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Full Discussion: Unix message Queue
Top Forums UNIX for Advanced & Expert Users Unix message Queue Post 38909 by kel on Wednesday 30th of July 2003 08:42:51 AM
Old 07-30-2003
Hi,
Thanks for your replay.

I'll try to be more clear -
1. i have created the Q as follow:
'o_qid = msgget(IPC_PRIVATE,IPC_CREAT|0777|IPC_EXCL|S_IRUSR|S_IWUSR);'

And worked with the Q as follow:
'msgsnd( qid, (void*)(&eventDataBuffer), MessageSize, 0) '
'qbytesread=msgrcv(qid, (void*)pMessage, max_msgsize, -MSGTYPE_MAX_APP_RANGE, 0)'

2. The Q has functioned OK for about an hour, where data was surely sent & received.

3. On a certain point, i could not send, nor receive from the Q.
The parameters on the Q where:
Qnum=0 (The number of messages currently outstanding on the
associated message queue.)
CBYTES= ~4k (The number of bytes in messages currently outstanding on the associated message queue.)

This is what i do not understand. How come there are no messages, and the Q inform me that the data size is greater than 0?

I hope i made more clear.
Thanks Again.
 

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msg.h(3HEAD)							      Headers							      msg.h(3HEAD)

NAME
msg.h, msg - message queue structures SYNOPSIS
#include <sys/msg.h> DESCRIPTION
The <sys/msg.h> header defines the following data types through typedef: msgqnum_t used for the number of messages in the message queue msglen_t used for the number of bytes allowed in the message queue These types are unsigned integer types that are able to store values at least as large as a type unsigned short. The <sys/msg.h> header defines the following constant as a message operation flag: MSG_NOERROR no error if big message The msqid_ds structure contains the following members: struct ipc_perm msg_perm Operation permission structure. msgqnum_t msg_qnum Number of messages currently on queue. msglen_t msg_qbytes Maximum number of bytes allowed on queue. pid_t msg_lspid Process ID of last msgsnd(2). pid_t msg_lrpid Process ID of last msgrcv(2). time_t msg_stime Time of last msgsnd(). time_t msg_rtime Time of last msgrcv(). time_t msg_ctime Time of last change. The pid_t, time_t, key_t, size_t, and ssize_t types are defined as described in <sys/types.h>. See types(3HEAD). ATTRIBUTES
See attributes(5) for descriptions of the following attributes: +-----------------------------+-----------------------------+ | ATTRIBUTE TYPE | ATTRIBUTE VALUE | +-----------------------------+-----------------------------+ |Interface Stability |Standard | +-----------------------------+-----------------------------+ SEE ALSO
msgctl(2), msgget(2), msgrcv(2), msgsnd(2), ipc.h(3HEAD), types.h(3HEAD), attributes(5), standards(5) SunOS 5.11 10 Sep 2004 msg.h(3HEAD)
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