summaryrefslogtreecommitdiffstats
path: root/lib/libpthread/thread/thr_cond.c
diff options
context:
space:
mode:
Diffstat (limited to 'lib/libpthread/thread/thr_cond.c')
-rw-r--r--lib/libpthread/thread/thr_cond.c735
1 files changed, 735 insertions, 0 deletions
diff --git a/lib/libpthread/thread/thr_cond.c b/lib/libpthread/thread/thr_cond.c
new file mode 100644
index 0000000..a22d983
--- /dev/null
+++ b/lib/libpthread/thread/thr_cond.c
@@ -0,0 +1,735 @@
+/*
+ * 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <pthread.h>
+#include "thr_private.h"
+
+/*
+ * Prototypes
+ */
+static inline pthread_t cond_queue_deq(pthread_cond_t);
+static inline void cond_queue_remove(pthread_cond_t, pthread_t);
+static inline void cond_queue_enq(pthread_cond_t, pthread_t);
+
+__weak_reference(_pthread_cond_init, pthread_cond_init);
+__weak_reference(_pthread_cond_destroy, pthread_cond_destroy);
+__weak_reference(_pthread_cond_wait, pthread_cond_wait);
+__weak_reference(_pthread_cond_timedwait, pthread_cond_timedwait);
+__weak_reference(_pthread_cond_signal, pthread_cond_signal);
+__weak_reference(_pthread_cond_broadcast, pthread_cond_broadcast);
+
+
+/* Reinitialize a condition variable to defaults. */
+int
+_cond_reinit(pthread_cond_t *cond)
+{
+ int ret = 0;
+
+ if (cond == NULL)
+ ret = EINVAL;
+ else if (*cond == NULL)
+ ret = pthread_cond_init(cond, NULL);
+ else {
+ /*
+ * Initialize the condition variable structure:
+ */
+ TAILQ_INIT(&(*cond)->c_queue);
+ (*cond)->c_flags = COND_FLAGS_INITED;
+ (*cond)->c_type = COND_TYPE_FAST;
+ (*cond)->c_mutex = NULL;
+ (*cond)->c_seqno = 0;
+ memset(&(*cond)->lock, 0, sizeof((*cond)->lock));
+ }
+ return (ret);
+}
+
+int
+_pthread_cond_init(pthread_cond_t *cond, const pthread_condattr_t *cond_attr)
+{
+ enum pthread_cond_type type;
+ pthread_cond_t pcond;
+ int rval = 0;
+
+ if (cond == NULL)
+ rval = EINVAL;
+ else {
+ /*
+ * Check if a pointer to a condition variable attribute
+ * structure was passed by the caller:
+ */
+ if (cond_attr != NULL && *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: */
+ rval = EINVAL;
+ break;
+ }
+
+ /* Check for no errors: */
+ if (rval == 0) {
+ if ((pcond = (pthread_cond_t)
+ malloc(sizeof(struct pthread_cond))) == NULL) {
+ rval = ENOMEM;
+ } else {
+ /*
+ * Initialise the condition variable
+ * structure:
+ */
+ TAILQ_INIT(&pcond->c_queue);
+ pcond->c_flags |= COND_FLAGS_INITED;
+ pcond->c_type = type;
+ pcond->c_mutex = NULL;
+ pcond->c_seqno = 0;
+ memset(&pcond->lock,0,sizeof(pcond->lock));
+ *cond = pcond;
+ }
+ }
+ }
+ /* Return the completion status: */
+ return (rval);
+}
+
+int
+_pthread_cond_destroy(pthread_cond_t *cond)
+{
+ int rval = 0;
+
+ if (cond == NULL || *cond == NULL)
+ rval = EINVAL;
+ else {
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&(*cond)->lock);
+
+ /*
+ * Free the memory allocated for the condition
+ * variable structure:
+ */
+ free(*cond);
+
+ /*
+ * NULL the caller's pointer now that the condition
+ * variable has been destroyed:
+ */
+ *cond = NULL;
+ }
+ /* Return the completion status: */
+ return (rval);
+}
+
+int
+_pthread_cond_wait(pthread_cond_t *cond, pthread_mutex_t *mutex)
+{
+ struct pthread *curthread = _get_curthread();
+ int rval = 0;
+ int done = 0;
+ int interrupted = 0;
+ int seqno;
+
+ _thread_enter_cancellation_point();
+
+ if (cond == NULL)
+ return (EINVAL);
+
+ /*
+ * If the condition variable is statically initialized,
+ * perform the dynamic initialization:
+ */
+ if (*cond == NULL &&
+ (rval = pthread_cond_init(cond, NULL)) != 0)
+ return (rval);
+
+ /*
+ * Enter a loop waiting for a condition signal or broadcast
+ * to wake up this thread. A loop is needed in case the waiting
+ * thread is interrupted by a signal to execute a signal handler.
