| 1 |
<?php |
| 2 |
|
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/** |
| 4 |
* A buffer of items from the queue that can be checked out |
| 5 |
*/ |
| 6 |
class Jetpack_Sync_Queue_Buffer { |
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public $id; |
| 8 |
public $items_with_ids; |
| 9 |
|
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public function __construct( $id, $items_with_ids ) { |
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$this->id = $id; |
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$this->items_with_ids = $items_with_ids; |
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} |
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|
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public function get_items() { |
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return array_combine( $this->get_item_ids(), $this->get_item_values() ); |
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} |
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|
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public function get_item_values() { |
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return Jetpack_Sync_Utils::get_item_values( $this->items_with_ids ); |
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} |
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|
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public function get_item_ids() { |
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return Jetpack_Sync_Utils::get_item_ids( $this->items_with_ids ); |
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} |
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} |
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|
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/** |
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* A persistent queue that can be flushed in increments of N items, |
| 30 |
* and which blocks reads until checked-out buffers are checked in or |
| 31 |
* closed. This uses raw SQL for two reasons: speed, and not triggering |
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* tons of added_option callbacks. |
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*/ |
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class Jetpack_Sync_Queue { |
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public $id; |
| 36 |
private $row_iterator; |
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|
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function __construct( $id ) { |
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$this->id = str_replace( '-', '_', $id ); // necessary to ensure we don't have ID collisions in the SQL |
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$this->row_iterator = 0; |
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} |
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|
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function add( $item ) { |
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global $wpdb; |
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$added = false; |
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// this basically tries to add the option until enough time has elapsed that |
| 47 |
// it has a unique (microtime-based) option key |
| 48 |
while ( ! $added ) { |
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$rows_added = $wpdb->query( $wpdb->prepare( |
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"INSERT INTO $wpdb->options (option_name, option_value,autoload) VALUES (%s, %s,%s)", |
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$this->get_next_data_row_option_name(), |
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serialize( $item ), |
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'no' |
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) ); |
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$added = ( 0 !== $rows_added ); |
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} |
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|
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do_action( 'jpsq_item_added' ); |
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} |
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|
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// Attempts to insert all the items in a single SQL query. May be subject to query size limits! |
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function add_all( $items ) { |
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global $wpdb; |
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$base_option_name = $this->get_next_data_row_option_name(); |
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|
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$query = "INSERT INTO $wpdb->options (option_name, option_value,autoload) VALUES "; |
| 67 |
|
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$rows = array(); |
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|
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for ( $i = 0; $i < count( $items ); $i += 1 ) { |
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$option_name = esc_sql( $base_option_name . '-' . $i ); |
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$option_value = esc_sql( serialize( $items[ $i ] ) ); |
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$rows[] = "('$option_name', '$option_value', 'no')"; |
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} |
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|
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$rows_added = $wpdb->query( $query . join( ',', $rows ) ); |
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|
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if ( count( $items ) === $rows_added ) { |
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return new WP_Error( 'row_count_mismatch', "The number of rows inserted didn't match the size of the input array" ); |
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} |
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|
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do_action( 'jpsq_items_added', $rows_added ); |
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} |
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|
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// Peek at the front-most item on the queue without checking it out |
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function peek( $count = 1 ) { |
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$items = $this->fetch_items( $count ); |
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if ( $items ) { |
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return Jetpack_Sync_Utils::get_item_values( $items ); |
