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