/wp-content/plugins/jetpack/sync/class.jetpack-sync-queue.php
PHP | 459 lines | 334 code | 92 blank | 33 comment | 35 complexity | 5c1d76b2ec09ea89bdf04ee4174449eb MD5 | raw file
- <?php
- /**
- * A buffer of items from the queue that can be checked out
- */
- class Jetpack_Sync_Queue_Buffer {
- public $id;
- public $items_with_ids;
- public function __construct( $id, $items_with_ids ) {
- $this->id = $id;
- $this->items_with_ids = $items_with_ids;
- }
- public function get_items() {
- return array_combine( $this->get_item_ids(), $this->get_item_values() );
- }
- public function get_item_values() {
- return Jetpack_Sync_Utils::get_item_values( $this->items_with_ids );
- }
- public function get_item_ids() {
- return Jetpack_Sync_Utils::get_item_ids( $this->items_with_ids );
- }
- }
- /**
- * A persistent queue that can be flushed in increments of N items,
- * and which blocks reads until checked-out buffers are checked in or
- * closed. This uses raw SQL for two reasons: speed, and not triggering
- * tons of added_option callbacks.
- */
- class Jetpack_Sync_Queue {
- public $id;
- private $row_iterator;
- function __construct( $id ) {
- $this->id = str_replace( '-', '_', $id ); // necessary to ensure we don't have ID collisions in the SQL
- $this->row_iterator = 0;
- $this->random_int = mt_rand( 1, 1000000 );
- }
- function add( $item ) {
- global $wpdb;
- $added = false;
- // this basically tries to add the option until enough time has elapsed that
- // it has a unique (microtime-based) option key
- while ( ! $added ) {
- $rows_added = $wpdb->query( $wpdb->prepare(
- "INSERT INTO $wpdb->options (option_name, option_value, autoload) VALUES (%s, %s,%s)",
- $this->get_next_data_row_option_name(),
- serialize( $item ),
- 'no'
- ) );
- $added = ( 0 !== $rows_added );
- }
- do_action( 'jpsq_item_added' );
- }
- // Attempts to insert all the items in a single SQL query. May be subject to query size limits!
- function add_all( $items ) {
- global $wpdb;
- $base_option_name = $this->get_next_data_row_option_name();
- $query = "INSERT INTO $wpdb->options (option_name, option_value, autoload) VALUES ";
- $rows = array();
- for ( $i = 0; $i < count( $items ); $i += 1 ) {
- $option_name = esc_sql( $base_option_name . '-' . $i );
- $option_value = esc_sql( serialize( $items[ $i ] ) );
- $rows[] = "('$option_name', '$option_value', 'no')";
- }
- $rows_added = $wpdb->query( $query . join( ',', $rows ) );
- if ( count( $items ) === $rows_added ) {
- return new WP_Error( 'row_count_mismatch', "The number of rows inserted didn't match the size of the input array" );
- }
- do_action( 'jpsq_items_added', $rows_added );
- }
- // Peek at the front-most item on the queue without checking it out
- function peek( $count = 1 ) {
- $items = $this->fetch_items( $count );
- if ( $items ) {
- return Jetpack_Sync_Utils::get_item_values( $items );
- }
- return array();
- }
- // lag is the difference in time between the age of the oldest item
- // (aka first or frontmost item) and the current time
- function lag() {
- global $wpdb;
- $first_item_name = $wpdb->get_var( $wpdb->prepare(
- "SELECT option_name FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT 1",
- "jpsq_{$this->id}-%"
- ) );
- if ( ! $first_item_name ) {
- return 0;
- }
- // break apart the item name to get the timestamp
- $matches = null;
- if ( preg_match( '/^jpsq_' . $this->id . '-(\d+\.\d+)-/', $first_item_name, $matches ) ) {
- return microtime( true ) - floatval( $matches[1] );
- } else {
- return 0;
- }
- }
- function reset() {
- global $wpdb;
- $this->delete_checkout_id();
- $wpdb->query( $wpdb->prepare(
- "DELETE FROM $wpdb->options WHERE option_name LIKE %s", "jpsq_{$this->id}-%"
- ) );
- }
- function size() {
- global $wpdb;
- return (int) $wpdb->get_var( $wpdb->prepare(
- "SELECT count(*) FROM $wpdb->options WHERE option_name LIKE %s", "jpsq_{$this->id}-%"
- ) );
- }
- // we use this peculiar implementation because it's much faster than count(*)
- function has_any_items() {
- global $wpdb;
- $value = $wpdb->get_var( $wpdb->prepare(
- "SELECT exists( SELECT option_name FROM $wpdb->options WHERE option_name LIKE %s )", "jpsq_{$this->id}-%"
- ) );
- return ( $value === '1' );
- }
- function checkout( $buffer_size ) {
- if ( $this->get_checkout_id() ) {
- return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' );
- }
- $buffer_id = uniqid();
- $result = $this->set_checkout_id( $buffer_id );
- if ( ! $result || is_wp_error( $result ) ) {
- return $result;
- }
- $items = $this->fetch_items( $buffer_size );
- if ( count( $items ) === 0 ) {
- return false;
- }
- $buffer = new Jetpack_Sync_Queue_Buffer( $buffer_id, array_slice( $items, 0, $buffer_size ) );
- return $buffer;
- }
- // this checks out rows until it either empties the queue or hits a certain memory limit
- // it loads the sizes from the DB first so that it doesn't accidentally
- // load more data into memory than it needs to.
