDOWN_RUNPLUGINS");
            L\crawlLog("... Wrote Run Plugin shutdown Message");
            $num_plugins = count($this->indexing_plugins);
            if ($num_plugins > 0) {
                L\crawlLog("... Will now shutdown $num_plugins plugins.");
            }
            foreach ($this->indexing_plugins as $plugin) {
                if (empty($plugin)) {
                    continue;
                }
                $plugin_instance_name =
                    lcfirst($plugin)."Plugin";
                $plugin_name = C\NS_PLUGINS . $plugin . "Plugin";
                $plugin_instance = new $plugin_name();
                if (method_exists($plugin_name, "setConfiguration") &&
                    isset($this->indexing_plugins_data[$plugin])) {
                    $plugin_instance->setConfiguration(
                        $this->indexing_plugins_data[$plugin]);
                }
                if ($plugin_instance) {
                    L\crawlLog(
                        "... executing $plugin_instance_name");
                    $plugin_instance->postProcessing($this->crawl_time);
                }
            }
        }
    }
    /**
     * Builds inverted index and saves active partition
     */
    public function indexSave()
    {
        $this->last_index_save_time = time();
        if (isset($this->index_archive) && $this->index_dirty) {
            $this->index_archive->forceSave();
            $is_double = L\generalIsA($this->index_archive,
                C\NS_LIB . "storage_formats\\DoubleIndexBundle");
            $base_name = ($is_double) ? self::double_index_base_name :
                self::index_data_base_name;
            $this->index_dirty = false;
            // chmod so apache can also write to these directories
            $this->db->setWorldPermissionsRecursive(
                C\CACHE_DIR . "/" . $base_name . $this->crawl_time);
        }
    }
    /**
     * Begins crawling base on time, order, restricted site $info
     * Setting up a crawl involves creating a queue bundle and an
     * index archive bundle
     *
     * @param array $info parameter for the crawl
     */
    public function startCrawl($info)
    {
        //to get here we at least have to have a crawl_time
        $this->crawl_time = $info[self::CRAWL_TIME];
        $try_to_set_from_old_index = [];
        $update_disallow = false;
        foreach (self::$info_parameter_map as $index_field => $info_field) {
            if (isset($info[$info_field])) {
                if ($index_field == "disallowed_sites") {
                    $update_disallow = true;
                }
                $this->$index_field = $info[$info_field];
            } else {
                array_push($try_to_set_from_old_index,  $index_field);
            }
        }
        /* We now do further processing or disallowed sites to see if any
           of them are really quota sites. We want both indexer and scheduler
           to be aware of the changes as the indexer is responsible for
           storing the values persistently into the IndexDocumentBundle
           in case we need to resume a crawl.
         */
        if ($update_disallow == true) {
            $this->updateDisallowedQuotaSites();
        }
        $this->initializeCrawlQueue();
        $this->initializeIndexBundle($info, $try_to_set_from_old_index);
        $messages_folder = C\SCHEDULES_DIR . "/" .
            self::messages_data_base_name .  $this->crawl_time;
        $this->messages_bundle = new MessagesBundle($messages_folder);
        $this->messages_bundle->initWindows(
            ($info[self::STATUS] == 'RESUME_CRAWL'));
    }
    /**
     * Function used to set up an indexer's IndexDocumentBundle or
     * DoubleIndexBundle according to the current crawl parameters or
     * the values stored in an existing bundle.
     *
     * @param array $info if initializing a new crawl this should contain
     *      the crawl parameters
     * @param array $try_to_set_from_old_index parameters of the crawl
     *      to try to set from values already stored in archive info,
     *      other parameters are assumed to have been updated since.
     */
    public function initializeIndexBundle($info = [],
        $try_to_set_from_old_index = null)
    {
        if ($try_to_set_from_old_index === null) {
            $try_to_set_from_old_index = array_keys(self::$info_parameter_map);
        }
        if(empty($this->repeat_type) || $this->repeat_type <= 0) {
            $class_name = C\NS_LIB . "storage_formats\\IndexDocumentBundle";
            $dir = C\CACHE_DIR . "/" . self::index_data_base_name .
                $this->crawl_time;
        } else {
            $class_name = C\NS_LIB . "storage_formats\\DoubleIndexBundle";
            $dir = C\CACHE_DIR . "/" . self::double_index_base_name .
                $this->crawl_time;
        }
        $this->last_next_partition_to_add = -1;
        $this->start_dictionary_time = -1;
        $archive_exists = false;
        if (file_exists($dir)) {
            $archive_info = $class_name::getArchiveInfo($dir);
            $index_info = unserialize($archive_info['DESCRIPTION']);
            foreach ($try_to_set_from_old_index as $index_field) {
                if (isset($index_info[self::$info_parameter_map[$index_field]])
                    ) {
                    $this->$index_field =
                        $index_info[self::$info_parameter_map[$index_field]];
                }
            }
            $archive_exists = true;
        }
        if ($this->isAIndexer()) {
            if ($archive_exists) {
                $this->index_archive = new $class_name($dir, false, null,
                    C\NUM_DOCS_PER_PARTITION);
                $recent_urls = [];
                /* write crawl status immediately on restart so can see counts
                   without having to wait till first indexed data handled
                 */
                $this->writeCrawlStatus($recent_urls);
            } else if (!empty($this->repeat_type) && $this->repeat_type > 0) {
                $this->index_archive = new $class_name($dir, false,
                    serialize($info), C\NUM_DOCS_PER_PARTITION,
                    $this->repeat_type);
            } else {
                $this->index_archive = new $class_name($dir, false,
                    serialize($info), C\NUM_DOCS_PER_PARTITION);
            }
            if (file_exists(C\SCHEDULES_DIR . "/" .
                self::index_closed_name . $this->crawl_time. " .txt")) {
                unlink(C\SCHEDULES_DIR . "/" . self::index_closed_name.
                    $this->crawl_time . ".txt");
            }
            $this->db->setWorldPermissionsRecursive($dir);
        }
        //this ensures as soon as get data will save index
        $this->last_index_save_time = 0;
        //Get modified time of initial setting of crawl params
        $this->archive_modified_time =
            $class_name::getParamModifiedTime($dir);
    }
    /**
     * This is called whenever the crawl options are modified to parse
     * from the disallowed sites, those sites of the format:
     * site#quota
     * where quota is the number of urls allowed to be downloaded in an hour
     * from the site. These sites are then deleted from disallowed_sites
     * and added to $this->quota sites. An entry in $this->quota_sites
     * has the format: $quota_site => [$quota, $num_urls_downloaded_this_hr]
     */
    public function updateDisallowedQuotaSites()
    {
        $num_sites = count($this->disallowed_sites);
        $active_quota_sites = [];
        for ($i = 0; $i < $num_sites; $i++) {
            $site_parts = explode("#", $this->disallowed_sites[$i]);
            if (count($site_parts) > 1) {
                $quota = intval(array_pop($site_parts));
                if ($quota <= 0) {
                    continue;
                }
                $this->disallowed_sites[$i] = false;
                $quota_site = implode("#", $site_parts);
                $active_quota_sites[] = $quota_site;
                if (isset($this->quota_sites[$quota_site])) {
                    $this->quota_sites[$quota_site] = [$quota,
                        $this->quota_sites[$quota_site][1]];
                } else {
                    //($quota, $num_scheduled_this_last_hour)
                    $this->quota_sites[$quota_site] = [$quota, 0];
                }
            }
        }
        foreach ($this->quota_sites as $site => $info) {
            if (!in_array($site, $active_quota_sites)) {
                $this->quota_sites[$site] = false;
            }
        }
        $this->disallowed_sites = array_filter($this->disallowed_sites);
        $this->quota_sites = array_filter($this->quota_sites);
        $this->quota_sites_keys = array_keys($this->quota_sites);
    }
    /**
     * This method sets up a CrawlQueueBundle according to the current crawl
     * order so that it can receive urls and prioritize them.
     */
    public function initializeCrawlQueue()
    {
        if ($this->isAScheduler()) {
            if ($this->crawl_type == self::WEB_CRAWL ||
                !isset($this->crawl_type)) {
                $this->crawl_queue = new CrawlQueueBundle(
                    C\CACHE_DIR . "/" . self::queue_base_name.
