Roland Häder
6a8a36f12d
- count() returns very different results and never a boolean (not even false on error condition). - therefore you should NOT use it in boolean expressions. This still *can* be done in PHP because of its lazyness. But it is discouraged if it comes to more clean code. Signed-off-by: Roland Häder <roland@mxchange.org>
78 lines
2.2 KiB
PHP
78 lines
2.2 KiB
PHP
<?php
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// Provide some ability to lock a PHP function so that multiple processes
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// can't run the function concurrently
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if(! function_exists('lock_function')) {
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function lock_function($fn_name, $block = true, $wait_sec = 2, $timeout = 30) {
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if( $wait_sec == 0 )
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$wait_sec = 2; // don't let the user pick a value that's likely to crash the system
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$got_lock = false;
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$start = time();
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do {
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q("LOCK TABLE `locks` WRITE");
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$r = q("SELECT `locked`, `created` FROM `locks` WHERE `name` = '%s' LIMIT 1",
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dbesc($fn_name)
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);
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if((dbm::is_result($r)) AND (!$r[0]['locked'] OR (strtotime($r[0]['created']) < time() - 3600))) {
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q("UPDATE `locks` SET `locked` = 1, `created` = '%s' WHERE `name` = '%s'",
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dbesc(datetime_convert()),
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dbesc($fn_name)
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);
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$got_lock = true;
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}
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elseif(! dbm::is_result($r)) { // the Boolean value for count($r) should be equivalent to the Boolean value of $r
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q("INSERT INTO `locks` (`name`, `created`, `locked`) VALUES ('%s', '%s', 1)",
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dbesc($fn_name),
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dbesc(datetime_convert())
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);
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$got_lock = true;
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}
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q("UNLOCK TABLES");
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if(($block) && (! $got_lock))
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sleep($wait_sec);
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} while(($block) && (! $got_lock) && ((time() - $start) < $timeout));
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logger('lock_function: function ' . $fn_name . ' with blocking = ' . $block . ' got_lock = ' . $got_lock . ' time = ' . (time() - $start), LOGGER_DEBUG);
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return $got_lock;
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}}
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if(! function_exists('block_on_function_lock')) {
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function block_on_function_lock($fn_name, $wait_sec = 2, $timeout = 30) {
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if( $wait_sec == 0 )
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$wait_sec = 2; // don't let the user pick a value that's likely to crash the system
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$start = time();
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do {
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$r = q("SELECT locked FROM locks WHERE name = '%s' LIMIT 1",
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dbesc($fn_name)
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);
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if(dbm::is_result($r) && $r[0]['locked'])
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sleep($wait_sec);
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} while(dbm::is_result($r) && $r[0]['locked'] && ((time() - $start) < $timeout));
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return;
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}}
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if(! function_exists('unlock_function')) {
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function unlock_function($fn_name) {
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$r = q("UPDATE `locks` SET `locked` = 0, `created` = '0000-00-00 00:00:00' WHERE `name` = '%s'",
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dbesc($fn_name)
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);
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logger('unlock_function: released lock for function ' . $fn_name, LOGGER_DEBUG);
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return;
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}}
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