apcu_entry
(PECL apcu >= 5.1.0)
Atomically fetch or generate a cache entry
Description
Atomically attempts to find key in the cache, if it cannot be found callback is called, passing key as the only argument. The return value of the call is then cached with the optionally specified ttl, and returned.
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 callback into 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 callback is apcu_entry().
Parameters
keyIdentity of cache entry
callbackA callable that accepts
keyas the only argument and returns the value to cache.ttlTime To Live; store the
callback's return value in the cache forttlseconds. After thettlhas passed, the stored entry 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.).
Return Values
Returns the cached value
Examples
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);
?>The above example will output:
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"
}
}