                    $this->crawl_time, C\URL_FILTER_SIZE,
                        C\NUM_URLS_QUEUE_RAM);
            } else {
                $this->crawl_queue = null;
            }
            // chmod so web server can also write to these directories
            if ($this->crawl_type == self::WEB_CRAWL) {
                $this->db->setWorldPermissionsRecursive(
                   C\CACHE_DIR . "/" . self::queue_base_name .
                   $this->crawl_time);
            }
        } else {
            $this->index_archive = null;
        }
        L\garbageCollect(); // garbage collect old crawls
    }
    /**
     * Checks to see if the parameters by which the active crawl are being
     * conducted have been modified since the last time the values were put
     * into queue server field variables. If so, it updates the values to
     * to their new values
     */
    public function checkUpdateCrawlParameters()
    {
        L\crawlLog("Check for update in crawl parameters...");
        $index_archive_class = C\NS_LIB . (($this->repeat_type > 0 ) ?
            "DoubleIndexBundle" : "IndexDocumentBundle");
        $base_name = ($this->repeat_type > 0 ) ? self::double_index_base_name :
            self::index_data_base_name;
        $dir = C\CACHE_DIR . "/" . $base_name . $this->crawl_time;
        $modified_time = $index_archive_class::getParamModifiedTime($dir);
        if ($this->archive_modified_time == $modified_time) {
            L\crawlLog("...none.");
            return;
        }
        $updatable_info = self::$info_parameter_map;
        unset($updatable_info["crawl_order"], $updatable_info["crawl_type"],
            $updatable_info["crawl_index"], $updatable_info["crawl_pages"]);
        $keys = array_keys($updatable_info);
        $archive_info = $index_archive_class::getArchiveInfo($dir);
        $index_info = unserialize($archive_info['DESCRIPTION']);
        $check_cull_fields = ["restrict_sites_by_url", "allowed_sites",
            "disallowed_sites"];
        $cull_now_non_crawlable = false;
        $update_disallow = false;
        foreach ($keys as $index_field) {
            if (isset($index_info[$updatable_info[$index_field]]) ) {
                if ($index_field == "disallowed_sites") {
                    $update_disallow = true;
                }
                if (in_array($index_field, $check_cull_fields) &&
                    (!isset($this->$index_field) ||
                    $this->$index_field !=
                    $index_info[$updatable_info[$index_field]]) ) {
                    $cull_now_non_crawlable = true;
                }
                $this->$index_field =
                    $index_info[$updatable_info[$index_field]];
                if ($this->isOnlyScheduler()) {
                    L\crawlLog("Scheduler Updating ...$index_field.");
                } else {
                    L\crawlLog("Updating ...$index_field.");
                }
            }
        }
        /* We now do further processing or disallowed sites to see if any
           of them are really quota sites. We want both indexer and scheduler
           to be aware of the changes as the indexer is responsible for
           storing the values persistently into the IndexDocumentBundle
           in case we need to resume a crawl.
         */
        if ($update_disallow == true) {
            $this->updateDisallowedQuotaSites();
        }
        $this->archive_modified_time = $modified_time;
    }
    /**
     * Delete all the queue bundles and schedules that don't have an
     * associated index bundle as this means that crawl has been deleted.
     */
    public function deleteOrphanedBundles()
    {
        $dirs = glob(C\CACHE_DIR . '/*', GLOB_ONLYDIR);
        $num_dirs = count($dirs);
        $living_stamps = [];
        $dir_cnt = 0;
        foreach ($dirs as $dir) {
            $dir_cnt++;
            L\crawlTimeoutLog("..Indexer looking through directory %s of %s".
                " to see if orphaned", $dir_cnt, $num_dirs);
            if (strlen(
                $pre_timestamp = strstr($dir, self::queue_base_name)) > 0) {
                $timestamp =
                    substr($pre_timestamp, strlen(self::queue_base_name));
                if (!file_exists(C\CACHE_DIR . "/" .
                    self::index_data_base_name . $timestamp) &&
                    !file_exists(C\CACHE_DIR . "/" .
                        self::double_index_base_name . $timestamp)) {
                    $this->db->unlinkRecursive($dir, true);
                }
            }
            $is_double = true;
            $pre_timestamp = strstr($dir, self::double_index_base_name);
            $name_len = strlen( self::double_index_base_name);
            if (empty($pre_timestamp)) {
                $pre_timestamp = strstr($dir, self::index_data_base_name);
                $name_len = strlen(self::index_data_base_name);
                $is_double = false;
            }
            if (strlen($pre_timestamp) > 0) {
                $timestamp = substr($pre_timestamp, $name_len);
                $close_file = C\SCHEDULES_DIR . "/" .
                    self::index_closed_name . $timestamp . ".txt";
                $close_exists = file_exists($close_file);
                $state = "1";
                if (!$is_double && $close_exists) {
                    $state = trim(file_get_contents($close_file));
                }
                if (!$is_double &&
                    (!$close_exists || strcmp($state, "1") != 0) &&
                    $this->crawl_time != $timestamp) {
                    L\crawlLog("Properly closing Index with Timestamp " .
                        $timestamp . ".");
                    $index_archive = new IndexDocumentBundle($dir, false, null,
                        C\NUM_DOCS_PER_PARTITION);
                    touch($this->crawl_status_file_name, time());
                    file_put_contents($close_file, "1");
                }
                $living_stamps[] = $timestamp;
            }
        }
        $files = glob(C\SCHEDULES_DIR . '/*');
        $file_cnt = 0;
        $crawl_prefixes = [self::double_index_base_name,
            self::fetch_archive_iterator,
            self::index_closed_name, self::index_data_base_name,
            self::messages_data_base_name, self::name_archive_iterator,
            self::save_point, self::schedule_name,
            ];
        $prefix_pattern = "/(".implode("|", $crawl_prefixes) .")(\d{10})/";
        foreach ($files as $file) {
            $file_cnt++;
            L\crawlTimeoutLog("..Indexer still deleting %s of %s orphaned " .
                "files", $file_cnt, $file_cnt);
            if (preg_match($prefix_pattern, $file, $matches)) {
                if (!empty($matches[2]) &&
                    !in_array($matches[2], $living_stamps)) {
                    if (is_dir($file)) {
                        $this->db->unlinkRecursive($file, true);
                    } else {
                        unlink($file);
                    }
                }
            }
        }
    }
    /**
     * Determines the most recent fetcher that has spoken with the
     * web server of this queue server and stored the result in the
     * field variable most_recent_fetcher
     */
    public function updateMostRecentFetcher()
    {
        $robot_table_name = C\WORK_DIRECTORY . "/" . $this->channel . "-" .
            self::robot_table_name;
        L\crawlLog("Updating most recent fetcher...");
        if (file_exists($robot_table_name)) {
            $robot_table = unserialize(file_get_contents($robot_table_name));
            if (!is_array($robot_table)) {
                L\crawlLog("... couldn't unserialize robot table correctly.");
                return;
            }
            $recent = 0 ;
            foreach ($robot_table as $robot_name => $robot_data) {
                if ($robot_data[2] > $recent) {
                    $this->most_recent_fetcher =  $robot_name;
                    $recent = $robot_data[2];
                }
            }
            L\crawlLog("... Most recent fetcher was: " .
                $this->most_recent_fetcher);
        } else {
            L\crawlLog("... couldn't find robot table.");
        }
    }
    /**
     * Sets up the directory to look for a file of unprocessed
     * index archive data from fetchers then calls the function
     * processDataFile to process the oldest file found
     */
    public function processIndexData()
    {
        L\crawlLog("Indexer: Checking for index data files to process...");
        $index_dir = C\SCHEDULES_DIR . "/" .
            self::index_data_base_name . $this->crawl_time;
        if (is_object($this->messages_bundle)) {
            $pre_sites_and_index = $this->messages_bundle->nextMessages(
                MessagesBundle::INDEX_DATA_FOLDER, false);
            if (empty($pre_sites_and_index)) {
                L\crawlLog("Indexer: ...no index data found.");
            } else {
                $this->processIndexArchive($pre_sites_and_index);
            }
        }
        L\crawlLog("Indexer: done index data check and process.");
    }
    /**
     * Adds the summary and index data in $file to summary bundle and word index
     *
     * @param string $pre_sites_and_index containing web pages summaries
     */
    public function processIndexArchive(&$pre_sites_and_index)
    {
        L\crawlLog(
            "{$this->server_name} is starting to process index data,".