+ * It is not (currently) possible to remain in the waiting queue
+ * while running a handler. Instead, the thread is interrupted
+ * and backed out of the waiting queue prior to executing the
+ * signal handler.
+ */
+ do {
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&(*cond)->lock);
+
+ /*
+ * If the condvar was statically allocated, properly
+ * initialize the tail queue.
+ */
+ if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
+ TAILQ_INIT(&(*cond)->c_queue);
+ (*cond)->c_flags |= COND_FLAGS_INITED;
+ }
+
+ /* Process according to condition variable type: */
+ switch ((*cond)->c_type) {
+ /* Fast condition variable: */
+ case COND_TYPE_FAST:
+ if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
+ ((*cond)->c_mutex != *mutex))) {
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+
+ /* Return invalid argument error: */
+ rval = EINVAL;
+ } else {
+ /* Reset the timeout and interrupted flags: */
+ curthread->timeout = 0;
+ curthread->interrupted = 0;
+
+ /*
+ * Queue the running thread for the condition
+ * variable:
+ */
+ cond_queue_enq(*cond, curthread);
+
+ /* Remember the mutex and sequence number: */
+ (*cond)->c_mutex = *mutex;
+ seqno = (*cond)->c_seqno;
+
+ /* Wait forever: */
+ curthread->wakeup_time.tv_sec = -1;
+
+ /* Unlock the mutex: */
+ if ((rval = _mutex_cv_unlock(mutex)) != 0) {
+ /*
+ * Cannot unlock the mutex, so remove
+ * the running thread from the condition
+ * variable queue:
+ */
+ cond_queue_remove(*cond, curthread);
+
+ /* Check for no more waiters: */
+ if (TAILQ_FIRST(&(*cond)->c_queue) ==
+ NULL)
+ (*cond)->c_mutex = NULL;
+
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+ } else {
+ /*
+ * Schedule the next thread and unlock
+ * the condition variable structure:
+ */
+ _thread_kern_sched_state_unlock(PS_COND_WAIT,
+ &(*cond)->lock, __FILE__, __LINE__);
+
+ done = (seqno != (*cond)->c_seqno);
+
+ interrupted = curthread->interrupted;
+
+ /*
+ * Check if the wait was interrupted
+ * (canceled) or needs to be resumed
+ * after handling a signal.
+ */
+ if (interrupted != 0) {
+ /*
+ * Lock the mutex and ignore any
+ * errors. Note that even
+ * though this thread may have
+ * been canceled, POSIX requires
+ * that the mutex be reaquired
+ * prior to cancellation.
+ */
+ (void)_mutex_cv_lock(mutex);
+ } else {
+ /*
+ * Lock the condition variable
+ * while removing the thread.
