resmgr_msg_again()

Process a message again in a resource manager

Synopsis:

#include <sys/iofunc.h>
#include <sys/resmgr.h>

int resmgr_msg_again( resmgr_context_t *ctp,
                      int rcvid);

Arguments:

ctp: A pointer to a resmgr_context_t structure that the resource-manager library uses to pass context information between functions.
rcvid: The receive ID of the message that you want to process again.

Library:

libc

Use the -l c option to qcc to link against this library. This library is usually included automatically.

Description:

The resmgr_msg_again() function reprocesses the message corresponding to the given rcvid. It does this by:

calling MsgInfo() and MsgRead() to refresh the resmgr_context_t structure as if it had just arrived
calling MsgCurrent() to adjust your server thread's priority to that of the blocked client
processing the message as if it had just arrived

You use this function if your resource manager can't process a message right away. For example, if a read operation is blocked, your io_read handler would save the rcvid of the request, and then return _RESMGR_NOREPLY, leaving the client blocked. Later, when the resource manager can handle the request, it can call resmgr_msg_again() to reprocess the message.

CAUTION:

The resmgr_msg_again() function overwrites the ctp with data and state information of the message you want to process again. If you use this function in any callback other than a pulse handler, then further processing behaviour can be undefined. To proceed without resulting in undefined behaviour, provide a clean ctp allocated with a call to dispatch_context_alloc(); then free the dispatch context by calling dispatch_context_free() with the new ctp.

Furthermore, the function processes the new message in the context of the current thread. If the current thread holds any mutexes or other synchronization objects that are not relockable by the calling thread, this can result in self-deadlock or other failures.

Returns:

-1: Failure.
0: Success.

Errors:

EFAULT: A fault occurred when the kernel tried to access the buffers provided.
ESRCH: The thread indicated by rcvid doesn't exist, has had its connection detached, or isn't in either STATE_REPLY or STATE_NET_REPLY, or it isn't blocked on the connection associated with the rcvid.
ESRVRFAULT: The receive side of a message transfer encountered a memory fault accessing the receive/reply buffer.

Classification:

QNX Neutrino

Safety:
Cancellation point	No
Interrupt handler	No
Signal handler	No
Thread	Yes