Make cache type selectable based on config value

Provie a mechanism to specify cache type from NONE, APC, or MEMCACHE
based on a config variable.

If MEMCACHE type is selected, a list of servers can be specified to
provide multiserver support. Note that php-memcaced is required for
MEMCACHE support.

Lukas: Minor commenting style fixes.

Signed-off-by: Lukas Fleischer <archlinux@cryptocrack.de>

1 files changed, 82 insertions, 0 deletions

diff --git a/web/lib/cachefuncs.inc.php b/web/lib/cachefuncs.inc.php
new file mode 100644
index 0000000..3485b01
--- /dev/null
+++ b/web/lib/cachefuncs.inc.php
@@ -0,0 +1,82 @@
+<?php
+
+if (!defined('CACHE_TYPE')) {
+	define('CACHE_TYPE', 'NONE');
+}
+
+# Check if APC extension is loaded, and set cache prefix if it is.
+if (CACHE_TYPE == 'APC' && !defined('EXTENSION_LOADED_APC')) {
+	define('EXTENSION_LOADED_APC', extension_loaded('apc'));
+	define('CACHE_PREFIX', 'aur:');
+}
+
+# Check if memcache extension is loaded, and set cache prefix if it is.
+if (CACHE_TYPE == 'MEMCACHE' && !defined('EXTENSION_LOADED_MEMCACHE')) {
+	define('EXTENSION_LOADED_MEMCACHE', extension_loaded('memcached'));
+	define('CACHE_PREFIX', 'aur:');
+	global $memcache;
+	$memcache = new Memcached();
+	$mcs = defined('MEMCACHE_SERVERS') ? MEMCACHE_SERVERS : '127.0.0.1:11211';
+	foreach (explode(',', $mcs) as $elem) {
+		$telem = trim($elem);
+		$mcserver = explode(':', $telem);
+		$memcache->addServer($mcserver[0], intval($mcserver[1]));
+	}
+}
+
+# Set a value in the cache (currently APC) if cache is available for use. If
+# not available, this becomes effectively a no-op (return value is
+# false). Accepts an optional TTL (defaults to 600 seconds).
+function set_cache_value($key, $value, $ttl=600) {
+	$status = false;
+	if (defined('EXTENSION_LOADED_APC')) {
+		$status = apc_store(CACHE_PREFIX.$key, $value, $ttl);
+	}
+	if (defined('EXTENSION_LOADED_MEMCACHE')) {
+		global $memcache;
+		$status = $memcache->set(CACHE_PREFIX.$key, $value, $ttl);
+	}
+	return $status;
+}
+
+# Get a value from the cache (currently APC) if cache is available for use. If
+# not available, this returns false (optionally sets passed in variable $status
+# to false, much like apc_fetch() behaves). This allows for testing the fetch
+# result appropriately even in the event that a 'false' value was the value in
+# the cache.
+function get_cache_value($key, &$status=false) {
+	if(defined('EXTENSION_LOADED_APC')) {
+		$ret = apc_fetch(CACHE_PREFIX.$key, $status);
+		if ($status) {
+			return $ret;
+		}
+	}
+	if (defined('EXTENSION_LOADED_MEMCACHE')) {
+		global $memcache;
+		$ret = $memcache->get(CACHE_PREFIX.$key);
+		if (!$ret) {
+			$status = false;
+		}
+		else {
+			$status = true;
+		}
+		return $ret;
+	}
+	return $status;
+}
+
+# Run a simple db query, retrieving and/or caching the value if APC is
+# available for use. Accepts an optional TTL value (defaults to 600 seconds).
+function db_cache_value($dbq, $dbh, $key, $ttl=600) {
+	$status = false;
+	$value = get_cache_value($key, $status);
+	if (!$status) {
+		$result = db_query($dbq, $dbh);
+		$row = mysql_fetch_row($result);
+		$value = $row[0];
+		set_cache_value($key, $value, $ttl);
+	}
+	return $value;
+}
+
+?>