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} |
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|
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return array(); |
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} |
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|
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// lag is the difference in time between the age of the oldest item |
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// (aka first or frontmost item) and the current time |
| 97 |
function lag() { |
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return self::get_lag( $this->id ); |
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} |
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|
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static function get_lag( $id ) { |
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global $wpdb; |
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|
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$first_item_name = $wpdb->get_var( $wpdb->prepare( |
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"SELECT option_name FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT 1", |
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"jpsq_{$id}-%" |
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) ); |
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|
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if ( ! $first_item_name ) { |
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return 0; |
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} |
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|
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// break apart the item name to get the timestamp |
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$matches = null; |
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if ( preg_match( '/^jpsq_' . $id . '-(\d+\.\d+)-/', $first_item_name, $matches ) ) { |
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return microtime( true ) - floatval( $matches[1] ); |
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} else { |
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return 0; |
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} |
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} |
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|
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function reset() { |
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global $wpdb; |
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$this->delete_checkout_id(); |
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$wpdb->query( $wpdb->prepare( |
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"DELETE FROM $wpdb->options WHERE option_name LIKE %s", "jpsq_{$this->id}-%" |
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) ); |
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} |
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|
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function size() { |
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global $wpdb; |
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|
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return (int) $wpdb->get_var( $wpdb->prepare( |
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"SELECT count(*) FROM $wpdb->options WHERE option_name LIKE %s", "jpsq_{$this->id}-%" |
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) ); |
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} |
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|
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// we use this peculiar implementation because it's much faster than count(*) |
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function has_any_items() { |
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global $wpdb; |
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$value = $wpdb->get_var( $wpdb->prepare( |
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"SELECT exists( SELECT option_name FROM $wpdb->options WHERE option_name LIKE %s )", "jpsq_{$this->id}-%" |
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) ); |
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|
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return ( $value === '1' ); |
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} |
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|
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function checkout( $buffer_size ) { |
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if ( $this->get_checkout_id() ) { |
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return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' ); |
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} |
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|
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$buffer_id = uniqid(); |
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|
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$result = $this->set_checkout_id( $buffer_id ); |
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|
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if ( ! $result || is_wp_error( $result ) ) { |
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return $result; |
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} |
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|
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$items = $this->fetch_items( $buffer_size ); |
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|
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if ( count( $items ) === 0 ) { |
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return false; |
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} |
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|
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$buffer = new Jetpack_Sync_Queue_Buffer( $buffer_id, array_slice( $items, 0, $buffer_size ) ); |
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|
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return $buffer; |
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} |
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|
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// this checks out rows until it either empties the queue or hits a certain memory limit |
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// it loads the sizes from the DB first so that it doesn't accidentally |
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// load more data into memory than it needs to. |
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// The only way it will load more items than $max_size is if a single queue item |
