Locks now work - ready to be used in the wild

diff --git a/src/Util/Lock.php b/src/Util/Lock.php
index 03e8545adfdaadc20866268ce7b8c1156648955c..e8fa03f7843047497650e2706c97b6bc6d0a14e2 100644 (file)
--- a/src/Util/Lock.php
+++ b/src/Util/Lock.php
@@ -16,11 +16,16 @@ use dbm;
  */
 class Lock {
 
-
-// Provide some ability to lock a PHP function so that multiple processes
-// can't run the function concurrently
-
-       public static function set($fn_name, $wait_sec = 2, $timeout = 30) {
+       /**
+        * @brief Sets a lock for a given name
+        *
+        * @param string $fn_name Name of the lock
+        * @param integer $timeout Seconds until we give up
+        * @param integer $wait_sec Time between to lock attempts
+        *
+        * @return boolean Was the lock successful?
+        */
+       public static function set($fn_name, $timeout = 30, $wait_sec = 2) {
                if ($wait_sec == 0) {
                        $wait_sec = 2;
                }
@@ -29,34 +34,46 @@ class Lock {
                $start = time();
 
                do {
-                       dba:p("LOCK TABLE `locks` WRITE");
-                       $lock = dba::select('locks', array('locked'), array('name' => $fn_name), array('limit' => 1));
-
-                       if ((dbm::is_result($lock)) AND !$lock['locked']) {
-                               dba::update('locks', array('locked' => true), array('name' => $fn_name));
-                               $got_lock = true;
+                       dba::p("LOCK TABLE `locks` WRITE");
+                       $lock = dba::select('locks', array('locked', 'pid'), array('name' => $fn_name), array('limit' => 1));
+
+                       if (dbm::is_result($lock)) {
+                               if ($lock['locked']) {
+                                       // When the process id isn't used anymore, we can safely claim the lock for us.
+                                       if (!posix_kill($lock['pid'], 0)) {
+                                               $lock['locked'] = false;
+                                       }
+                                       // We want to lock something that was already locked by us? So we got the lock.
+                                       if ($lock['pid'] == getmypid()) {
+                                               $got_lock = true;
+                                       }
+                               }
+                               if (!$lock['locked']) {
+                                       dba::update('locks', array('locked' => true, 'pid' => getmypid()), array('name' => $fn_name));
+                                       $got_lock = true;
+                               }
                        } elseif (!dbm::is_result($lock)) {
-                               dbm::insert('locks', array('name' => $fn_name, 'locked' => true));
+                               dba::insert('locks', array('name' => $fn_name, 'locked' => true, 'pid' => getmypid()));
                                $got_lock = true;
                        }
 
-                       dbm::p("UNLOCK TABLES");
+                       dba::p("UNLOCK TABLES");
 
                        if (!$got_lock) {
                                sleep($wait_sec);
                        }
                } while (!$got_lock AND ((time() - $start) < $timeout));
 
-               logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock . ' time = ' . (time() - $start), LOGGER_DEBUG);
-
                return $got_lock;
        }
 
+       /**
+        * @brief Removes a lock if it was set by us
+        *
+        * @param string $fn_name Name of the lock
+        */
        public static function remove($fn_name) {
-               dba::update('locks', array('locked' => false), array('name' => $fn_name));
-
-               logger('unlock_function: released lock for function ' . $fn_name, LOGGER_DEBUG);
-
+               dba::update('locks', array('locked' => false, 'pid' => 0), array('name' => $fn_name, 'pid' => getmypid()));
                return;
        }
 }