ftok
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";
?>
msg_get_queue
(PHP 4 >= 4.3.0, PHP 5)
msg_get_queue — Create or attach to a message queue
Description
resource msg_get_queue
( int $key
[, int $perms
] )
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.
Parameters
- key
-
Message queue numeric ID
- perms
-
Queue permissions. Default to 0666. If the message queue already exists, the perms will be ignored.
Return Values
Returns a resource handle that can be used to access the System V message queue.
add a note
User Contributed Notesmsg_get_queue
martin dot velek at gmail dot com
01-Aug-2007 01:23
01-Aug-2007 01:23
zxd at zhangxiaodong dot net
16-Dec-2004 06:55
16-Dec-2004 06:55
#
# require --enable-sysvmsg configure option
#
# see phpinfo() to find how to check
#
joeldg AT listbid.com
02-May-2003 09:10
02-May-2003 09:10
// 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);