            " memory usage: " . memory_get_usage() . "...");
        L\crawlLog("Indexer: Processing index data...");
        $start_time = microtime(true);
        $start_total_time = microtime(true);
        $len_urls = L\unpackInt(substr($pre_sites_and_index, 0, 4));
        $seen_urls_string = substr($pre_sites_and_index, 4, $len_urls);
        $seen_sites = [];
        $pos = 0;
        $num = 0;
        $bad = false;
        /* number of urls including batch url and links at that url that
         * could be found by crawling a batch
         */
        $max_batch_sites_and_links = C\MAX_FETCH_SIZE *
            (max(C\MAX_LINKS_TO_EXTRACT, $this->max_links_to_extract) + 1);
        while($pos < $len_urls && $num <= $max_batch_sites_and_links) {
            L\crawlTimeoutLog("..Indexer still processing index data at " .
                "position %s of out of %s", $pos, $len_urls);
            $len_site = L\unpackInt(substr($seen_urls_string, $pos, 4));
            if ($len_site > 2 * $this->page_range_request) {
                L\crawlLog("Indexer: Site string too long, $len_site,".
                    " data file may be corrupted? Skip rest.");
                $bad = true;
                break;
            }
            $pos += 4;
            $site_string = substr($seen_urls_string, $pos, $len_site);
            $pos += strlen($site_string);
            $tmp = unserialize(gzuncompress($site_string));
            if (!$tmp  || !is_array($tmp)) {
                L\crawlLog("Compressed array null,".
                    " data file may be corrupted? Skip rest.");
                $bad = true;
                break;
            }
            $doc_id = $this->index_archive->computeDocId($tmp);
            if ($doc_id) {
                $page = $tmp[self::PAGE] ?? "";
                unset($tmp[self::PAGE]);
                $seen_sites[] = [self::DOC_ID => $doc_id, self::SUMMARY =>
                    $tmp, self::PAGE => $page];
                $num++;
            }
        }
        if ($num > $max_batch_sites_and_links || $bad) {
            L\crawlLog("Index data file len_urls was $len_urls, num was $num, ".
                "may be corrupt so skipping this file.");
            L\crawlLog("Indexer Done Index Processing File. " .
                "Total time: " . L\changeInMicrotime($start_total_time));
            return;
        }
        L\crawlLog("A. Indexer unpack index data. Memory usage:" .
             memory_get_usage() . " init local shard time: " .
            L\changeInMicrotime($start_time));
        $start_time = microtime(true);
        $num_seen = count($seen_sites);
        L\crawlLog("Indexer: SEEN_URLS array had $num_seen sites ".
                "(including links).");
        // compute counts and recent urls array
        $visited_urls_count = 0;
        $recent_urls_count = 0;
        $recent_urls = [];
        for ($i = 0; $i < $num_seen; $i++) {
            if ($seen_sites[$i][self::SUMMARY][self::TYPE] != "link") {
                $seen_sites[$i][self::SUMMARY][self::HASH_URL] =
                    L\crawlHash($seen_sites[$i][self::SUMMARY][self::URL],
                    true);
                $seen_sites[$i][self::SUMMARY][self::IS_DOC] = true;
                $visited_urls_count++;
                array_push($recent_urls,
                    explode("###",
                    $seen_sites[$i][self::SUMMARY][self::URL])[0]);
                if ($recent_urls_count >= C\NUM_RECENT_URLS_TO_DISPLAY) {
                    array_shift($recent_urls);
                }
                $recent_urls_count++;
            }
        }
        if (!empty($seen_sites)) {
            if ($this->index_archive->addPages($seen_sites,
                $visited_urls_count)) {
                $this->index_dirty = true;
                L\crawlLog("..Store web pages succeeded.");
            } else {
                L\crawlLog("..STORE ERROR!!!!");
                L\crawlLog("..Store web pages failed.");
            }
            unset($seen_sites);
        }
        L\crawlLog("B. Store web pages memory usage: ". memory_get_usage() .
            " time: " . L\changeInMicrotime($start_time));
        if (!empty($recent_urls)) {
            $this->writeCrawlStatus($recent_urls);
        }
        L\crawlLog("Indexer Done Index Processing File. Total time: ".
            L\changeInMicrotime($start_total_time));
        L\crawlLog("Indexer checking whether to advance archive partition: ".
            L\changeInMicrotime($start_total_time));
        $base_name = ($this->repeat_type > 0 ) ?
            self::double_index_base_name : self::index_data_base_name;
        $bundle_name = C\CACHE_DIR . "/" . $base_name . $this->crawl_time;
        $next_partition_file = $this->index_archive->dir_name . "/" .
            IndexDocumentBundle::NEXT_PARTITION_FILE;
        $next_partition_to_add = (file_exists($next_partition_file)) ?
            intval(file_get_contents($next_partition_file)) : 0;
        $next_partition_file_advanced = $next_partition_file . "-advanced";
        if (file_exists($next_partition_file_advanced)) {
            $this->start_dictionary_time = time();
            unlink($next_partition_file_advanced);
        }
        $documents = $this->index_archive->documents;
        $save_partition = $documents->parameters["SAVE_PARTITION"] ?? 0;
        if ($save_partition == 0) { //double check
            $documents = $this->index_archive->documents;
            // this will read and if 0 recompute using a glob
            $documents_parameters =
                $this->index_archive->documents->getParameterInfo(
                    $documents->folder);
            $save_partition = $documents_parameters['SAVE_PARTITION'] ?? 0;
        }
        L\crawlLog("Indexer Advance check details: Last:" .
            $this->last_next_partition_to_add . " Next:" .
            $next_partition_to_add . " Save:" . $save_partition);
        /* first condition below is to ensure not to call if still processing
           previous partition
         */
        $dictionary_name = L\CrawlDaemon::getNameString("DictionaryUpdater",
            $this->channel);
        $dictionary_log = C\LOG_DIR . "/$dictionary_name.log";
        clearstatcache(); // so don't cache filemtimes
        $time = time();
        if ($this->last_next_partition_to_add < $next_partition_to_add &&
            $next_partition_to_add < $save_partition) {
            $this->last_next_partition_to_add = $next_partition_to_add;
            $this->start_dictionary_time = $time;
            $options = "run {$this->channel} '$bundle_name'";
            L\crawlLog("Indexer Exec'ing DictionaryUpdater with parameters: " .
                $options);
            CrawlDaemon::execScriptInOwnProcess(C\BASE_DIR .
                "/executables/DictionaryUpdater.php", $options);
        } else if ($this->last_next_partition_to_add ==
            $next_partition_to_add && $next_partition_to_add < $save_partition
            && $time > filemtime($next_partition_file) + 5 * C\LOG_TIMEOUT
            && $this->start_dictionary_time > 0 &&
            $time > $this->start_dictionary_time +  5 * C\LOG_TIMEOUT
            && $time > filemtime($dictionary_log) + 5 * C\LOG_TIMEOUT) {
            L\crawlLog("DictionaryUpdater seems to have crashed, exiting ".
                "Indexer");
            exit();
        }
        L\garbageCollect();
    }
    /**
     * Checks how old the oldest robot data is and dumps if older then a
     * threshold, then sets up the path to the robot schedule directory
     * and tries to process a file of robots.txt robot paths data from there
     */
    public function processRobotUrls()
    {
        if (!isset($this->crawl_queue) ) {
            return;
        }
        L\crawlLog("Scheduler Checking age of DNS data in queue server ");
        if ($this->crawl_queue->getDnsAge() > C\CACHE_DNS_TIME) {
            L\crawlLog("Scheduler: Deleting DNS Cache data..");
            $message = $this->crawl_queue->emptyDNSCache();
            L\crawlLog("Scheduler: Delete task responded:\n $message");
        } else {
            L\crawlLog("Scheduler: ... less than max age\n");
        }
        L\crawlLog("Scheduler: Checking for robots.txt files to process...");
        if (is_object($this->messages_bundle)) {
            $sites = $this->messages_bundle->nextMessages(
                MessagesBundle::ROBOTS_FOLDER);
            if (empty($sites)) {
                L\crawlLog("Scheduler: ...no robots.txt data found. ");
            } else {
                $this->processRobotArchive($sites);
            }
        }
        L\crawlLog("Scheduler done robot check and process. ");
    }
    /**
     * Reads in $sites of robot data host and associated robots.txt
     * allowed/disallowed paths, crawl delay info, and dns info.
