Build/Test Tools: Add an object cache drop-in.

This adds an object cache drop-in to the `tests/phpunit/includes` directory to avoid relying on and having to copy from an external repository.

Follow up to [50313].

See #50401.

git-svn-id: https://develop.svn.wordpress.org/branches/4.5@50315 602fd350-edb4-49c9-b593-d223f7449a82

1 files changed, 2106 insertions, 0 deletions

diff --git a/tests/phpunit/includes/object-cache.php b/tests/phpunit/includes/object-cache.php
new file mode 100644
index 0000000000..51f3e910b9
--- /dev/null
+++ b/tests/phpunit/includes/object-cache.php
@@ -0,0 +1,2106 @@
+<?php
+/**
+ * Adds a value to cache.
+ *
+ * If the specified key already exists, the value is not stored and the function
+ * returns false.
+ *
+ * @link http://www.php.net/manual/en/memcached.add.php
+ *
+ * @param string    $key        The key under which to store the value.
+ * @param mixed     $value      The value to store.
+ * @param string    $group      The group value appended to the $key.
+ * @param int       $expiration The expiration time, defaults to 0.
+ * @return bool                 Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_add( $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->add( $key, $value, $group, $expiration );
+}
+
+/**
+ * Adds a value to cache on a specific server.
+ *
+ * Using a server_key value, the object can be stored on a specified server as opposed
+ * to a random server in the stack. Note that this method will add the key/value to the
+ * _cache object as part of the runtime cache. It will add it to an array for the
+ * specified server_key.
+ *
+ * @link http://www.php.net/manual/en/memcached.addbykey.php
+ *
+ * @param string    $server_key     The key identifying the server to store the value on.
+ * @param string    $key            The key under which to store the value.
+ * @param mixed     $value          The value to store.
+ * @param string    $group          The group value appended to the $key.
+ * @param int       $expiration     The expiration time, defaults to 0.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_add_by_key( $server_key, $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->addByKey( $server_key, $key, $value, $group, $expiration );
+}
+
+/**
+ * Add a single server to the list of Memcached servers.
+ *
+ * @link http://www.php.net/manual/en/memcached.addserver.php
+ *
+ * @param string        $host   The hostname of the memcache server.
+ * @param int           $port   The port on which memcache is running.
+ * @param int           $weight The weight of the server relative to the total weight of all the servers in the pool.
+ * @return bool                 Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_add_server( $host, $port, $weight = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->addServer( $host, $port, $weight );
+}
+
+/**
+ * Adds an array of servers to the pool.
+ *
+ * Each individual server in the array must include a domain and port, with an optional
+ * weight value: $servers = array( array( '127.0.0.1', 11211, 0 ) );
+ *
+ * @link http://www.php.net/manual/en/memcached.addservers.php
+ *
+ * @param array     $servers    Array of server to register.
+ * @return bool                 True on success; false on failure.
+ */
+function wp_cache_add_servers( $servers ) {
+	global $wp_object_cache;
+	return $wp_object_cache->addServers( $servers );
+}
+
+/**
+ * Append data to an existing item.
+ *
+ * This method should throw an error if it is used with compressed data. This
+ * is an expected behavior. Memcached casts the value to be appended to the initial value to the
+ * type of the initial value. Be careful as this leads to unexpected behavior at times. Due to
+ * how memcached treats types, the behavior has been mimicked in the internal cache to produce
+ * similar results and improve consistency. It is recommend that appends only occur with data of
+ * the same type.
+ *
+ * @link http://www.php.net/manual/en/memcached.append.php
+ *
+ * @param string    $key    The key under which to store the value.
+ * @param mixed     $value  Must be string as appending mixed values is not well-defined
+ * @param string    $group  The group value appended to the $key.
+ * @return bool             Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_append( $key, $value, $group = '' ) {
+	global $wp_object_cache;
+	return $wp_object_cache->append( $key, $value, $group );
+}
+
+/**
+ * Append data to an existing item by server key.
+ *
+ * This method should throw an error if it is used with compressed data. This
+ * is an expected behavior. Memcached casts the value to be appended to the initial value to the
+ * type of the initial value. Be careful as this leads to unexpected behavior at times. Due to
+ * how memcached treats types, the behavior has been mimicked in the internal cache to produce
+ * similar results and improve consistency. It is recommend that appends only occur with data of
+ * the same type.
+ *
+ * @link http://www.php.net/manual/en/memcached.appendbykey.php
+ *
+ * @param string    $server_key     The key identifying the server to store the value on.
+ * @param string    $key            The key under which to store the value.
+ * @param mixed     $value          Must be string as appending mixed values is not well-defined
+ * @param string    $group          The group value appended to the $key.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_append_by_key( $server_key, $key, $value, $group = '' ) {
+	global $wp_object_cache;
+	return $wp_object_cache->appendByKey( $server_key, $key, $value, $group );
+}
+
+/**
+ * Performs a "check and set" to store data.
+ *
+ * The set will be successful only if the no other request has updated the value since it was fetched by
+ * this request.
+ *
+ * @link http://www.php.net/manual/en/memcached.cas.php
+ *
+ * @param float     $cas_token  Unique value associated with the existing item. Generated by memcached.
+ * @param string    $key        The key under which to store the value.
+ * @param mixed     $value      The value to store.
+ * @param string    $group      The group value appended to the $key.
+ * @param int       $expiration The expiration time, defaults to 0.
+ * @return bool                 Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_cas( $cas_token, $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->cas( $cas_token, $key, $value, $group, $expiration );
+}
+
+/**
+ * Performs a "check and set" to store data with a server key.
+ *
+ * The set will be successful only if the no other request has updated the value since it was fetched by
+ * this request.
+ *
+ * @link http://www.php.net/manual/en/memcached.casbykey.php
+ *
+ * @param string    $server_key The key identifying the server to store the value on.
+ * @param float     $cas_token  Unique value associated with the existing item. Generated by memcached.
+ * @param string    $key        The key under which to store the value.
+ * @param mixed     $value      The value to store.
+ * @param string    $group      The group value appended to the $key.
+ * @param int       $expiration The expiration time, defaults to 0.
+ * @return bool                 Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_cas_by_key( $cas_token, $server_key, $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->casByKey( $cas_token, $server_key, $key, $value, $group, $expiration );
+}
+
+/**
+ * Closes the cache.
+ *
+ * This function has ceased to do anything since WordPress 2.5. The
+ * functionality was removed along with the rest of the persistent cache. This
+ * does not mean that plugins can't implement this function when they need to
+ * make sure that the cache is cleaned up after WordPress no longer needs it.
+ *
+ * @since 2.0.0
+ *
+ * @return  bool    Always returns True
+ */
+function wp_cache_close() {
+	return true;
+}
+
+/**
+ * Decrement a numeric item's value.
+ *
+ * @link http://www.php.net/manual/en/memcached.decrement.php
+ *
+ * @param string    $key    The key under which to store the value.
+ * @param int       $offset The amount by which to decrement the item's value.
+ * @param string    $group  The group value appended to the $key.
+ * @return int|bool         Returns item's new value on success or FALSE on failure.
+ */
+function wp_cache_decrement( $key, $offset = 1, $group = '' ) {
+	global $wp_object_cache;
+	return $wp_object_cache->decrement( $key, $offset, $group );
+}
+
+/**
+ * Decrement a numeric item's value.
+ *
+ * Same as wp_cache_decrement. Original WordPress caching backends use wp_cache_decr. I
+ * want both spellings to work.
+ *
+ * @link http://www.php.net/manual/en/memcached.decrement.php
+ *
+ * @param string    $key    The key under which to store the value.
+ * @param int       $offset The amount by which to decrement the item's value.
+ * @param string    $group  The group value appended to the $key.
+ * @return int|bool         Returns item's new value on success or FALSE on failure.
+ */
+function wp_cache_decr( $key, $offset = 1, $group = '' ) {
+	return wp_cache_decrement( $key, $offset, $group );
+}
+
+/**
+ * Remove the item from the cache.
+ *
+ * Remove an item from memcached with identified by $key after $time seconds. The
+ * $time parameter allows an object to be queued for deletion without immediately
+ * deleting. Between the time that it is queued and the time it's deleted, add,
+ * replace, and get will fail, but set will succeed.
+ *
+ * @link http://www.php.net/manual/en/memcached.delete.php
+ *
+ * @param string    $key    The key under which to store the value.
+ * @param string    $group  The group value appended to the $key.
+ * @param int       $time   The amount of time the server will wait to delete the item in seconds.
+ * @return bool             Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_delete( $key, $group = '', $time = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->delete( $key, $group, $time );
+}
+
+/**
+ * Remove the item from the cache by server key.
+ *
+ * Remove an item from memcached with identified by $key after $time seconds. The
+ * $time parameter allows an object to be queued for deletion without immediately
+ * deleting. Between the time that it is queued and the time it's deleted, add,
+ * replace, and get will fail, but set will succeed.
+ *
+ * @link http://www.php.net/manual/en/memcached.deletebykey.php
+ *
+ * @param string        $server_key The key identifying the server to store the value on.
+ * @param string        $key        The key under which to store the value.
+ * @param string        $group      The group value appended to the $key.
+ * @param int           $time       The amount of time the server will wait to delete the item in seconds.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_delete_by_key( $server_key, $key, $group = '', $time = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->deleteByKey( $server_key, $key, $group, $time );
+}
+
+/**
+ * Fetch the next result.
+ *
+ * @link http://www.php.net/manual/en/memcached.fetch.php
+ *
+ * @return  array|bool   Returns the next result or FALSE otherwise.
