/wp-content/plugins/wp-multilang/includes/libraries/abstract-wp-background-process.php

<?php

namespace WPM\Includes\Libraries;



if ( ! defined( 'ABSPATH' ) ) {

	exit;

}



/**

 * Abstract WP_Background_Process class.

 *

 * @abstract

 * @package WP-Background-Processing

 * @extends WP_Async_Request

 */

abstract class WP_Background_Process extends WP_Async_Request {



	/**

	 * Action

	 *

	 * (default value: 'background_process')

	 *

	 * @var string

	 * @access protected

	 */

	protected $action = 'background_process';



	/**

	 * Start time of current process.

	 *

	 * (default value: 0)

	 *

	 * @var int

	 * @access protected

	 */

	protected $start_time = 0;



	/**

	 * Cron_hook_identifier

	 *

	 * @var mixed

	 * @access protected

	 */

	protected $cron_hook_identifier;



	/**

	 * Cron_interval_identifier

	 *

	 * @var mixed

	 * @access protected

	 */

	protected $cron_interval_identifier;



	/**

	 * Initiate new background process

	 */

	public function __construct() {

		parent::__construct();



		$this->cron_hook_identifier     = $this->identifier . '_cron';

		$this->cron_interval_identifier = $this->identifier . '_cron_interval';



		add_action( $this->cron_hook_identifier, array( $this, 'handle_cron_healthcheck' ) );

		add_filter( 'cron_schedules', array( $this, 'schedule_cron_healthcheck' ) );

	}



	/**

	 * Dispatch

	 *

	 * @access public

	 * @return void

	 */

	public function dispatch() {

		// Schedule the cron healthcheck.

		$this->schedule_event();



		// Perform remote post.

		return parent::dispatch();

	}



	/**

	 * Push to queue

	 *

	 * @param mixed $data Data.

	 *

	 * @return $this

	 */

	public function push_to_queue( $data ) {

		$this->data[] = $data;



		return $this;

	}



	/**

	 * Save queue

	 *

	 * @return $this

	 */

	public function save() {

		$key = $this->generate_key();



		if ( ! empty( $this->data ) ) {

			update_site_option( $key, $this->data );

		}



		return $this;

	}



	/**

	 * Update queue

	 *

	 * @param string $key Key.

	 * @param array  $data Data.

	 *

	 * @return $this

	 */

	public function update( $key, $data ) {

		if ( ! empty( $data ) ) {

			update_site_option( $key, $data );

		}



		return $this;

	}



	/**

	 * Delete queue

	 *

	 * @param string $key Key.

	 *

	 * @return $this

	 */

	public function delete( $key ) {

		delete_site_option( $key );



		return $this;

	}



	/**

	 * Generate key

	 *

	 * Generates a unique key based on microtime. Queue items are

	 * given a unique key so that they can be merged upon save.

	 *

	 * @param int $length Length.

	 *

	 * @return string

	 */

	protected function generate_key( $length = 64 ) {

		$unique  = md5( microtime() . rand() );

		$prepend = $this->identifier . '_batch_';



		return substr( $prepend . $unique, 0, $length );

	}



	/**

	 * Maybe process queue

	 *

	 * Checks whether data exists within the queue and that

	 * the process is not already running.

	 */

	public function maybe_handle() {

		// Don't lock up other requests while processing

		session_write_close();



		if ( $this->is_process_running() ) {

			// Background process already running.

			wp_die();

		}



		if ( $this->is_queue_empty() ) {

			// No data to process.

			wp_die();

		}



		check_ajax_referer( $this->identifier, 'nonce' );



		$this->handle();



		wp_die();

	}



	/**

	 * Is queue empty

	 *

	 * @return bool

	 */

	protected function is_queue_empty() {

		global $wpdb;



		$table  = $wpdb->options;

		$column = 'option_name';



		if ( is_multisite() ) {

			$table  = $wpdb->sitemeta;

			$column = 'meta_key';

		}



		$key = $wpdb->esc_like( $this->identifier . '_batch_' ) . '%';



		$count = $wpdb->get_var( $wpdb->prepare( "

		SELECT COUNT(*)

		FROM {$table}

		WHERE {$column} LIKE %s

	", $key ) );



		return ( $count > 0 ) ? false : true;

	}



	/**

	 * Is process running

	 *

	 * Check whether the current process is already running

	 * in a background process.