     * Adds this to the robot_table entry for this host. Adds dns info
     * to the RAM-based dns cache hash table.
     * @param array Y$sites robot data to process
     */
    public function processRobotArchive(&$sites)
    {
        L\crawlLog("Scheduler Processing Robots data");
        $start_time = microtime(true);
        $this->crawl_queue->robot_notify_hosts = [];
        L\crawlLog("Scheduler done decompressing robot file");
        if (!empty($sites)) {
            $num_sites = count($sites);
            $i = 0;
            $time = time();
            $robot_rows = [];
            foreach ($sites as $robot_host => $robot_info) {
                L\crawlTimeoutLog(
                    "..Scheduler reformatting robot item %s of %s.",
                    $i, $num_sites);
                $i++;
                $crawl_delay = $robot_info[self::CRAWL_DELAY] ?? 0;
                $row = ["HOSTNAME" => $robot_host,
                    "CAPTURE_TIME" => $time, "CRAWL_DELAY" => $crawl_delay,
                    "ROBOT_PATHS" => $robot_info[self::ROBOT_PATHS] ?? []];
                $robot_rows[] = $row;
                if (isset($robot_info[self::IP_ADDRESSES])) {
                    $final_ip = array_pop($robot_info[self::IP_ADDRESSES]);
                    $this->crawl_queue->addDNSCache($robot_host, $final_ip);
                }
            }
            $this->crawl_queue->robot_table->put($robot_rows);
            $this->crawl_queue->robot_notify_hosts = array_keys($sites);
        }
        L\crawlLog("Scheduler Robot time: ".
            L\changeInMicrotime($start_time)."\n");
    }
    /**
     * Process cache page validation data files sent by Fetcher
     */
    public function processEtagExpires()
    {
        L\crawlLog("Scheduler Checking for etag expires http header data");
        if (is_object($this->messages_bundle)) {
            $etag_expires_data = $this->messages_bundle->nextMessages(
                MessagesBundle::ETAG_EXPIRES_FOLDER);
            if (empty($etag_expires_data)) {
                L\crawlLog("Scheduler: ...no etag expires data found.");
            } else {
                $this->processEtagExpiresArchive($etag_expires_data);
            }
        }
        L\crawlLog("Scheduler done etag check and process.");
    }
    /**
     * Processes a cache page validation data. Extracts key-value pairs
     * from data and inserts into the LinearHashTable used for storing cache
     * page validation data.
     * @param array &$etag_expires_data is the cache page validation data from
     *      the Fetchers.
     */
    public function processEtagExpiresArchive(&$etag_expires_data)
    {
        $start_time = microtime(true);
        L\crawlLog("Scheduler done uncompressing etag data.".
            " Starting to add to linear hash table");
        if (!is_array($etag_expires_data)) {
            L\crawlLog("Invalid format ETag Expires Data. Data was:\n" .
                var_export($etag_expires_data));
            return;
        }
        $num_entries = count($etag_expires_data);
        $i = 0;
        foreach ($etag_expires_data as $data) {
            L\crawlTimeoutLog(
                "..Scheduler still etag processing on item %s of %s.",
                $i, $num_entries);
            $i++;
            if (is_array($data)) {
                list($link, $entry) = $data;
                if (is_array($entry)) {
                    $entry['URL'] = $link;
                    $this->crawl_queue->etag_table->put($entry);
                } else {
                    L\crawlLog(
                        "ETag Expires Entry Format Problem. Entry was:\n" .
                        var_export($entry));
                }
            } else {
                L\crawlLog("ETag Expires Data Format Problem. Data was:\n" .
                    var_export($data));
            }
        }
        L\crawlLog("Etag Expires Processing time: " .
            L\changeInMicrotime($start_time)."\n");
    }
    /**
     * Checks for a new crawl file or a schedule data for the current crawl and
     * if such a exists then processes its contents adding the relevant urls to
     * the priority queue
     */
    public function processToCrawlUrls()
    {
        L\crawlLog("Scheduler Start checking for new URLs data memory usage: ".
            memory_get_usage());
        $start_schedule_filename = C\SCHEDULES_DIR . "/" .
            $this->channel . "-" . self::schedule_start_name;
        $sites = [];
        if (file_exists($start_schedule_filename)) {
            if ($this->repeat_type > 0) {
                $dir_name = C\CACHE_DIR . "/" .
                    self::double_index_base_name . $this->crawl_time;
                DoubleIndexBundle::setStartSchedule($dir_name, $this->channel);
            }
            L\crawlLog("Scheduler Start schedule urls from " .
                $start_schedule_filename);
            if (is_object($this->messages_bundle)) {
                $sites = $this->messages_bundle->unpackMessages(
                    $start_schedule_filename);
                L\crawlLog("Start schedule received for this ".
                    "QueueServer was:\n");
                $site_ctr = 0;
                foreach ($sites[self::TO_CRAWL] as $site) {
                    $site_ctr++;
                    L\crawlLog("...$site_ctr {$site[0]}");
                }
                unlink($start_schedule_filename);
            }
        } else if (is_object($this->messages_bundle)) {
            $sites = $this->messages_bundle->nextMessages(
                MessagesBundle::SCHEDULES_FOLDER);
        }
        if (empty($sites)) {
            L\crawlLog("Scheduler: ...no new URLS data found.");
        } else {
            $this->processToCrawlArchive($sites);
        }
        L\crawlLog("done.");
    }
    /**
     * Process to-crawl urls adding to or adjusting the weight in
     * the PriorityQueue of those which have not been seen. Also
     * updates the queue with seen url info
     *
     * @param array &$sites containing to crawl and seen url info
     */
    public function processToCrawlArchive(&$sites)
    {
        if (isset($sites[self::TO_CRAWL]) &&
            count($sites[self::TO_CRAWL]) > C\MAX_FETCH_SIZE) {
            L\crawlLog("...New URLS file has too many to-crawl sites ...");
            L\crawlLog("...Splitting first into smaller files ".
                "before processing...");
            $left_over = array_slice($sites[self::TO_CRAWL], C\MAX_FETCH_SIZE);
            $sites[self::TO_CRAWL] = array_slice($sites[self::TO_CRAWL], 0,
                C\MAX_FETCH_SIZE);
            $schedule_time = $sites[self::SCHEDULE_TIME] ??
                floor(($this->crawl_time + time())/2);
                //the average will probably be the most recent schedule
            $this->dumpBigScheduleToSmall($schedule_time, $left_over);
            unset($left_over);
        }
        if (isset($sites[self::SCHEDULE_TIME])) {
            $start_time = microtime(true);
            L\crawlLog("...Scheduler Notify Hosts Delayed By Schedule ".
                $sites[self::SCHEDULE_TIME] . "...");
            $this->crawl_queue->notifyDelayedHosts(
                $sites[self::SCHEDULE_TIME]);
            L\crawlLog(" time: ". L\changeInMicrotime($start_time));
        }
        L\crawlLog("... Scheduler Queueing To Crawl ...");
        $start_time = microtime(true);
        if (isset($sites[self::TO_CRAWL])) {
            L\crawlLog("A.. Scheduler: Queue delete previously  ".
                "seen urls from add set");
            $to_crawl_sites = $sites[self::TO_CRAWL];
            /* delete seen urls from admin_controller_crawl_setting
             * sites (using 0 component). We use th e2 component of
             * of a $sites[self::TO_CRAWL] 4-tuple as well.
             * This has site_hash + which link it was for site
             * url came from. To avoid multiple sites with the same
             *    hash adding a url...