+ */
+function wp_cache_fetch() {
+	global $wp_object_cache;
+	return $wp_object_cache->fetch();
+}
+
+/**
+ * Fetch all remaining results from the last request.
+ *
+ * @link http://www.php.net/manual/en/memcached.fetchall.php
+ *
+ * @return  array|bool  Returns the results or FALSE on failure.
+ */
+function wp_cache_fetch_all() {
+	global $wp_object_cache;
+	return $wp_object_cache->fetchAll();
+}
+
+/**
+ * Invalidate all items in the cache.
+ *
+ * @link http://www.php.net/manual/en/memcached.flush.php
+ *
+ * @param int       $delay  Number of seconds to wait before invalidating the items.
+ * @return bool             Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_flush( $delay = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->flush( $delay );
+}
+
+/**
+ * Retrieve object from cache.
+ *
+ * Gets an object from cache based on $key and $group. In order to fully support the $cache_cb and $cas_token
+ * parameters, the runtime cache is ignored by this function if either of those values are set. If either of
+ * those values are set, the request is made directly to the memcached server for proper handling of the
+ * callback and/or token.
+ *
+ * Note that the $deprecated and $found args are only here for compatibility with the native wp_cache_get function.
+ *
+ * @link http://www.php.net/manual/en/memcached.get.php
+ *
+ * @param string        $key        The key under which to store the value.
+ * @param string        $group      The group value appended to the $key.
+ * @param bool          $force      Whether or not to force a cache invalidation.
+ * @param null|bool     $found      Variable passed by reference to determine if the value was found or not.
+ * @param null|string   $cache_cb   Read-through caching callback.
+ * @param null|float    $cas_token  The variable to store the CAS token in.
+ * @return bool|mixed               Cached object value.
+ */
+function wp_cache_get( $key, $group = '', $force = false, &$found = null, $cache_cb = null, &$cas_token = null ) {
+	global $wp_object_cache;
+
+	if ( func_num_args() > 4 )
+		return $wp_object_cache->get( $key, $group, $force, $found, '', false, $cache_cb, $cas_token );
+	else
+		return $wp_object_cache->get( $key, $group, $force, $found );
+}
+
+/**
+ * Retrieve object from cache from specified server.
+ *
+ * Gets an object from cache based on $key, $group and $server_key. In order to fully support the $cache_cb and $cas_token
+ * parameters, the runtime cache is ignored by this function if either of those values are set. If either of
+ * those values are set, the request is made directly to the memcached server for proper handling of the
+ * callback and/or token.
+ *
+ * @link http://www.php.net/manual/en/memcached.getbykey.php
+ *
+ * @param string        $server_key The key identifying the server to store the value on.
+ * @param string        $key        The key under which to store the value.
+ * @param string        $group      The group value appended to the $key.
+ * @param bool          $force      Whether or not to force a cache invalidation.
+ * @param null|bool     $found      Variable passed by reference to determine if the value was found or not.
+ * @param null|string   $cache_cb   Read-through caching callback.
+ * @param null|float    $cas_token  The variable to store the CAS token in.
+ * @return bool|mixed               Cached object value.
+ */
+function wp_cache_get_by_key( $server_key, $key, $group = '', $force = false, &$found = null, $cache_cb = NULL, &$cas_token = NULL ) {
+	global $wp_object_cache;
+
+	if ( func_num_args() > 5 )
+		return $wp_object_cache->getByKey( $server_key, $key, $group, $force, $found, $cache_cb, $cas_token );
+	else
+		return $wp_object_cache->getByKey( $server_key, $key, $group, $force, $found );
+}
+
+/**
+ * Request multiple keys without blocking.
+ *
+ * @link http://www.php.net/manual/en/memcached.getdelayed.php
+ *
+ * @param string|array  $keys       Array or string of key(s) to request.
+ * @param string|array  $groups     Array or string of group(s) for the key(s). See buildKeys for more on how these are handled.
+ * @param bool          $with_cas   Whether to request CAS token values also.
+ * @param null          $value_cb   The result callback or NULL.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_get_delayed( $keys, $groups = '', $with_cas = false, $value_cb = NULL ) {
+	global $wp_object_cache;
+	return $wp_object_cache->getDelayed( $keys, $groups, $with_cas, $value_cb );
+}
+
+/**
+ * Request multiple keys without blocking from a specified server.
+ *
+ * @link http://www.php.net/manual/en/memcached.getdelayed.php
+ *
+ * @param string        $server_key The key identifying the server to store the value on.
+ * @param string|array  $keys       Array or string of key(s) to request.
+ * @param string|array  $groups     Array or string of group(s) for the key(s). See buildKeys for more on how these are handled.
+ * @param bool          $with_cas   Whether to request CAS token values also.
+ * @param null          $value_cb   The result callback or NULL.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_get_delayed_by_key( $server_key, $keys, $groups = '', $with_cas = false, $value_cb = NULL ) {
+	global $wp_object_cache;
+	return $wp_object_cache->getDelayedByKey( $server_key, $keys, $groups, $with_cas, $value_cb );
+}
+
+/**
+ * Gets multiple values from memcached in one request.
+ *
+ * See the buildKeys method definition to understand the $keys/$groups parameters.
+ *
+ * @link http://www.php.net/manual/en/memcached.getmulti.php
+ *
+ * @param array         $keys       Array of keys to retrieve.
+ * @param string|array  $groups     If string, used for all keys. If arrays, corresponds with the $keys array.
+ * @param null|array    $cas_tokens The variable to store the CAS tokens for the found items.
+ * @param int           $flags      The flags for the get operation.
+ * @return bool|array               Returns the array of found items or FALSE on failure.
+ */
+function wp_cache_get_multi( $keys, $groups = '', &$cas_tokens = NULL, $flags = NULL ) {
+	global $wp_object_cache;
+
+	if ( func_num_args() > 2 )
+		return $wp_object_cache->getMulti( $keys, $groups, '', $cas_tokens, $flags );
+	else
+		return $wp_object_cache->getMulti( $keys, $groups );
+}
+
+/**
+ * Gets multiple values from memcached in one request by specified server key.
+ *
+ * See the buildKeys method definition to understand the $keys/$groups parameters.
+ *
+ * @link http://www.php.net/manual/en/memcached.getmultibykey.php
+ *
+ * @param string        $server_key The key identifying the server to store the value on.
+ * @param array         $keys       Array of keys to retrieve.
+ * @param string|array  $groups     If string, used for all keys. If arrays, corresponds with the $keys array.
+ * @param null|array    $cas_tokens The variable to store the CAS tokens for the found items.
+ * @param int           $flags      The flags for the get operation.
+ * @return bool|array               Returns the array of found items or FALSE on failure.
+ */
+function wp_cache_get_multi_by_key( $server_key, $keys, $groups = '', &$cas_tokens = NULL, $flags = NULL ) {
+	global $wp_object_cache;
+
+	if ( func_num_args() > 3 )
+		return $wp_object_cache->getMultiByKey( $server_key, $keys, $groups, $cas_tokens, $flags );
+	else
+		return $wp_object_cache->getMultiByKey( $server_key, $keys, $groups );
+}
+
+/**
+ * Retrieve a Memcached option value.
+ *
+ * @link http://www.php.net/manual/en/memcached.getoption.php
+ *
+ * @param int   $option One of the Memcached::OPT_* constants.
+ * @return mixed        Returns the value of the requested option, or FALSE on error.
+ */
+function wp_cache_get_option( $option ) {
+	global $wp_object_cache;
+	return $wp_object_cache->getOption( $option );
+}
+
+/**
+ * Return the result code of the last option.
+ *
+ * @link http://www.php.net/manual/en/memcached.getresultcode.php
+ *
+ * @return int  Result code of the last Memcached operation.
+ */
+function wp_cache_get_result_code() {
+	global $wp_object_cache;
+	return $wp_object_cache->getResultCode();
+}
+
+/**
+ * Return the message describing the result of the last operation.
+ *
+ * @link http://www.php.net/manual/en/memcached.getresultmessage.php
+ *
+ * @return string   Message describing the result of the last Memcached operation.
+ */
+function wp_cache_get_result_message() {
+	global $wp_object_cache;
+	return $wp_object_cache->getResultMessage();
+}
+
+/**
+ * Get server information by key.
+ *
+ * @link http://www.php.net/manual/en/memcached.getserverbykey.php
+ *
+ * @param string    $server_key The key identifying the server to store the value on.
+ * @return array                Array with host, post, and weight on success, FALSE on failure.
+ */
+function wp_cache_get_server_by_key( $server_key ) {
+	global $wp_object_cache;
+	return $wp_object_cache->getServerByKey( $server_key );
+}
+
+/**
+ * Get the list of servers in the pool.
+ *
+ * @link http://www.php.net/manual/en/memcached.getserverlist.php
+ *
+ * @return array    The list of all servers in the server pool.
+ */
+function wp_cache_get_server_list() {
+	global $wp_object_cache;
+	return $wp_object_cache->getServerList();
+}
+
+/**
+ * Get server pool statistics.
+ *
+ * @link http://www.php.net/manual/en/memcached.getstats.php
+ *
+ * @return array    Array of server statistics, one entry per server.
+ */
+function wp_cache_get_stats() {
+	global $wp_object_cache;
+	return $wp_object_cache->getStats();
+}
+
+/**
+ * Get server pool memcached version information.
+ *
+ * @link http://www.php.net/manual/en/memcached.getversion.php
+ *
+ * @return array    Array of server versions, one entry per server.
+ */
+function wp_cache_get_version() {
+	global $wp_object_cache;
+	return $wp_object_cache->getVersion();
+}
+
+/**
+ * Increment a numeric item's value.
