ConFoo Montreal 2017 Calling for Papers

Memcached::getServerByKey

(PECL memcached >= 0.1.0)

Memcached::getServerByKeyMap a key to a server

Descrição

public array Memcached::getServerByKey ( string $server_key )

Memcached::getServerByKey() returns the server that would be selected by a particular server_key in all the Memcached::*ByKey() operations.

Parâmetros

server_key

A chave identificando o servidor onde armazenar ou recuperar o valor. Em vez de fazer o hash do item, é feito o hash da chave do servidor quando decidindo com qual servidor memcached conectar. Isto permite que itens relacionados sejam agrupados em um único servidor para maior eficiência de operações múltiplas.

Valor Retornado

Returns an array containing three keys of host, port, and weight on success or FALSE on failure. Use Memcached::getResultCode() se necessário.

Exemplos

Exemplo #1 Memcached::getServerByKey() example

<?php
$m 
= new Memcached();
$m->addServers(array(
    array(
'mem1.domain.com'1121140),
    array(
'mem2.domain.com'1121140),
    array(
'mem3.domain.com'1121120),
));

$m->setOption(Memcached::OPT_LIBKETAMA_COMPATIBLEtrue);

var_dump($m->getServerByKey('user'));
var_dump($m->getServerByKey('log'));
var_dump($m->getServerByKey('ip'));
?>

O exemplo acima irá imprimir algo similar à:

array(3) {
  ["host"]=>
  string(15) "mem3.domain.com"
  ["port"]=>
  int(11211)
  ["weight"]=>
  int(20)
}
array(3) {
  ["host"]=>
  string(15) "mem2.domain.com"
  ["port"]=>
  int(11211)
  ["weight"]=>
  int(40)
}
array(3) {
  ["host"]=>
  string(15) "mem2.domain.com"
  ["port"]=>
  int(11211)
  ["weight"]=>
  int(40)
}

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User Contributed Notes 2 notes

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4
zhaoyong dot lc at gmail dot com
3 years ago
The parameter server_key is very confusing, it's not a server key for MemCached Server, but it's key,in key-value pair which you stored in server.

<?php
$m
= new Memcached;
$m->addServers(array(
    array(
'127.0.0.1',11212),
    array(
'127.0.0.1',11211)
));
for(
$i=0;$i<10;$i++){
   
$key = 'key_'.$i;
   
$m->add($key, 1);
}
for(
$i=0;$i<10;$i++) {
   
$key = 'key_'.$i;
   
$arr = $m->getServerByKey($key);
    echo (
$key.":\t".$arr['port']."\n");
}
?>

key_0:  11212
key_1:  11211
key_2:  11212
key_3:  11212
key_4:  11212
key_5:  11211
key_6:  11211
key_7:  11212
key_8:  11212
key_9:  11211
up
1
morphles
5 months ago
Just to clarify (as documentation of memcached, even for C lib, frankly is quite lacking), $server_key is hashed using same method as regular keys for values (I checked C source, as again docs......). So you should be able to see where set($key, $value) goes by using getServerByKey($key) with same key. This can be useful if one does not wish to bother with using/has no need to use *ByKey functions, but still want to know which servers are/should be used with regular keys, for implementing fallback or failure reporting.
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