- // The only way it will load more items than $max_size is if a single queue item
- // exceeds the memory limit, but in that case it will send that item by itself.
- function checkout_with_memory_limit( $max_memory, $max_buffer_size = 500 ) {
- if ( $this->get_checkout_id() ) {
- return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' );
- }
- $buffer_id = uniqid();
- $result = $this->set_checkout_id( $buffer_id );
- if ( ! $result || is_wp_error( $result ) ) {
- return $result;
- }
- // get the map of buffer_id -> memory_size
- global $wpdb;
- $items_with_size = $wpdb->get_results(
- $wpdb->prepare(
- "SELECT option_name AS id, LENGTH(option_value) AS value_size FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT %d",
- "jpsq_{$this->id}-%",
- $max_buffer_size
- ),
- OBJECT
- );
- if ( count( $items_with_size ) === 0 ) {
- return false;
- }
- $total_memory = 0;
- $min_item_id = $max_item_id = $items_with_size[0]->id;
- foreach ( $items_with_size as $id => $item_with_size ) {
- $total_memory += $item_with_size->value_size;
- // if this is the first item and it exceeds memory, allow loop to continue
- // we will exit on the next iteration instead
- if ( $total_memory > $max_memory && $id > 0 ) {
- break;
- }
- $max_item_id = $item_with_size->id;
- }
- $query = $wpdb->prepare(
- "SELECT option_name AS id, option_value AS value FROM $wpdb->options WHERE option_name >= %s and option_name <= %s ORDER BY option_name ASC",
- $min_item_id,
- $max_item_id
- );
- $items = $wpdb->get_results( $query, OBJECT );
- foreach ( $items as $item ) {
- $item->value = maybe_unserialize( $item->value );
- }
- if ( count( $items ) === 0 ) {
- $this->delete_checkout_id();
- return false;
- }
- $buffer = new Jetpack_Sync_Queue_Buffer( $buffer_id, $items );
- return $buffer;
- }
- function checkin( $buffer ) {
- $is_valid = $this->validate_checkout( $buffer );
- if ( is_wp_error( $is_valid ) ) {
- return $is_valid;
- }
- $this->delete_checkout_id();
- return true;
- }
- function close( $buffer, $ids_to_remove = null ) {
- $is_valid = $this->validate_checkout( $buffer );
- if ( is_wp_error( $is_valid ) ) {
- return $is_valid;
- }
- $this->delete_checkout_id();
- // by default clear all items in the buffer
- if ( is_null( $ids_to_remove ) ) {
- $ids_to_remove = $buffer->get_item_ids();
- }
- global $wpdb;
- if ( count( $ids_to_remove ) > 0 ) {
- $sql = "DELETE FROM $wpdb->options WHERE option_name IN (" . implode( ', ', array_fill( 0, count( $ids_to_remove ), '%s' ) ) . ')';
- $query = call_user_func_array( array( $wpdb, 'prepare' ), array_merge( array( $sql ), $ids_to_remove ) );
- $wpdb->query( $query );
- }
- return true;
- }
- function flush_all() {
- $items = Jetpack_Sync_Utils::get_item_values( $this->fetch_items() );
- $this->reset();
- return $items;
- }
- function get_all() {
- return $this->fetch_items();
- }
- // use with caution, this could allow multiple processes to delete
- // and send from the queue at the same time
- function force_checkin() {
- $this->delete_checkout_id();
- }
- // used to lock checkouts from the queue.
- // tries to wait up to $timeout seconds for the queue to be empty
- function lock( $timeout = 30 ) {
- $tries = 0;
- while ( $this->has_any_items() && $tries < $timeout ) {
- sleep( 1 );
- $tries += 1;
- }
- if ( $tries === 30 ) {
- return new WP_Error( 'lock_timeout', 'Timeout waiting for sync queue to empty' );
- }
- if ( $this->get_checkout_id() ) {
- return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' );
- }
- // hopefully this means we can acquire a checkout?
