Semaphore 函数
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msg_get_queue

(PHP 4 >= 4.3.0, PHP 5)

msg_get_queue — Create or attach to a message queue

说明

resource msg_get_queue ( int $key [, int $perms = 0666 ] )

msg_get_queue() returns an id that can be used to access the System V message queue with the given key. The first call creates the message queue with the optional perms. A second call to msg_get_queue() for the same key will return a different message queue identifier, but both identifiers access the same underlying message queue.

参数

key

Message queue numeric ID

perms

Queue permissions. Default to 0666. If the message queue already exists, the perms will be ignored.

返回值

Returns a resource handle that can be used to access the System V message queue.

参见

Semaphore 函数
在线手册：中文 英文
PHP手册
PHP手册 - N: Create or attach to a message queue

用户评论:

Michael Iatrou (02-Jul-2010 05:47)

If you are getting the following message (on Linux):

Warning: msg_get_queue() [function.msg-get-queue]: failed for key 0x12345678: No space left on device in /path/to/script.php on line 1

aside from what [others have] suggested, you should also check and set an appropriate value for kernel parameter kernel.msgmni, e.g. sysctl -w kernel.msgmni=256

Morten Brrup (17-Mar-2010 09:08)

IPC_CREAT has no effect in this function. The PHP source code (file sysvmsg.c) reveals that only if msgget(key,0) fails, msgget(key, IPC_CREAT | IPC_EXCL | perms) is used.

pail dot luo at gmail dot com (28-Feb-2009 05:22)

A simple Sample to introduce Message Queue.

<?php
if ( sizeof($argv)<2 ) {
        echo "Usage: $argv[0] stat|send|receive|remove msgType MSG [msg] \n\n" ;
        echo "   EX: $argv[0] send 1 \"This is no 1\" \n" ;
        echo "       $argv[0] receive ID \n" ;
        echo "       $argv[0] stat \n" ;
        echo "       $argv[0] remove \n" ;
        exit;
}

$MSGKey = "123456" ;

## Create or attach to a message queue
$seg = msg_get_queue($MSGKey) ;

switch ( $argv[1] ) {
    case "send":
        msg_send($seg, $argv[2], $argv[3]);
        echo "msg_send done...\n" ;
        break;
       
    case "receive":
        $stat = msg_stat_queue( $seg );
        echo 'Messages in the queue: '.$stat['msg_qnum']."\n";
        if ( $stat['msg_qnum']>0 ) {
            msg_receive($seg, $argv[2], $msgtype, 1024, $data);
            var_dump($msgtype);
            var_dump($data);
            echo "\n";
        }
        else {
            echo "No Msg...\n";
        }
        break;
   
    case "stat":
      print_r( msg_stat_queue($seg) );
        break;
       
    case "remove":
        msg_remove_queue($seg);
        break;
}
?>

david dot schueler at tel-billig dot de (17-Dec-2008 04:17)

If you are getting this message on your *NIX box:

Warning: msg_get_queue() [function.msg-get-queue]: failed for key 0x12345678: No space left on device in /path/to/script.php on line 1

you may use the command "ipcrm" as root to clear the message queue. Use "man ipcrm" to get more info on it.
The default setting for maximum messages in the queue is stored in /proc/sys/fs/mqueue/msg_max. To increase it to a maximum of 100 messages, just run:
echo 100 > /proc/sys/fs/mqueue/msg_max

Please ensure to follow a good programming style and close/free all your message queues before your script exits to avoid those warning messages.

martin dot velek at gmail dot com (01-Aug-2007 12:23)

Lack of IPC_EXCL makes me unhappy. Of course, you can use ftok() to generate a unique key. This code is not allmighty, another process under the same user can open the queue and function returns true. But in some situation it could help.

code:

<?
function ipcEXCL($res,$perm)
{
 $pole = msg_stat_queue($res);
 
 if($pole['msg_perm.uid']==posix_getuid() &&
    $pole['msg_perm.gid']==posix_getgid()  &&
    $pole['msg_perm.mode']==$perm  &&
    $pole['msg_stime']==0  &&
    $pole['msg_rtime']==0  &&
    $pole['msg_qnum']==0  &&
    $pole['msg_lspid']==0  &&
    $pole['msg_rspid']==0)
        return true;
 else
        return false;
}

$res=msg_get_queue($key,$perm);

if(ipcEXCL($res,$perm))
   echo "probably I am a creator:";
else
   echo "probably not";
?>

joeldg AT listbid.com (02-May-2003 08:10)

// Here is an example of working with message queues.
// if you have forked processes, this could be a great way of passing
// out work to them

// create the message queue
// pick a file..
  $key_t = msg_get_queue(ftok("/tmp/php_msgqueue.stat", 'R'),0666 | IPC_CREAT);

    // place two messages on the queue
    if (!msg_send ($key_t, 1, 'This is message #1', true, true, $msg_err))
       echo "Msg not sent because $msg_err\n";
    if (!msg_send ($key_t, 1, 'This is message #2 ', true, true, $msg_err))
       echo "Msg not sent because $msg_err\n";
     
    // lets look at the queue structure 'msg_qnum' is really what we want to see
    // it should be '2'
    print_r(msg_stat_queue($key_t));
   
    // pull off the stack
        if (msg_receive ($key_t, 1, $msg_type, 16384, $msg, true, 0, $msg_error)) {
           if ($msg == 'Quit');
           echo "$msg\n"; // prints 'This is message #1'
        } else {
           echo "Received $msg_error fetching message\n";
        }
    // look at the structure again, ms_qnum should be '1'   
    print_r(msg_stat_queue($key_t));
        if (msg_receive ($key_t, 1, $msg_type, 16384, $msg, true, 0, $msg_error)) {
           if ($msg == 'Quit');
           echo "$msg\n"; // prints 'This is message #2'
        } else {
           echo "Received $msg_error fetching message\n";
        }
   // look at the structure again, ms_qnum should be '0', no more messages on the queue
   print_r(msg_stat_queue($key_t)); 

   // get rid of the queue we created
   msg_remove_queue ($key_t);