From: Eileen <eileen@fuzion.co.nz>
Date: Fri, 30 May 2014 04:11:23 +0000 (-0400)
Subject: CRM-12856 hack to stop problems arising from mis-use of locks - need to review correc... 
X-Git-Url: https://vcs.fsf.org/?a=commitdiff_plain;h=f877d534c7e15b589511cac14f79f6dcdab142ec;p=civicrm-core.git

CRM-12856 hack to stop problems arising from mis-use of locks - need to review correct approach
---

diff --git a/CRM/Core/Lock.php b/CRM/Core/Lock.php
index eef6cb6ed8..134ba1ab0b 100644
--- a/CRM/Core/Lock.php
+++ b/CRM/Core/Lock.php
@@ -66,6 +66,15 @@ class CRM_Core_Lock {
     else {
       $this->_name = $database . '.' . $domainID . '.' . $name;
     }
+    CRM_Core_Error::debug_log_message('trying to construct lock for ' . $this->_name);
+    static $jobLog = FALSE;
+    if($jobLog && CRM_Core_DAO::singleValueQuery("SELECT IS_USED_LOCK( '{$jobLog}')")) {
+      return $this->hackyHandleBrokenCode($jobLog);
+    }
+    if(stristr($name, 'civimail.job.')) {
+      $jobLog = $this->_name;
+    }
+    //CRM_Core_Error::debug_var('backtrace', debug_backtrace());
     $this->_timeout = $timeout !== NULL ? $timeout : self::TIMEOUT;
 
     $this->acquire();
@@ -76,6 +85,8 @@ class CRM_Core_Lock {
   }
 
   function acquire() {
+
+    CRM_Core_Error::debug_log_message('aquire lock for ' . $this->_name);
     if (!$this->_hasLock) {
       $query = "SELECT GET_LOCK( %1, %2 )";
       $params = array(1 => array($this->_name, 'String'),
@@ -108,5 +119,27 @@ class CRM_Core_Lock {
   function isAcquired() {
     return $this->_hasLock;
   }
+
+  /**
+   * CRM-12856 locks were originally set up for jobs, but the concept was extended to caching & groups without
+   * understanding that would undermine the job locks (because grabbing a lock implicitly releases existing ones)
+   * this is all a big hack to mitigate the impact of that - but should not be seen as a fix. Not sure correct fix
+   * but maybe locks should be used more selectively? Or else we need to handle is some cool way that Tim is yet to write :-)
+   * if we are running in the context of the cron log then we would rather die (or at least let our process die)
+   * than release that lock - so if the attempt is being made by setCache or something relatively trivial
+   * we'll just return TRUE, but if it's another job then we will crash as that seems 'safer'
+   *
+   * @param string $jobLog
+   * @throws CRM_Core_Exception
+   * @return boolean
+   */
+  function hackyHandleBrokenCode($jobLog) {
+    if(stristr($this->_name, 'job')) {
+      throw new CRM_Core_Exception('lock aquisition for ' . $this->_name . 'attempted when ' . $jobLog . 'is not released');
+    }
+    CRM_Core_Error::debug_log_message('(CRM-12856) faking lock for ' . $this->_name);
+    $this->_hasLock = TRUE;
+    return TRUE;
+  }
 }