Commit 586709bc authored by robertDouglass's avatar robertDouglass
Browse files

shuffling file names and moving current memcache.inc to memcache.db.inc in...

shuffling file names and moving current memcache.inc to memcache.db.inc in preparation for a memcache-only memcache.inc
parent 458a8114
<?php
// $Id$
global $_memcache_statistics;
$_memcache_statistics = array('get' => array(), 'set' => array(), 'hit' => array());
/*
* A memcache API for Drupal.
*/
/**
* Place an item into memcache
*
* @param $key The string with with you will retrieve this item later.
* @param $value The item to be stored.
* @param $exp Parameter expire is expiration time in seconds. If it's 0, the item never expires
* (but memcached server doesn't guarantee this item to be stored all the time, it could be
* deleted from the cache to make place for other items).
* @param $bin The name of the Drupal subsystem that is making this call. Examples could be
* 'cache', 'alias', 'taxonomy term' etc. It is possible to map different $bin values to
* different memcache servers.
*
* @return bool
*/
function dmemcache_set($key, $value, $exp = 0, $bin = 'cache') {
global $_memcache_statistics;
$_memcache_statistics['set'][] = $key;
$_memcache_statistics['bins'][] = $bin;
if ($mc = dmemcache_object($bin)) {
$full_key = dmemcache_key($key, $bin);
if (!$mc->set($full_key, $value, TRUE, $exp)) {
watchdog('memcache', 'Failed to set key: ' . $full_key, WATCHDOG_ERROR);
}
else {
return TRUE;
}
}
return FALSE;
}
/**
* Retrieve a value from the cache.
*
* @param $key The key with which the item was stored.
* @param $bin The bin in which the item was stored.
*
* @return The item which was originally saved or FALSE
*/
function dmemcache_get($key, $bin = 'cache') {
global $_memcache_statistics;
$_memcache_statistics['get'][] = $key;
$_memcache_statistics['bins'][] = $bin;
if ($mc = dmemcache_object($bin)) {
$full_key = dmemcache_key($key, $bin);
$result = $mc->get($full_key);
if ($result) {
$_memcache_statistics['hit'][] = $key;
}
return $result;
}
}
/**
* Deletes an item from the cache.
*
* @param $key The key with which the item was stored.
* @param $bin The bin in which the item was stored.
*
* @return Returns TRUE on success or FALSE on failure.
*/
function dmemcache_delete($key, $bin = 'cache') {
if ($mc = dmemcache_object($bin)) {
$full_key = dmemcache_key($key, $bin);
return $mc->delete($full_key);
}
return FALSE;
}
/**
* Immediately invalidates all existing items. dmemcache_flush doesn't actually free any
* resources, it only marks all the items as expired, so occupied memory will be overwritten by
* new items.
*
* @param $bin The bin to flush. Note that this will flush all bins mapped to the same server
* as $bin. There is no way at this time to empty just one bin.
*
* @return Returns TRUE on success or FALSE on failure.
*/
function dmemcache_flush($bin = 'cache') {
if ($mc = dmemcache_object($bin)) {
return $mc->flush();
}
}
function dmemcache_stats($bin = 'cache') {
if ($mc = dmemcache_object($bin)) {
return $mc->getStats();
}
}
/**
* Returns an Memcache object based on the bin requested. Note that there is
* nothing preventing developers from calling this function directly to get the
* Memcache object. Do this if you need functionality not provided by this API
* or if you need to use legacy code. Otherwise, use the dmemcache (get, set,
* delete, flush) API functions provided here.
*
* @param $bin The bin which is to be used.
*
* @param $flush Rebuild the bin/server/cache mapping.
*
* @return an Memcache object or FALSE.
*/
function dmemcache_object($bin = NULL, $flush = FALSE) {
static $memcacheCache = array(), $memcache_servers, $memcache_bins;
if ($flush) {
foreach ($memcacheCache as $cluster) {
$cluster->close();
}
$memcacheCache = array();
}
if (empty($memcacheCache) || empty($memcacheCache[$bin])) {
// $memcache_servers and $memcache_bins originate from settings.php.
// $memcache_servers_custom and $memcache_bins_custom get set by
// memcache.module. They are then merged into $memcache_servers and
// $memcache_bins, which are statically cached for performance.
if (empty($memcache_servers)) {
// Values from settings.php
$memcache_servers = variable_get('memcache_servers', array('127.0.0.1:11211' => 'default'));
$memcache_bins = variable_get('memcache_bins', array('cache' => 'default'));
}
// If there is no cluster for this bin in $memcache_bins, cluster is 'default'.
