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Diffstat (limited to 'nuttx/sched/pthread_condtimedwait.c')
-rw-r--r-- | nuttx/sched/pthread_condtimedwait.c | 308 |
1 files changed, 308 insertions, 0 deletions
diff --git a/nuttx/sched/pthread_condtimedwait.c b/nuttx/sched/pthread_condtimedwait.c new file mode 100644 index 000000000..25f86d813 --- /dev/null +++ b/nuttx/sched/pthread_condtimedwait.c @@ -0,0 +1,308 @@ +/**************************************************************************** + * 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; +} + |