msg_stat_queue() returns the message queue meta data
for the message queue specified by the queue.
This is useful, for example, to determine which process sent the message
that was just received.
The return value is an array whose keys and values have the following meanings:
Table 1. Array structure for msg_stat_queue
| msg_perm.uid | The uid of the owner of the queue. |
| msg_perm.gid | The gid of the owner of the queue. |
| msg_perm.mode | The file access mode of the queue. |
| msg_stime | The time that the last message was sent to the queue. |
| msg_rtime | The time that the last message was received from the queue. |
| msg_ctime | The time that the queue was last changed. |
| msg_qnum | The number of messages waiting to be read from the queue. |
| msg_qbytes | The number of bytes of space currently available in the queue to hold sent messages until they are received. |
| msg_lspid | The pid of the process that sent the last message to the queue. |
| msg_lrpid | The pid of the process that received the last message from the queue. |