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Dokumen ini menggunakan Manual laman web PHP Cina Lepaskan
(PECL apc >= 3.0.0)
apc_store — Cache a variable in the data store
$key
, mixed $var
[, int $ttl
= 0
] )$values
[, mixed $unused
= NULL
[, int $ttl
= 0
]] )缓存一个变量到APC中
Note: 与PHP中其他的机制不同,使用 apc_store() 存储的变量 在不同的请求之间一直持久存在(直到从缓存系统中移除)。
key
存储缓存变量使用的名称.key
是唯一的,所以
两个值使用同一个 key
,原来的将被新的值覆盖。
var
The variable to store
ttl
生存时间;在缓存中存储var
共ttl
秒,
在ttl
秒过去后,存储的变量将会从缓存中擦除(在下一次请求时),
如果没有设置ttl
(或者ttl
是0),
变量将一直存活到被手动移除为止,除此之外不在缓存中的可能原因是,
缓存系统使用clear,或者restart等。
values
Names in key, variables in value.
成功时返回 TRUE
, 或者在失败时返回 FALSE
。
Second syntax returns array with error keys.
Example #1 apc_store() 例子
<?php
$bar = 'BAR' ;
apc_store ( 'foo' , $bar );
var_dump ( apc_fetch ( 'foo' ));
?>
以上例程会输出:
string(3) "BAR"
[#1] brunohass2303 at gmail dot com [2013-06-05 18:10:14]
Functions to update arrays and get the values from an unique key.
<?php
function apc_array_store($apc_var, $key, $valor)
{
$apcTemp = array();
if ( $valor == NULL ) return FALSE;
if ( $apcTemp = apc_fetch($apc_var) ) // Verifica se a variavel $apc_var existe no cache APC
{ // Se existir
if ( !array_key_exists($apcTemp, $key) ) // Verifica se a chave $key existe no array
$apcTemp[$key] = $valor; // Se $valor n?o for NULL, adiciona no array
if ( apc_store("$apc_var", $apcTemp) ) // Tenta atualizar o array no cache
return TRUE;
else return FALSE;
}
else
{ // Se a variavel $apc_var nao existir no cache adiciona
if ( $valor == NULL ) // Se $valor for NULL retorna FALSE
return FALSE;
else
{ // Se $valor n?o for NULL, cria o array
$apcTemp[$key] = $valor;
if ( apc_add("$apc_var", $apcTemp) ) // Tenta adicionar o array no cache
return TRUE;
else return FALSE;
}
}
}
function apc_array_fetch($apc_var, $key)
{
if ( $apcTemp = apc_fetch($apc_var) ) // Verifica se a variavel $apc_var existe no cache APC
{ // Se existir
if ( !array_key_exists($apcTemp, $key) ) // Verifica se a chave $key existe no array
return FALSE; // Se n?o existir retorna FALSE
else
return $apcTemp[$key]; // Se existir retorna o valor
}
else // Se n?o existir
return FALSE;
}
?>
[#2] Anonymous [2013-05-31 09:44:20]
Interesting info to read before apc_store() implementation:
http://stackoverflow.com/questions/10494744/deadlock-with-apc-exists-apc-add-apc-php
http://stackoverflow.com/questions/4468805/apc-values-randomly-disappear/4532905#4532905
[#3] alexey dot maksutov at gmail dot com [2013-05-22 21:13:53]
APC does serialization/deserialization during store/fetch operations as well as it calls __sleep()/__wakeup(), or Serializable::serialize()/Serializable::unserialize(). Tested on PHP 5.4.1.0.
[#4] MaxTheDragon at home dot nl [2012-09-21 13:39:30]
When specifying a ttl (Time-To-Live), you are allowed to use negative values. This causes a stored entry to be invalidated immediately, but note that it will not physically be removed until you read (eg. apc_fetch or apc_exists) it:
<?php
apc_store('testKey', 'testValue', -1); // ... or any negative integer.
// at this point, the key exists physically but is already technically invalidated by the ttl.