+ *
+ * @link http://www.php.net/manual/en/memcached.increment.php
+ *
+ * @param string    $key    The key under which to store the value.
+ * @param int       $offset The amount by which to increment the item's value.
+ * @param string    $group  The group value appended to the $key.
+ * @return int|bool         Returns item's new value on success or FALSE on failure.
+ */
+function wp_cache_increment( $key, $offset = 1, $group = '' ) {
+	global $wp_object_cache;
+	return $wp_object_cache->increment( $key, $offset, $group );
+}
+
+/**
+ * Increment a numeric item's value.
+ *
+ * This is the same as wp_cache_increment, but kept for back compatibility. The original
+ * WordPress caching backends use wp_cache_incr. I want both to work.
+ *
+ * @link http://www.php.net/manual/en/memcached.increment.php
+ *
+ * @param string    $key    The key under which to store the value.
+ * @param int       $offset The amount by which to increment the item's value.
+ * @param string    $group  The group value appended to the $key.
+ * @return int|bool         Returns item's new value on success or FALSE on failure.
+ */
+function wp_cache_incr( $key, $offset = 1, $group = '' ) {
+	return wp_cache_increment( $key, $offset, $group );
+}
+
+/**
+ * Prepend data to an existing item.
+ *
+ * This method should throw an error if it is used with compressed data. This is an expected behavior.
+ * Memcached casts the value to be prepended to the initial value to the type of the initial value. Be
+ * careful as this leads to unexpected behavior at times. For instance, prepending (float) 45.23 to
+ * (int) 23 will result in 45, because the value is first combined (45.2323) then cast to "integer"
+ * (the original value), which will be (int) 45. Due to how memcached treats types, the behavior has been
+ * mimicked in the internal cache to produce similar results and improve consistency. It is recommend
+ * that prepends only occur with data of the same type.
+ *
+ * @link http://www.php.net/manual/en/memcached.prepend.php
+ *
+ * @param string    $key    The key under which to store the value.
+ * @param string    $value  Must be string as prepending mixed values is not well-defined.
+ * @param string    $group  The group value prepended to the $key.
+ * @return bool             Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_prepend( $key, $value, $group = '' ) {
+	global $wp_object_cache;
+	return $wp_object_cache->prepend( $key, $value, $group );
+}
+
+/**
+ * Append data to an existing item by server key.
+ *
+ * This method should throw an error if it is used with compressed data. This is an expected behavior.
+ * Memcached casts the value to be prepended to the initial value to the type of the initial value. Be
+ * careful as this leads to unexpected behavior at times. For instance, prepending (float) 45.23 to
+ * (int) 23 will result in 45, because the value is first combined (45.2323) then cast to "integer"
+ * (the original value), which will be (int) 45. Due to how memcached treats types, the behavior has been
+ * mimicked in the internal cache to produce similar results and improve consistency. It is recommend
+ * that prepends only occur with data of the same type.
+ *
+ * @link http://www.php.net/manual/en/memcached.prependbykey.php
+ *
+ * @param string    $server_key     The key identifying the server to store the value on.
+ * @param string    $key            The key under which to store the value.
+ * @param string    $value          Must be string as prepending mixed values is not well-defined.
+ * @param string    $group          The group value prepended to the $key.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_prepend_by_key( $server_key, $key, $value, $group = '' ) {
+	global $wp_object_cache;
+	return $wp_object_cache->prependByKey( $server_key, $key, $value, $group );
+}
+
+/**
+ * Replaces a value in cache.
+ *
+ * This method is similar to "add"; however, is does not successfully set a value if
+ * the object's key is not already set in cache.
+ *
+ * @link http://www.php.net/manual/en/memcached.replace.php
+ *
+ * @param string    $key        The key under which to store the value.
+ * @param mixed     $value      The value to store.
+ * @param string    $group      The group value appended to the $key.
+ * @param int       $expiration The expiration time, defaults to 0.
+ * @return bool                 Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_replace( $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->replace( $key, $value, $group, $expiration );
+}
+
+/**
+ * Replaces a value in cache on a specific server.
+ *
+ * This method is similar to "addByKey"; however, is does not successfully set a value if
+ * the object's key is not already set in cache.
+ *
+ * @link http://www.php.net/manual/en/memcached.addbykey.php
+ *
+ * @param string    $server_key     The key identifying the server to store the value on.
+ * @param string    $key            The key under which to store the value.
+ * @param mixed     $value          The value to store.
+ * @param string    $group          The group value appended to the $key.
+ * @param int       $expiration     The expiration time, defaults to 0.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_replace_by_key( $server_key, $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->replaceByKey( $server_key, $key, $value, $group, $expiration );
+}
+
+/**
+ * Sets a value in cache.
+ *
+ * The value is set whether or not this key already exists in memcached.
+ *
+ * @link http://www.php.net/manual/en/memcached.set.php
+ *
+ * @param string    $key        The key under which to store the value.
+ * @param mixed     $value      The value to store.
+ * @param string    $group      The group value appended to the $key.
+ * @param int       $expiration The expiration time, defaults to 0.
+ * @return bool                 Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_set( $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->set( $key, $value, $group, $expiration );
+}
+
+/**
+ * Sets a value in cache.
+ *
+ * The value is set whether or not this key already exists in memcached.
+ *
+ * @link http://www.php.net/manual/en/memcached.set.php
+ *
+ * @param string    $server_key     The key identifying the server to store the value on.
+ * @param string    $key            The key under which to store the value.
+ * @param mixed     $value          The value to store.
+ * @param string    $group          The group value appended to the $key.
+ * @param int       $expiration     The expiration time, defaults to 0.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_set_by_key( $server_key, $key, $value, $group = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->setByKey( $server_key, $key, $value, $group, $expiration );
+}
+
+/**
+ * Set multiple values to cache at once.
+ *
+ * By sending an array of $items to this function, all values are saved at once to
+ * memcached, reducing the need for multiple requests to memcached. The $items array
+ * keys and values are what are stored to memcached. The keys in the $items array
+ * are merged with the $groups array/string value via buildKeys to determine the
+ * final key for the object.
+ *
+ * @param array         $items      An array of key/value pairs to store on the server.
+ * @param string|array  $groups     Group(s) to merge with key(s) in $items.
+ * @param int           $expiration The expiration time, defaults to 0.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_set_multi( $items, $groups = '', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->setMulti( $items, $groups, $expiration );
+}
+
+/**
+ * Set multiple values to cache at once on specified server.
+ *
+ * By sending an array of $items to this function, all values are saved at once to
+ * memcached, reducing the need for multiple requests to memcached. The $items array
+ * keys and values are what are stored to memcached. The keys in the $items array
+ * are merged with the $groups array/string value via buildKeys to determine the
+ * final key for the object.
+ *
+ * @param string        $server_key The key identifying the server to store the value on.
+ * @param array         $items      An array of key/value pairs to store on the server.
+ * @param string|array  $groups     Group(s) to merge with key(s) in $items.
+ * @param int           $expiration The expiration time, defaults to 0.
+ * @return bool                     Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_set_multi_by_key( $server_key, $items, $groups = 'default', $expiration = 0 ) {
+	global $wp_object_cache;
+	return $wp_object_cache->setMultiByKey( $server_key, $items, $groups, $expiration );
+}
+
+/**
+ * Set a Memcached option.
+ *
+ * @link http://www.php.net/manual/en/memcached.setoption.php
+ *
+ * @param int       $option Option name.
+ * @param mixed     $value  Option value.
+ * @return bool             Returns TRUE on success or FALSE on failure.
+ */
+function wp_cache_set_option( $option, $value ) {
+	global $wp_object_cache;
+	return $wp_object_cache->setOption( $option, $value );
+}
+
+/**
+ * Switch blog prefix, which changes the cache that is accessed.
+ *
+ * @param  int     $blog_id    Blog to switch to.
+ * @return void
+ */
+function wp_cache_switch_to_blog( $blog_id ) {
+	global $wp_object_cache;
+	return $wp_object_cache->switch_to_blog( $blog_id );
+}
+
+
+/**
+ * Sets up Object Cache Global and assigns it.
+ *
+ * @global  WP_Object_Cache     $wp_object_cache    WordPress Object Cache
+ * @return  void
+ */
+function wp_cache_init() {
+	global $wp_object_cache;
+	$wp_object_cache = new WP_Object_Cache();
+}
+
+/**
+ * Adds a group or set of groups to the list of non-persistent groups.
+ *
+ * @param   string|array    $groups     A group or an array of groups to add.
+ * @return  void
+ */
+function wp_cache_add_global_groups( $groups ) {
+	global $wp_object_cache;
+	$wp_object_cache->add_global_groups( $groups );
+}
+
+/**
+ * Adds a group or set of groups to the list of non-Memcached groups.
+ *
+ * @param   string|array    $groups     A group or an array of groups to add.
+ * @return  void
+ */
+function wp_cache_add_non_persistent_groups( $groups ) {
+	global $wp_object_cache;
+	$wp_object_cache->add_non_persistent_groups( $groups );
+}
+
+class WP_Object_Cache {
+
+	/**
+	 * Holds the Memcached object.
+	 *
+	 * @var Memcached
+	 */
+	public $m;
+
+	/**
+	 * Hold the Memcached server details.
+	 *
+	 * @var array
+	 */
+	public $servers;
+
+	/**
+	 * Holds the non-Memcached objects.
+	 *
+	 * @var array
+	 */
+	public $cache = array();
+
+	/**
+	 * List of global groups.
+	 *
+	 * @var array
+	 */
+	public $global_groups = array( 'users', 'userlogins', 'usermeta', 'site-options', 'site-lookup', 'blog-lookup', 'blog-details', 'rss' );
+
+	/**
+	 * List of groups not saved to Memcached.
