Changeset 4495

Timestamp:

01/22/12 21:11:37 (4 months ago)

Author:

tboutell

Message:

Refactored the locking code. Since the mysql implementation didn't work (too much pooling of connections in PDO going on) and the flock implementation is still the default, there is little change in behavior for existing users.

You can now substitute your own implementation of the new aLock interface by setting app_a_lock_class and app_a_lock_options.

More exciting is the inclusion of aLockPkLockServer, an implementation that takes advantage of the new pkLockServer distributed lockserver:

 https://github.com/punkave/pkLockServer

While pkLockServer is brand spanking new, it stands up very well to some new features of apostrophenow.com that put a lot of stress on locking (which is how we found out the mysql implementation wasn't working for web requests, ouch).

Location:

plugins/apostrophePlugin/branches/1.5/lib

Files:

• lock (added)
• lock/aLock.class.php (added)
• lock/aLockFlock.class.php (added)
• lock/aLockPkLockServer.class.php (added)
• toolkit/BaseaTools.class.php (modified) (1 diff)

plugins/apostrophePlugin/branches/1.5/lib/toolkit/BaseaTools.class.php

@@ -1140 +1140 @@
   }
   
-  static protected $locks = array();
-
-  /**
-   * Lock names must be \w+
-   * @param mixed $name
+  static protected $lockService = null;
+
+  /**
+   * Lock names must be ascii alphanumeric and underscore characters
+   * and must not be empty. If $wait is false, tries to get a lock
+   * and returns false promptly if it is unable to do so right now,
+   * true on success. If $wait is true, returns true on a successful
+   * lock after waiting up to 30 seconds, otherwise throws an sfException.
+   *
+   * By default an implementation based on flock() is used, which is fine
+   * for the vast majority of sites (see aLockFlock for details). If you
+   * wish to use an alternative implementation, set app_a_lock_class to
+   * the name of any implementation of our aLock interface, and set
+   * app_a_lock_options to contain any necessary options to initialize it.
+   * 
+   * @param string $name
+   * @param bool $wait
    */
   static public function lock($name, $wait = true)
   {
-    $lockType = sfConfig::get('app_a_lock_type', 'flock');
-    if ($lockType === 'mysql')
-    {
-      $info = aTools::getLockDbInfo();
-      $dbName = $info['dbName'];
-      $sql = $info['sql'];
-      $key = "$dbName-$name";
-      if ($wait)
-      {
-        $timeout = 30;
-      }
-      else
-      {
-        $timeout = 0;
-      }
-      $locked = $sql->queryOneScalar('SELECT GET_LOCK(:key, :timeout)', array('key' => $key, 'timeout' => $timeout));
-      if (!$locked)
-      {
-        if (!$wait)
-        {
-          return false;
-        }
-        else
-        {
-          throw new sfException("Unable to obtain a lock after 30 seconds. MySQL must be very busy.");
-        }
-      }
-      aTools::$locks[] = $name;
-      return true;
-    }
-    else
-    {
-      $dir = aFiles::getWritableDataFolder(array('a', 'locks'));
-      if (!preg_match('/^\w+$/', $name))
-      {
-        throw new sfException("Lock name is empty or contains non-word characters");
-      }
-      $file = "$dir/$name.lck";
-      $tries = 0;
-      while (true)
-      {
-        $fp = fopen($file, 'a');
-        if ($fp)
-        {
-          $flags = LOCK_EX;
-          if (!$wait)
-          {
-            $flags |= LOCK_NB;
-          }
-          if (flock($fp, $flags))
-          {
-            break;
-          }
-        }
-        if (!$wait)
-        {
-          return false;
-        }
-        $tries++;
-        if ($tries == 30)
-        {
-          throw new sfException("Unable to obtain a lock after 30 seconds. Set app_a_lockType to mysql or make sure $dir is on a filesystem that supports flock() calls.");
-        }
-        sleep(1);
-      } 
-      aTools::$locks[] = $fp;
-      return true;
-    }
-  }
-
-  static protected $lockSql;
-  static protected $dbName;
-  
-  /**
-   * Connect to the lock database and return an array containing
-   * dbName (the name of the *main* database for this site) and
-   * sql (an aMysql object ready to talk to the *lock* database, which
-   * can be separate). We need dbName to namespace our locks properly
-   *
-   * If app_a_lock_db is unspecified we use the default database
-   * for locks too. IF THIS DATABASE IS A MASTER/SLAVE SETUP, LOCKS WILL NOT 
-   * BE PROPERLY MANAGED AND YOUR PAGE TREE WILL NOT BE SAFE. If this is a problem 
-   * for you, set up a separate mysql instance that is NOT master/slave as a lockserver 
-   * and specify the credentials for it in app_a_lock_db, giving the keys
-   * host, user and password. No database name is required.
-   *
-   * Results are cached between calls during the same PHP request. Otherwise
-   * we'd have separate connections to the lockdb and be unable to release what
-   * we locked
-   */
-   
-  static public function getLockDbInfo()
-  {
-    if (!isset(aTools::$lockSql))
-    {
-      $mainSql = new aMysql();
-      $dbName = $mainSql->queryOneScalar('SELECT DATABASE()');
-      if (!strlen($dbName))
-      {
-        throw new sfException('Unable to get name of main database for lock namespacing purposes');
-      }
-      $params = sfConfig::get('app_a_lock_db');
-      if ($params)
-      {
-        $pdo = new PDO('mysql:host=' . $params['host'], $params['user'], $params['password']);
-        if (!$pdo)
-        {
-          throw new sfException('Unable to connect to lock db specified by app_a_lock_db');
-        }
-        $sql = new aMysql($pdo);
-      }
-      else
-      {
-        // OK, use the main database. This is NOT SAFE if you use MySQL replication 
-        $sql = new $mainSql;
-      }
-      aTools::$dbName = $dbName;
-      aTools::$lockSql = $sql;
-    }
-    return array('dbName' => aTools::$dbName, 'sql' => aTools::$lockSql);
-  }
-
-  /**
-   * Release the most recent lock
+    if (!aTools::$lockService)
+    {
+      $class = sfConfig::get('app_a_lock_class', 'aLockFlock');
+      $options = sfConfig::get('app_a_lock_options', array());
+      aTools::$lockService = new $class($options);
+    }
+    $result = aTools::$lockService->lock($name, $wait);
+    if ($result)
+    {
+      error_log("Locked $name");
+    }
+    return $result;
+  }
+
+  /**
+   * Release the most recent lock. It is not an error to call with no locks
    */
   static public function unlock()
   {
-    $lockType = sfConfig::get('app_a_lock_type', 'flock');
-    
-    if ($lockType === 'mysql')
-    {
-      if (count(aTools::$locks))
-      {
-        $name = array_pop(aTools::$locks);
-        $info = aTools::getLockDbInfo();
-        $dbName = $info['dbName'];
-        $sql = $info['sql'];
-        $key = "$dbName-$name";
-        $sql->queryOneScalar('SELECT RELEASE_LOCK(:key)', array('key' => $key));
-      }
-    }
-    else
-    {
-      if (count(aTools::$locks))
-      {
-        $fp = array_pop(aTools::$locks);
-        fclose($fp);
-      }
-      else
-      {
-        // It's OK to call with no lock, this greatly simplifies methods like flunkUnless()
-        // If you are using multiple names you are responsible for making sure you unlock consistently
-      }
-    }
+    if (!isset(aTools::$lockService))
+    {
+      /**
+       * It is not an error to call with no locks
+       */
+      return;
+    }
+    aTools::$lockService->unlock();
+    error_log("Unlocked");
   }