507 lines
11 KiB
PHP
507 lines
11 KiB
PHP
<?php
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/**
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* WP Background Process
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*
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* @package WP-Background-Processing
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*/
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if ( ! class_exists( 'WP_Background_Process' ) ) {
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/**
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* Abstract WP_Background_Process class.
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*
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* @abstract
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* @extends WP_Async_Request
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*/
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abstract class WP_Background_Process extends WP_Async_Request {
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/**
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* Action
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*
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* (default value: 'background_process')
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*
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* @var string
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* @access protected
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*/
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protected $action = 'background_process';
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/**
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* Start time of current process.
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*
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* (default value: 0)
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*
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* @var int
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* @access protected
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*/
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protected $start_time = 0;
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/**
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* Cron_hook_identifier
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*
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* @var mixed
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* @access protected
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*/
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protected $cron_hook_identifier;
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/**
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* Cron_interval_identifier
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*
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* @var mixed
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* @access protected
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*/
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protected $cron_interval_identifier;
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/**
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* Initiate new background process
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*/
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public function __construct() {
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parent::__construct();
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$this->cron_hook_identifier = $this->identifier . '_cron';
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$this->cron_interval_identifier = $this->identifier . '_cron_interval';
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add_action( $this->cron_hook_identifier, array( $this, 'handle_cron_healthcheck' ) );
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add_filter( 'cron_schedules', array( $this, 'schedule_cron_healthcheck' ) );
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}
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/**
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* Dispatch
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*
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* @access public
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* @return void
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*/
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public function dispatch() {
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// Schedule the cron healthcheck.
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$this->schedule_event();
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// Perform remote post.
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return parent::dispatch();
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}
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/**
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* Push to queue
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*
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* @param mixed $data Data.
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*
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* @return $this
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*/
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public function push_to_queue( $data ) {
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$this->data[] = $data;
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return $this;
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}
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/**
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* Save queue
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*
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* @return $this
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*/
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public function save() {
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$key = $this->generate_key();
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if ( ! empty( $this->data ) ) {
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update_site_option( $key, $this->data );
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}
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return $this;
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}
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/**
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* Update queue
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*
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* @param string $key Key.
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* @param array $data Data.
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*
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* @return $this
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*/
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public function update( $key, $data ) {
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if ( ! empty( $data ) ) {
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update_site_option( $key, $data );
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}
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return $this;
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}
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/**
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* Delete queue
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*
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* @param string $key Key.
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*
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* @return $this
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*/
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public function delete( $key ) {
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delete_site_option( $key );
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return $this;
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}
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/**
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* Generate key
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*
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* Generates a unique key based on microtime. Queue items are
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* given a unique key so that they can be merged upon save.
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*
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* @param int $length Length.
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*
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* @return string
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*/
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protected function generate_key( $length = 64 ) {
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$unique = md5( microtime() . rand() );
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$prepend = $this->identifier . '_batch_';
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return substr( $prepend . $unique, 0, $length );
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}
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/**
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* Maybe process queue
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*
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* Checks whether data exists within the queue and that
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* the process is not already running.
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*/
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public function maybe_handle() {
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// Don't lock up other requests while processing
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session_write_close();
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if ( $this->is_process_running() ) {
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// Background process already running.
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wp_die();
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}
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if ( $this->is_queue_empty() ) {
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// No data to process.
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wp_die();
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}
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check_ajax_referer( $this->identifier, 'nonce' );
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$this->handle();
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wp_die();
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}
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/**
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* Is queue empty
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*
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* @return bool
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*/
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protected function is_queue_empty() {
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global $wpdb;
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$table = $wpdb->options;
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$column = 'option_name';
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if ( is_multisite() ) {
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$table = $wpdb->sitemeta;
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$column = 'meta_key';
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}
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$key = $wpdb->esc_like( $this->identifier . '_batch_' ) . '%';
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$count = $wpdb->get_var( $wpdb->prepare( "
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SELECT COUNT(*)
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FROM {$table}
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WHERE {$column} LIKE %s
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", $key ) );
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return ( $count > 0 ) ? false : true;
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}
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/**
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* Is process running
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*
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* Check whether the current process is already running
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* in a background process.
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*/
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protected function is_process_running() {
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if ( get_site_transient( $this->identifier . '_process_lock' ) ) {
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// Process already running.
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return true;
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}
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return false;
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}
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/**
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* Lock process
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*
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* Lock the process so that multiple instances can't run simultaneously.
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* Override if applicable, but the duration should be greater than that
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* defined in the time_exceeded() method.
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*/
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protected function lock_process() {
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$this->start_time = time(); // Set start time of current process.
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$lock_duration = ( property_exists( $this, 'queue_lock_time' ) ) ? $this->queue_lock_time : 60; // 1 minute
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$lock_duration = apply_filters( $this->identifier . '_queue_lock_time', $lock_duration );
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set_site_transient( $this->identifier . '_process_lock', microtime(), $lock_duration );
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}
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/**
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* Unlock process
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*
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* Unlock the process so that other instances can spawn.
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*
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* @return $this
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*/
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protected function unlock_process() {
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delete_site_transient( $this->identifier . '_process_lock' );
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return $this;
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}
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/**
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* Get batch
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*
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* @return stdClass Return the first batch from the queue
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*/
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protected function get_batch() {
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global $wpdb;
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$table = $wpdb->options;
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$column = 'option_name';
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$key_column = 'option_id';
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$value_column = 'option_value';
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if ( is_multisite() ) {
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$table = $wpdb->sitemeta;
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$column = 'meta_key';
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$key_column = 'meta_id';
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$value_column = 'meta_value';
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}
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$key = $wpdb->esc_like( $this->identifier . '_batch_' ) . '%';
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$query = $wpdb->get_row( $wpdb->prepare( "
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SELECT *
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FROM {$table}
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WHERE {$column} LIKE %s
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ORDER BY {$key_column} ASC
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LIMIT 1
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", $key ) );
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$batch = new stdClass();
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$batch->key = $query->$column;
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$batch->data = maybe_unserialize( $query->$value_column );
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return $batch;
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}
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/**
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* Handle
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*
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* Pass each queue item to the task handler, while remaining
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* within server memory and time limit constraints.
