mariadb/mit-pthreads/pthreads/wait.c

/* ==== wait.c ============================================================
 * Copyright (c) 1994 by Chris Provenzano, proven@mit.edu
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *  This product includes software developed by Chris Provenzano.
 * 4. The name of Chris Provenzano may not be used to endorse or promote 
 *	  products derived from this software without specific prior written
 *	  permission.
 *
 * THIS SOFTWARE IS PROVIDED BY CHRIS PROVENZANO ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL CHRIS PROVENZANO BE LIABLE FOR ANY 
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR 
 * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 
 * SUCH DAMAGE.
 *
 * Description : All the appropriate wait routines.
 *
 *  1.38 94/06/13 proven
 *      -Started coding this file.
 *
 */

#ifndef lint
static const char rcsid[] = "$Id$";
#endif

#include <pthread.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/time.h>
#include <pthread/posix.h>
#include <sys/compat.h>
#include <sys/wait.h>

/* This is an UGLY hack to get wait to compile, something better is needed. */
/* #define _POSIX_SOURCE
#undef _POSIX_SOURCE
*/

struct pthread_queue wait_queue = { NULL, NULL, NULL };
extern void sig_handler_real();

/* ==========================================================================
 * wait_wakeup()
 *
 * This routine is called by the interrupt handler which has locked
 * the current kthread semaphore. Since only threads owned by the 
 * current kthread can be queue here, no additional locks are necessary.
 */
int wait_wakeup()
{
	struct pthread *pthread;
	int ret = 0;

	if (pthread = pthread_queue_deq(& wait_queue)) {
		/* Wakeup all threads, and enqueue them on the run queue */
		do {
			pthread->state = PS_RUNNING;
			if (pthread->pthread_priority > ret) {
				ret = pthread->pthread_priority;
			}
			pthread_prio_queue_enq(pthread_current_prio_queue, pthread);
		} while (pthread = pthread_queue_deq(&wait_queue));
		return(ret);
	}
	return(NOTOK);
}

/* ==========================================================================
 * For the wait calls, it is important that the current kthread is locked
 * before the apropriate wait syscall is preformed. This way we ensure
 * that there is never a case where a thread is waiting for a child but
 * missed the interrupt for that child.
 * Patched by William S. Lear  1997-02-02
 */

/* ==========================================================================
 * waitpid()
 */
pid_t waitpid(pid_t pid, int *status, int options)
{
  pid_t ret;

  pthread_sched_prevent();
  ret = machdep_sys_waitpid(pid, status, options | WNOHANG);
  /* If we are not doing nohang, try again, else return immediately */
  if (!(options & WNOHANG)) {
    while (ret == OK) {
      /* Enqueue thread on wait queue */
      pthread_queue_enq(&wait_queue, pthread_run);

      /* reschedule unlocks scheduler */
      SET_PF_AT_CANCEL_POINT(pthread_run); /* This is a cancel point */
      pthread_resched_resume(PS_WAIT_WAIT);
      CLEAR_PF_AT_CANCEL_POINT(pthread_run); /* No longer at cancel point */

      pthread_sched_prevent();

      ret = machdep_sys_waitpid(pid, status, options | WNOHANG);
    }
  }
  pthread_sched_resume();
  return(ret);
}

/* ==========================================================================
 * wait3()
 * Patched by Monty 1997-02-02
 */
pid_t wait3(__WAIT_STATUS status, int options, void * rusage)
{
  semaphore * lock;
  pid_t ret;

  pthread_sched_prevent();
  ret = machdep_sys_wait3(status, options | WNOHANG, rusage);
  /* If we are not doing nohang, try again, else return immediately */
  if (!(options & WNOHANG)) {
    while (ret == OK) {
      /* Enqueue thread on wait queue */
      pthread_queue_enq(&wait_queue, pthread_run);

      /* reschedule unlocks scheduler */
      SET_PF_AT_CANCEL_POINT(pthread_run); /* This is a cancel point */
      pthread_resched_resume(PS_WAIT_WAIT);
      CLEAR_PF_AT_CANCEL_POINT(pthread_run); /* No longer at cancel point */

      pthread_sched_prevent();

      machdep_sys_wait3(status, options | WNOHANG, rusage);
    }
  }
  pthread_sched_resume();
  return(ret);
}

/* ==========================================================================
 * wait()
 */
pid_t wait(__WAIT_STATUS status)
{
	return(waitpid((pid_t)-1, (int *)status, 0));
}