Getting Message Queuing information under Linux

In the program you want to get the message queue length you can use the properties of Message Queuing This data structure: Requires # include <sys/msg.h>

/* one msqid structure for each queue on the system */structmsqid_ds {    structipc_perm msg_perm;    structmsg *msg_first;  /* first message on queue */    structmsg *msg_last;   /* last message in queue */    time_tmsg_stime;       /* last msgsnd time */    time_tmsg_rtime;       /* last msgrcv time */    time_tmsg_ctime;       /* last change time */    structwait_queue *wwait;    structwait_queue *rwait;    ushort msg_cbytes;    //当前消息队列中的字节数    ushort msg_qnum;     //当前消息队列中的消息个数    ushort msg_qbytes;      /* max number of bytes on queue */    ushort msg_lspid;       /* pid of last msgsnd */    ushort msg_lrpid;       /* last receive pid */};

Simple Program Example:

structmsqid_ds msg_info;if (msgctl(msgQid,IPC_STAT,&msg_info) == ERROR){    return ERROR;}else{    returnmsg_info.msg_qnum;}

Each parameter of the data structure is explained as follows: Msg_permAn instance of the IPC_PERM structure, which are defined for us in linux/ipc.h. This holds the permission information for the message queue, including the access permissions, and information about the C Reator of the queue (UID, etc). Msg_firstLink to the first message in the queue (the head of the list). Msg_lastLink to the last message in the queue (the tail of the list). Msg_stimeTimestamp (time_t), the last message, is sent to the queue. Msg_rtimeTimestamp of the last message retrieved from the queue. Msg_ctimeTimestamp of the Last "change" made to the "queue" (more on this later). wwaitand rwaitPointers into the kernel ' s Wait Queue. They is used if an operation on a message queue deems the process go to a sleep state (i.e. queue was full and the pro Cess is waiting for a opening). msg_cbytesTotal number of bytes residing in the queue (sum of the sizes of all messages). Msg_qnumNumber of messages currently in the queue. msg_qbytesMaximum number of bytes on the queue. Msg_lspidThe PID of the process who sent the last message. Msg_lrpidThe PID of the process who retrieved the last message.

Getting Message Queuing information under Linux