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+/****************************************************************************
+ * sched/pthread_condtimedwait.c
+ *
+ * Copyright (C) 2007-2009 Gregory Nutt. All rights reserved.
+ * Author: Gregory Nutt <gnutt@nuttx.org>
+ *
+ * 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. Neither the name NuttX nor the names of its contributors may be
+ * used to endorse or promote products derived from this software
+ * without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
+ * COPYRIGHT OWNER 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.
+ *
+ ****************************************************************************/
+
+/****************************************************************************
+ * Included Files
+ ****************************************************************************/
+
+#include <nuttx/config.h>
+#include <nuttx/compiler.h>
+
+#include <stdint.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <signal.h>
+#include <time.h>
+#include <errno.h>
+#include <wdog.h>
+#include <debug.h>
+
+#include "os_internal.h"
+#include "pthread_internal.h"
+#include "clock_internal.h"
+
+/****************************************************************************
+ * Definitions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Type Declarations
+ ****************************************************************************/
+
+/****************************************************************************
+ * Global Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Variables
+ ****************************************************************************/
+
+/****************************************************************************
+ * Private Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: pthread_condtimedout
+ *
+ * Description:
+ * This function is called if the timeout elapses before
+ * the condition is signaled.
+ *
+ * Parameters:
+ * argc - the number of arguments (should be 2)
+ * pid - the task ID of the task to wakeup
+ * signo - The signal to use to wake up the task
+ *
+ * Return Value:
+ * None
+ *
+ * Assumptions:
+ *
+ ****************************************************************************/
+
+static void pthread_condtimedout(int argc, uint32_t pid, uint32_t signo)
+{
+#ifdef CONFIG_CAN_PASS_STRUCTS
+ union sigval value;
+
+ /* Send the specified signal to the specified task. */
+
+ value.sival_ptr = NULL;
+ (void)sigqueue((int)pid, (int)signo, value);
+#else
+ (void)sigqueue((int)pid, (int)signo, NULL);
+#endif
+}
+
+/****************************************************************************
+ * Public Functions
+ ****************************************************************************/
+
+/****************************************************************************
+ * Name: pthread_cond_timedwait
+ *
+ * Description:
+ * A thread can perform a timed wait on a condition variable.
+ *
+ * Parameters:
+ * cond - the condition variable to wait on
+ * mutex - the mutex that protects the condition variable
+ * abstime - wait until this absolute time
+ *
+ * Return Value:
+ * OK (0) on success; ERROR (-1) on failure with errno
+ * set appropriately.
+ *
+ * Assumptions:
+ * Timing is of resolution 1 msec, with +/-1 millisecond
+ * accuracy.
+ *
+ ****************************************************************************/
+
+int pthread_cond_timedwait(FAR pthread_cond_t *cond, FAR pthread_mutex_t *mutex,
+ FAR const struct timespec *abstime)
+{
+ WDOG_ID wdog;
+ int ticks;
+ int mypid = (int)getpid();
+ irqstate_t int_state;
+ int ret = OK;
+ int status;
+
+ sdbg("cond=0x%p mutex=0x%p abstime=0x%p\n", cond, mutex, abstime);
+
+ /* Make sure that non-NULL references were provided. */
+
+ if (!cond || !mutex)
+ {
+ ret = EINVAL;
+ }
+
+ /* Make sure that the caller holds the mutex */
+
+ else if (mutex->pid != mypid)
+ {
+ ret = EPERM;
+ }
+
+ /* If no wait time is provided, this function degenerates to
+ * the same behavior as pthread_cond_wait().
+ */
+
+ else if (!abstime)
+ {
+ ret = pthread_cond_wait(cond, mutex);
+ }
+
+ else
+ {
+ /* Create a watchdog */
+
+ wdog = wd_create();
+ if (!wdog)
+ {
+ ret = EINVAL;
+ }
+ else
+ {
+ sdbg("Give up mutex...\n");
+
+ /* We must disable pre-emption and interrupts here so that
+ * the time stays valid until the wait begins. This adds
+ * complexity because we assure that interrupts and
+ * pre-emption are re-enabled correctly.
+ */
+
+ sched_lock();
+ int_state = irqsave();
+
+ /* Convert the timespec to clock ticks. We must disable pre-emption
+ * here so that this time stays valid until the wait begins.
+ */
+
+ ret = clock_abstime2ticks(CLOCK_REALTIME, abstime, &ticks);
+ if (ret)
+ {
+ /* Restore interrupts (pre-emption will be enabled when
+ * we fall through the if/then/else
+ */
+
+ irqrestore(int_state);
+ }
+ else
+ {
+ /* Check the absolute time to wait. If it is now or in the past, then
+ * just return with the timedout condition.
+ */
+
+ if (ticks <= 0)
+ {
+ /* Restore interrupts and indicate that we have already timed out.
+ * (pre-emption will be enabled when we fall through the
+ * if/then/else
+ */
+
+ irqrestore(int_state);
+ ret = ETIMEDOUT;
+ }
+ else
+ {
+ /* Give up the mutex */
+
+ mutex->pid = 0;
+ ret = pthread_givesemaphore((sem_t*)&mutex->sem);
+ if (ret)
+ {
+ /* Restore interrupts (pre-emption will be enabled when
+ * we fall through the if/then/else)
+ */
+
+ irqrestore(int_state);
+ }
+ else
+ {
+ /* Start the watchdog */
+
+ wd_start(wdog, ticks, (wdentry_t)pthread_condtimedout,
+ 2, (uint32_t)mypid, (uint32_t)SIGCONDTIMEDOUT);
+
+ /* Take the condition semaphore. Do not restore interrupts
+ * until we return from the wait. This is necessary to
+ * make sure that the watchdog timer and the condition wait
+ * are started atomically.
+ */
+
+ status = sem_wait((sem_t*)&cond->sem);
+
+ /* Did we get the condition semaphore. */
+
+ if (status != OK)
+ {
+ /* NO.. Handle the special case where the semaphore wait was
+ * awakened by the receipt of a signal -- presumably the
+ * signal posted by pthread_condtimedout().
+ */
+
+ if (get_errno() == EINTR)
+ {
+ sdbg("Timedout!\n");
+ ret = ETIMEDOUT;
+ }
+ else
+ {
+ ret = EINVAL;
+ }
+ }
+
+ /* The interrupts stay disabled until after we sample the errno.
+ * This is because when debug is enabled and the console is used
+ * for debug output, then the errno can be altered by interrupt
+ * handling! (bad)
+ */
+
+ irqrestore(int_state);
+ }
+
+ /* Reacquire the mutex (retaining the ret). */
+
+ sdbg("Re-locking...\n");
+ status = pthread_takesemaphore((sem_t*)&mutex->sem);
+ if (!status)
+ {
+ mutex->pid = mypid;
+ }
+ else if (!ret)
+ {
+ ret = status;
+ }
+ }
+
+ /* Re-enable pre-emption (It is expected that interrupts
+ * have already been re-enabled in the above logic)
+ */
+
+ sched_unlock();
+ }
+
+ /* We no longer need the watchdog */
+
+ wd_delete(wdog);
+ }
+ }
+
+ sdbg("Returning %d\n", ret);
+ return ret;
+}
+
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