+ */
+ _SPINLOCK(&(*cond)->lock);
+
+ cond_queue_remove(*cond,
+ curthread);
+
+ /* Check for no more waiters: */
+ if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
+ (*cond)->c_mutex = NULL;
+
+ _SPINUNLOCK(&(*cond)->lock);
+
+ /* Lock the mutex: */
+ rval = _mutex_cv_lock(mutex);
+ }
+ }
+ }
+ break;
+
+ /* Trap invalid condition variable types: */
+ default:
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+
+ /* Return an invalid argument error: */
+ rval = EINVAL;
+ break;
+ }
+
+ if ((interrupted != 0) && (curthread->continuation != NULL))
+ curthread->continuation((void *) curthread);
+ } while ((done == 0) && (rval == 0));
+
+ _thread_leave_cancellation_point();
+
+ /* Return the completion status: */
+ return (rval);
+}
+
+int
+_pthread_cond_timedwait(pthread_cond_t * cond, pthread_mutex_t * mutex,
+ const struct timespec * abstime)
+{
+ struct pthread *curthread = _get_curthread();
+ int rval = 0;
+ int done = 0;
+ int interrupted = 0;
+ int seqno;
+
+ _thread_enter_cancellation_point();
+
+ if (abstime == NULL || abstime->tv_sec < 0 || abstime->tv_nsec < 0 ||
+ abstime->tv_nsec >= 1000000000)
+ return (EINVAL);
+ /*
+ * If the condition variable is statically initialized, perform dynamic
+ * initialization.
+ */
+ if (*cond == NULL && (rval = pthread_cond_init(cond, NULL)) != 0)
+ return (rval);
+
+ /*
+ * Enter a loop waiting for a condition signal or broadcast
+ * to wake up this thread. A loop is needed in case the waiting
+ * thread is interrupted by a signal to execute a signal handler.
+ * It is not (currently) possible to remain in the waiting queue
+ * while running a handler. Instead, the thread is interrupted
+ * and backed out of the waiting queue prior to executing the
+ * signal handler.
+ */
+ do {
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&(*cond)->lock);
+
+ /*
+ * If the condvar was statically allocated, properly
+ * initialize the tail queue.
+ */
+ if (((*cond)->c_flags & COND_FLAGS_INITED) == 0) {
+ TAILQ_INIT(&(*cond)->c_queue);
+ (*cond)->c_flags |= COND_FLAGS_INITED;
+ }
+
+ /* Process according to condition variable type: */
+ switch ((*cond)->c_type) {
+ /* Fast condition variable: */
+ case COND_TYPE_FAST:
+ if ((mutex == NULL) || (((*cond)->c_mutex != NULL) &&
+ ((*cond)->c_mutex != *mutex))) {
+ /* Return invalid argument error: */
+ rval = EINVAL;
+
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+ } else {
+ /* Set the wakeup time: */
+ curthread->wakeup_time.tv_sec =
+ abstime->tv_sec;
+ curthread->wakeup_time.tv_nsec =
+ abstime->tv_nsec;
+
+ /* Reset the timeout and interrupted flags: */
+ curthread->timeout = 0;
+ curthread->interrupted = 0;
+
+ /*
+ * Queue the running thread for the condition
+ * variable:
+ */
+ cond_queue_enq(*cond, curthread);
+
+ /* Remember the mutex and sequence number: */
+ (*cond)->c_mutex = *mutex;
+ seqno = (*cond)->c_seqno;
+
+ /* Unlock the mutex: */
+ if ((rval = _mutex_cv_unlock(mutex)) != 0) {
+ /*
+ * Cannot unlock the mutex, so remove
+ * the running thread from the condition
+ * variable queue:
+ */
+ cond_queue_remove(*cond, curthread);
+
+ /* Check for no more waiters: */
+ if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
+ (*cond)->c_mutex = NULL;
+
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+ } else {
+ /*
+ * Schedule the next thread and unlock
+ * the condition variable structure:
+ */
+ _thread_kern_sched_state_unlock(PS_COND_WAIT,
+ &(*cond)->lock, __FILE__, __LINE__);
+
+ done = (seqno != (*cond)->c_seqno);
+
+ interrupted = curthread->interrupted;
+
+ /*
+ * Check if the wait was interrupted
+ * (canceled) or needs to be resumed
+ * after handling a signal.
+ */
+ if (interrupted != 0) {
+ /*
+ * Lock the mutex and ignore any
+ * errors. Note that even
+ * though this thread may have
+ * been canceled, POSIX requires
+ * that the mutex be reaquired
+ * prior to cancellation.