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*/
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protected function handle() {
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$this->lock_process();
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do {
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$batch = $this->get_batch();
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foreach ( $batch->data as $key => $value ) {
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$task = $this->task( $value );
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if ( false !== $task ) {
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$batch->data[ $key ] = $task;
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} else {
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unset( $batch->data[ $key ] );
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}
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if ( $this->time_exceeded() || $this->memory_exceeded() ) {
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// Batch limits reached.
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break;
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}
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}
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// Update or delete current batch.
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if ( ! empty( $batch->data ) ) {
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$this->update( $batch->key, $batch->data );
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} else {
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$this->delete( $batch->key );
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}
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} while ( ! $this->time_exceeded() && ! $this->memory_exceeded() && ! $this->is_queue_empty() );
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$this->unlock_process();
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// Start next batch or complete process.
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if ( ! $this->is_queue_empty() ) {
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$this->dispatch();
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} else {
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$this->complete();
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}
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wp_die();
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}
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/**
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* Memory exceeded
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*
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* Ensures the batch process never exceeds 90%
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* of the maximum WordPress memory.
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*
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* @return bool
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*/
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protected function memory_exceeded() {
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$memory_limit = $this->get_memory_limit() * 0.9; // 90% of max memory
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$current_memory = memory_get_usage( true );
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$return = false;
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if ( $current_memory >= $memory_limit ) {
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$return = true;
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}
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return apply_filters( $this->identifier . '_memory_exceeded', $return );
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}
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/**
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* Get memory limit
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*
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* @return int
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*/
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protected function get_memory_limit() {
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if ( function_exists( 'ini_get' ) ) {
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$memory_limit = ini_get( 'memory_limit' );
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} else {
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// Sensible default.
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$memory_limit = '128M';
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}
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if ( ! $memory_limit || -1 === intval( $memory_limit ) ) {
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// Unlimited, set to 32GB.
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$memory_limit = '32000M';
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}
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return intval( $memory_limit ) * 1024 * 1024;
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}
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/**
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* Time exceeded.
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*
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* Ensures the batch never exceeds a sensible time limit.
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* A timeout limit of 30s is common on shared hosting.
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*
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* @return bool
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*/
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protected function time_exceeded() {
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$finish = $this->start_time + apply_filters( $this->identifier . '_default_time_limit', 20 ); // 20 seconds
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$return = false;
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if ( time() >= $finish ) {
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$return = true;
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}
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return apply_filters( $this->identifier . '_time_exceeded', $return );
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}
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/**
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* Complete.
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*
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* Override if applicable, but ensure that the below actions are
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* performed, or, call parent::complete().
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*/
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protected function complete() {
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// Unschedule the cron healthcheck.
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$this->clear_scheduled_event();
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}
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/**
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* Schedule cron healthcheck
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*
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* @access public
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* @param mixed $schedules Schedules.
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* @return mixed
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*/
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public function schedule_cron_healthcheck( $schedules ) {
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$interval = apply_filters( $this->identifier . '_cron_interval', 5 );
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if ( property_exists( $this, 'cron_interval' ) ) {
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$interval = apply_filters( $this->identifier . '_cron_interval', $this->cron_interval );
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}
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// Adds every 5 minutes to the existing schedules.
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$schedules[ $this->identifier . '_cron_interval' ] = array(
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'interval' => MINUTE_IN_SECONDS * $interval,
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'display' => sprintf( __( 'Every %d Minutes' ), $interval ),
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);
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return $schedules;
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}
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/**
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* Handle cron healthcheck
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*
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* Restart the background process if not already running
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* and data exists in the queue.
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*/
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public function handle_cron_healthcheck() {
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if ( $this->is_process_running() ) {
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// Background process already running.
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exit;
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}
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if ( $this->is_queue_empty() ) {
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// No data to process.
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$this->clear_scheduled_event();
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exit;
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}
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$this->handle();
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exit;
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}
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/**
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* Schedule event
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*/
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protected function schedule_event() {
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if ( ! wp_next_scheduled( $this->cron_hook_identifier ) ) {
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wp_schedule_event( time(), $this->cron_interval_identifier, $this->cron_hook_identifier );
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}
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}
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/**
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* Clear scheduled event
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*/
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protected function clear_scheduled_event() {
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$timestamp = wp_next_scheduled( $this->cron_hook_identifier );
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if ( $timestamp ) {
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wp_unschedule_event( $timestamp, $this->cron_hook_identifier );
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}
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}
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/**
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* Cancel Process
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*
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* Stop processing queue items, clear cronjob and delete batch.
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*
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*/
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public function cancel_process() {
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if ( ! $this->is_queue_empty() ) {
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$batch = $this->get_batch();
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$this->delete( $batch->key );
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wp_clear_scheduled_hook( $this->cron_hook_identifier );
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}
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}
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/**
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* Task
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*
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* Override this method to perform any actions required on each
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* queue item. Return the modified item for further processing
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* in the next pass through. Or, return false to remove the
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* item from the queue.
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*
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* @param mixed $item Queue item to iterate over.
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*
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* @return mixed
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*/
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abstract protected function task( $item );
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}
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}
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