mirror of
https://github.com/predis/predis.git
synced 2026-08-18 01:50:28 +00:00
Daniele Alessandri
42 lines
1.3 KiB
PHP
42 lines
1.3 KiB
PHP
<?php
|
|
require_once 'SharedConfigurations.php';
|
|
|
|
/*
|
|
This is an implementation of an atomic client-side ZPOP using the support for
|
|
check-and-set (CAS) operations with MULTI/EXEC transactions, as described in
|
|
"WATCH explained" from http://redis.io/topics/transactions
|
|
|
|
First, populate your database with a tiny sample data set:
|
|
|
|
./redis-cli
|
|
SELECT 15
|
|
ZADD zset 1 a
|
|
ZADD zset 2 b
|
|
ZADD zset 3 c
|
|
*/
|
|
|
|
function zpop($client, $zsetKey) {
|
|
$element = null;
|
|
$options = array(
|
|
'cas' => true, // Initialize with support for CAS operations
|
|
'watch' => $zsetKey, // Key that needs to be WATCHed to detect changes
|
|
'retry' => 3, // Number of retries on aborted transactions, after
|
|
// which the client bails out with an exception.
|
|
);
|
|
|
|
$txReply = $client->multiExec($options, function($tx)
|
|
use ($zsetKey, &$element) {
|
|
@list($element) = $tx->zrange($zsetKey, 0, 0);
|
|
if (isset($element)) {
|
|
$tx->multi(); // With CAS, MULTI *must* be explicitly invoked.
|
|
$tx->zrem($zsetKey, $element);
|
|
}
|
|
});
|
|
return $element;
|
|
}
|
|
|
|
$redis = new Predis\Client($single_server, 'dev');
|
|
$zpopped = zpop($redis, 'zset');
|
|
echo isset($zpopped) ? "ZPOPed $zpopped" : "Nothing to ZPOP!", "\n";
|
|
?>
|