+ */
+ (void)_mutex_cv_lock(mutex);
+ } else {
+ /*
+ * Lock the condition variable
+ * while removing the thread.
+ */
+ _SPINLOCK(&(*cond)->lock);
+
+ cond_queue_remove(*cond,
+ curthread);
+
+ /* Check for no more waiters: */
+ if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
+ (*cond)->c_mutex = NULL;
+
+ _SPINUNLOCK(&(*cond)->lock);
+
+ /* Lock the mutex: */
+ rval = _mutex_cv_lock(mutex);
+
+ /*
+ * Return ETIMEDOUT if the wait
+ * timed out and there wasn't an
+ * error locking the mutex:
+ */
+ if ((curthread->timeout != 0)
+ && rval == 0)
+ rval = ETIMEDOUT;
+
+ }
+ }
+ }
+ break;
+
+ /* Trap invalid condition variable types: */
+ default:
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+
+ /* Return an invalid argument error: */
+ rval = EINVAL;
+ break;
+ }
+
+ if ((interrupted != 0) && (curthread->continuation != NULL))
+ curthread->continuation((void *) curthread);
+ } while ((done == 0) && (rval == 0));
+
+ _thread_leave_cancellation_point();
+
+ /* Return the completion status: */
+ return (rval);
+}
+
+int
+_pthread_cond_signal(pthread_cond_t * cond)
+{
+ int rval = 0;
+ pthread_t pthread;
+
+ if (cond == NULL)
+ rval = EINVAL;
+ /*
+ * If the condition variable is statically initialized, perform dynamic
+ * initialization.
+ */
+ else if (*cond != NULL || (rval = pthread_cond_init(cond, NULL)) == 0) {
+ /*
+ * Defer signals to protect the scheduling queues
+ * from access by the signal handler:
+ */
+ _thread_kern_sig_defer();
+
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&(*cond)->lock);
+
+ /* Process according to condition variable type: */
+ switch ((*cond)->c_type) {
+ /* Fast condition variable: */
+ case COND_TYPE_FAST:
+ /* Increment the sequence number: */
+ (*cond)->c_seqno++;
+
+ if ((pthread = cond_queue_deq(*cond)) != NULL) {
+ /*
+ * Wake up the signaled thread:
+ */
+ PTHREAD_NEW_STATE(pthread, PS_RUNNING);
+ }
+
+ /* Check for no more waiters: */
+ if (TAILQ_FIRST(&(*cond)->c_queue) == NULL)
+ (*cond)->c_mutex = NULL;
+ break;
+
+ /* Trap invalid condition variable types: */
+ default:
+ /* Return an invalid argument error: */
+ rval = EINVAL;
+ break;
+ }
+
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+
+ /*
+ * Undefer and handle pending signals, yielding if
+ * necessary:
+ */
+ _thread_kern_sig_undefer();
+ }
+
+ /* Return the completion status: */
+ return (rval);
+}
+
+int
+_pthread_cond_broadcast(pthread_cond_t * cond)
+{
+ int rval = 0;
+ pthread_t pthread;
+
+ if (cond == NULL)
+ rval = EINVAL;
+ /*
+ * If the condition variable is statically initialized, perform dynamic
+ * initialization.
