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
}
?>
Memcache::connect
(PECL memcache >= 0.2.0)
Memcache::connect — Open memcached server connection
설명
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.
인수
-
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
portmust 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:
portdefaults 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.
주의
Warning
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.
반환값
성공 시 TRUE를, 실패 시 FALSE를 반환합니다.
예제
Example #1 Memcache::connect() example
<?php
/* procedural API */
$memcache_obj = memcache_connect('memcache_host', 11211);
/* OO API */
$memcache = new Memcache;
$memcache->connect('memcache_host', 11211);
?>
참고
- Memcache::pconnect() - Open memcached server persistent connection
- Memcache::close() - Close memcached server connection
add a note
User Contributed Notes 5 notes
geoffrey dot hoffman at gmail dot com ¶
14 years ago
webysther at gmail dot com ¶
10 years ago
In describing the timeout there is a statement that is not completely correct, increase the timeout does not necessarily preclude or unfeasible memcache, only allows the system to wait for more concurrent connections, which is a large minority of the number of connections, this causes several problems and could simply be corrected if the timeout was increased and perform some tests.
To prove the concept and show that the connection does not wait if the server goes down:
<?PHP
while ( ++$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.
chrisn at allipo dot com ¶
18 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);
$mmc->connect('node1', 11211);
?>
The last connect() call clears out the pool and then add and connect node1:11211 making it the only server.
If you want a pool of memcache servers, do not use the connect() function.
If you only want a single memcache server then there is no need to use the addServer() function.
djbrd ¶
13 years ago
To suppress (or handle) the warning and notice thrown by a failed attempt to connect, you can use a custom error handler function, like this:
<?php
function myErrorHandler($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, $errline", Logging::NOTICE);
return true;
}
return false;
}
set_error_handler('myErrorHandler');
?>
tom at all dash community dot de ¶
12 years ago
There is a not-so-obvious way to check whether or not a MemCache-Server is available.
Using ($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.
