3 // Provide some ability to lock a PHP function so that multiple processes
4 // can't run the function concurrently
5 // The function must have a line inserted into the 'lock' table with the
6 // function's name in the 'name' field
7 if(! function_exists('lock_function')) {
8 function lock_function($fn_name, $block = true, $wait_sec = 2) {
10 $wait_sec = 2; // don't let the user pick a value that's likely to crash the system
15 q("LOCK TABLE lock WRITE");
16 $r = q("SELECT locked FROM lock WHERE name = '%s' LIMIT 1",
20 if((count($r)) && (! $r[0]['locked'])) {
21 q("UPDATE lock SET locked = 1 WHERE name = '%s' LIMIT 1",
26 elseif(! $r) { // the Boolean value for count($r) should be equivalent to the Boolean value of $r
27 q("INSERT INTO lock ( name, locked ) VALUES ( '%s', 1 )",
35 if(($block) && (! $got_lock))
38 } while(($block) && (! $got_lock));
40 logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock, LOGGER_DEBUG);
46 if(! function_exists('block_on_function_lock')) {
47 function block_on_function_lock($fn_name, $wait_sec = 2) {
49 $wait_sec = 2; // don't let the user pick a value that's likely to crash the system
52 $r = q("SELECT locked FROM lock WHERE name = '%s' LIMIT 1",
56 if(count($r) && $r[0]['locked'])
59 } while(count($r) && $r[0]['locked']);
65 if(! function_exists('unlock_function')) {
66 function unlock_function(fn_name) {
67 //$r = q("LOCK TABLE lock WRITE");
68 $r = q("UPDATE lock SET locked = 0 WHERE name = '%s' LIMIT 1",
71 //$r = q("UNLOCK TABLES");
73 logger('unlock_function: released lock for function ' . fn_name, LOGGER_DEBUG);