apcu_entry
(PECL apcu >= 5.1.0)
apcu_entry — Atomically fetch or generate a cache entry
说明
Atomically attempts to find key in the cache, if it cannot be found generator
is called, passing key as the only argument. The return value of the call is then cached with the optionally specified
ttl, and returned.
注意: When control enters apcu_entry() the lock for the cache is acquired exclusively, it is released when control leaves apcu_entry(): In effect, this turns the body of
generatorinto a critical section, disallowing two processes from executing the same code paths concurrently. In addition, it prohibits the concurrent execution of any other APCu functions, since they will acquire the same lock.
The only APCu function that can be called safely by generator is apcu_entry().
参数
-
key -
Identity of cache entry
-
generator -
A callable that accepts
keyas the only argument and returns the value to cache. -
ttl -
Time To Live; store
varin the cache forttlseconds. After thettlhas passed, the stored variable will be expunged from the cache (on the next request). If nottlis supplied (or if thettlis0), the value will persist until it is removed from the cache manually, or otherwise fails to exist in the cache (clear, restart, etc.).
返回值
Returns the cached value
示例
示例 #1 An apcu_entry() example
<?php
$config = apcu_entry("config", function($key) {
return [
"fruit" => apcu_entry("config.fruit", function($key){
return [
"apples",
"pears"
];
}),
"people" => apcu_entry("config.people", function($key){
return [
"bob",
"joe",
"niki"
];
})
];
});
var_dump($config);
?>以上示例会输出：
array(2) {
["fruit"]=>
array(2) {
[0]=>
string(6) "apples"
[1]=>
string(5) "pears"
}
["people"]=>
array(3) {
[0]=>
string(3) "bob"
[1]=>
string(3) "joe"
[2]=>
string(4) "niki"
}
}
参见
- apcu_store() - 缓存一个变量到存储中
- apcu_fetch() - Fetch a stored variable from the cache
- apcu_delete() - Removes a stored variable from the cache
add a note