+	 *
+	 * @var array
+	 */
+	public $no_mc_groups = array( 'comment', 'counts' );
+
+	/**
+	 * Prefix used for global groups.
+	 *
+	 * @var string
+	 */
+	public $global_prefix = '';
+
+	/**
+	 * Prefix used for non-global groups.
+	 *
+	 * @var string
+	 */
+	public $blog_prefix = '';
+
+	/**
+	 * Instantiate the Memcached class.
+	 *
+	 * Instantiates the Memcached class and returns adds the servers specified
+	 * in the $memcached_servers global array.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.construct.php
+	 *
+	 * @param   null    $persistent_id      To create an instance that persists between requests, use persistent_id to specify a unique ID for the instance.
+	 */
+	public function __construct( $persistent_id = NULL ) {
+		global $memcached_servers, $blog_id, $table_prefix;
+
+		if ( is_null( $persistent_id ) || ! is_string( $persistent_id ) )
+			$this->m = new Memcached();
+		else
+			$this->m = new Memcached( $persistent_id );
+
+		if ( isset( $memcached_servers ) )
+			$this->servers = $memcached_servers;
+		else
+			$this->servers = array( array( '127.0.0.1', 11211 ) );
+
+		$this->addServers( $this->servers );
+
+		/**
+		 * This approach is borrowed from Sivel and Boren. Use the salt for easy cache invalidation and for
+		 * multi single WP installs on the same server.
+		 */
+		if ( ! defined( 'WP_CACHE_KEY_SALT' ) )
+			define( 'WP_CACHE_KEY_SALT', '' );
+
+		// Assign global and blog prefixes for use with keys
+		if ( function_exists( 'is_multisite' ) ) {
+			$this->global_prefix = ( is_multisite() || defined( 'CUSTOM_USER_TABLE' ) && defined( 'CUSTOM_USER_META_TABLE' ) ) ? '' : $table_prefix;
+			$this->blog_prefix = ( is_multisite() ? $blog_id : $table_prefix ) . ':';
+		}
+
+		// Setup cacheable values for handling expiration times
+		$this->thirty_days = 60 * 60 * 24 * 30;
+		$this->now         = time();
+	}
+
+	/**
+	 * Adds a value to cache.
+	 *
+	 * If the specified key already exists, the value is not stored and the function
+	 * returns false.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.add.php
+	 *
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          The value to store.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   int         $expiration     The expiration time, defaults to 0.
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   bool        $byKey          True to store in internal cache by key; false to not store by key
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function add( $key, $value, $group = 'default', $expiration = 0, $server_key = '', $byKey = false ) {
+		/*
+		 * Ensuring that wp_suspend_cache_addition is defined before calling, because sometimes an advanced-cache.php
+		 * file will load object-cache.php before wp-includes/functions.php is loaded. In those cases, if wp_cache_add
+		 * is called in advanced-cache.php before any more of WordPress is loaded, we get a fatal error because
+		 * wp_suspend_cache_addition will not be defined until wp-includes/functions.php is loaded.
+		 */
+		if ( function_exists( 'wp_suspend_cache_addition' ) && wp_suspend_cache_addition() ) {
+			return false;
+		}
+
+		$derived_key = $this->buildKey( $key, $group );
+		$expiration  = $this->sanitize_expiration( $expiration );
+
+		// If group is a non-Memcached group, save to runtime cache, not Memcached
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+
+			// Add does not set the value if the key exists; mimic that here
+			if ( isset( $this->cache[$derived_key] ) )
+				return false;
+
+			$this->add_to_internal_cache( $derived_key, $value );
+
+			return true;
+		}
+
+		// Save to Memcached
+		if ( $byKey )
+			$result = $this->m->addByKey( $server_key, $derived_key, $value, $expiration );
+		else
+			$result = $this->m->add( $derived_key, $value, $expiration );
+
+		// Store in runtime cache if add was successful
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->add_to_internal_cache( $derived_key, $value );
+
+		return $result;
+	}
+
+	/**
+	 * Adds a value to cache on a specific server.
+	 *
+	 * Using a server_key value, the object can be stored on a specified server as opposed
+	 * to a random server in the stack. Note that this method will add the key/value to the
+	 * _cache object as part of the runtime cache. It will add it to an array for the
+	 * specified server_key.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.addbykey.php
+	 *
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          The value to store.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   int         $expiration     The expiration time, defaults to 0.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function addByKey( $server_key, $key, $value, $group = 'default', $expiration = 0 ) {
+		return $this->add( $key, $value, $group, $expiration, $server_key, true );
+	}
+
+	/**
+	 * Add a single server to the list of Memcached servers.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.addserver.php
+	 *
+	 * @param   string      $host           The hostname of the memcache server.
+	 * @param   int         $port           The port on which memcache is running.
+	 * @param   int         $weight         The weight of the server relative to the total weight of all the servers in the pool.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function addServer( $host, $port, $weight = 0 ) {
+		$host = is_string( $host ) ? $host : '127.0.0.1';
+		$port = is_numeric( $port ) && $port > 0 ? $port : 11211;
+		$weight = is_numeric( $weight ) && $weight > 0 ? $weight : 1;
+
+		return $this->m->addServer( $host, $port, $weight );
+	}
+
+	/**
+	 * Adds an array of servers to the pool.
+	 *
+	 * Each individual server in the array must include a domain and port, with an optional
+	 * weight value: $servers = array( array( '127.0.0.1', 11211, 0 ) );
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.addservers.php
+	 *
+	 * @param   array       $servers        Array of server to register.
+	 * @return  bool                        True on success; false on failure.
+	 */
+	public function addServers( $servers ) {
+		if ( ! is_object( $this->m ) )
+			return false;
+
+		return $this->m->addServers( $servers );
+	}
+
+	/**
+	 * Append data to an existing item.
+	 *
+	 * This method should throw an error if it is used with compressed data. This
+	 * is an expected behavior. Memcached casts the value to be appended to the initial value to the
+	 * type of the initial value. Be careful as this leads to unexpected behavior at times. Due to
+	 * how memcached treats types, the behavior has been mimicked in the internal cache to produce
+	 * similar results and improve consistency. It is recommend that appends only occur with data of
+	 * the same type.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.append.php
+	 *
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          Must be string as appending mixed values is not well-defined.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   bool        $byKey          True to store in internal cache by key; false to not store by key
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function append( $key, $value, $group = 'default', $server_key = '', $byKey = false ) {
+		if ( ! is_string( $value ) && ! is_int( $value ) && ! is_float( $value ) )
+			return false;
+
+		$derived_key = $this->buildKey( $key, $group );
+
+		// If group is a non-Memcached group, append to runtime cache value, not Memcached
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+			if ( ! isset( $this->cache[$derived_key] ) )
+				return false;
+
+			$combined = $this->combine_values( $this->cache[$derived_key], $value, 'app' );
+			$this->add_to_internal_cache( $derived_key, $combined );
+			return true;
+		}
+
+		// Append to Memcached value
+		if ( $byKey )
+			$result = $this->m->appendByKey( $server_key, $derived_key, $value );
+		else
+			$result = $this->m->append( $derived_key, $value );
+
+		// Store in runtime cache if add was successful
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() ) {
+			$combined = $this->combine_values( $this->cache[$derived_key], $value, 'app' );
+			$this->add_to_internal_cache( $derived_key, $combined );
+		}
+
+		return $result;
+	}
+
+	/**
+	 * Append data to an existing item by server key.
+	 *
+	 * This method should throw an error if it is used with compressed data. This
+	 * is an expected behavior. Memcached casts the value to be appended to the initial value to the
+	 * type of the initial value. Be careful as this leads to unexpected behavior at times. Due to
+	 * how memcached treats types, the behavior has been mimicked in the internal cache to produce
+	 * similar results and improve consistency. It is recommend that appends only occur with data of
+	 * the same type.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.appendbykey.php
+	 *
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          Must be string as appending mixed values is not well-defined
+	 * @param   string      $group          The group value appended to the $key.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function appendByKey( $server_key, $key, $value, $group = 'default' ) {
+		return $this->append( $key, $value, $group, $server_key, true );
+	}
+
+	/**
+	 * Performs a "check and set" to store data.
+	 *
+	 * The set will be successful only if the no other request has updated the value since it was fetched since
+	 * this request.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.cas.php
+	 *
+	 * @param   float       $cas_token      Unique value associated with the existing item. Generated by memcached.
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          The value to store.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   int         $expiration     The expiration time, defaults to 0.
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   bool        $byKey          True to store in internal cache by key; false to not store by key
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function cas( $cas_token, $key, $value, $group = 'default', $expiration = 0, $server_key = '', $byKey = false ) {
+		$derived_key = $this->buildKey( $key, $group );
+		$expiration  = $this->sanitize_expiration( $expiration );
+
+		/**
+		 * If group is a non-Memcached group, save to runtime cache, not Memcached. Note
+		 * that since check and set cannot be emulated in the run time cache, this value
+		 * operation is treated as a normal "add" for no_mc_groups.
+		 */
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+			$this->add_to_internal_cache( $derived_key, $value );
+			return true;
+		}
+
+		// Save to Memcached
+		if ( $byKey )
+			$result = $this->m->casByKey( $cas_token, $server_key, $derived_key, $value, $expiration );
+		else
+			$result = $this->m->cas( $cas_token, $derived_key, $value, $expiration );
+
+		// Store in runtime cache if cas was successful
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->add_to_internal_cache( $derived_key, $value );
+
+		return $result;
+	}
+
+	/**
+	 * Performs a "check and set" to store data with a server key.
