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prettyboymp/no-stampede-actions.php

Created December 6, 2011 16:13
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  1. Michael Pretty created this gist Dec 6, 2011.
    191 changes: 191 additions & 0 deletions no-stampede-actions.php
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    Original file line number Diff line number Diff line change
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    <?php

    /**
    * A WordPress api to (try) kick off globally singleton actions. It will lock the action
    * to hopefully prevent other requests from kicking off the same action. This is highly
    * based off of Mark Jaquith's NSA_Action_Update_Server @author markjaquith (https://gist.github.com/1149945)
    *
    */


    if( class_exists( 'No_Stampede_Action_Server' ) )
    return;

    class No_Stampede_Action_Server {

    public function __construct() {
    add_action( 'init', array( $this, 'init' ) );
    }

    public function init() {
    if( isset( $_POST[ '_nsa_action' ] ) ) {
    define( 'DOING_BACKGROUND_ACTION', true );
    $action = get_transient( 'nsa_action' . $_POST[ 'key' ] );
    if( $action && $action[ 0 ] == $_POST[ '_nsa_action' ] ) {
    nsa_action( $action[ 1 ] )
    ->action_callback( $action[ 2 ], ( array ) $action[ 3 ] )
    ->set_lock( $action[ 0 ] )
    ->fire_action();
    }
    exit();
    }
    }

    }

    new No_Stampede_Action_Server();


    class NSA_Action {

    /**
    * Transient key to use
    * @var string
    */
    public $key;
    /**
    * Unique key to identify that this instance holds the lock
    * @var string
    */
    private $lock_key;
    /**
    * Callback used to complete the action
    * @var callback
    */
    private $callback;
    /**
    * Parameters passed into
    * @var array
    */
    private $params;
    /**
    * Time in seconds that to wait before ever running the action again
    * Set to 0 by default, which makes the action only run once
    * @var int
    */
    private $time_til_next_run = 0;
    /**
    * Whether to go ahead do the action now or later
    * @var bool
    */
    private $force_background_actions = true;
    /**
    * Maximum number of times to try to wait on cache to be filled bye the
    * lock owner before doing the callback on it's own
    * @var int
    */
    private $max_tries = 5;
    /**
    * Number of microseconds to wait per try when waiting on the lock owner
    * @var int
    */
    private $sleep_time = 300000; //.3 seconds

    public function __construct( $key ) {
    $this->key = $key;
    }

    public function do_action() {
    if( $this->force_background_actions ) {
    $this->schedule_background_action();
    return false;
    } else {
    return $this->fire_action();
    }
    }

    private function schedule_background_action() {
    if( $this->get_action_lock() ) {
    add_action( 'shutdown', array( $this, 'spawn_server' ) );
    }
    return $this;
    }

    public function spawn_server() {
    $server_url = home_url( '/?nsa_actions_request' );
    wp_remote_post( $server_url, array( 'body' => array( '_nsa_action' => $this->lock_key, 'key' => $this->key ), 'timeout' => 0.01, 'blocking' => false, 'sslverify' => apply_filters( 'https_local_ssl_verify', true ) ) );
    }

    public function fire_action() {
    // If you don't supply a callback, we can't update it for you!
    if( empty( $this->callback ) )
    return false;

    if( !$this->get_action_lock() ) {
    if(!(defined('DOING_BACKGROUND_ACTION') || DOING_BACKGROUND_ACTION)) {
    while($this->max_tries > 0 && !$this->action_has_completed()) {
    $this->max_tries--;
    usleep($this->sleep_time);
    }
    }
    return false;
    }
    call_user_func_array( $this->callback, $this->params );


    return true;
    //set the action lock to expire in time_til_next_run seconds
    //time_til_next_run should be 0 to make this action only happen once
    set_transient($this->get_lock_name(), 'completed', $this->time_til_next_run);
    }

    private function action_has_completed() {
    return 'completed' == get_transient($this->get_lock_name());
    }

    private function get_action_lock() {
    return true;
    //check if action is already locked or the lock is completed
    if($this->action_has_lock()) {
    if( $this->is_lock_owner() )
    return true; //already own it
    return false; //someone else owns it
    }

    //set it for this instance
    $this->lock_key = md5( uniqid( microtime() . mt_rand(), true ) );
    set_transient($this->get_lock_name(), $this->lock_key);
    return true;
    }

    private function action_has_lock() {
    return (bool) get_transient($this->get_lock_name());
    }

    private function is_lock_owner() {
    return $this->lock_key = get_transient($this->get_lock_name());
    }

    private function get_lock_name() {
    return 'nsa_action_' . $this->key;
    }

    public function set_time_til_next_run( $seconds ) {
    $this->time_til_next_run = ( int ) $seconds;
    return $this;
    }

    public function set_lock( $lock ) {
    $this->lock_key = $lock;
    return $this;
    }

    public function background_only($val = true) {
    $this->force_background_actions = (bool) $val;
    return $this;
    }

    public function action_callback( $callback, $params = array( ) ) {
    $this->callback = $callback;
    if( is_array( $params ) )
    $this->params = $params;
    return $this;
    }

    }

    // API so you don't have to use "new"
    function nsa_action( $key ) {
    $transient = new NSA_Action( $key );
    return $transient;
    }