             */
            $this->crawl_queue->url_exists_filter_bundle->
                differenceFilter($to_crawl_sites, [0]);
            L\crawlLog(" time: " . L\changeInMicrotime($start_time));
            L\crawlLog("B.. Scheduler: Queue insert unseen robots.txt urls.");
            $start_time = microtime(true);
            $cnt = 0;
            $num_tuples = count($to_crawl_sites);
            $added_urls = [];
            $contains_host = [];
            /* if we allow web page recrawls then check here to see if delete
               url filter*/
            if ($this->page_recrawl_frequency > 0 &&
                $this->crawl_queue->getUrlFilterAge() >
                C\ONE_DAY * $this->page_recrawl_frequency) {
                L\crawlLog("Scheduler: Emptying queue page url filter!!!!!!");
                $this->crawl_queue->emptyUrlFilter();
            }
            $this->allow_disallow_cache_time = microtime(true);
            $add_schedule_queue = [];
            $add_wait_robot_queue = [];
            $seen_robot_time = [];
            $http_scheme_len = strlen("http://");
            foreach ($to_crawl_sites as $tuple) {
                list($url, $weight, $depth, $referer, $old_weight) = $tuple;
                $cnt++;
                L\crawlTimeoutLog("..Scheduler: Processing url %s of %s ",
                    $cnt, $num_tuples);
                if (strlen($url) < $http_scheme_len) {
                    continue;
                }
                if ($url[0] != 'h' && trim($url) == "localhost") {
                    $url = "http://localhost/";
                }
                $hard_coded = (strpos($url, "###!") > 0 );
                $host_url = UrlParser::getHost($url);
                $hash_host = L\crawlHash($host_url);
                if (strlen($host_url) < $http_scheme_len) {
                    continue;
                }
                $this->crawl_queue->url_exists_filter_bundle->add($url);
                if (!$hard_coded) {
                    //sitemaps will have #sitemap add to the url, so strip
                    $check_url = explode("#", $url)[0];
                    if (!$this->allowedToCrawlSite($check_url) ||
                        $this->disallowedToCrawlSite($check_url) ||
                        !$this->withinQuota($check_url, 0)) {
                        continue;
                    }
                }
                $scheme = UrlParser::getScheme($host_url);
                if (empty($seen_robot_time[$hash_host])) {
                    $robot_time =
                        $this->crawl_queue->gotRobotTxtTime($host_url);
                } else {
                    $robot_time = $seen_robot_time[$hash_host];
                }
                if ((!$hard_coded && empty($robot_time))) {
                    if($robot_time === false &&
                        !isset($seen_robot_time[$hash_host])) {
                        $host_with_robots = ($scheme == "gopher") ? $host_url .
                             "/0/robots.txt" : $host_url . "/robots.txt";
                        $host_robot_urls = [$host_with_robots];
                        $this->crawl_queue->url_exists_filter_bundle->
                            differenceFilter($host_robot_urls, null);
                        if (!empty($host_robot_urls)) {
                            $add_schedule_queue[] = [$host_with_robots,
                                $weight, $depth, "", 0.0];
                            $this->crawl_queue->
                                url_exists_filter_bundle->add(
                                $host_with_robots);
                        }
                    }
                    $add_wait_robot_queue[] = [$url, $weight, $depth, $referer,
                        $old_weight];
                } else {
                    $add_schedule_queue[] = [$url, $weight, $depth, $referer,
                        $old_weight];
                }
                $seen_robot_time[$hash_host] = $robot_time;
            }
            $this->crawl_queue->addWaitRobotQueue($add_wait_robot_queue);
            $this->crawl_queue->addSendFetcherQueue($add_schedule_queue,
                $this->crawl_order);
            L\crawlLog(" time: " . L\changeInMicrotime($start_time));
        }
        L\crawlLog("Scheduler: time: " . L\changeInMicrotime($start_time));
        L\crawlLog("Scheduler: Done queue schedule file.");
    }
    /**
     * This method is used to send urls that are in the waiting hosts folder
     * for hosts listed in $this->crawl_queue->robot_notify_hosts
     * to be received to be moved to the queue because host membership in
     * $this->crawl_queue->robot_notify_hosts indicates that a robots.txt
     * file has just been received for the particular domain.
     */
    public function processReceivedRobotTxtUrls()
    {
        $this->crawl_queue->processReceivedRobotTxtUrls($this->crawl_order);
    }
    /**
     * Used to split a large schedule of to crawl sites into small
     * ones (which are written to disk) and which can be handled by
     * processToCrawlUrls
     *
     * The size of the to crawl list depends on the number of found links
     * during a fetch batch. This can be quite large compared to the fetch
     * batch and during processing, we might be doing a fair bit of manipulation
     * of arrays of sites, so the idea is this splitting like this will
     * hopefully reduce the memory burden of scheduling.
     *
     * @param int $schedule_time timestamp of schedule we are splitting
     * @param array &$sites array containing to crawl data
     */
    public function dumpBigScheduleToSmall($schedule_time, &$sites)
    {
        L\crawlLog("Writing small schedules...");
        $count = count($sites);
        $schedule_data = [];
        $schedule_data[self::TO_CRAWL] = [];
        for ($i = 0; $i < $count; $i += C\MAX_FETCH_SIZE) {
            L\crawlTimeoutLog("..have written %s urls of %s urls so far", $i,
                $count);
            $schedule_data[self::TO_CRAWL] = array_slice($sites, $i,
                C\MAX_FETCH_SIZE);
            if (count($schedule_data[self::TO_CRAWL]) > 0) {
                $schedule_data[self::SCHEDULE_TIME] = $schedule_time + $i;
                $data_string = L\webencode(
                    gzcompress(serialize($schedule_data)));
                $data_hash = L\crawlHash($data_string);
                $this->messages_bundle->addMessages(
                    MessagesBundle::SCHEDULES_FOLDER,
                    $data_string, $schedule_data[self::SCHEDULE_TIME]);
                $data_string = "";
                $schedule_data[self::TO_CRAWL] = [];
            }
        }
        $this->db->setWorldPermissionsRecursive(
            C\CACHE_DIR . "/" . self::queue_base_name . $this->crawl_time);
    }
    /**
     * Writes status information about the current crawl so that the webserver
     * app can use it for its display.
     *
     * @param array $recent_urls contains the most recently crawled sites
     */
    public function writeCrawlStatus($recent_urls)
    {
        $crawl_status = [];
        $stat_file = $this->crawl_status_file_name;
        if (file_exists($stat_file) ) {
            $crawl_status = unserialize(file_get_contents($stat_file));
            if (!isset($crawl_status['CRAWL_TIME']) ||
                $crawl_status['CRAWL_TIME'] != $this->crawl_time) {
                $crawl_status = []; // status of some other crawl
            }
        }
        $crawl_status['MOST_RECENT_FETCHER'] = $this->most_recent_fetcher;
        if (!empty($recent_urls)) {
            $crawl_status['MOST_RECENT_URLS_SEEN'] = $recent_urls;
        }
        $crawl_status['CRAWL_TIME'] = $this->crawl_time;
        $crawl_status['CHANNEL'] = $this->channel;
        $crawl_status['REPEAT_TYPE'] = (!isset($this->repeat_type)) ?
            -1 : $this->repeat_type;
        if (!empty($this->index_archive->repeat_time)) {
            $crawl_status['REPEAT_TIME'] = $this->index_archive->repeat_time;
        }
        $crawl_status['ROBOTS_TXT'] = (!isset($this->robots_txt)) ?
            C\ALWAYS_FOLLOW_ROBOTS : $this->robots_txt;
        $crawl_status['MAX_DEPTH'] = (!isset($this->max_depth)) ?
            -1 : $this->max_depth;
        $index_archive_class = C\NS_LIB . (($crawl_status['REPEAT_TYPE'] > 0 ) ?