+	 *
+	 * The set will be successful only if the no other request has updated the value since it was fetched by
+	 * this request.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.casbykey.php
+	 *
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   float       $cas_token      Unique value associated with the existing item. Generated by memcached.
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          The value to store.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   int         $expiration     The expiration time, defaults to 0.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function casByKey( $cas_token, $server_key, $key, $value, $group = 'default', $expiration = 0 ) {
+		return $this->cas( $cas_token, $key, $value, $group, $expiration, $server_key, true );
+	}
+
+	/**
+	 * Decrement a numeric item's value.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.decrement.php
+	 *
+	 * @param string    $key    The key under which to store the value.
+	 * @param int       $offset The amount by which to decrement the item's value.
+	 * @param string    $group  The group value appended to the $key.
+	 * @return int|bool         Returns item's new value on success or FALSE on failure.
+	 */
+	public function decrement( $key, $offset = 1, $group = 'default' ) {
+		$derived_key = $this->buildKey( $key, $group );
+
+		// Decrement values in no_mc_groups
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+
+			// Only decrement if the key already exists and value is 0 or greater (mimics memcached behavior)
+			if ( isset( $this->cache[$derived_key] ) && $this->cache[$derived_key] >= 0 ) {
+
+				// If numeric, subtract; otherwise, consider it 0 and do nothing
+				if ( is_numeric( $this->cache[$derived_key] ) )
+					$this->cache[$derived_key] -= (int) $offset;
+				else
+					$this->cache[$derived_key] = 0;
+
+				// Returned value cannot be less than 0
+				if ( $this->cache[$derived_key] < 0 )
+					$this->cache[$derived_key] = 0;
+
+				return $this->cache[$derived_key];
+			} else {
+				return false;
+			}
+		}
+
+		$result = $this->m->decrement( $derived_key, $offset );
+
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->add_to_internal_cache( $derived_key, $result );
+
+		return $result;
+	}
+
+	/**
+	 * Decrement a numeric item's value.
+	 *
+	 * Alias for $this->decrement. Other caching backends use this abbreviated form of the function. It *may* cause
+	 * breakage somewhere, so it is nice to have. This function will also allow the core unit tests to pass.
+	 *
+	 * @param string    $key    The key under which to store the value.
+	 * @param int       $offset The amount by which to decrement the item's value.
+	 * @param string    $group  The group value appended to the $key.
+	 * @return int|bool         Returns item's new value on success or FALSE on failure.
+	 */
+	public function decr( $key, $offset = 1, $group = 'default' ) {
+		return $this->decrement( $key, $offset, $group );
+	}
+
+	/**
+	 * Remove the item from the cache.
+	 *
+	 * Remove an item from memcached with identified by $key after $time seconds. The
+	 * $time parameter allows an object to be queued for deletion without immediately
+	 * deleting. Between the time that it is queued and the time it's deleted, add,
+	 * replace, and get will fail, but set will succeed.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.delete.php
+	 *
+	 * @param   string      $key        The key under which to store the value.
+	 * @param   string      $group      The group value appended to the $key.
+	 * @param   int         $time       The amount of time the server will wait to delete the item in seconds.
+	 * @param   string      $server_key The key identifying the server to store the value on.
+	 * @param   bool        $byKey      True to store in internal cache by key; false to not store by key
+	 * @return  bool                    Returns TRUE on success or FALSE on failure.
+	 */
+	public function delete( $key, $group = 'default', $time = 0, $server_key = '', $byKey = false ) {
+		$derived_key = $this->buildKey( $key, $group );
+
+		// Remove from no_mc_groups array
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+			if ( isset( $this->cache[$derived_key] ) )
+				unset( $this->cache[$derived_key] );
+
+			return true;
+		}
+
+		if ( $byKey )
+			$result = $this->m->deleteByKey( $server_key, $derived_key, $time );
+		else
+			$result = $this->m->delete( $derived_key, $time );
+
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			unset( $this->cache[$derived_key] );
+
+		return $result;
+	}
+
+	/**
+	 * Remove the item from the cache by server key.
+	 *
+	 * Remove an item from memcached with identified by $key after $time seconds. The
+	 * $time parameter allows an object to be queued for deletion without immediately
+	 * deleting. Between the time that it is queued and the time it's deleted, add,
+	 * replace, and get will fail, but set will succeed.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.deletebykey.php
+	 *
+	 * @param   string      $server_key The key identifying the server to store the value on.
+	 * @param   string      $key        The key under which to store the value.
+	 * @param   string      $group      The group value appended to the $key.
+	 * @param   int         $time       The amount of time the server will wait to delete the item in seconds.
+	 * @return  bool                    Returns TRUE on success or FALSE on failure.
+	 */
+	public function deleteByKey( $server_key, $key, $group = 'default', $time = 0 ) {
+		return $this->delete( $key, $group, $time, $server_key, true );
+	}
+
+	/**
+	 * Fetch the next result.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.fetch.php
+	 *
+	 * @return array|bool   Returns the next result or FALSE on failure.
+	 */
+	public function fetch() {
+		return $this->m->fetch();
+	}
+
+	/**
+	 * Fetch all remaining results from the last request.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.fetchall.php
+	 *
+	 * @return  array|bool          Returns the results or FALSE on failure.
+	 */
+	public function fetchAll() {
+	 	return $this->m->fetchAll();
+	}
+
+	/**
+	 * Invalidate all items in the cache.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.flush.php
+	 *
+	 * @param   int     $delay      Number of seconds to wait before invalidating the items.
+	 * @return  bool                Returns TRUE on success or FALSE on failure.
+	 */
+	public function flush( $delay = 0 ) {
+		$result = $this->m->flush( $delay );
+
+		// Only reset the runtime cache if memcached was properly flushed
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->cache = array();
+
+		return $result;
+	}
+
+	/**
+	 * Retrieve object from cache.
+	 *
+	 * Gets an object from cache based on $key and $group. In order to fully support the $cache_cb and $cas_token
+	 * parameters, the runtime cache is ignored by this function if either of those values are set. If either of
+	 * those values are set, the request is made directly to the memcached server for proper handling of the
+	 * callback and/or token. Note that the $cas_token variable cannot be directly passed to the function. The
+	 * variable need to be first defined with a non null value.
+	 *
+	 * If using the $cache_cb argument, the new value will always have an expiration of time of 0 (forever). This
+	 * is a limitation of the Memcached PECL extension.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.get.php
+	 *
+	 * @param   string          $key        The key under which to store the value.
+	 * @param   string          $group      The group value appended to the $key.
+	 * @param   bool            $force      Whether or not to force a cache invalidation.
+	 * @param   null|bool       $found      Variable passed by reference to determine if the value was found or not.
+	 * @param   string          $server_key The key identifying the server to store the value on.
+	 * @param   bool            $byKey      True to store in internal cache by key; false to not store by key
+	 * @param   null|callable   $cache_cb   Read-through caching callback.
+	 * @param   null|float      $cas_token  The variable to store the CAS token in.
+	 * @return  bool|mixed                  Cached object value.
+	 */
+	public function get( $key, $group = 'default', $force = false, &$found = null, $server_key = '', $byKey = false, $cache_cb = NULL, &$cas_token = NULL ) {
+		$derived_key = $this->buildKey( $key, $group );
+
+		// Assume object is not found
+		$found = false;
+
+		// If either $cache_db, or $cas_token is set, must hit Memcached and bypass runtime cache
+		if ( func_num_args() > 6 && ! in_array( $group, $this->no_mc_groups ) ) {
+			if ( $byKey )
+				$value = $this->m->getByKey( $server_key, $derived_key, $cache_cb, $cas_token );
+			else
+				$value = $this->m->get( $derived_key, $cache_cb, $cas_token );
+		} else {
+			if ( isset( $this->cache[$derived_key] ) ) {
+				$found = true;
+				return is_object( $this->cache[$derived_key] ) ? clone $this->cache[$derived_key] : $this->cache[$derived_key];
+			} elseif ( in_array( $group, $this->no_mc_groups ) ) {
+				return false;
+			} else {
+				if ( $byKey )
+					$value = $this->m->getByKey( $server_key, $derived_key );
+				else
+					$value = $this->m->get( $derived_key );
+			}
+		}
+
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() ) {
+			$this->add_to_internal_cache( $derived_key, $value );
+			$found = true;
+		}
+
+		return is_object( $value ) ? clone $value : $value;
+	}
+
+	/**
+	 * Retrieve object from cache from specified server.
+	 *
+	 * Gets an object from cache based on $key, $group and $server_key. In order to fully support the $cache_cb and $cas_token
+	 * parameters, the runtime cache is ignored by this function if either of those values are set. If either of
+	 * those values are set, the request is made directly to the memcached server for proper handling of the
+	 * callback and/or token. Note that the $cas_token variable cannot be directly passed to the function. The
+	 * variable need to be first defined with a non null value.
+	 *
+	 * If using the $cache_cb argument, the new value will always have an expiration of time of 0 (forever). This
+	 * is a limitation of the Memcached PECL extension.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.getbykey.php
+	 *
+	 * @param   string          $server_key The key identifying the server to store the value on.
+	 * @param   string          $key        The key under which to store the value.
+	 * @param   string          $group      The group value appended to the $key.
+	 * @param   bool            $force      Whether or not to force a cache invalidation.
+	 * @param   null|bool       $found      Variable passed by reference to determine if the value was found or not.
+	 * @param   null|string     $cache_cb   Read-through caching callback.
+	 * @param   null|float      $cas_token  The variable to store the CAS token in.
+	 * @return  bool|mixed                  Cached object value.
