78 lines
1.9 KiB
PHP
78 lines
1.9 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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$r = q("SELECT locked FROM locks WHERE name = '%s' LIMIT 1",
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dbesc($fn_name)
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);
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if((count($r)) && (! $r[0]['locked'])) {
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q("UPDATE locks SET locked = 1 WHERE name = '%s' LIMIT 1",
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dbesc($fn_name)
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);
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$got_lock = true;
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}
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elseif(! $r) { // the Boolean value for count($r) should be equivalent to the Boolean value of $r
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q("INSERT INTO locks ( name, locked ) VALUES ( '%s', 1 )",
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dbesc($fn_name)
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);
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$got_lock = true;
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}
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q("UNLOCK TABLES");
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if(($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($fn_name)
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);
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if(count($r) && $r[0]['locked'])
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sleep($wait_sec);
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} while(count($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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$r = q("UPDATE locks SET locked = 0 WHERE name = '%s' LIMIT 1",
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dbesc($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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?>
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