            "DoubleIndexBundle" : "IndexDocumentBundle");
        $base_name = ($crawl_status['REPEAT_TYPE'] > 0 ) ?
            self::double_index_base_name : self::index_data_base_name;
        $info_bundle = $index_archive_class::getArchiveInfo(
            C\CACHE_DIR . "/" . $base_name . $this->crawl_time);
        $index_archive_info = unserialize($info_bundle['DESCRIPTION']);
        $crawl_status['ACTIVE_COUNT'] = $info_bundle['ACTIVE_COUNT'] ?? 0;
        $crawl_status['COUNT'] = $info_bundle['COUNT'] ?? 0;
        $now = time();
        $change_in_time = C\ONE_HOUR + 1;
        while (count($this->hourly_crawl_data) > 0 &&
            $change_in_time > C\ONE_HOUR) {
            $least_recent_hourly_pair = array_pop($this->hourly_crawl_data);
            $change_in_time =
                ($now - $least_recent_hourly_pair[0]);
        }
        if ($change_in_time <= C\ONE_HOUR) {
            $this->hourly_crawl_data[] = $least_recent_hourly_pair;
        }
        array_unshift($this->hourly_crawl_data,
            [$now, $info_bundle['VISITED_URLS_COUNT']]);
        $description = $index_archive_info['DESCRIPTION'] ?? "empty";
        $crawl_status['VISITED_COUNT_HISTORY'] = $this->hourly_crawl_data;
        $crawl_status['VISITED_URLS_COUNT'] =
            $info_bundle['VISITED_URLS_COUNT'];
        $crawl_status['DESCRIPTION'] = $description;
        $crawl_status['QUEUE_PEAK_MEMORY'] = memory_get_peak_usage();
        file_put_contents($stat_file, serialize($crawl_status), LOCK_EX);
        chmod($stat_file, 0777);
        L\crawlLog("End checking for new URLs data memory usage: " .
            memory_get_usage());
        L\crawlLog("The current crawl description is: " . $description);
        L\crawlLog("Number of unique pages so far: ".
            $info_bundle['VISITED_URLS_COUNT']);
        L\crawlLog("Total urls extracted so far: " . $info_bundle['COUNT']);
        if (!empty($recent_urls)) {
            L\crawlLog("Of these, the most recent urls are:");
            set_error_handler(null);
            foreach ($recent_urls as $url) {
                L\crawlLog("URL: " .
                @iconv("UTF-8", "ISO-8859-1//IGNORE", $url));
            }
            restore_error_handler();
        }
    }
    /**
     * Used to create encode a string representing with meta info for
     * a fetcher schedule.
     *
     * @param int $schedule_time timestamp of the schedule
     * @return string base64 encoded meta info
     */
    public function calculateScheduleMetaInfo($schedule_time)
    {
        //notice does not contain self::QUEUE_SERVERS
        $sites = [];
        $sites[self::CRAWL_TIME] = $this->crawl_time;
        $sites[self::SCHEDULE_TIME] = $schedule_time;
        $sites[self::CRAWL_ORDER] = $this->crawl_order;
        $sites[self::MAX_DEPTH] = $this->max_depth;
        $sites[self::REPEAT_TYPE] = $this->repeat_type;
        $sites[self::ROBOTS_TXT] = $this->robots_txt;
        $sites[self::CRAWL_TYPE] = $this->crawl_type;
        $sites[self::CRAWL_INDEX] = $this->crawl_index;
        $sites[self::CACHE_PAGES] = $this->cache_pages;
        $sites[self::PAGE_RULES] = $this->page_rules;
        $sites[self::RESTRICT_SITES_BY_URL] = $this->restrict_sites_by_url;
        $sites[self::INDEXED_FILE_TYPES] = $this->indexed_file_types;
        $sites[self::ALLOWED_SITES] = $this->allowed_sites;
        $sites[self::DISALLOWED_SITES] = $this->disallowed_sites;
        $sites[self::INDEXING_PLUGINS] =  $this->indexing_plugins;
        $sites[self::INDEXING_PLUGINS_DATA] =  $this->indexing_plugins_data;
        $sites[self::PAGE_RANGE_REQUEST] = $this->page_range_request;
        $sites[self::MAX_DESCRIPTION_LEN] = $this->max_description_len;
        $sites[self::MAX_LINKS_TO_EXTRACT] = $this->max_links_to_extract;
        $sites[self::POST_MAX_SIZE] = L\metricToInt(ini_get("post_max_size"));
        $sites[self::SITES] = [];
        $sites[self::SEQUENCE_NUMBER] =
            $this->messages_bundle->max_sequence_number + 1;
        return base64_encode(serialize($sites)) . "\n";
    }
    /**
     * Produces a schedule.txt file of url data for a fetcher to crawl next.
     *
     * The hard part of scheduling is to make sure that the overall crawl
     * process obeys robots.txt files. This involves checking the url is in
     * an allowed path for that host and it also involves making sure the
     * Crawl-delay directive is respected. The first fetcher that contacts the
     * server requesting data to crawl will get the schedule.txt
     * produced by produceFetchBatch() at which point it will be unlinked
     * (these latter things are controlled in FetchController).
     *
     * @see FetchController
     */
    public function produceFetchBatch()
    {
        $fetch_size = 0;
        $fetch_weight = 0;
        L\crawlLog("FB Scheduler: Start Produce Fetch Batch.");
        L\crawlLog("FB Scheduler: Crawl Time is: ". $this->crawl_time);
        L\crawlLog("FB Scheduler: Memory usage is " . memory_get_usage() );
        $schedule_time = time();
        $first_line = $this->calculateScheduleMetaInfo($schedule_time);
        $sites = [];
        $max_buffer_before_write =
            CrawlQueueBundle::MAX_URL_BUFFER_BEFORE_WRITE;
        $rescheldule_urls = [];
        $crawl_delay_hosts = [];
        $time_per_request_guess = C\MINIMUM_FETCH_LOOP_TIME;
            // it would be impressive if we can achieve this speed
        $current_crawl_index = -1;
        L\crawlLog("FB Scheduler: Trying to Produce Fetch Batch");
        $start_time = microtime(true);
        $fetch_batch_queue = $this->crawl_queue->chooseFetchBatchQueueFolder(
            $this->crawl_order);
        if (empty($fetch_batch_queue)) {
            L\crawlLog("FB Scheduler: No fetch batch queue, bailing on making".
                " a schedule!!!");
            return;
        }
        L\crawlLog("FB Scheduler: Queue tier to make schedule from: " .
            substr($fetch_batch_queue, strlen($this->crawl_queue->dir_name .
            "/" . CrawlQueueBundle::URL_QUEUE_FOLDER) + 1));
        $day_folders = $this->crawl_queue->getDayFolders($fetch_batch_queue);
        if (empty($day_folders)) {
            L\crawlLog("FB Scheduler: No days with schedules in fetch batch" .
                " queue, bailing on making a schedule!!!");
            return;
        }
        $url_tuples = [];
        $reschedule_tuples = [];
        $add_delayed_hosts = [];
        $crawl_delay_hosts = [];
        $url_files = [];
        $current_day = 0;
        $current_file = 0;
        $examined_count = 0;
        $num_files_processed = 0;
        while ($fetch_size < C\MAX_FETCH_SIZE &&
            $fetch_weight < C\MAX_FETCH_WEIGHT &&
            $num_files_processed < C\MAX_FILES_PROCESS_BATCH) {
            while (empty($url_tuples) && !empty($day_folders)) {
                if (empty($url_files)) {
                    $url_files = $this->crawl_queue->getUrlsFiles(
                        $day_folders[$current_day]);
                    if (empty($url_files)) {
                        $this->db->unlinkRecursive($day_folders[$current_day],
                            true);
                        unset($day_folders[$current_day]);
                        $current_file = 0;
                        $current_day++;
                    }
                } else {
                    $current_file = array_key_first($url_files);
                    $current_file_name = $url_files[$current_file];
                    if (!empty($current_file_name)) {
                        $url_file_contents =
                            $this->crawl_queue->getUrlsFileContents(
                            $current_file_name);
                        $url_tuples = [];
                        if (!empty($url_file_contents)
                            && is_array($url_file_contents)) {
                            $url_tuples = array_values($url_file_contents);
                        }
                        unlink($current_file_name);
                    }
                    $tuple_index = 0;
                    unset($url_files[$current_file]);
                    $num_files_processed++;
                }
            }
            if (empty($url_tuples) && empty($day_folders)) {
                break;
            }
            $current_tuple = $url_tuples[$tuple_index] ?? [];
            unset($url_tuples[$tuple_index]);
            $tuple_index++;
            if (empty($current_tuple)) {
                L\crawlLog("FB Scheduler: saw empty tuple at " .