- $result = $this->set_checkout_id( 'lock' );
- if ( ! $result || is_wp_error( $result ) ) {
- return $result;
- }
- return true;
- }
- function unlock() {
- return $this->delete_checkout_id();
- }
- private function get_checkout_id() {
- global $wpdb;
- $checkout_value = $wpdb->get_var(
- $wpdb->prepare(
- "SELECT option_value FROM $wpdb->options WHERE option_name = %s",
- $this->get_lock_option_name()
- )
- );
- if ( $checkout_value ) {
- list( $checkout_id, $timestamp ) = explode( ':', $checkout_value );
- if ( intval( $timestamp ) > time() ) {
- return $checkout_id;
- }
- }
- return false;
- }
- private function set_checkout_id( $checkout_id ) {
- global $wpdb;
- $expires = time() + Jetpack_Sync_Defaults::$default_sync_queue_lock_timeout;
- $updated_num = $wpdb->query(
- $wpdb->prepare(
- "UPDATE $wpdb->options SET option_value = %s WHERE option_name = %s",
- "$checkout_id:$expires",
- $this->get_lock_option_name()
- )
- );
- if ( ! $updated_num ) {
- $updated_num = $wpdb->query(
- $wpdb->prepare(
- "INSERT INTO $wpdb->options ( option_name, option_value, autoload ) VALUES ( %s, %s, 'no' )",
- $this->get_lock_option_name(),
- "$checkout_id:$expires"
- )
- );
- }
- return $updated_num;
- }
- private function delete_checkout_id() {
- global $wpdb;
- // rather than delete, which causes fragmentation, we update in place
- return $wpdb->query(
- $wpdb->prepare(
- "UPDATE $wpdb->options SET option_value = %s WHERE option_name = %s",
- "0:0",
- $this->get_lock_option_name()
- )
- );
- }
- private function get_lock_option_name() {
- return "jpsq_{$this->id}_checkout";
- }
- private function get_next_data_row_option_name() {
- // this option is specifically chosen to, as much as possible, preserve time order
- // and minimise the possibility of collisions between multiple processes working
- // at the same time
- // TODO: confirm we only need to support PHP 5.05+ (otherwise we'll need to emulate microtime as float, and avoid PHP_INT_MAX)
- // @see: http://php.net/manual/en/function.microtime.php
- $timestamp = sprintf( '%.6f', microtime( true ) );
- // row iterator is used to avoid collisions where we're writing data waaay fast in a single process
- if ( $this->row_iterator === PHP_INT_MAX ) {
- $this->row_iterator = 0;
- } else {
- $this->row_iterator += 1;
- }
- return 'jpsq_' . $this->id . '-' . $timestamp . '-' . $this->random_int . '-' . $this->row_iterator;
- }
- private function fetch_items( $limit = null ) {
- global $wpdb;
- if ( $limit ) {
- $query_sql = $wpdb->prepare( "SELECT option_name AS id, option_value AS value FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT %d", "jpsq_{$this->id}-%", $limit );
- } else {
- $query_sql = $wpdb->prepare( "SELECT option_name AS id, option_value AS value FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC", "jpsq_{$this->id}-%" );
- }
- $items = $wpdb->get_results( $query_sql, OBJECT );
- foreach ( $items as $item ) {
- $item->value = maybe_unserialize( $item->value );
- }
- return $items;
- }
- private function validate_checkout( $buffer ) {
- if ( ! $buffer instanceof Jetpack_Sync_Queue_Buffer ) {
- return new WP_Error( 'not_a_buffer', 'You must checkin an instance of Jetpack_Sync_Queue_Buffer' );
- }
- $checkout_id = $this->get_checkout_id();
- if ( ! $checkout_id ) {
- return new WP_Error( 'buffer_not_checked_out', 'There are no checked out buffers' );
- }
- if ( $checkout_id != $buffer->id ) {
- return new WP_Error( 'buffer_mismatch', 'The buffer you checked in was not checked out' );
- }
- return true;
- }
- }
- class Jetpack_Sync_Utils {
- static function get_item_values( $items ) {
- return array_map( array( __CLASS__, 'get_item_value' ), $items );
- }
- static function get_item_ids( $items ) {
- return array_map( array( __CLASS__, 'get_item_id' ), $items );
- }
- static private function get_item_value( $item ) {
- return $item->value;
- }
- static private function get_item_id( $item ) {
- return $item->id;
- }
- }