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// exceeds the memory limit, but in that case it will send that item by itself. |
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function checkout_with_memory_limit( $max_memory, $max_buffer_size = 500 ) { |
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if ( $this->get_checkout_id() ) { |
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return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' ); |
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} |
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|
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$buffer_id = uniqid(); |
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|
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$result = $this->set_checkout_id( $buffer_id ); |
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|
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if ( ! $result || is_wp_error( $result ) ) { |
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return $result; |
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} |
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|
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// get the map of buffer_id -> memory_size |
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global $wpdb; |
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|
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$items_with_size = $wpdb->get_results( |
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$wpdb->prepare( |
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"SELECT option_name AS id, LENGTH(option_value) AS value_size FROM $wpdb->options WHERE option_name LIKE %s ORDER BY option_name ASC LIMIT %d", |
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"jpsq_{$this->id}-%", |
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$max_buffer_size |
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), |
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OBJECT |
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); |
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|
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$total_memory = 0; |
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$item_ids = array(); |
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|
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foreach ( $items_with_size as $item_with_size ) { |
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$total_memory += $item_with_size->value_size; |
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|
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// if this is the first item and it exceeds memory, allow loop to continue |
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// we will exit on the next iteration instead |
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if ( $total_memory > $max_memory && count( $item_ids ) > 0 ) { |
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break; |
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} |
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$item_ids[] = $item_with_size->id; |
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} |
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|
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$items = $this->fetch_items_by_id( $item_ids ); |
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|
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if ( count( $items ) === 0 ) { |
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$this->delete_checkout_id(); |
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|
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return false; |
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} |
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|
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$buffer = new Jetpack_Sync_Queue_Buffer( $buffer_id, $items ); |
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|
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return $buffer; |
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} |
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|
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function checkin( $buffer ) { |
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$is_valid = $this->validate_checkout( $buffer ); |
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|
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if ( is_wp_error( $is_valid ) ) { |
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return $is_valid; |
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} |
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|
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$this->delete_checkout_id(); |
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|
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return true; |
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} |
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|
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function close( $buffer, $ids_to_remove = null ) { |
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$is_valid = $this->validate_checkout( $buffer ); |
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|
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if ( is_wp_error( $is_valid ) ) { |
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return $is_valid; |
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} |
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|
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$this->delete_checkout_id(); |
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|
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// by default clear all items in the buffer |
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if ( is_null( $ids_to_remove ) ) { |
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$ids_to_remove = $buffer->get_item_ids(); |
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} |
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|
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global $wpdb; |
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|
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if ( count( $ids_to_remove ) > 0 ) { |
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$sql = "DELETE FROM $wpdb->options WHERE option_name IN (" . implode( ', ', array_fill( 0, count( $ids_to_remove ), '%s' ) ) . ')'; |
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$query = call_user_func_array( array( $wpdb, 'prepare' ), array_merge( array( $sql ), $ids_to_remove ) ); |