                    ($tuple_index - 1));
                continue;
            }
            L\crawlTimeoutLog("FB..Scheduler: still producing fetch batch. " .
                "Examining location %s in queue.", $examined_count);
            //look in queue for url and its weight
            list($url, $weight, $depth, $referer, $old_weight) = $current_tuple;
            // if queue error remove entry any loop
            if (empty($url)) {
                L\crawlLog("FB Scheduler: Empty url error at".
                    " $examined_count during produce fetch");
                continue;
            }
            $examined_count++;
            $host_url = UrlParser::getHost($url);
            $hash_host = L\crawlHash($host_url);
            $hard_coded = (strpos($url, "###!") > 0 );
            $url = ($hard_coded) ? $url : explode("#", $url)[0];
            $scheme = UrlParser::getScheme($host_url);
            if ($scheme == "gopher") {
                $is_robot =
                    (strcmp($host_url . "/0/robots.txt", $url) == 0);
            } else {
                $is_robot =
                    (strcmp($host_url . "/robots.txt", $url) == 0);
            }
            //if $url is a robots.txt url see if we need to schedule or not
            if ($is_robot) {
                $next_slot = $this->getEarliestSlot($current_crawl_index,
                    $sites);
                if ($next_slot < C\MAX_FETCH_SIZE) {
                    /* note don't add to seen url filter
                       since check robots every 24 hours as needed
                     */
                    $sites[$next_slot] = [$url, $weight, $depth, 0, $referer];
                    $current_crawl_index++;
                    $fetch_size++;
                    $fetch_weight += UrlParser::guessFileSizeFromUrl($url);
                } else { //no more available slots so prepare to bail
                    $url_tuples[$tuple_index] = $current_tuple;
                    break;
                }
                continue;
            }
            if ($this->robots_txt == C\IGNORE_ROBOTS ||
                ($this->robots_txt == C\ALLOW_LANDING_ROBOTS &&
                rtrim($url, "/") == rtrim($host_url, "/"))) {
                $robots_okay = true;
            } else if (!isset($hard_coded) || !$hard_coded) {
                $robots_okay = $this->crawl_queue->checkRobotOkay($url);
                if (!$this->allowedToCrawlSite($url) ||
                    $this->disallowedToCrawlSite($url)) {
                    /* This is checked when added to queue,
                       we check again here in case allowed and disallowed
                       sites have changed since then
                     */
                    $robots_okay = false;
                }
            } else {
                $robots_okay = true;
            }
            if (!$robots_okay) {
                L\crawlLog("FB Scheduler: $url removed by robot".
                    " policy");
                continue;
            }
            $robot_data = $this->crawl_queue->getRobotData($host_url);
            $delay = $robot_data['CRAWL_DELAY'] ?? 0;
            $is_delayed = $this->crawl_queue->isDelayedHost($host_url);
            if ($is_delayed) {
                L\crawlLog("$host_url is delayed");
            }
            /* if company level domain delays, then we're delayed
                as well
             */
            $cld = UrlParser::getCompanyLevelDomain($host_url);
            $cld_host = UrlParser::getScheme($host_url) . "://" . $cld;
            $use_cld = false;
            if ($cld_host != $host_url) {
                $cld_robot_data = $this->crawl_queue->getRobotData($cld_host);
                if ($delay == 0) {
                    $delay = $cld_robot_data['CRAWL_DELAY'] ?? 0;
                    if ($delay > 0) {
                        $use_cld = true;
                    }
                }
                if (!$is_delayed) {
                    $is_delayed = $this->crawl_queue->isDelayedHost($cld_host);
                    if ($is_delayed) {
                        L\crawlLog("$cld_host is delayed");
                    }
                }
            }
            if ($is_delayed || !$this->withinQuota($url)) {
                L\crawlLog("FB Scheduler: $url rescheduled due to quota".
                    " or crawl delay.");
                $reschedule_tuples[] = $current_tuple;
                if (count($reschedule_tuples) > $max_buffer_before_write) {
                    $this->crawl_queue->addSendFetcherQueue(
                        $reschedule_tuples, $this->crawl_order);
                    $reschedule_tuples = [];
                }
                continue;
            }
            if ($delay > 0) {
                if (C\nsdefined('VERBOSE_LOGGING') && C\VERBOSE_LOGGING) {
                    L\crawlLog("Scheduler: Host $host_url of $url has a ".
                        "crawl-delay of $delay seconds. Processing...");
                }
                /*
                  To ensure that crawl-delay isn't violated by two separate
                  fetchers crawling the same host, if a host has a crawl
                  delay we only let it appear in one outstanding schedule
                  at a time. When data appears back from the fetcher handling
                  a crawl-delayed host, we'll clear it to appear in another
                  schedule
                 */
                $request_batches_per_delay =
                    ceil($delay/$time_per_request_guess);
                if (!isset($crawl_delay_hosts[$hash_host])) {
                    $next_earliest_slot = $current_crawl_index;
                    $crawl_delay_hosts[$hash_host] = $next_earliest_slot;
                } else {
                    $next_earliest_slot = $crawl_delay_hosts[$hash_host]
                        + $request_batches_per_delay
                        * C\NUM_MULTI_CURL_PAGES;
                }
                if (($next_slot =
                    $this->getEarliestSlot($next_earliest_slot,
                        $sites)) < C\MAX_FETCH_SIZE) {
                    $crawl_delay_hosts[$hash_host] = $next_slot;
                    $sites[$next_slot] = [$url, $weight, $depth,
                        $delay, $referer];
                    $fetch_size++;
                    $fetch_weight += UrlParser::guessFileSizeFromUrl($url);
                } else {
                    $reschedule_tuples[] = $current_tuple;
                    if (count($reschedule_tuples) > $max_buffer_before_write) {
                        $this->crawl_queue->addSendFetcherQueue(
                            $reschedule_tuples, $this->crawl_order);
                        $reschedule_tuples = [];
                    }
                }
                if ($use_cld) {
                    $add_delayed_hosts[L\crawlHash($cld_host)] = $cld_host;
                } else {
                    $add_delayed_hosts[L\crawlHash($host_url)] = $host_url;
                }
                if (count($add_delayed_hosts) > $max_buffer_before_write) {
                    $this->crawl_queue->addDelayedHosts($schedule_time,
                        $add_delayed_hosts);
                    $add_delayed_hosts = [];
                }
            } else { // add a url no crawl delay
                $next_slot = $this->getEarliestSlot($current_crawl_index,
                    $sites);
                if ($next_slot < C\MAX_FETCH_SIZE) {
                    $sites[$next_slot] = [$url, $weight, $depth, 0, $referer];
                    $current_crawl_index++;
                    $fetch_size++;
                    $fetch_weight += UrlParser::guessFileSizeFromUrl($url);
                } else { //no more available slots so prepare to bail
                    $url_tuples[$tuple_index] = $current_tuple;
                    break;
                }
            } //no crawl-delay else
        } //end while
        L\crawlLog("FB...Sheduler Final estimated fetch weight of selected ".
            "urls $fetch_weight");
        L\crawlLog("FB...Sheduler max allowed fetch weight is " .
            C\MAX_FETCH_WEIGHT);
        if (!empty($url_tuples)) {
            $url_tuples = array_values($url_tuples);
            $this->crawl_queue->putUrlsFileContents($current_file_name,
                $url_tuples);
        }
        if (!empty($reschedule_tuples)) {
            $this->crawl_queue->addSendFetcherQueue($reschedule_tuples,
                $this->crawl_order);
        }
        if (!empty($add_delayed_hosts)) {
            $this->crawl_queue->addDelayedHosts($schedule_time,
                $add_delayed_hosts);
        }
        $new_time = microtime(true);
        L\crawlLog("FB...Scheduler: Done selecting URLS for fetch batch time ".
            "so far:". L\changeInMicrotime($start_time));
        L\crawlLog("FB...Scheduler: Examined urls while making fetch batch:" .
            $examined_count);
        $new_time = microtime(true);
        if (isset($sites) && count($sites) > 0) {
            $dummy_slot = [self::DUMMY, 0.0, 0, 0, ""];
            /* dummy's are used for crawl delays of sites with longer delays
               when we don't have much else to crawl.