$test = apc_fetch('testKey'); // $test equals false.
// at this point, the key no longer exists physically.
?>
Although you could mimic apc_delete with a negative TTL (like when dealing with cookies), note that the difference is that apc_delete actually physically removes the entry.
This example comes in handy when you want to unit-test a class that uses APC. It's faster to use a negative TTL than a positive in combination with a sleep call to test whether the cache entry has actually been deleted. Other than that I can't think of any situations in which you could use this example, but I'm simply pointing out that doing this will not generate Exceptions or errors.
[#5] danil dot gazizov at gmail dot com [2012-02-03 11:49:38]
Don't save empty arrays and empty values. Sometimes, you can get wrong apc_exists($someKey) result, that this key doesn't exists.
[#6] pere dot cil dot remove dot this at wanadoo dot fr [2011-12-09 01:49:41]
Note that caching resources is not possible; even if the apc cache doesn't seems to call the serialize / unserialize functions, that doesn't means that resources can be cached!
Small non-working example:
<?php
// Setter code
$r = fopen( '/tmp/test.txt', 'r' );
var_dump( $r );
apc_store( 'test', $r );
?>
<?php
// Getter code
$d = apc_fetch( 'test' );
var_dump( $d );
echo fread( $d, 1024 );
?>
var_dump( $d ) returns Resource #n of type (Unknown). The resource is still here, but unavailable.
[#7] Dominik Deobald / Interdose [2010-11-17 11:17:49]
It might be interesting to note that storing an object in the cache does not serialize the object, i.e. does not call the __sleep()/__wakeup() or serialize()/unserialize() methods.
[#8] TaRaKa [2010-08-25 01:32:34]
Note APC version 3.1.3 there is a bug (http://pecl.php.net/bugs/bug.php?id=16814) that will display a cache slam averted warning for all writes to a cache var that exists. Slam checking can be disabled by setting apc.slam_defense = 0.
[#9] eda-qa at disemia dot com [2010-01-05 07:40:48]
Note that the TTL only takes effect when you attempt to access the variable again (at least in my version). That is, just issuing a new request to a page won't clear outdated items -- you have to call apc_fetch on that specific item.
If you call apc_info after the TTL of an item it will still be listed.
This is important if you are expecting items to be cleared to conserve memory.
[#10] sebastian at 7val dot com [2008-03-10 00:53:32]
Note that since APC 3.0.15 or 3.0.16, the time-to-live-feature does not work within the same request (see http://pecl.php.net/bugs/bug.php?id=13331).
[#11] JaskaS [2007-03-01 06:06:23]
if you want to store array of objects in apc use ArrayObject wrapper (PHP5).
<?php
$objs = array();
$objs[] = new TestClass();
$objs[] = new TestClass();
$objs[] = new TestClass();
//Doesn't work
apc_store('objs',$objs,60);
$tmp = apc_fetch('objs');
print_r($tmp);
//Works
apc_store('objs',new ArrayObject($objs),60);
$tmp = apc_fetch('objs');
print_r($tmp->getArrayCopy());
?>
[#12] Roberto Spadim [2007-01-12 02:11:49]
be sure that setting FALSE values can be wrong returned from fetch since fetch return FALSE on errors
[#13] php at tequilasolutions dot com [2006-11-03 03:45:27]
Seems to be no (easy) way at the to know how old a value fetched is and to check whether it is out of date.
I've made these wrappers so that you can fetch and store values based on a udt returned from get_last_modified_date() which should return a udt of when your data was last changed, and hence needs junking out of the cache.
<?php
function apc_fetch_udt($key){
$g = apc_fetch($key);
if ($g){
list($udt,$val) = $g;
if (get_last_modified_date()<$udt) {
$val = unserialize($val);
return $val;
} else {
apc_delete($key);
}
}
}
function apc_store_udt($key,$g){
$udt = time();
$g = serialize($g);
$apc = array($udt,$g);
apc_store($key, $apc);
}
?>