	 */

	protected function is_process_running() {

		if ( get_site_transient( $this->identifier . '_process_lock' ) ) {

			// Process already running.

			return true;

		}



		return false;

	}



	/**

	 * Lock process

	 *

	 * Lock the process so that multiple instances can't run simultaneously.

	 * Override if applicable, but the duration should be greater than that

	 * defined in the time_exceeded() method.

	 */

	protected function lock_process() {

		$this->start_time = time(); // Set start time of current process.



		$lock_duration = ( property_exists( $this, 'queue_lock_time' ) ) ? $this->queue_lock_time : 60; // 1 minute

		$lock_duration = apply_filters( $this->identifier . '_queue_lock_time', $lock_duration );



		set_site_transient( $this->identifier . '_process_lock', microtime(), $lock_duration );

	}



	/**

	 * Unlock process

	 *

	 * Unlock the process so that other instances can spawn.

	 *

	 * @return $this

	 */

	protected function unlock_process() {

		delete_site_transient( $this->identifier . '_process_lock' );



		return $this;

	}



	/**

	 * Get batch

	 *

	 * @return \stdClass Return the first batch from the queue

	 */

	protected function get_batch() {

		global $wpdb;



		$table        = $wpdb->options;

		$column       = 'option_name';

		$key_column   = 'option_id';

		$value_column = 'option_value';



		if ( is_multisite() ) {

			$table        = $wpdb->sitemeta;

			$column       = 'meta_key';

			$key_column   = 'meta_id';

			$value_column = 'meta_value';

		}



		$key = $wpdb->esc_like( $this->identifier . '_batch_' ) . '%';



		$query = $wpdb->get_row( $wpdb->prepare( "

		SELECT *

		FROM {$table}

		WHERE {$column} LIKE %s

		ORDER BY {$key_column} ASC

		LIMIT 1

		", $key ) );



		$batch       = new \stdClass();

		$batch->key  = $query->$column;

		$batch->data = maybe_unserialize( $query->$value_column );



		return $batch;

	}



	/**

	 * Handle

	 *

	 * Pass each queue item to the task handler, while remaining

	 * within server memory and time limit constraints.

	 */

	protected function handle() {

		$this->lock_process();



		do {

			$batch = $this->get_batch();



			foreach ( $batch->data as $key => $value ) {

				$task = $this->task( $value );



				if ( false !== $task ) {

					$batch->data[ $key ] = $task;

				} else {

					unset( $batch->data[ $key ] );

				}



				if ( $this->time_exceeded() || $this->memory_exceeded() ) {

					// Batch limits reached.

					break;

				}

			}



			// Update or delete current batch.

			if ( ! empty( $batch->data ) ) {

				$this->update( $batch->key, $batch->data );

			} else {

				$this->delete( $batch->key );

			}

		} while ( ! $this->time_exceeded() && ! $this->memory_exceeded() && ! $this->is_queue_empty() );



		$this->unlock_process();



		// Start next batch or complete process.

		if ( ! $this->is_queue_empty() ) {

			$this->dispatch();

		} else {

			$this->complete();

		}

	}



	/**

	 * Memory exceeded

	 *

	 * Ensures the batch process never exceeds 90%

	 * of the maximum WordPress memory.

