Memcached::addServers
(PECL memcached >= 0.1.1)
Memcached::addServers — Add multiple servers to the server pool
Description
public bool Memcached::addServers
( array
$servers
)
Memcached::addServers() adds
servers to the server pool. Each entry in
servers is supposed to be an array containing hostname,
port, and, optionally, weight of the server. No connection is established
to the servers at this time.
The same server may appear multiple times in the server pool, because no
duplication checks are made. This is not advisable; instead, use the
weight option to increase the selection weighting of
this server.
Parameters
-
array -
Array of the servers to add to the pool.
Return Values
Returns TRUE on success or FALSE on failure.
Examples
Example #1 Memcached::addServers() example
<?php
$m = new Memcached();
$servers = array(
array('mem1.domain.com', 11211, 33),
array('mem2.domain.com', 11211, 67)
);
$m->addServers($servers);
?>
See Also
- Memcached::addServer() - Add a server to the server pool
- Memcached::resetServerList() - Clears all servers from the server list
- Функция Memcached::add() - Add an item under a new key
- Функция Memcached::addByKey() - Add an item under a new key on a specific server
- Функция Memcached::addServer() - Add a server to the server pool
- Функция Memcached::addServers() - Add multiple servers to the server pool
- Функция Memcached::append() - Append data to an existing item
- Функция Memcached::appendByKey() - Append data to an existing item on a specific server
- Функция Memcached::cas() - Compare and swap an item
- Функция Memcached::casByKey() - Compare and swap an item on a specific server
- Функция Memcached::__construct() - Create a Memcached instance
- Функция Memcached::decrement() - Decrement numeric item's value
- Функция Memcached::decrementByKey() - Decrement numeric item's value, stored on a specific server
- Функция Memcached::delete() - Delete an item
- Функция Memcached::deleteByKey() - Delete an item from a specific server
- Функция Memcached::deleteMulti() - Delete multiple items
- Функция Memcached::deleteMultiByKey() - Delete multiple items from a specific server
- Функция Memcached::fetch() - Fetch the next result
- Функция Memcached::fetchAll() - Fetch all the remaining results
- Функция Memcached::flush() - Invalidate all items in the cache
- Функция Memcached::get() - Retrieve an item
- Функция Memcached::getAllKeys() - Gets the keys stored on all the servers
- Функция Memcached::getByKey() - Retrieve an item from a specific server
- Функция Memcached::getDelayed() - Request multiple items
- Функция Memcached::getDelayedByKey() - Request multiple items from a specific server
- Функция Memcached::getMulti() - Retrieve multiple items
- Функция Memcached::getMultiByKey() - Retrieve multiple items from a specific server
- Функция Memcached::getOption() - Retrieve a Memcached option value
- Функция Memcached::getResultCode() - Return the result code of the last operation
- Функция Memcached::getResultMessage() - Return the message describing the result of the last operation
- Функция Memcached::getServerByKey() - Map a key to a server
- Функция Memcached::getServerList() - Get the list of the servers in the pool
- Функция Memcached::getStats() - Get server pool statistics
- Функция Memcached::getVersion() - Get server pool version info
- Функция Memcached::increment() - Increment numeric item's value
- Функция Memcached::incrementByKey() - Increment numeric item's value, stored on a specific server
- Функция Memcached::isPersistent() - Check if a persitent connection to memcache is being used
- Функция Memcached::isPristine() - Check if the instance was recently created
- Функция Memcached::prepend() - Prepend data to an existing item
- Функция Memcached::prependByKey() - Prepend data to an existing item on a specific server
- Функция Memcached::quit() - Close any open connections
- Функция Memcached::replace() - Replace the item under an existing key
- Функция Memcached::replaceByKey() - Replace the item under an existing key on a specific server
- Функция Memcached::resetServerList() - Clears all servers from the server list
- Функция Memcached::set() - Store an item
- Функция Memcached::setByKey() - Store an item on a specific server
- Функция Memcached::setMulti() - Store multiple items
- Функция Memcached::setMultiByKey() - Store multiple items on a specific server
- Функция Memcached::setOption() - Set a Memcached option
- Функция Memcached::setOptions() - Set Memcached options
- Функция Memcached::setSaslAuthData() - Set the credentials to use for authentication
- Функция Memcached::touch() - Set a new expiration on an item
- Функция Memcached::touchByKey() - Set a new expiration on an item on a specific server
Коментарии
See the note for __construct()
Important to not call ->addServers() every run -- only call it if no servers exist (check getServerList() ); otherwise, since addServers() does not check for dups, it will let you add the same server again and again and again, resultings in hundreds if not thousands of connections to the MC daemon.
For a proper FailOver mechanism:
$memcached = new Memcached();
$memcached->setOption(Memcached::OPT_CONNECT_TIMEOUT, 10);
$memcached->setOption(Memcached::OPT_DISTRIBUTION, Memcached::DISTRIBUTION_CONSISTENT);
$memcached->setOption(Memcached::OPT_SERVER_FAILURE_LIMIT, 2);
$memcached->setOption(Memcached::OPT_REMOVE_FAILED_SERVERS, true);
$memcached->setOption(Memcached::OPT_RETRY_TIMEOUT, 1);
$memcached->addServers($servers);
Memcached::OPT_DISTRIBUTION: set it to consistent hashing. If one memcached node is dead, its keys (and only its keys) will be evenly distributed to other nodes. This is where the magic is done. This is really different from removing one server in your ->addServers() call.
Memcached::OPT_SERVER_FAILURE_LIMIT: number of connection issues before a server is marked as DEAD, and removed from the list of servers (default: 5).
Memcached::OPT_REMOVE_FAILED_SERVERS: set it to «true», to enable the removal of dead servers.
Memcached::OPT_RETRY_TIMEOUT: after a node is declared DEAD, libmemcached will try it again after that many seconds. Here I've set it to 1 second, but I'm working on PHP scripts that run for less than 100ms most of the time. That would only be useful for cron/daemonize scripts.
Memcached::OPT_CONNECT_TIMEOUT: the timeout after which a server is considered DEAD. As my servers are on the same LAN, ping is ~0.5ms, so 10ms is large enough to consider the server is DEAD. Note that you have to wait twice that time before a node is marked DEAD, so if it's 1000ms, your script will lock for 2 seconds before ignoring the DEAD server. That may affect your response times a lot, and that's why I've set it very low
Author of this is Yvan from Dugwood