$cluster = empty($memcache_bins[$bin]) ? 'default' : $memcache_bins[$bin];
// If this bin isn't in our $memcache_bins configuration array, and the
// 'default' cluster is already initialized, map the bin to 'cache' because
// we always map the 'cache' bin to the 'default' cluster.
if (empty($memcache_bins[$bin]) && !empty($memcacheCache['cache'])) {
$memcacheCache[$bin] = &$memcacheCache['cache'];
}
else {
// Create a new Memcache object. Each cluster gets its own Memcache object.
$memcache = new Memcache;
// A variable to track whether we've connected to the first server.
$init = FALSE;
// Link all the servers to this cluster.
foreach ($memcache_servers as $s => $c) {
if ($c == $cluster) {
list($host, $port) = explode(':', $s);
// This is a server that belongs to this cluster.
if (!$init) {
// First server gets the connect.
if (@$memcache->addServer($host, $port)) {
// Only set init to true if a connection was made.
$init = TRUE;
}
}
else {
// Subsequent servers gett addServer.
@$memcache->addServer($host, $port);
}
}
}
if ($init) {
// Map the current bin with the new Memcache object.
$memcacheCache[$bin] = $memcache;
// Now that all the servers have been mapped to this cluster, look for
// other bins that belong to the cluster and map them too.
foreach ($memcache_bins as $b => $c) {
if ($c == $cluster && $b != $bin) {
// Map this bin and cluster by reference.
$memcacheCache[$b] = &$memcacheCache[$bin];
}
}
}
}
}
return empty($memcacheCache[$bin]) ? FALSE : $memcacheCache[$bin];
}
function dmemcache_key($key, $bin = 'cache') {
static $prefix;
// memcache_key_prefix can be set in settings.php to support site namespaces
// in a multisite environment.
if (empty($prefix)) {
$prefix = variable_get('memcache_key_prefix', '');
}
$full_key = ($prefix ? $prefix. '-' : '') . $bin . '-' . $key;
return urlencode($full_key);
}
/** Implementation of cache.inc with memcache logic included **/
/**
* Return data from the persistent cache.
*
* @param $key
* The cache ID of the data to retrieve.
* @param $table
* The table $table to store the data in. Valid core values are 'cache_filter',
* 'cache_menu', 'cache_page', or 'cache' for the default cache.
*/
function cache_get($key, $table = 'cache') {
global $user;
// Garbage collection necessary when enforcing a minimum cache lifetime
$cache_flush = variable_get('cache_flush', 0);
if ($cache_flush && ($cache_flush + variable_get('cache_lifetime', 0) <= time())) {
// Time to flush old cache data
db_query("DELETE FROM {%s} WHERE expire != %d AND expire <= %d", $table, CACHE_PERMANENT, $cache_flush);
variable_set('cache_flush', 0);
}
// If we have a memcache hit for this, return it.
if ($cache = dmemcache_get($key, $table)) {
return $cache;
}
// Look for a database cache hit.
if ($cache = db_fetch_object(db_query("SELECT data, created, headers, expire, serialized FROM {%s} WHERE cid = '%s'", $table, $key))) {
if (isset($cache->data)) {
// If the data is permanent or we're not enforcing a minimum cache lifetime
// always return the cached data.
if ($cache->expire == CACHE_PERMANENT || !variable_get('cache_lifetime', 0)) {
$cache->data = db_decode_blob($cache->data);
if ($cache->serialized) {
$cache->data = unserialize($cache->data);
}
}
// If enforcing a minimum cache lifetime, validate that the data is
// currently valid for this user before we return it by making sure the
// cache entry was created before the timestamp in the current session's
// cache timer. The cache variable is loaded into the $user object by
// sess_read() in session.inc.
else {
if ($user->cache > $cache->created) {
// This cache data is too old and thus not valid for us, ignore it.
return 0;
}
else {
$cache->data = db_decode_blob($cache->data);
if ($cache->serialized) {
$cache->data = unserialize($cache->data);
}
}
}
}
// By calling cache_set with an extra paramater to signify no db storage,
// we can lazy instantiate memcache that just comes online.
cache_set($key, $table, $cache->data, $cache->expire, $cache->headers, FALSE);
return $cache;
}
return 0;
}
/**
* Store data in the persistent cache.
*
* The persistent cache is split up into four database
* tables. Contributed modules can add additional tables.
*
* 'cache_page': This table stores generated pages for anonymous
* users. This is the only table affected by the page cache setting on
* the administrator panel.
*
* 'cache_menu': Stores the cachable part of the users' menus.
*
* 'cache_filter': Stores filtered pieces of content. This table is
* periodically cleared of stale entries by cron.
*
* 'cache': Generic cache storage table.