+	 */
+	public function getByKey( $server_key, $key, $group = 'default', $force = false, &$found = null, $cache_cb = NULL, &$cas_token = NULL ) {
+		/**
+		 * Need to be careful how "get" is called. If you send $cache_cb, and $cas_token, it will hit memcached.
+		 * Only send those args if they were sent to this function.
+		 */
+		if ( func_num_args() > 5 )
+			return $this->get( $key, $group, $force, $found, $server_key, true, $cache_cb, $cas_token );
+		else
+			return $this->get( $key, $group, $force, $found, $server_key, true );
+	}
+
+	/**
+	 * Request multiple keys without blocking.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.getdelayed.php
+	 *
+	 * @param   string|array    $keys       Array or string of key(s) to request.
+	 * @param   string|array    $groups     Array or string of group(s) for the key(s). See buildKeys for more on how these are handled.
+	 * @param   bool            $with_cas   Whether to request CAS token values also.
+	 * @param   null            $value_cb   The result callback or NULL.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function getDelayed( $keys, $groups = 'default', $with_cas = false, $value_cb = NULL ) {
+		$derived_keys = $this->buildKeys( $keys, $groups );
+		return $this->m->getDelayed( $derived_keys, $with_cas, $value_cb );
+	}
+
+	/**
+	 * Request multiple keys without blocking from a specified server.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.getdelayed.php
+	 *
+	 * @param   string          $server_key The key identifying the server to store the value on.
+	 * @param   string|array    $keys       Array or string of key(s) to request.
+	 * @param   string|array    $groups     Array or string of group(s) for the key(s). See buildKeys for more on how these are handled.
+	 * @param   bool            $with_cas   Whether to request CAS token values also.
+	 * @param   null            $value_cb   The result callback or NULL.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function getDelayedByKey( $server_key, $keys, $groups = 'default', $with_cas = false, $value_cb = NULL ) {
+		$derived_keys = $this->buildKeys( $keys, $groups );
+		return $this->m->getDelayedByKey( $server_key, $derived_keys, $with_cas, $value_cb );
+	}
+
+	/**
+	 * Gets multiple values from memcached in one request.
+	 *
+	 * See the buildKeys method definition to understand the $keys/$groups parameters.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.getmulti.php
+	 *
+	 * @param   array           $keys       Array of keys to retrieve.
+	 * @param   string|array    $groups     If string, used for all keys. If arrays, corresponds with the $keys array.
+	 * @param   string          $server_key The key identifying the server to store the value on.
+	 * @param   null|array      $cas_tokens The variable to store the CAS tokens for the found items.
+	 * @param   int             $flags      The flags for the get operation.
+	 * @return  bool|array                  Returns the array of found items or FALSE on failure.
+	 */
+	public function getMulti( $keys, $groups = 'default', $server_key = '', &$cas_tokens = NULL, $flags = NULL ) {
+		$derived_keys = $this->buildKeys( $keys, $groups );
+
+		/**
+		 * If either $cas_tokens, or $flags is set, must hit Memcached and bypass runtime cache. Note that
+		 * this will purposely ignore no_mc_groups values as they cannot handle CAS tokens or the special
+		 * flags; however, if the groups of groups contains a no_mc_group, this is bypassed.
+		 */
+		if ( func_num_args() > 3 && ! $this->contains_no_mc_group( $groups ) ) {
+			if ( ! empty( $server_key ) )
+				$values = $this->m->getMultiByKey( $server_key, $derived_keys, $cas_tokens, $flags );
+			else
+				$values = $this->m->getMulti( $derived_keys, $cas_tokens, $flags );
+		} else {
+			$values = array();
+			$need_to_get = array();
+
+			// Pull out values from runtime cache, or mark for retrieval
+			foreach ( $derived_keys as $key ) {
+				if ( isset( $this->cache[$key] ) )
+					$values[$key] = $this->cache[$key];
+				else
+					$need_to_get[$key] = $key;
+			}
+
+			// Get those keys not found in the runtime cache
+			if ( ! empty( $need_to_get ) ) {
+				if ( ! empty( $server_key ) )
+					$result = $this->m->getMultiByKey( $server_key, array_keys( $need_to_get ) );
+				else
+					$result = $this->m->getMulti( array_keys( $need_to_get ) );
+			}
+
+			// Merge with values found in runtime cache
+			if ( isset( $result ) && Memcached::RES_SUCCESS === $this->getResultCode() )
+				$values = array_merge( $values, $result );
+
+			// If order should be preserved, reorder now
+			if ( ! empty( $need_to_get ) && $flags === Memcached::GET_PRESERVE_ORDER ) {
+				$ordered_values = array();
+
+				foreach ( $derived_keys as $key ) {
+					if ( isset( $values[$key] ) )
+						$ordered_values[$key] = $values[$key];
+				}
+
+				$values = $ordered_values;
+				unset( $ordered_values );
+			}
+		}
+
+		// Add the values to the runtime cache
+		$this->cache = array_merge( $this->cache, $values );
+
+		return $values;
+	}
+
+	/**
+	 * Gets multiple values from memcached in one request by specified server key.
+	 *
+	 * See the buildKeys method definition to understand the $keys/$groups parameters.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.getmultibykey.php
+	 *
+	 * @param   string          $server_key The key identifying the server to store the value on.
+	 * @param   array           $keys       Array of keys to retrieve.
+	 * @param   string|array    $groups     If string, used for all keys. If arrays, corresponds with the $keys array.
+	 * @param   null|array      $cas_tokens The variable to store the CAS tokens for the found items.
+	 * @param   int             $flags      The flags for the get operation.
+	 * @return  bool|array                  Returns the array of found items or FALSE on failure.
+	 */
+	public function getMultiByKey( $server_key, $keys, $groups = 'default', &$cas_tokens = NULL, $flags = NULL ) {
+		/**
+		 * Need to be careful how "getMulti" is called. If you send $cache_cb, and $cas_token, it will hit memcached.
+		 * Only send those args if they were sent to this function.
+		 */
+		if ( func_num_args() > 3 )
+			return $this->getMulti( $keys, $groups, $server_key, $cas_tokens, $flags );
+		else
+			return $this->getMulti( $keys, $groups, $server_key );
+	}
+
+	/**
+	 * Retrieve a Memcached option value.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.getoption.php
+	 *
+	 * @param   int         $option     One of the Memcached::OPT_* constants.
+	 * @return  mixed                   Returns the value of the requested option, or FALSE on error.
+	 */
+	public function getOption( $option ) {
+		return $this->m->getOption( $option );
+	}
+
+	/**
+	 * Return the result code of the last option.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.getresultcode.php
+	 *
+	 * @return  int     Result code of the last Memcached operation.
+	 */
+	public function getResultCode() {
+ 	    return $this->m->getResultCode();
+	}
+
+	/**
+	 * Return the message describing the result of the last operation.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.getresultmessage.php
+	 *
+	 * @return  string      Message describing the result of the last Memcached operation.
+	 */
+	public function getResultMessage() {
+   	    return $this->m->getResultMessage();
+	}
+
+	/**
+	 * Get server information by key.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.getserverbykey.php
+	 *
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @return  array                       Array with host, post, and weight on success, FALSE on failure.
+	 */
+	public function getServerByKey( $server_key ) {
+		return $this->m->getServerByKey( $server_key );
+	}
+
+	/**
+	 * Get the list of servers in the pool.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.getserverlist.php
+	 *
+	 * @return  array       The list of all servers in the server pool.
+	 */
+	public function getServerList() {
+		return $this->m->getServerList();
+	}
+
+	/**
+     * Get server pool statistics.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.getstats.php
+	 *
+	 * @return  array       Array of server statistics, one entry per server.
+	 */
+	public function getStats() {
+		return $this->m->getStats();
+	}
+
+	/**
+	 * Get server pool memcached version information.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.getversion.php
+	 *
+	 * @return  array       Array of server versions, one entry per server.
+	 */
+	public function getVersion() {
+		return $this->m->getVersion();
+	}
+
+	/**
+	 * Increment a numeric item's value.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.increment.php
+	 *
+	 * @param   string      $key        The key under which to store the value.
+	 * @param   int         $offset     The amount by which to increment the item's value.
+	 * @param   string      $group      The group value appended to the $key.
+	 * @return  int|bool                Returns item's new value on success or FALSE on failure.
+	 */
+	public function increment( $key, $offset = 1, $group = 'default' ) {
+		$derived_key = $this->buildKey( $key, $group );
+
+		// Increment values in no_mc_groups
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+
+			// Only increment if the key already exists and the number is currently 0 or greater (mimics memcached behavior)
+			if ( isset( $this->cache[$derived_key] ) &&  $this->cache[$derived_key] >= 0 ) {
+
+				// If numeric, add; otherwise, consider it 0 and do nothing
+				if ( is_numeric( $this->cache[$derived_key] ) )
+					$this->cache[$derived_key] += (int) $offset;
+				else
+					$this->cache[$derived_key] = 0;
+
+				// Returned value cannot be less than 0
+				if ( $this->cache[$derived_key] < 0 )
+					$this->cache[$derived_key] = 0;
+
+				return $this->cache[$derived_key];
+			} else {
+				return false;
+			}
+		}
+
+		$result = $this->m->increment( $derived_key, $offset );
+
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->add_to_internal_cache( $derived_key, $result );
+
+		return $result;
+	}
+
+	/**
+	 * Synonymous with $this->incr.
+	 *
+	 * Certain plugins expect an "incr" method on the $wp_object_cache object (e.g., Batcache). Since the original
+	 * version of this library matched names to the memcached methods, the "incr" method was missing. Adding this
+	 * method restores compatibility with plugins expecting an "incr" method.