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$wpdb->query( $query ); |
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} |
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|
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return true; |
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} |
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|
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function flush_all() { |
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$items = Jetpack_Sync_Utils::get_item_values( $this->fetch_items() ); |
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$this->reset(); |
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|
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return $items; |
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} |
| 272 |
|
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function get_all() { |
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return $this->fetch_items(); |
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} |
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|
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// use with caution, this could allow multiple processes to delete |
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// and send from the queue at the same time |
| 279 |
function force_checkin() { |
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$this->delete_checkout_id(); |
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} |
| 282 |
|
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// used to lock checkouts from the queue. |
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// tries to wait up to $timeout seconds for the queue to be empty |
| 285 |
function lock( $timeout = 30 ) { |
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$tries = 0; |
| 287 |
|
| 288 |
while ( $this->has_any_items() && $tries < $timeout ) { |
| 289 |
sleep( 1 ); |
| 290 |
$tries += 1; |
| 291 |
} |
| 292 |
|
| 293 |
if ( $tries === 30 ) { |
| 294 |
return new WP_Error( 'lock_timeout', 'Timeout waiting for sync queue to empty' ); |
| 295 |
} |
| 296 |
|
| 297 |
if ( $this->get_checkout_id() ) { |
| 298 |
return new WP_Error( 'unclosed_buffer', 'There is an unclosed buffer' ); |
| 299 |
} |
| 300 |
|
| 301 |
// hopefully this means we can acquire a checkout? |
| 302 |
$result = $this->set_checkout_id( 'lock' ); |
| 303 |
|
| 304 |
if ( ! $result || is_wp_error( $result ) ) { |
| 305 |
return $result; |
| 306 |
} |
| 307 |
|
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return true; |
| 309 |
} |
| 310 |
|
| 311 |
function unlock() { |
| 312 |
$this->delete_checkout_id(); |
| 313 |
} |
| 314 |
|
| 315 |
private function get_checkout_id() { |
| 316 |
return get_transient( $this->get_checkout_transient_name() ); |
| 317 |
} |
| 318 |
|
| 319 |
private function set_checkout_id( $checkout_id ) { |
| 320 |
return set_transient( $this->get_checkout_transient_name(), $checkout_id, 5 * 60 ); // 5 minute timeout |
| 321 |
} |
| 322 |
|
| 323 |
private function delete_checkout_id() { |
| 324 |
delete_transient( $this->get_checkout_transient_name() ); |
| 325 |
} |
| 326 |
|
| 327 |
private function get_checkout_transient_name() { |
| 328 |
return "jpsq_{$this->id}_checkout"; |
| 329 |
} |
| 330 |
|
| 331 |
private function get_next_data_row_option_name() { |
| 332 |
// this option is specifically chosen to, as much as possible, preserve time order |
| 333 |
// and minimise the possibility of collisions between multiple processes working |
| 334 |
// at the same time |
| 335 |
// TODO: confirm we only need to support PHP 5.05+ (otherwise we'll need to emulate microtime as float, and avoid PHP_INT_MAX) |
| 336 |
// @see: http://php.net/manual/en/function.microtime.php |
| 337 |
$timestamp = sprintf( '%.6f', microtime( true ) ); |
| 338 |
|
| 339 |
// row iterator is used to avoid collisions where we're writing data waaay fast in a single process |
| 340 |
if ( $this->row_iterator === PHP_INT_MAX ) { |
| 341 |
$this->row_iterator = 0; |
| 342 |
} else { |
| 343 |
$this->row_iterator += 1; |
| 344 |
} |
| 345 |
|
| 346 |
return 'jpsq_' . $this->id . '-' . $timestamp . '-' . getmypid() . '-' . $this->row_iterator; |
| 347 |
} |
| 348 |
|
| 349 |
private function fetch_items( $limit = null ) { |
| 350 |
global $wpdb; |
| 351 |
|
| 352 |
if ( $limit ) { |
| 353 |
$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 ); |
| 354 |
} else { |
| 355 |
$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}-%" ); |
| 356 |
} |
| 357 |
|
| 358 |
$items = $wpdb->get_results( $query_sql, OBJECT ); |
| 359 |
foreach ( $items as $item ) { |
| 360 |
$item->value = maybe_unserialize( $item->value ); |
| 361 |
} |
| 362 |
|
| 363 |
return $items; |
| 364 |
} |
| 365 |
|
| 366 |
private function fetch_items_by_id( $item_ids ) { |
| 367 |
global $wpdb; |
| 368 |
|
| 369 |
if ( count( $item_ids ) > 0 ) { |
| 370 |
$sql = "SELECT option_name AS id, option_value AS value FROM $wpdb->options WHERE option_name IN (" . implode( ', ', array_fill( 0, count( $item_ids ), '%s' ) ) . ') ORDER BY option_name ASC'; |
| 371 |
$query = call_user_func_array( array( $wpdb, 'prepare' ), array_merge( array( $sql ), $item_ids ) ); |
| 372 |
$items = $wpdb->get_results( $query, OBJECT ); |
| 373 |
foreach ( $items as $item ) { |
| 374 |
$item->value = maybe_unserialize( $item->value ); |
| 375 |
} |
| 376 |
|
| 377 |
return $items; |
| 378 |
} else { |
| 379 |
return array(); |
| 380 |
} |
| 381 |
} |
| 382 |
|
| 383 |
private function validate_checkout( $buffer ) { |
| 384 |
if ( ! $buffer instanceof Jetpack_Sync_Queue_Buffer ) { |
| 385 |
return new WP_Error( 'not_a_buffer', 'You must checkin an instance of Jetpack_Sync_Queue_Buffer' ); |
| 386 |
} |
| 387 |
|
| 388 |
$checkout_id = $this->get_checkout_id(); |
| 389 |
|
| 390 |
if ( ! $checkout_id ) { |
| 391 |
return new WP_Error( 'buffer_not_checked_out', 'There are no checked out buffers' ); |
| 392 |
} |
| 393 |
|
| 394 |
if ( $checkout_id != $buffer->id ) { |
| 395 |
return new WP_Error( 'buffer_mismatch', 'The buffer you checked in was not checked out' ); |
| 396 |
} |
| 397 |
|
| 398 |
return true; |
| 399 |
} |
| 400 |
} |
| 401 |
|
| 402 |
class Jetpack_Sync_Utils { |
| 403 |
|
| 404 |
static function get_item_values( $items ) { |
| 405 |
return array_map( array( __CLASS__, 'get_item_value' ), $items ); |
| 406 |
} |
| 407 |
|
| 408 |
static function get_item_ids( $items ) { |
| 409 |
return array_map( array( __CLASS__, 'get_item_id' ), $items ); |
| 410 |
} |
| 411 |
|
| 412 |
static private function get_item_value( $item ) { |
| 413 |
return $item->value; |
| 414 |
} |
| 415 |
|
| 416 |
static private function get_item_id( $item ) { |
| 417 |
return $item->id; |
| 418 |
} |
| 419 |
} |
| 420 |
|
