<?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; }}