	 *

	 * @return bool

	 */

	protected function memory_exceeded() {

		$memory_limit   = $this->get_memory_limit() * 0.9; // 90% of max memory

		$current_memory = memory_get_usage( true );

		$return         = false;



		if ( $current_memory >= $memory_limit ) {

			$return = true;

		}



		return apply_filters( $this->identifier . '_memory_exceeded', $return );

	}



	/**

	 * Get memory limit

	 *

	 * @return int

	 */

	protected function get_memory_limit() {

		if ( function_exists( 'ini_get' ) ) {

			$memory_limit = ini_get( 'memory_limit' );

		} else {

			// Sensible default.

			$memory_limit = '128M';

		}



		if ( ! $memory_limit || -1 === intval( $memory_limit ) ) {

			// Unlimited, set to 32GB.

			$memory_limit = '32000M';

		}



		return intval( $memory_limit ) * 1024 * 1024;

	}



	/**

	 * Time exceeded.

	 *

	 * Ensures the batch never exceeds a sensible time limit.

	 * A timeout limit of 30s is common on shared hosting.

	 *

	 * @return bool

	 */

	protected function time_exceeded() {

		$finish = $this->start_time + apply_filters( $this->identifier . '_default_time_limit', 20 ); // 20 seconds

		$return = false;



		if ( time() >= $finish ) {

			$return = true;

		}



		return apply_filters( $this->identifier . '_time_exceeded', $return );

	}



	/**

	 * Complete.

	 *

	 * Override if applicable, but ensure that the below actions are

	 * performed, or, call parent::complete().

	 */

	protected function complete() {

		// Unschedule the cron healthcheck.

		$this->clear_scheduled_event();

	}



	/**

	 * Schedule cron healthcheck

	 *

	 * @access public

	 * @param mixed $schedules Schedules.

	 * @return mixed

	 */

	public function schedule_cron_healthcheck( $schedules ) {

		$interval = apply_filters( $this->identifier . '_cron_interval', 5 );



		if ( property_exists( $this, 'cron_interval' ) ) {

			$interval = apply_filters( $this->identifier . '_cron_interval', $this->cron_interval_identifier );

		}



		// Adds every 5 minutes to the existing schedules.

		$schedules[ $this->identifier . '_cron_interval' ] = array(

			'interval' => MINUTE_IN_SECONDS * $interval,

			'display'  => sprintf( __( 'Every %d minutes', 'wp-multilang' ), $interval ),

		);



		return $schedules;

	}



	/**

	 * Handle cron healthcheck

	 *

	 * Restart the background process if not already running

	 * and data exists in the queue.

	 */

	public function handle_cron_healthcheck() {

		if ( $this->is_process_running() ) {

			// Background process already running.

			exit;

		}



		if ( $this->is_queue_empty() ) {

			// No data to process.

			$this->clear_scheduled_event();

			exit;

		}



		$this->handle();



		exit;

	}



	/**

	 * Schedule event

	 */

	protected function schedule_event() {

		if ( ! wp_next_scheduled( $this->cron_hook_identifier ) ) {

			wp_schedule_event( time(), $this->cron_interval_identifier, $this->cron_hook_identifier );

		}

	}



	/**

	 * Clear scheduled event

	 */

	protected function clear_scheduled_event() {

		$timestamp = wp_next_scheduled( $this->cron_hook_identifier );



		if ( $timestamp ) {

			wp_unschedule_event( $timestamp, $this->cron_hook_identifier );

		}

	}



	/**

	 * Cancel Process

	 *

	 * Stop processing queue items, clear cronjob and delete batch.

	 *

	 */

	public function cancel_process() {

		if ( ! $this->is_queue_empty() ) {

			$batch = $this->get_batch();



			$this->delete( $batch->key );



			wp_clear_scheduled_hook( $this->cron_hook_identifier );

		}



	}



	/**

	 * Task

	 *

	 * Override this method to perform any actions required on each

	 * queue item. Return the modified item for further processing

	 * in the next pass through. Or, return false to remove the

	 * item from the queue.

	 *

	 * @param mixed $item Queue item to iterate over.

	 *

	 * @return mixed

	 */

	abstract protected function task( $item );



}