freebsd-src/lib/libpthread/thread/thr_cond.c

/*
 * Copyright (c) 1995 John Birrell <jb@cimlogic.com.au>.
 * 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 John Birrell.
 * 4. Neither the name of the author nor the names of any co-contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY JOHN BIRRELL AND CONTRIBUTORS ``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 THE REGENTS OR CONTRIBUTORS 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.
 *
 */
#include <stdlib.h>
#include <errno.h>
#ifdef _THREAD_SAFE
#include <pthread.h>
#include "pthread_private.h"

int
pthread_cond_init(pthread_cond_t * cond, const pthread_condattr_t * cond_attr)
{
	enum pthread_cond_type type;
	int             rval = 0;

	/*
	 * Check if a pointer to a condition variable attribute structure was
	 * passed by the caller: 
	 */
	if (cond_attr != NULL) {
		/* Default to a fast condition variable: */
		type = cond_attr->c_type;
	} else {
		/* Default to a fast condition variable: */
		type = COND_TYPE_FAST;
	}

	/* Process according to condition variable type: */
	switch (type) {
		/* Fast condition variable: */
	case COND_TYPE_FAST:
		/* Nothing to do here. */
		break;

		/* Trap invalid condition variable types: */
	default:
		/* Return an invalid argument error: */
		_thread_seterrno(_thread_run, EINVAL);
		rval = -1;
		break;
	}

	/* Check for no errors: */
	if (rval == 0) {
		/* Initialise the condition variable structure: */
		_thread_queue_init(&cond->c_queue);
		cond->c_flags |= COND_FLAGS_INITED;
		cond->c_type = type;
	}
	/* Return the completion status: */
	return (rval);
}

int
pthread_cond_destroy(pthread_cond_t * cond)
{
	int             rval = 0;

	/* Process according to condition variable type: */
	switch (cond->c_type) {
		/* Fast condition variable: */
	case COND_TYPE_FAST:
		/* Nothing to do here. */
		break;

		/* Trap invalid condition variable types: */
	default:
		/* Return an invalid argument error: */
		_thread_seterrno(_thread_run, EINVAL);
		rval = -1;
		break;
	}

	/* Check for errors: */
	if (rval == 0) {
		/* Destroy the contents of the condition structure: */
		_thread_queue_init(&cond->c_queue);
		cond->c_flags = 0;
	}
	/* Return the completion status: */
	return (rval);
}

int
pthread_cond_wait(pthread_cond_t * cond, pthread_mutex_t * mutex)
{
	int             rval = 0;
	int             status;

	/* Block signals: */
	_thread_kern_sig_block(&status);

	/* Process according to condition variable type: */
	switch (cond->c_type) {
		/* Fast condition variable: */
	case COND_TYPE_FAST:
		/* Queue the running thread for the condition variable: */
			_thread_queue_enq(&cond->c_queue, _thread_run);

		/* Unlock the mutex: */
		pthread_mutex_unlock(mutex);

		/* Schedule the next thread: */
		_thread_kern_sched_state(PS_COND_WAIT, __FILE__, __LINE__);

		/* Block signals: */
		_thread_kern_sig_block(NULL);

		/* Lock the mutex: */
		rval = pthread_mutex_lock(mutex);
		break;

		/* Trap invalid condition variable types: */
	default:
		/* Return an invalid argument error: */
		_thread_seterrno(_thread_run, EINVAL);
		rval = -1;
		break;
	}

	/* Unblock signals: */
	_thread_kern_sig_unblock(status);

	/* Return the completion status: */
	return (rval);
}

int
pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
		       const struct timespec * abstime)
{
	int             rval = 0;
	int             status;

	/* Block signals: */
	_thread_kern_sig_block(&status);

	/* Process according to condition variable type: */
	switch (cond->c_type) {
		/* Fast condition variable: */
	case COND_TYPE_FAST:
		/* Set the wakeup time: */
		_thread_run->wakeup_time.ts_sec = abstime->ts_sec;
		_thread_run->wakeup_time.ts_nsec = abstime->ts_nsec;

		/* Reset the timeout flag: */
		_thread_run->timeout = 0;

		/* Queue the running thread for the condition variable: */
		_thread_queue_enq(&cond->c_queue, _thread_run);

		/* Unlock the mutex: */
		if ((rval = pthread_mutex_unlock(mutex)) != 0) {
			/*
			 * Cannot unlock the mutex, so remove the running
			 * thread from the condition variable queue: 
			 */
			_thread_queue_deq(&cond->c_queue);
		} else {
			/* Schedule the next thread: */
			_thread_kern_sched_state(PS_COND_WAIT, __FILE__, __LINE__);

			/* Block signals: */
			_thread_kern_sig_block(NULL);

			/* Lock the mutex: */
			if ((rval = pthread_mutex_lock(mutex)) != 0) {
			}
			/* Check if the wait timed out: */
			else if (_thread_run->timeout) {
				/* Return a timeout error: */
				_thread_seterrno(_thread_run, EAGAIN);
				rval = -1;
			}
		}
		break;

		/* Trap invalid condition variable types: */
	default:
		/* Return an invalid argument error: */
		_thread_seterrno(_thread_run, EINVAL);
		rval = -1;
		break;
	}

	/* Unblock signals: */
	_thread_kern_sig_unblock(status);

	/* Return the completion status: */
	return (rval);
}

int
pthread_cond_signal(pthread_cond_t * cond)
{
	int             rval = 0;
	int             status;
	pthread_t       pthread;

	/* Block signals: */
	_thread_kern_sig_block(&status);

	/* Process according to condition variable type: */
	switch (cond->c_type) {
		/* Fast condition variable: */
	case COND_TYPE_FAST:
		/* Bring the next thread off the condition queue: */
		if ((pthread = _thread_queue_deq(&cond->c_queue)) != NULL) {
			/* Allow the thread to run: */
			pthread->state = PS_RUNNING;
		}
		break;

		/* Trap invalid condition variable types: */
	default:
		/* Return an invalid argument error: */
		_thread_seterrno(_thread_run, EINVAL);
		rval = -1;
		break;
	}

	/* Unblock signals: */
	_thread_kern_sig_unblock(status);

	/* Return the completion status: */
	return (rval);
}

int
pthread_cond_broadcast(pthread_cond_t * cond)
{
	int             rval = 0;
	int             status;
	pthread_t       pthread;

	/* Block signals: */
	_thread_kern_sig_block(&status);

	/* Process according to condition variable type: */
	switch (cond->c_type) {
		/* Fast condition variable: */
	case COND_TYPE_FAST:
		/* Enter a loop to bring all threads off the condition queue: */
		while ((pthread = _thread_queue_deq(&cond->c_queue)) != NULL) {
			/* Allow the thread to run: */
			pthread->state = PS_RUNNING;
		}
		break;

		/* Trap invalid condition variable types: */
	default:
		/* Return an invalid argument error: */
		_thread_seterrno(_thread_run, EINVAL);
		rval = -1;
		break;
	}

	/* Unblock signals: */
	_thread_kern_sig_unblock(status);

	/* Return the completion status: */
	return (rval);
}
#endif