+ */
+ else if (*cond != NULL || (rval = pthread_cond_init(cond, NULL)) == 0) {
+ /*
+ * Defer signals to protect the scheduling queues
+ * from access by the signal handler:
+ */
+ _thread_kern_sig_defer();
+
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&(*cond)->lock);
+
+ /* Process according to condition variable type: */
+ switch ((*cond)->c_type) {
+ /* Fast condition variable: */
+ case COND_TYPE_FAST:
+ /* Increment the sequence number: */
+ (*cond)->c_seqno++;
+
+ /*
+ * Enter a loop to bring all threads off the
+ * condition queue:
+ */
+ while ((pthread = cond_queue_deq(*cond)) != NULL) {
+ /*
+ * Wake up the signaled thread:
+ */
+ PTHREAD_NEW_STATE(pthread, PS_RUNNING);
+ }
+
+ /* There are no more waiting threads: */
+ (*cond)->c_mutex = NULL;
+ break;
+
+ /* Trap invalid condition variable types: */
+ default:
+ /* Return an invalid argument error: */
+ rval = EINVAL;
+ break;
+ }
+
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&(*cond)->lock);
+
+ /*
+ * Undefer and handle pending signals, yielding if
+ * necessary:
+ */
+ _thread_kern_sig_undefer();
+ }
+
+ /* Return the completion status: */
+ return (rval);
+}
+
+void
+_cond_wait_backout(pthread_t pthread)
+{
+ pthread_cond_t cond;
+
+ cond = pthread->data.cond;
+ if (cond != NULL) {
+ /*
+ * Defer signals to protect the scheduling queues
+ * from access by the signal handler:
+ */
+ _thread_kern_sig_defer();
+
+ /* Lock the condition variable structure: */
+ _SPINLOCK(&cond->lock);
+
+ /* Process according to condition variable type: */
+ switch (cond->c_type) {
+ /* Fast condition variable: */
+ case COND_TYPE_FAST:
+ cond_queue_remove(cond, pthread);
+
+ /* Check for no more waiters: */
+ if (TAILQ_FIRST(&cond->c_queue) == NULL)
+ cond->c_mutex = NULL;
+ break;
+
+ default:
+ break;
+ }
+
+ /* Unlock the condition variable structure: */
+ _SPINUNLOCK(&cond->lock);
+
+ /*
+ * Undefer and handle pending signals, yielding if
+ * necessary:
+ */
+ _thread_kern_sig_undefer();
+ }
+}
+
+/*
+ * Dequeue a waiting thread from the head of a condition queue in
+ * descending priority order.
+ */
+static inline pthread_t
+cond_queue_deq(pthread_cond_t cond)
+{
+ pthread_t pthread;
+
+ while ((pthread = TAILQ_FIRST(&cond->c_queue)) != NULL) {
+ TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
+ pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
+ if ((pthread->timeout == 0) && (pthread->interrupted == 0))
+ /*
+ * Only exit the loop when we find a thread
+ * that hasn't timed out or been canceled;
+ * those threads are already running and don't
+ * need their run state changed.
+ */
+ break;
+ }
+
+ return(pthread);
+}
+
+/*
+ * Remove a waiting thread from a condition queue in descending priority
+ * order.
+ */
+static inline void
+cond_queue_remove(pthread_cond_t cond, pthread_t pthread)
+{
+ /*
+ * Because pthread_cond_timedwait() can timeout as well
+ * as be signaled by another thread, it is necessary to
+ * guard against removing the thread from the queue if
+ * it isn't in the queue.
+ */
+ if (pthread->flags & PTHREAD_FLAGS_IN_CONDQ) {
+ TAILQ_REMOVE(&cond->c_queue, pthread, sqe);
+ pthread->flags &= ~PTHREAD_FLAGS_IN_CONDQ;
+ }
+}
+
+/*
+ * Enqueue a waiting thread to a condition queue in descending priority
+ * order.
+ */
+static inline void
+cond_queue_enq(pthread_cond_t cond, pthread_t pthread)
+{
+ pthread_t tid = TAILQ_LAST(&cond->c_queue, cond_head);
+
+ PTHREAD_ASSERT_NOT_IN_SYNCQ(pthread);
+
+ /*
+ * For the common case of all threads having equal priority,
+ * we perform a quick check against the priority of the thread
+ * at the tail of the queue.
+ */
+ if ((tid == NULL) || (pthread->active_priority <= tid->active_priority))
+ TAILQ_INSERT_TAIL(&cond->c_queue, pthread, sqe);
+ else {
+ tid = TAILQ_FIRST(&cond->c_queue);
+ while (pthread->active_priority <= tid->active_priority)
+ tid = TAILQ_NEXT(tid, sqe);
+ TAILQ_INSERT_BEFORE(tid, pthread, sqe);
+ }
+ pthread->flags |= PTHREAD_FLAGS_IN_CONDQ;
+ pthread->data.cond = cond;
+}
OpenPOWER on IntegriCloud