Predefined Constants
It seems there are issues when using APC to cache database result sets as PDOStatements. Any attempts I have made always result in an exception being thrown with the message: 'You cannot serialize or unserialize PDOStatement instances'
APC Functions
Table of Contents
- apc_add — Cache a new variable in the data store
- apc_bin_dump — Get a binary dump of the given files and user variables
- apc_bin_dumpfile — Output a binary dump of cached files and user variables to a file
- apc_bin_load — Load a binary dump into the APC file/user cache
- apc_bin_loadfile — Load a binary dump from a file into the APC file/user cache
- apc_cache_info — Retrieves cached information from APC's data store
- apc_cas — Updates an old value with a new value
- apc_clear_cache — Clears the APC cache
- apc_compile_file — Stores a file in the bytecode cache, bypassing all filters.
- apc_dec — Decrease a stored number
- apc_define_constants — Defines a set of constants for retrieval and mass-definition
- apc_delete_file — Deletes files from the opcode cache
- apc_delete — Removes a stored variable from the cache
- apc_exists — Checks if APC key exists
- apc_fetch — Fetch a stored variable from the cache
- apc_inc — Increase a stored number
- apc_load_constants — Loads a set of constants from the cache
- apc_sma_info — Retrieves APC's Shared Memory Allocation information
- apc_store — Cache a variable in the data store
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User Contributed Notes
APC Functions - [7 notes]
joe at simpson dot com ¶
5 years ago
zytzagoo at NOSPAMPLEASEgmail dot com ¶
5 years ago
Keep in mind to always prefix or suffix your cache key names with something specific to your site/app/setup, to avoid the risk of your apc cache entries being overwritten/deleted/modified by someone else on the same server.
Assume we have some code like this:
<?php apc_store('config', $cfg); ?>
Now assume someone else on the same server is also using 'config' as the key passed to an apc_store(), apc_delete() (etc.) call in some other piece of code on the whole server.
Since you're both working on the exact same cache entry, all sorts of wierd things can happen, but the problem is not in your code at all.
anon ¶
5 years ago
If you don't want any APC info visible without logging in, insert this code at line 173 of apc.php:
<?php
if (!$AUTHENTICATED) {
echo '<div class="authneeded">You need to login to see the user values here!<br/> <br/>';
put_login_link("Login now!");
echo '</div>';
die();
}
?>
bjoern dot andersen at atosorigin dot com ¶
6 years ago
In IIS6 you can't use php_apc.dll with application pools or webgardens (Multi-Instance/Multi-Threading). Maybe this applies even to all Multithreading environments - i don't know.
When you try it, the Application pools terminate when requests run simultaneously.
ashus at atlas dot cz ¶
6 years ago
If you don't really need caching and plan to use it for one page only, you could try an alternative; writing a file and then flushing it back if specified time hasn't passed. I use it to read and parse third party websites, to check for new subtitles and output a RSS xml file.
<?php
if ((is_file($_SERVER['SCRIPT_FILENAME'].'.cached'))
&& (time()-filemtime($_SERVER['SCRIPT_FILENAME'].'.cached') < 3600))
{
readfile($_SERVER['SCRIPT_FILENAME'].'.cached');
exit;
}
// (the php script itself goes here)
echo $out;
$fp = fopen($_SERVER['SCRIPT_FILENAME'].'.cached', 'w');
fwrite($fp, $out);
fclose($fp);
?>
Note, that this only works for pages, which are without GET or POST variables, sessions, etc. You can change the number of seconds the cache works for (3600 = an hour). Also, use "$out.=" instead of "echo" command. Just store all output to that variable (if you need to use it inside a function, use "global $out" instead).
This workaround was written in about 5 minutes and may contain bugs.
dustymugs ¶
6 years ago
In windows, if you load php_apc.dll but do not enable it, apache may crash when attempting to restart or stop.
So, if you've not enabled APC but are loading it, comment out the loading.
mike at eastghost dot com ¶
1 year ago
I've been testing Memcache and Memcached extensions versus storing and fetching data to/from APC. No scientifics or hard numbers yet, but APC seems to be noticeably faster. One drawback appears to be if APC fills, it seems to flush everything alive beyond TTL in a huge purge.