+	 *
+	 * @param   string      $key        The key under which to store the value.
+	 * @param   int         $offset     The amount by which to increment the item's value.
+	 * @param   string      $group      The group value appended to the $key.
+	 * @return  int|bool                Returns item's new value on success or FALSE on failure.
+	 */
+	public function incr( $key, $offset = 1, $group = 'default' ) {
+		return $this->increment( $key, $offset, $group );
+	}
+
+	/**
+	 * Prepend data to an existing item.
+	 *
+	 * This method should throw an error if it is used with compressed data. This is an expected behavior.
+	 * Memcached casts the value to be prepended to the initial value to the type of the initial value. Be
+	 * careful as this leads to unexpected behavior at times. For instance, prepending (float) 45.23 to
+	 * (int) 23 will result in 45, because the value is first combined (45.2323) then cast to "integer"
+	 * (the original value), which will be (int) 45. Due to how memcached treats types, the behavior has been
+	 * mimicked in the internal cache to produce similar results and improve consistency. It is recommend
+	 * that prepends only occur with data of the same type.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.prepend.php
+	 *
+	 * @param   string    $key          The key under which to store the value.
+	 * @param   string    $value        Must be string as prepending mixed values is not well-defined.
+	 * @param   string    $group        The group value prepended to the $key.
+	 * @param   string    $server_key   The key identifying the server to store the value on.
+	 * @param   bool      $byKey        True to store in internal cache by key; false to not store by key
+	 * @return  bool                    Returns TRUE on success or FALSE on failure.
+	 */
+	public function prepend( $key, $value, $group = 'default', $server_key = '', $byKey = false ) {
+		if ( ! is_string( $value ) && ! is_int( $value ) && ! is_float( $value ) )
+			return false;
+
+		$derived_key = $this->buildKey( $key, $group );
+
+		// If group is a non-Memcached group, prepend to runtime cache value, not Memcached
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+			if ( ! isset( $this->cache[$derived_key] ) )
+				return false;
+
+			$combined = $this->combine_values( $this->cache[$derived_key], $value, 'pre' );
+			$this->add_to_internal_cache( $derived_key, $combined );
+			return true;
+		}
+
+		// Append to Memcached value
+		if ( $byKey )
+			$result = $this->m->prependByKey( $server_key, $derived_key, $value );
+		else
+			$result = $this->m->prepend( $derived_key, $value );
+
+		// Store in runtime cache if add was successful
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() ) {
+			$combined = $this->combine_values( $this->cache[$derived_key], $value, 'pre' );
+			$this->add_to_internal_cache( $derived_key, $combined );
+		}
+
+		return $result;
+	}
+
+	/**
+	 * Append data to an existing item by server key.
+	 *
+	 * This method should throw an error if it is used with compressed data. This is an expected behavior.
+	 * Memcached casts the value to be prepended to the initial value to the type of the initial value. Be
+	 * careful as this leads to unexpected behavior at times. For instance, prepending (float) 45.23 to
+	 * (int) 23 will result in 45, because the value is first combined (45.2323) then cast to "integer"
+	 * (the original value), which will be (int) 45. Due to how memcached treats types, the behavior has been
+	 * mimicked in the internal cache to produce similar results and improve consistency. It is recommend
+	 * that prepends only occur with data of the same type.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.prependbykey.php
+	 *
+	 * @param   string    $server_key   The key identifying the server to store the value on.
+	 * @param   string    $key          The key under which to store the value.
+	 * @param   string    $value        Must be string as prepending mixed values is not well-defined.
+	 * @param   string    $group        The group value prepended to the $key.
+	 * @return  bool                    Returns TRUE on success or FALSE on failure.
+	 */
+	public function prependByKey( $server_key, $key, $value, $group = 'default' ) {
+		return $this->prepend( $key, $value, $group, $server_key, true );
+	}
+
+	/**
+	 * Replaces a value in cache.
+	 *
+	 * This method is similar to "add"; however, is does not successfully set a value if
+	 * the object's key is not already set in cache.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.replace.php
+	 *
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          The value to store.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   bool        $byKey          True to store in internal cache by key; false to not store by key
+	 * @param   int         $expiration     The expiration time, defaults to 0.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function replace( $key, $value, $group = 'default', $expiration = 0, $server_key = '', $byKey = false ) {
+		$derived_key = $this->buildKey( $key, $group );
+		$expiration  = $this->sanitize_expiration( $expiration );
+
+		// If group is a non-Memcached group, save to runtime cache, not Memcached
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+
+			// Replace won't save unless the key already exists; mimic this behavior here
+			if ( ! isset( $this->cache[$derived_key] ) )
+				return false;
+
+			$this->cache[$derived_key] = $value;
+			return true;
+		}
+
+		// Save to Memcached
+		if ( $byKey )
+			$result = $this->m->replaceByKey( $server_key, $derived_key, $value, $expiration );
+		else
+			$result = $this->m->replace( $derived_key, $value, $expiration );
+
+		// Store in runtime cache if add was successful
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->add_to_internal_cache( $derived_key, $value );
+
+		return $result;
+	}
+
+	/**
+	 * Replaces a value in cache on a specific server.
+	 *
+	 * This method is similar to "addByKey"; however, is does not successfully set a value if
+	 * the object's key is not already set in cache.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.addbykey.php
+	 *
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          The value to store.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   int         $expiration     The expiration time, defaults to 0.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function replaceByKey( $server_key, $key, $value, $group = 'default', $expiration = 0 ) {
+		return $this->replace( $key, $value, $group, $expiration, $server_key, true );
+	}
+
+	/**
+	 * Sets a value in cache.
+	 *
+	 * The value is set whether or not this key already exists in memcached.
+	 *
+	 * @link http://www.php.net/manual/en/memcached.set.php
+	 *
+	 * @param   string      $key        The key under which to store the value.
+	 * @param   mixed       $value      The value to store.
+	 * @param   string      $group      The group value appended to the $key.
+	 * @param   int         $expiration The expiration time, defaults to 0.
+	 * @param   string      $server_key The key identifying the server to store the value on.
+	 * @param   bool        $byKey      True to store in internal cache by key; false to not store by key
+	 * @return  bool                    Returns TRUE on success or FALSE on failure.
+	 */
+	public function set( $key, $value, $group = 'default', $expiration = 0, $server_key = '', $byKey = false ) {
+		$derived_key = $this->buildKey( $key, $group );
+		$expiration  = $this->sanitize_expiration( $expiration );
+
+		// If group is a non-Memcached group, save to runtime cache, not Memcached
+		if ( in_array( $group, $this->no_mc_groups ) ) {
+			$this->add_to_internal_cache( $derived_key, $value );
+			return true;
+		}
+
+		// Save to Memcached
+		if ( $byKey ) {
+			$result = $this->m->setByKey( $server_key, $derived_key, $value, $expiration );
+		} else {
+			$result = $this->m->set( $derived_key, $value, $expiration );
+		}
+
+		// Store in runtime cache if add was successful
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->add_to_internal_cache( $derived_key, $value );
+
+		return $result;
+	}
+
+	/**
+	 * Sets a value in cache on a specific server.
+	 *
+	 * The value is set whether or not this key already exists in memcached.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.setbykey.php
+	 *
+	 * @param   string      $server_key     The key identifying the server to store the value on.
+	 * @param   string      $key            The key under which to store the value.
+	 * @param   mixed       $value          The value to store.
+	 * @param   string      $group          The group value appended to the $key.
+	 * @param   int         $expiration     The expiration time, defaults to 0.
+	 * @return  bool                        Returns TRUE on success or FALSE on failure.
+	 */
+	public function setByKey( $server_key, $key, $value, $group = 'default', $expiration = 0 ) {
+		return $this->set( $key, $value, $group, $expiration, $server_key, true );
+	}
+
+	/**
+	 * Set multiple values to cache at once.
+	 *
+	 * By sending an array of $items to this function, all values are saved at once to
+	 * memcached, reducing the need for multiple requests to memcached. The $items array
+	 * keys and values are what are stored to memcached. The keys in the $items array
+	 * are merged with the $groups array/string value via buildKeys to determine the
+	 * final key for the object.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.setmulti.php
+	 *
+	 * @param   array           $items          An array of key/value pairs to store on the server.
+	 * @param   string|array    $groups         Group(s) to merge with key(s) in $items.
+	 * @param   int             $expiration     The expiration time, defaults to 0.
+	 * @param   string          $server_key     The key identifying the server to store the value on.
+	 * @param   bool            $byKey          True to store in internal cache by key; false to not store by key
+	 * @return  bool                            Returns TRUE on success or FALSE on failure.
+	 */
+	public function setMulti( $items, $groups = 'default', $expiration = 0, $server_key = '', $byKey = false ) {
+		// Build final keys and replace $items keys with the new keys
+		$derived_keys  = $this->buildKeys( array_keys( $items ), $groups );
+		$expiration    = $this->sanitize_expiration( $expiration );
+		$derived_items = array_combine( $derived_keys, $items );
+
+		// Do not add to memcached if in no_mc_groups
+		foreach ( $derived_items as $derived_key => $value ) {
+
+			// Get the individual item's group
+			$key_pieces = explode( ':', $derived_key );
+
+			// If group is a non-Memcached group, save to runtime cache, not Memcached
+			if ( in_array( $key_pieces[1], $this->no_mc_groups ) ) {
+				$this->add_to_internal_cache( $derived_key, $value );
+				unset( $derived_items[$derived_key] );
+			}
+		}
+
+		// Save to memcached
+		if ( $byKey )
+			$result = $this->m->setMultiByKey( $server_key, $derived_items, $expiration );
+		else
+			$result = $this->m->setMulti( $derived_items, $expiration );
+
+		// Store in runtime cache if add was successful
+		if ( Memcached::RES_SUCCESS === $this->getResultCode() )
+			$this->cache = array_merge( $this->cache, $derived_items );
+
+		return $result;
+	}
+
+	/**
+	 * Set multiple values to cache at once on specified server.
