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authorVasudev Kamath <kamathvasudev@gmail.com>2012-07-06 22:47:27 +0530
committerVasudev Kamath <kamathvasudev@gmail.com>2012-07-06 22:47:27 +0530
commitba4db236ecff1ffdb56adc2715b3f53515f8cb34 (patch)
treef0b9928aade8aab95d1608890fde1918ce163754 /include/lock.php
parent6e4760dd9c512147309b5e4a98d25216610f81da (diff)
parenta122fecf50d06856a2ada8b564f711fb52c327f0 (diff)
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Merge branch 'master' of git://github.com/friendica/friendica
Diffstat (limited to 'include/lock.php')
-rw-r--r--include/lock.php77
1 files changed, 77 insertions, 0 deletions
diff --git a/include/lock.php b/include/lock.php
new file mode 100644
index 000000000..5f1ca6323
--- /dev/null
+++ b/include/lock.php
@@ -0,0 +1,77 @@
+<?php
+
+// 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, $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");
+ $r = q("SELECT locked FROM locks WHERE name = '%s' LIMIT 1",
+ dbesc($fn_name)
+ );
+
+ if((count($r)) && (! $r[0]['locked'])) {
+ q("UPDATE locks SET locked = 1 WHERE name = '%s' LIMIT 1",
+ dbesc($fn_name)
+ );
+ $got_lock = true;
+ }
+ elseif(! $r) { // the Boolean value for count($r) should be equivalent to the Boolean value of $r
+ q("INSERT INTO locks ( name, locked ) VALUES ( '%s', 1 )",
+ dbesc($fn_name)
+ );
+ $got_lock = true;
+ }
+
+ q("UNLOCK TABLES");
+
+ if(($block) && (! $got_lock))
+ sleep($wait_sec);
+
+ } while(($block) && (! $got_lock) && ((time() - $start) < $timeout));
+
+ 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, $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)
+ );
+
+ if(count($r) && $r[0]['locked'])
+ sleep($wait_sec);
+
+ } while(count($r) && $r[0]['locked'] && ((time() - $start) < $timeout));
+
+ return;
+}}
+
+
+if(! function_exists('unlock_function')) {
+function unlock_function($fn_name) {
+ $r = q("UPDATE locks SET locked = 0 WHERE name = '%s' LIMIT 1",
+ dbesc($fn_name)
+ );
+
+ logger('unlock_function: released lock for function ' . $fn_name, LOGGER_DEBUG);
+
+ return;
+}}
+
+?>