From 5dcce1ed9378c4a1ef2f5272e34baf8fee5cc8be Mon Sep 17 00:00:00 2001
From: Zach Prezkuta <fermion@gmx.com>
Date: Thu, 5 Jul 2012 19:01:13 -0600
Subject: add some timeouts to prevent deadlock

---
 include/lock.php | 15 ++++++++-------
 1 file changed, 8 insertions(+), 7 deletions(-)

(limited to 'include/lock.php')

diff --git a/include/lock.php b/include/lock.php
index 9bdb71125..5f1ca6323 100644
--- a/include/lock.php
+++ b/include/lock.php
@@ -3,11 +3,12 @@
 // Provide some ability to lock a PHP function so that multiple processes
 // can't run the function concurrently
 if(! function_exists('lock_function')) {
-function lock_function($fn_name, $block = true, $wait_sec = 2) {
+function lock_function($fn_name, $block = true, $wait_sec = 2, $timeout = 30) {
 	if( $wait_sec == 0 )
 		$wait_sec = 2;	// don't let the user pick a value that's likely to crash the system
 
 	$got_lock = false;
+	$start = time();
 
 	do {
 		q("LOCK TABLE locks WRITE");
@@ -33,19 +34,21 @@ function lock_function($fn_name, $block = true, $wait_sec = 2) {
 		if(($block) && (! $got_lock))
 			sleep($wait_sec);
 
-	} while(($block) && (! $got_lock));
+	} while(($block) && (! $got_lock) && ((time() - $start) < $timeout));
 
-	logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock, LOGGER_DEBUG);
+	logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock . ' time = ' . (time() - $start), LOGGER_DEBUG);
 	
 	return $got_lock;
 }}
 
 
 if(! function_exists('block_on_function_lock')) {
-function block_on_function_lock($fn_name, $wait_sec = 2) {
+function block_on_function_lock($fn_name, $wait_sec = 2, $timeout = 30) {
 	if( $wait_sec == 0 )
 		$wait_sec = 2;	// don't let the user pick a value that's likely to crash the system
 
+	$start = time();
+
 	do {
 		$r = q("SELECT locked FROM locks WHERE name = '%s' LIMIT 1",
 				dbesc($fn_name)
@@ -54,7 +57,7 @@ function block_on_function_lock($fn_name, $wait_sec = 2) {
 		if(count($r) && $r[0]['locked'])
 			sleep($wait_sec);
 
-	} while(count($r) && $r[0]['locked']);
+	} while(count($r) && $r[0]['locked'] && ((time() - $start) < $timeout));
 
 	return;
 }}
@@ -62,11 +65,9 @@ function block_on_function_lock($fn_name, $wait_sec = 2) {
 
 if(! function_exists('unlock_function')) {
 function unlock_function($fn_name) {
-	//$r = q("LOCK TABLE lock WRITE");
 	$r = q("UPDATE locks SET locked = 0 WHERE name = '%s' LIMIT 1",
 			dbesc($fn_name)
 	     );
-	//$r = q("UNLOCK TABLES");
 
 	logger('unlock_function: released lock for function ' . $fn_name, LOGGER_DEBUG);
 
-- 
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