+	 *
+	 * By sending an array of $items to this function, all values are saved at once to
+	 * memcached, reducing the need for multiple requests to memcached. The $items array
+	 * keys and values are what are stored to memcached. The keys in the $items array
+	 * are merged with the $groups array/string value via buildKeys to determine the
+	 * final key for the object.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.setmultibykey.php
+	 *
+	 * @param   string          $server_key     The key identifying the server to store the value on.
+	 * @param   array           $items          An array of key/value pairs to store on the server.
+	 * @param   string|array    $groups         Group(s) to merge with key(s) in $items.
+	 * @param   int             $expiration     The expiration time, defaults to 0.
+	 * @return  bool                            Returns TRUE on success or FALSE on failure.
+	 */
+	public function setMultiByKey( $server_key, $items, $groups = 'default', $expiration = 0 ) {
+		return $this->setMulti( $items, $groups, $expiration, $server_key, true );
+	}
+
+	/**
+	 * Set a Memcached option.
+	 *
+	 * @link    http://www.php.net/manual/en/memcached.setoption.php
+	 *
+	 * @param   int         $option     Option name.
+	 * @param   mixed       $value      Option value.
+	 * @return  bool                Returns TRUE on success or FALSE on failure.
+	 */
+	public function setOption( $option, $value ) {
+		return $this->m->setOption( $option, $value );
+	}
+
+	/**
+	 * Builds a key for the cached object using the blog_id, key, and group values.
+	 *
+	 * @author  Ryan Boren   This function is inspired by the original WP Memcached Object cache.
+	 * @link    http://wordpress.org/extend/plugins/memcached/
+	 *
+	 * @param   string      $key        The key under which to store the value.
+	 * @param   string      $group      The group value appended to the $key.
+	 * @return  string
+	 */
+	public function buildKey( $key, $group = 'default' ) {
+		if ( empty( $group ) )
+			$group = 'default';
+
+		if ( false !== array_search( $group, $this->global_groups ) )
+			$prefix = $this->global_prefix;
+		else
+			$prefix = $this->blog_prefix;
+
+		return preg_replace( '/\s+/', '', WP_CACHE_KEY_SALT . "$prefix$group:$key" );
+	}
+
+	/**
+	 * Creates an array of keys from passed key(s) and group(s).
+	 *
+	 * This function takes a string or array of key(s) and group(s) and combines them into a single dimensional
+	 * array that merges the keys and groups. If the same number of keys and groups exist, the final keys will
+	 * append $groups[n] to $keys[n]. If there are more keys than groups and the $groups parameter is an array,
+	 * $keys[n] will be combined with $groups[n] until $groups runs out of values. 'default' will be used for remaining
+	 * values. If $keys is an array and $groups is a string, all final values will append $groups to $keys[n].
+	 * If both values are strings, they will be combined into a single string. Note that if more $groups are received
+	 * than $keys, the method will return an empty array. This method is primarily a helper method for methods
+	 * that call memcached with an array of keys.
+	 *
+	 * @param   string|array    $keys       Key(s) to merge with group(s).
+	 * @param   string|array    $groups     Group(s) to merge with key(s).
+	 * @return  array                       Array that combines keys and groups into a single set of memcached keys.
+	 */
+	public function buildKeys( $keys, $groups = 'default' ) {
+		$derived_keys = array();
+
+		// If strings sent, convert to arrays for proper handling
+		if ( ! is_array( $groups ) )
+			$groups = (array) $groups;
+
+		if ( ! is_array( $keys ) )
+			$keys = (array) $keys;
+
+		// If we have equal numbers of keys and groups, merge $keys[n] and $group[n]
+		if ( count( $keys ) == count( $groups ) ) {
+			for ( $i = 0; $i < count( $keys ); $i++ ) {
+				$derived_keys[] = $this->buildKey( $keys[$i], $groups[$i] );
+			}
+
+		// If more keys are received than groups, merge $keys[n] and $group[n] until no more group are left; remaining groups are 'default'
+		} elseif ( count( $keys ) > count( $groups ) ) {
+			for ( $i = 0; $i < count( $keys ); $i++ ) {
+				if ( isset( $groups[$i] ) )
+					$derived_keys[] = $this->buildKey( $keys[$i], $groups[$i] );
+				elseif ( count( $groups ) == 1 )
+					$derived_keys[] = $this->buildKey( $keys[$i], $groups[0] );
+				else
+					$derived_keys[] = $this->buildKey( $keys[$i], 'default' );
+			}
+		}
+
+		return $derived_keys;
+	}
+
+	/**
+	 * Ensure that a proper expiration time is set.
+	 *
+	 * Memcached treats any value over 30 days as a timestamp. If a developer sets the expiration for greater than 30
+	 * days or less than the current timestamp, the timestamp is in the past and the value isn't cached. This function
+	 * detects values in that range and corrects them.
+	 *
+	 * @param  string|int    $expiration    The dirty expiration time.
+	 * @return string|int                   The sanitized expiration time.
+	 */
+	public function sanitize_expiration( $expiration ) {
+		if ( $expiration > $this->thirty_days && $expiration <= $this->now ) {
+			$expiration = $expiration + $this->now;
+		}
+
+		return $expiration;
+	}
+
+	/**
+	 * Concatenates two values and casts to type of the first value.
+	 *
+	 * This is used in append and prepend operations to match how these functions are handled
+	 * by memcached. In both cases, whichever value is the original value in the combined value
+	 * will dictate the type of the combined value.
+	 *
+	 * @param   mixed       $original   Original value that dictates the combined type.
+	 * @param   mixed       $pended     Value to combine with original value.
+	 * @param   string      $direction  Either 'pre' or 'app'.
+	 * @return  mixed                   Combined value casted to the type of the first value.
+	 */
+	public function combine_values( $original, $pended, $direction ) {
+		$type = gettype( $original );
+
+		// Combine the values based on direction of the "pend"
+		if ( 'pre' == $direction )
+			$combined = $pended . $original;
+		else
+			$combined = $original . $pended;
+
+		// Cast type of combined value
+		settype( $combined, $type );
+
+		return $combined;
+	}
+
+	/**
+	 * Simple wrapper for saving object to the internal cache.
+	 *
+	 * @param   string      $derived_key    Key to save value under.
+	 * @param   mixed       $value          Object value.
+	 */
+	public function add_to_internal_cache( $derived_key, $value ) {
+		if ( is_object( $value ) ) {
+			$value = clone $value;
+		}
+
+		$this->cache[$derived_key] = $value;
+	}
+
+	/**
+	 * Determines if a no_mc_group exists in a group of groups.
+	 *
+	 * @param   mixed   $groups     The groups to search.
+	 * @return  bool                True if a no_mc_group is present; false if a no_mc_group is not present.
+	 */
+	public function contains_no_mc_group( $groups ) {
+		if ( is_scalar( $groups ) )
+			return in_array( $groups, $this->no_mc_groups );
+
+		if ( ! is_array( $groups ) )
+			return false;
+
+		foreach ( $groups as $group ) {
+			if ( in_array( $group, $this->no_mc_groups ) )
+				return true;
+		}
+
+		return false;
+	}
+
+	/**
+	 * Add global groups.
+	 *
+	 * @author  Ryan Boren   This function comes straight from the original WP Memcached Object cache
+	 * @link    http://wordpress.org/extend/plugins/memcached/
+	 *
+	 * @param   array       $groups     Array of groups.
+	 * @return  void
+	 */
+	public function add_global_groups( $groups ) {
+		if ( ! is_array( $groups ) )
+			$groups = (array) $groups;
+
+		$this->global_groups = array_merge( $this->global_groups, $groups);
+		$this->global_groups = array_unique( $this->global_groups );
+	}
+
+	/**
+	 * Add non-persistent groups.
+	 *
+	 * @author  Ryan Boren   This function comes straight from the original WP Memcached Object cache
+	 * @link    http://wordpress.org/extend/plugins/memcached/
+	 *
+	 * @param   array       $groups     Array of groups.
+	 * @return  void
+	 */
+	public function add_non_persistent_groups( $groups ) {
+		if ( ! is_array( $groups ) )
+			$groups = (array) $groups;
+
+		$this->no_mc_groups = array_merge( $this->no_mc_groups, $groups );
+		$this->no_mc_groups = array_unique( $this->no_mc_groups );
+	}
+
+	/**
+	 * Get a value specifically from the internal, run-time cache, not memcached.
+	 *
+	 * @param   int|string  $key        Key value.
+	 * @param   int|string  $group      Group that the value belongs to.
+	 * @return  bool|mixed              Value on success; false on failure.
+	 */
+	public function get_from_runtime_cache( $key, $group ) {
+		$derived_key = $this->buildKey( $key, $group );
+
+		if ( isset( $this->cache[$derived_key] ) )
+			return $this->cache[$derived_key];
+
+		return false;
+	}
+
+	/**
+	 * Switch blog prefix, which changes the cache that is accessed.
+	 *
+	 * @param  int     $blog_id    Blog to switch to.
+	 * @return void
+	 */
+	public function switch_to_blog( $blog_id ) {
+		global $table_prefix;
+		$blog_id           = (int) $blog_id;
+		$this->blog_prefix = ( is_multisite() ? $blog_id : $table_prefix ) . ':';
+	}
+}