             */
            $cnt = 0;
            for ($j = 0; $j < C\MAX_FETCH_SIZE; $j++) {
                if (isset( $sites[$j])) {
                    $cnt++;
                    if ($cnt == $fetch_size) {
                        break;
                    }
                } else {
                    if ($j % C\NUM_MULTI_CURL_PAGES == 0) {
                        $sites[$j] = $dummy_slot;
                    }
                }
            }
            ksort($sites);
            $fetch_batch_name = C\TEMP_DIR . "/" .
                self::schedule_name . $this->crawl_time . ".txt";
            //write schedule to disk
            $fh = fopen($fetch_batch_name, "wb");
            fwrite($fh, $first_line);
            $num_sites = count($sites);
            $k = 0;
            foreach ($sites as $site) {
                L\crawlTimeoutLog(
                    "FB..Scheduler: Still Writing fetch schedule %s of %s.",
                    $k, $num_sites);
                $k++;
                $extracted_etag = null;
                list($url, $weight, $depth, $delay, ) = $site;
                $referer = $site[4] ?? "";
                if (C\USE_ETAG_EXPIRES) {
                /*check if we have cache validation data for a URL. If both
                  ETag and Expires timestamp are found or only an expires
                  timestamp is found, the timestamp is compared with the current
                  time. If the current time is less than the expires timestamp,
                  the URL is not added to the fetch batch. If only an ETag is
                  found, the ETag is appended to the URL so that it can be
                  processed by the fetcher.
                 */
                    $cache_validation_data =
                        $this->crawl_queue->etag_table->get($url);
                    if (!empty($cache_validation_data)) {
                        if ($cache_validation_data['ETAG'] !== -1 &&
                            $cache_validation_data['EXPIRES'] !== -1) {
                            $expires_timestamp =
                                $cache_validation_data['EXPIRES'];
                            $current_time = time();
                            if ($current_time < $expires_timestamp) {
                                continue;
                            } else {
                                $etag = $cache_validation_data['ETAG'];
                                $extracted_etag = "ETag: " . $etag;
                            }
                        } else if ($cache_validation_data['ETAG'] !== -1) {
                            $etag = $cache_validation_data['ETAG'];
                            $extracted_etag = "ETag: " . $etag;
                        } else if ($cache_validation_data['EXPIRES'] !== -1) {
                            $expires_timestamp =
                                $cache_validation_data['EXPIRES'];
                            $current_time = time();
                            if ($current_time < $expires_timestamp) {
                                continue;
                            }
                        }
                    }
                }
                $host_url = UrlParser::getHost($url);
                $dns_lookup = $this->crawl_queue->dnsLookup($host_url);
                $append_url = "###";
                if ($dns_lookup) {
                    $append_url = "###" . urlencode($dns_lookup);
                }
                if (!empty($referer)) {
                    $append_url .= "###" . $referer;
                }
                $etag_separator = "";
                if ($append_url != "###") {
                    $url .= $append_url;
                    $etag_separator = "###";
                }
                if ($extracted_etag !== null) {
                    $url .=  $etag_separator . $extracted_etag;
                }
                $out_string = base64_encode(
                    pack("G", $weight) . L\packInt($depth) .
                    L\packInt($delay) . $url) . "\n";
                fwrite($fh, $out_string);
            }
            fclose($fh);
            $this->messages_bundle->insertSendWindow($fetch_batch_name);
            L\crawlLog("FB...Scheduler: Sort URLS and write schedule time: " .
                L\changeInMicrotime($new_time));
            L\crawlLog("FB Scheduler: End Produce Fetch Batch Memory usage: " .
                memory_get_usage() );
            L\crawlLog("FB Scheduler: Created fetch batch " .
                $this->messages_bundle->max_sequence_number .
                " of size $num_sites." . "...Total Time to create batch: ".
                L\changeInMicrotime($start_time));;
        }
    }
    /**
     * Gets the first unfilled schedule slot after $index in $arr
     *
     * A schedule of sites for a fetcher to crawl consists of MAX_FETCH_SIZE
     * many slots each of which could eventually hold url information.
     * This function is used to schedule slots for crawl-delayed host.
     *
     * @param int $index location to begin searching for an empty slot
     * @param array &$arr list of slots to look in
     * @return int index of first available slot
     */
    public function getEarliestSlot($index, &$arr)
    {
        $cnt = count($arr);
        for ( $i = $index + 1; $i < $cnt; $i++) {
            if (!isset($arr[$i])) {
                break;
            }
        }
        return $i;
    }
    /**
     * Checks if url belongs to a list of sites that are allowed to be
     * crawled and that the file type is crawlable
     *
     * @param string $url url to check
     * @return bool whether is allowed to be crawled or not
     */
    public function allowedToCrawlSite($url)
    {
        $doc_type = UrlParser::getDocumentType($url);
        if (!in_array($doc_type, $this->all_file_types)) {
            $doc_type = "unknown";
        }
        if (!in_array($doc_type, $this->indexed_file_types)) {
            return false;
        }
        // try to eliminate spam sites, but still crawl onion urls
        $tld = "";
        if ($host = parse_url($url, \PHP_URL_HOST)) {
            $host_parts = explode(".", $host);
            $tld = $host_parts[count($host_parts) - 1];
        }
        if (!C\nsdefined("KEEP_SPAM_DOMAINS") && $tld != 'onion') {
            $consonants = "bcdfghjklmnpqrstvwxyz";
            $vowels = "aeiouy";
            $host = @parse_url($url, PHP_URL_HOST);
            $port = UrlParser::getPort($url);
            $digit_consonants = "([$consonants]|\d)";
            $digit_vowels = "([$vowels]|\d)";
            if (preg_match("/($digit_consonants{5}|$digit_vowels{5})|" .
                "(($digit_consonants{4}|$digit_vowels{4})" .
                ".+\.(cn|tv|cc|se|tw|ru|in|xyz))/",
                $host)) {
                return false;
            }
            if (in_array(substr($host, -3), [".cn", ".tw", ".ru", ".in",
                "xyz"]) && !in_array($port, [80, 443])) {
                return false;
            }
        }
        if ($this->restrict_sites_by_url) {
           return UrlParser::urlMemberSiteArray($url, $this->allowed_sites,
                "a" . $this->allow_disallow_cache_time);
        }
        return true;
    }
    /**
     * Checks if url belongs to a list of sites that aren't supposed to be
     * crawled
     *
     * @param string $url url to check
     * @return bool whether is shouldn't be crawled
     */
    public function disallowedToCrawlSite($url)
    {
        return UrlParser::urlMemberSiteArray($url, $this->disallowed_sites,
            "d" . $this->allow_disallow_cache_time);
    }
    /**
     * Checks if the $url is from a site which has an hourly quota to download.
     * If so, it bumps the quota count and return true; false otherwise.
     * This method also resets the quota queue every over
     *
     * @param string $url to check if within quota
     * @param int $bump_count how much to bump quota count if url is from a
     *      site with a quota
     * @return bool whether $url exceeds the hourly quota of the site it is from
     */
    public function withinQuota($url, $bump_count = 1)
    {
        if (!($site = UrlParser::urlMemberSiteArray(
            $url, $this->quota_sites_keys,
            "q" . $this->allow_disallow_cache_time, true))) {
            return true;
        }
        list($quota, $current_count) = $this->quota_sites[$site];
        if ($current_count < $quota) {
            $this->quota_sites[$site] = [$quota, $current_count + $bump_count];
            $flag = true;
        } else {
            L\crawlLog("Quota exceeded removing " .
                "url:$url Quota Site:$site Count:$current_count Quota:$quota");
            $flag = false;
        }
        if ($this->quota_clear_time + C\ONE_HOUR < time()) {
            $this->quota_clear_time = time();
            foreach ($this->quota_sites as $site => $info) {
                list($quota,) = $info;
                $this->quota_sites[$site] = [$quota, 0];
            }
        }
        return $flag;
    }
}
if (!C\nsdefined("UNIT_TEST_MODE")) {
    /*
     * Instantiate and runs the QueueSever
     */
    $queue_server =  new QueueServer();
    $queue_server->start();
}
