Initial Commit

dependencies/woocommerce/action-scheduler/classes/ActionScheduler_OptionLock.php

@@ -0,0 +1,135 @@
+<?php
+
+/**
+ * Provide a way to set simple transient locks to block behaviour
+ * for up-to a given duration.
+ *
+ * Class ActionScheduler_OptionLock
+ * @since 3.0.0
+ */
+class ActionScheduler_OptionLock extends ActionScheduler_Lock {
+
+	/**
+	 * Set a lock using options for a given amount of time (60 seconds by default).
+	 *
+	 * Using an autoloaded option avoids running database queries or other resource intensive tasks
+	 * on frequently triggered hooks, like 'init' or 'shutdown'.
+	 *
+	 * For example, ActionScheduler_QueueRunner->maybe_dispatch_async_request() uses a lock to avoid
+	 * calling ActionScheduler_QueueRunner->has_maximum_concurrent_batches() every time the 'shutdown',
+	 * hook is triggered, because that method calls ActionScheduler_QueueRunner->store->get_claim_count()
+	 * to find the current number of claims in the database.
+	 *
+	 * @param string $lock_type A string to identify different lock types.
+	 * @bool True if lock value has changed, false if not or if set failed.
+	 */
+	public function set( $lock_type ) {
+		global $wpdb;
+
+		$lock_key            = $this->get_key( $lock_type );
+		$existing_lock_value = $this->get_existing_lock( $lock_type );
+		$new_lock_value      = $this->new_lock_value( $lock_type );
+
+		// The lock may not exist yet, or may have been deleted.
+		if ( empty( $existing_lock_value ) ) {
+			return (bool) $wpdb->insert(
+				$wpdb->options,
+				array(
+					'option_name'  => $lock_key,
+					'option_value' => $new_lock_value,
+					'autoload'     => 'no',
+				)
+			);
+		}
+
+		if ( $this->get_expiration_from( $existing_lock_value ) >= time() ) {
+			return false;
+		}
+
+		// Otherwise, try to obtain the lock.
+		return (bool) $wpdb->update(
+			$wpdb->options,
+			array( 'option_value' => $new_lock_value ),
+			array(
+				'option_name'  => $lock_key,
+				'option_value' => $existing_lock_value,
+			)
+		);
+	}
+
+	/**
+	 * If a lock is set, return the timestamp it was set to expiry.
+	 *
+	 * @param string $lock_type A string to identify different lock types.
+	 * @return bool|int False if no lock is set, otherwise the timestamp for when the lock is set to expire.
+	 */
+	public function get_expiration( $lock_type ) {
+		return $this->get_expiration_from( $this->get_existing_lock( $lock_type ) );
+	}
+
+	/**
+	 * Given the lock string, derives the lock expiration timestamp (or false if it cannot be determined).
+	 *
+	 * @param string $lock_value String containing a timestamp, or pipe-separated combination of unique value and timestamp.
+	 *
+	 * @return false|int
+	 */
+	private function get_expiration_from( $lock_value ) {
+		$lock_string = explode( '|', $lock_value );
+
+		// Old style lock?
+		if ( count( $lock_string ) === 1 && is_numeric( $lock_string[0] ) ) {
+			return (int) $lock_string[0];
+		}
+
+		// New style lock?
+		if ( count( $lock_string ) === 2 && is_numeric( $lock_string[1] ) ) {
+			return (int) $lock_string[1];
+		}
+
+		return false;
+	}
+
+	/**
+	 * Get the key to use for storing the lock in the transient
+	 *
+	 * @param string $lock_type A string to identify different lock types.
+	 * @return string
+	 */
+	protected function get_key( $lock_type ) {
+		return sprintf( 'action_scheduler_lock_%s', $lock_type );
+	}
+
+	/**
+	 * Supplies the existing lock value, or an empty string if not set.
+	 *
+	 * @param string $lock_type A string to identify different lock types.
+	 *
+	 * @return string
+	 */
+	private function get_existing_lock( $lock_type ) {
+		global $wpdb;
+
+		// Now grab the existing lock value, if there is one.
+		return (string) $wpdb->get_var(
+			$wpdb->prepare(
+				"SELECT option_value FROM $wpdb->options WHERE option_name = %s",
+				$this->get_key( $lock_type )
+			)
+		);
+	}
+
+	/**
+	 * Supplies a lock value consisting of a unique value and the current timestamp, which are separated by a pipe
+	 * character.
+	 *
+	 * Example: (string) "649de012e6b262.09774912|1688068114"
+	 *
+	 * @param string $lock_type A string to identify different lock types.
+	 *
+	 * @return string
+	 */
+	private function new_lock_value( $lock_type ) {
+		return uniqid( '', true ) . '|' . ( time() + $this->get_duration( $lock_type ) );
+	}
+}