srv_getmsgq

Get the next message from a message queue.

CS_RETCODE srv_getmsgq(msgqid, msgp, getflags, infop)

SRV_OBJID    msgqid;
CS_VOID       **msgp;
CS_INT          getflags;
CS_INT         *infop;

msgqid: The identifier for the message queue from which to get a message. To reference the message queue by name, call srv_getobjid with the name to yield the message queue ID.

msgp: A pointer to a pointer variable that srv_getmsgq sets to the message’s address.

The values for getflags can be OR’d together. Table 3-53 lists the legal values for getflags, and their significance:

**Table 3-53: Values for getflags (srv_getmsgq)**
Value	Significance
SRV_M_WAIT	If no message is available, srv_getmsgq sleeps until a message is delivered.
SRV_M_NOWAIT	srv_getmsgq returns immediately whether a message is available or not.
SRV_M_READ_ONLY	The default behavior of srv_getmsgq is to remove the message from the message list and to wake up any thread that is waiting for the message to be read. If SRV_M_READ_ONLY is set, a message pointer is returned, but the message is not removed from the list and the thread waiting for the message to be read does not wake up. This option can be used to peek at the head of the message queue to see if the message is intended for the thread.

A pointer to a CS_INT. Table 3-54 describes the possible values returned in *infop if srv_getmsgq returns CS_FAIL:

**Table 3-54: Values for infop (srv_getmsgq)**
Value	Meaning
SRV_I_WOULDWAIT	The SRV_M_NOWAIT flag was set in the getflags field and there are no messages to be read.
SRV_I_DELETED	While waiting for a message, the message queue was deleted.
SRV_I_INTERRUPTED	The SRV_M_WAIT flag was set in the getflags field and this call was interrupted before the message arrived.
SRV_I_UNKNOWN	Some other error occurred. Look in the log file for a message.

**Table 3-55: Return values (srv_getmsgq)**
Returns	To indicate
CS_SUCCEED	The routine completed successfully.
CS_FAIL	The routine failed.

#include <ospublic.h>

/*

 ** Local prototype

*/

CS_VOID    ex_srv_getmsgq PROTOTYPE((

SRV_OBJID  msgqid,

CS_INT     *infop

));

/*

 ** EX_SRV_GETMSGQ

**

**    Example routine to get messages from a message queue.

**

** Arguments:

**    msgqid-    The id of the message queue from which to get

 **               the message.

**

**    infop-     Will hold information about why this routine

 **               failed. Comes directly from srv_getmsg.

** Returns:

**    Nothing. If this routine returns, it is because srv_getmsgq

 **    failed. Check infop to see why it failed.

*/

CS_VOID    ex_srv_getmsgq(msgqid, infop)

SRV_OBJID  msgqid;

CS_INT     *infop;

     CS_CHAR   *message;   /* This message is a string. */

/*

     ** Loop processing messages. Go to sleep if no messages are

     ** available.

*/

    while (srv_getmsgq(msgqid, (CS_VOID *)&message, SRV_M_WAIT,

             infop)== CS_SUCCEED)

        /* Process message.*/

    /* infop will contain the reason why it failed. */

    return ;

srv_getmsgq puts the address of the next message from the message queue msgqid in *msgp.
If the thread that sent the message specified that it would sleep until the message is read, it wakes up.