diff options
author | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2007-02-17 23:21:28 +0000 |
---|---|---|
committer | patacongo <patacongo@42af7a65-404d-4744-a932-0658087f49c3> | 2007-02-17 23:21:28 +0000 |
commit | e3940eb2080711edac189cca3f642ee89dc215f2 (patch) | |
tree | 1c390958fae49e34dce698b175487e6d4681e540 /nuttx/sched/pthread_condtimedwait.c | |
parent | 2223612deb2cc6322992f8595b6d6f86fcb53ae1 (diff) | |
download | px4-nuttx-e3940eb2080711edac189cca3f642ee89dc215f2.tar.gz px4-nuttx-e3940eb2080711edac189cca3f642ee89dc215f2.tar.bz2 px4-nuttx-e3940eb2080711edac189cca3f642ee89dc215f2.zip |
NuttX RTOS
git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@3 42af7a65-404d-4744-a932-0658087f49c3
Diffstat (limited to 'nuttx/sched/pthread_condtimedwait.c')
-rw-r--r-- | nuttx/sched/pthread_condtimedwait.c | 306 |
1 files changed, 306 insertions, 0 deletions
diff --git a/nuttx/sched/pthread_condtimedwait.c b/nuttx/sched/pthread_condtimedwait.c new file mode 100644 index 000000000..f65122699 --- /dev/null +++ b/nuttx/sched/pthread_condtimedwait.c @@ -0,0 +1,306 @@ +/************************************************************ + * pthread_condtimedwait.c + * + * Copyright (C) 2007 Gregory Nutt. All rights reserved. + * Author: Gregory Nutt <spudmonkey@racsa.co.cr> + * + * 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 Gregory Nutt 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 <sys/types.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 + ************************************************************/ + +#define ECHO_COND_WAIT_SIGNO 3 + +/************************************************************ + * Private Type Declarations + ************************************************************/ + +/************************************************************ + * Global Variables + ************************************************************/ + +/************************************************************ + * Private Variables + ************************************************************/ + +/************************************************************ + * Private Functions + ************************************************************/ + +static void pthread_condtimedout(int pid, int signo, int arg3, int arg4) +{ + union sigval value; + + /* Send the specified signal to the specified task. */ + + value.sival_ptr = 0; + (void)sigqueue(pid, signo, value); +} + +/************************************************************ + * Public Functions + ************************************************************/ + +/************************************************************ + * Function: pthread_cond_timedwait + * + * Description: + * A thread can perform a timed wait on a condition variable. + * + * Parameters: + * None + * + * Return Value: + * None + * + * Assumptions: + * Timing is of resolution 1 msec, with +/-1 millisecond + * accuracy. + * + ************************************************************/ + +int pthread_cond_timedwait(pthread_cond_t *cond, pthread_mutex_t *mutex, + const struct timespec *abstime) +{ + struct timespec currtime; + struct timespec reltime; + WDOG_ID wdog; + sint32 relusec; + sint32 ticks; + int mypid = (int)getpid(); + int ret = OK; + int int_state; + int status; + + dbg("%s: cond=0x%p mutex=0x%p abstime=0x%p\n", + __FUNCTION__, 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 + { + dbg("%s: Give up mutex...\n", __FUNCTION__); + + /* 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. + * NOTE: Here we use internal knowledge that CLOCK_REALTIME is + * defined to be zero! + */ + + ret = clock_gettime(0, &currtime); + if (ret) + { + /* Restore interrupts (pre-emption will be enabled when + * we fall through the if/then/else + */ + + irqrestore(int_state); + } + else + { + /* The relative time to wait is the absolute time minus the + * the current time. + */ + + reltime.tv_nsec = (abstime->tv_nsec - currtime.tv_nsec); + reltime.tv_sec = (abstime->tv_sec - currtime.tv_sec); + + /* Check if we were supposed to borrow from the seconds + * to borrow from the seconds + */ + + if (reltime.tv_nsec < 0) + { + reltime.tv_nsec += NSEC_PER_SEC; + reltime.tv_sec -= 1; + } + + /* Convert this relative time into microseconds.*/ + + relusec = + reltime.tv_sec * USEC_PER_SEC + + reltime.tv_nsec / NSEC_PER_USEC; + + /* Convert microseconds to clock ticks */ + + ticks = relusec / USEC_PER_TICK; + + /* 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, + mypid, ECHO_COND_WAIT_SIGNO, 0, 0); + + /* 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); + irqrestore(int_state); + + /* 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_ptr() == EINTR) + { + dbg("%s: Timedout!\n", __FUNCTION__); + ret = ETIMEDOUT; + } + else + { + ret = EINVAL; + } + } + } + + /* Reacquire the mutex (retaining the ret). */ + + dbg("%s: Re-locking...\n", __FUNCTION__); + 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); + } + } + + dbg("%s: Returning %d\n", __FUNCTION__, ret); + return ret; +} + |