MWMAINLOOP

Section: MidWay Programmer's Manual (3C)
Updated: DATE
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NAME

mwMainLoop - Main loop in a MidWay server

SYNOPSIS

#include <MidWay.h>

int mwMainLoop(int flags);

DESCRIPTION

This is called by a server after it has attached it self to the domain with mattach() and provided all its service routines with mwprovide(). mwMainLoop() essentially calls mwservicerequest() indefinitely.
If MWSIGRST is not set it will return on a signal, with return code -EINTR.

Programmers may feel the need roll their own mwMainLoop, especially if you want to incorporate a MidWay server in a program that has a main loop else where. Thats pretty much OK, just be careful. An example mwMainLoop is shown below, taken from MidWay/src/lib/mwserver.c. You may also look in the code for mwserver(1) (MidWay/src/mwserver) for a more complex example.

After mwMainLoop() exits you are required to call mwdetach(). Failure to do so will leave IPC resources undeleted, and the info tables in shared memory will still hold information about this server, and some service calls may fail since they may still be addressed to this server. When mwMainLoop() returns the status if the server is set to "(suspended)".

RETURN VALUES

The return value is always a negative errno, giving the reason why the loop aborted.

ERRORS

EINTR: A signal was delivered to the program while in msgrcv. If you want to know which one, or to watch signals during execution of service routines, install a signal handler.
ENOTCONN: Either mwattach() has not yet been called, or it failed, or mwdetach() has been called.
ESHUTDOWN: The MidWay daemon mwd(1) has sent us an instruction to exit. We are required to do so.
ENOENT: No calls to mwprovide() has been made or in the last service request a mwunprovide() was called on the last service this server provided. To continue mwMainLoop() would be futile since the only "service" we can perform is a shutdown instruction from mwd(1). If you wanted to suspend a service in such a way it can be resumed from mwadm(1), use mw******().(Futurefunctionality.)

WARNINGS

EXAMPLES

An (almost) minimum implementation of mwMainLoop().

int mwMainLoop(int flags)
{
  int rc, counter = 0;
  
  while(1) {
    counter++;
    mwlog(MWLOG_DEBUG, "std MailLoop begining for the %d time.", 
          counter);
    rc = mwservicerequest(flags);
    if ( (rc == -EINTR) && (flags & MWSIGRSRT)) continue;
    if (rc < 0) return rc;
  };
};

BUGS

STANDARDS

NONE

This document was created by man2html, using the manual pages.
Time: 11:18:49 GMT, October 24, 2000