(PECL memcache >= 1.0.0)
Memcache::flush — 清洗（删除）已经存储的所有的元素
Memcache::flush()立即使所有已经存在的元素失效。方法 Memcache::flush() 并不会真正的释放任何资源，而是仅仅标记所有元素都失效了，因此已经被使用的内存会被新的元素复写。 同样你也可以使用函数 memcache_flush()完成相同功能。
成功时返回 TRUE， 或者在失败时返回 FALSE。
Example #1 Memcache::flush()示例
<?php
/* procedural API */
$memcache_obj = memcache_connect('memcache_host', 11211);
memcache_flush($memcache_obj);
/* OO API */
$memcache_obj = new Memcache;
$memcache_obj->connect('memcache_host', 11211);
$memcache_obj->flush();
?>
Anonymous (2008-02-27 07:51:17)
From the memcached mailing list:
"The flush has a one second granularity. The flush will expire all items up to the ones set within the same second."
It is imperative to wait at least one second after flush() command before further actions like repopulating the cache. Ohterwise new items < 1 second after flush() would be invalidatet instantaneous.
Example:
<?php
$memcache->flush();
$time = time()+1; //one second future
while(time() < $time) {
//sleep
}
$memcache->set('key', 'value'); // repopulate the cache
?>
maarten d/ot manders a/t tilllate dotcom (2007-07-12 01:20:15)
Please note that after flushing, you have to wait a certain amount of time (in my case < 1s) to be able to write to Memcached again. If you don't, Memcached::set() will return 1, although your data is in fact not saved.