PHP Unconference Europe 2015

Memcache::connect

(PECL memcache >= 0.2.0)

Memcache::connectOpen memcached server connection

Descrierea

bool Memcache::connect ( string $host [, int $port [, int $timeout ]] )

Memcache::connect() establishes a connection to the memcached server. The connection, which was opened using Memcache::connect() will be automatically closed at the end of script execution. Also you can close it with Memcache::close(). Also you can use memcache_connect() function.

Parametri

host

Point to the host where memcached is listening for connections. This parameter may also specify other transports like unix:///path/to/memcached.sock to use UNIX domain sockets, in this case port must also be set to 0.

port

Point to the port where memcached is listening for connections. Set this parameter to 0 when using UNIX domain sockets.

Please note: port defaults to memcache.default_port if not specified. For this reason it is wise to specify the port explicitly in this method call.

timeout

Value in seconds which will be used for connecting to the daemon. Think twice before changing the default value of 1 second - you can lose all the advantages of caching if your connection is too slow.

Note

Avertizare

When the port is unspecified, this method defaults to the value set of the PHP ini directive memcache.default_port If this value was changed elsewhere in your application it might lead to unexpected results: for this reason it is wise to always specify the port explicitly in this method call.

Valorile întoarse

Întoarce valoarea TRUE în cazul succesului sau FALSE în cazul eșecului.

Exemple

Example #1 Memcache::connect() example

<?php

/* procedural API */

$memcache_obj memcache_connect('memcache_host'11211);

/* OO API */

$memcache = new Memcache;
$memcache->connect('memcache_host'11211);

?>

Vedeți de asemenea

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User Contributed Notes 5 notes

up
4
chrisn at allipo dot com
8 years ago
The behavior of Memcache::connect() is to always reinitialize the pool from scratch regardless of any previous calls to addServer().

E.g.

<?php
$mmc
= new Memcache()
$mmc->addServer('node1', 11211);
$mmc->addServer('node2', 11211);
$mmc->addServer('node3', 11211);

$mmc->connect('node1', 11211);
?>

The last connect() call clears out the pool and then add and connect node1:11211 making it the only server.

If you want a pool of memcache servers, do not use the connect() function.

If you only want a single memcache server then there is no need to use the addServer() function.
up
1
djbrd
3 years ago
To suppress (or handle) the warning and notice thrown by a failed attempt to connect, you can use a custom error handler function, like this:

<?php
function myErrorHandler($errno, $errstr, $errfile, $errline)
{

    if (
E_WARNING === $errno)
    {
       
Log("PHP Warning: $errstr, $errfile, $errline", Logging::WARN);
        return
true;
    }
   
    if (
E_NOTICE === $errno)
    {
       
Log("PHP Notic: $errstr, $errfile, $errline", Logging::NOTICE);
        return
true;
    }   
   
    return
false;
}

set_error_handler('myErrorHandler');
?>
up
0
webysther at gmail dot com
5 months ago
In describing the timeout there is a statement that is not completely correct, increase the timeout does not necessarily preclude or unfeasible memcache, only allows the system to wait for more concurrent connections, which is a large minority of the number of connections, this causes several problems and could simply be corrected if the timeout was increased and perform some tests.
To prove the concept and show that the connection does not wait if the server goes down:

<?PHP

while ( ++$loop < 10000 ) {
    try {
       
$memcache = new Memcache;
        @
$memcache->pconnect( "127.0.0.1" , 11211 , 30 );
       
$loopset = 0;
       
$loopget = 0;
       
        while ( ++
$loopset < 50 ) {
            if ( @
$memcache->set( "foo" , "bar" ) === false ) {
                echo
"Fail!" . PHP_EOL;
            }
        }
       
        while ( ++
$loopget < 500 ) {
            if ( @
$memcache->get( "foo" ) === false ) {
                echo
"Fail!" . PHP_EOL;
            }
        }
       
        if (
$loop % 100 == 0 ) {
            echo
"Try: " . $loop . PHP_EOL;
        }
    } catch (
Exception $e ) {
        echo
"Fail: " . $e->getMessage() . PHP_EOL;
    }
}

?>

Replace with an invalid host and test the timeout will not make a difference! It serves only for connections to the socket that are occupied.

More detail about troubleshooting timeouts in memcached google code.
up
0
tom at all dash community dot de
2 years ago
There is a not-so-obvious way to check whether or not a MemCache-Server is available.

Using ($memCache->connect() == false) will wait for a timeout if it can't connect. If you got a high-traffic site this may not be an option. So when the server is down, you may want to avoid waiting for this timeout on every request and instead try to reconnect only once every X seconds.

If so, this code may help:

<?php
$memCache
= new \Memcache();
$memCache->addServer($host, $port);
$stats = @$memCache->getExtendedStats();
$available = (bool) $stats["$host:$port"];
if (
$available && @$memCache->connect($host, $port))
   
// MemCache is there
else
   
// go on without MemCache
?>

The result of getExtendedStats() is an array. The information is cached and maintained by MemCache itself. If the server is not available, the result will be FALSE.

Even if the result is not false, the server may still not be available. Thus you need to check for connect() != false too, but only if the first check returns TRUE, thus avoiding the 1 second timeout in most cases.
Both getExtendedStats() and connect() issue notices/warnings if the server is not there. Thus you have to mute both calls.

Do NOT use getServerStatus() for this purpose: the result is cached on server-start and will not recognize when the connection to the server is lost (or reestablished) in between.
up
0
geoffrey dot hoffman at gmail dot com
4 years ago
If memcached is working, calling memcache_connect( ) returns an Object instance, not a boolean. If memcached is not working, calling memcache_connect( ) throws a notice AND a warning (and returns false as expected).

<?php
/* memcache is running */
$test1 = memcache_connect('127.0.0.1',11211);
echo
gettype($test1);
// object
echo get_class($test1);
// Memcache

/* memcached is stopped */
$test2 = memcache_connect('127.0.0.1',11211);

/*
Notice: memcache_connect(): Server 127.0.0.1 (tcp 11211) failed with: A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
(10060) in C:\Program Files\Support Tools\- on line 1

Warning: memcache_connect(): Can't connect to 127.0.0.1:11211, A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.
(10060) in C:\Program Files\Support Tools\- on line 1
*/

echo gettype($test2);
// boolean
echo $test2===false;
// 1
?>

There appears to be no way to check whether memcached is actually running without resorting to error suppression:

<?php
$test3
= @memcache_connect('127.0.0.1',11211);
if(
$test3===false ){
  
// memcached is _probably_ not running
}
?>
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