*
* The reasons for having several tables are as follows:
*
* - smaller tables allow for faster selects and inserts
* - we try to put fast changing cache items and rather static
* ones into different tables. The effect is that only the fast
* changing tables will need a lot of writes to disk. The more
* static tables will also be better cachable with MySQL's query cache
*
* @param $cid
* The cache ID of the data to store.
* @param $table
* The table $table to store the data in. Valid core values are 'cache_filter',
* 'cache_menu', 'cache_page', or 'cache'.
* @param $data
* The data to store in the cache. Complex data types must be serialized first.
* @param $expire
* One of the following values:
* - CACHE_PERMANENT: Indicates that the item should never be removed unless
* explicitly told to using cache_clear_all() with a cache ID.
* - CACHE_TEMPORARY: Indicates that the item should be removed at the next
* general cache wipe.
* - A Unix timestamp: Indicates that the item should be kept at least until
* the given time, after which it behaves like CACHE_TEMPORARY.
* @param $headers
* A string containing HTTP header information for cached pages.
* @param $db_storage
* This boolean is unique to the memcache.inc implementation of cache set.
* It allows us to do a cache_set and not write to the database, but only
* to memcache.
*/
function cache_set($cid, $table = 'cache', $data, $expire = CACHE_PERMANENT, $headers = NULL, $db_storage = TRUE) {
// Create new cache object.
$cache = new stdClass;
$cache->cid = $cid;
$cache->data = $data;
$cache->created = time();
$cache->expire = $expire;
$cache->headers = $headers;
if ($db_storage) {
$serialized = 0;
if (is_object($data) || is_array($data)) {
$data = serialize($data);
$serialized = 1;
}
// Save to the database
db_lock_table($table);
db_query("UPDATE {$table} SET data = %b, created = %d, expire = %d, headers = '%s', serialized = %d WHERE cid = '%s'", $data, time(), $expire, $headers, $serialized, $cid);
if (!db_affected_rows()) {
@db_query("INSERT INTO {$table} (cid, data, created, expire, headers, serialized) VALUES ('%s', %b, %d, %d, '%s', %d)", $cid, $data, time(), $expire, $headers, $serialized);
}
db_unlock_tables();
}
// Save to memcache
if ($expire == CACHE_PERMANENT || $expire > time()) {
dmemcache_set($cid, $cache, $expire, $table);
}
}
/**
*
* Expire data from the cache. If called without arguments, expirable
* entries will be cleared from the cache_page table.
*
* @param $cid
* If set, the cache ID to delete. Otherwise, all cache entries that can
* expire are deleted.
*
* @param $table
* If set, the table $table to delete from. Mandatory
* argument if $cid is set.
*
* @param $wildcard
* If set to TRUE, the $cid is treated as a substring
* to match rather than a complete ID. The match is a right hand
* match. If '*' is given as $cid, the table $table will be emptied.
*/
function cache_clear_all($cid = NULL, $table = NULL, $wildcard = FALSE) {
global $user;
// Memcache logic is simpler because memcache doesn't have a minimum cache
// lifetime consideration (it handles it internally), and doesn't support
// wildcards.
$bin = empty($table) ? 'cache' : $table;
if (empty($cid) || $cid == '*') {
dmemcache_flush($table);
}
else {
dmemcache_delete($cid, $table);
}
if (!isset($cid) && !isset($table)) {
cache_clear_all(NULL, 'cache_page');
return;
}
if (empty($cid)) {
if (variable_get('cache_lifetime', 0)) {
// We store the time in the current user's $user->cache variable which
// will be saved into the sessions table by sess_write(). We then
// simulate that the cache was flushed for this user by not returning
// cached data that was cached before the timestamp.
$user->cache = time();
$cache_flush = variable_get('cache_flush', 0);
if ($cache_flush == 0) {
// This is the first request to clear the cache, start a timer.
variable_set('cache_flush', time());
}
else if (time() > ($cache_flush + variable_get('cache_lifetime', 0))) {
// Clear the cache for everyone, cache_flush_delay seconds have
// passed since the first request to clear the cache.
db_query("DELETE FROM {%s} WHERE expire != %d AND expire < %d", $table, CACHE_PERMANENT, time());
variable_set('cache_flush', 0);
}
}
else {
// No minimum cache lifetime, flush all temporary cache entries now.
db_query("DELETE FROM {%s} WHERE expire != %d AND expire < %d", $table, CACHE_PERMANENT, time());
}
}
else {
if ($wildcard) {
if ($cid == '*') {
db_query("DELETE FROM {%s}", $table);
}
else {
db_query("DELETE FROM {%s} WHERE cid LIKE '%s%%'", $table, $cid);
}
}
else {
db_query("DELETE FROM {%s} WHERE cid = '%s'", $table, $cid);
}
}
}
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