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  1. abraziv

    pthread_cond_timedeait()

    Всем привет , столкнулся с проблемой . Есть код #include <pthread.h> //#include "/home/abraziv/Desktop/glibc-2.14/nptl/sysdeps/pthread" #include <stdio.h> #include <time.h> #include <stdio.h> #include <sys/time.h> #include <errno.h> void out(int ); void* compute_thread (void*); int lab_pthread_cond_timedwait(pthread_cond_t * ,pthread_mutex_t *, unsigned int ); pthread_mutex_t my_sync; pthread_cond_t rx; unsigned int tw = 100; struct timespec timetowait ; int retcode = 1 ; int thread_done = 0; int x=1; main( ) { pthread_t tid; pthread_attr_t attr; pthread_attr_init (&attr); pthread_mutex_init (&my_sync, NULL); pthread_cond_init (&rx, NULL); pthread_create(&tid, &attr, compute_thread, (void *)NULL); pthread_mutex_lock(&my_sync); out(3); while (!thread_done) { lab_pthread_cond_timedwait(&rx, &my_sync, tw ); pthread_cond_wait(&rx, &my_sync ); } out(4); x++; pthread_mutex_unlock(&my_sync); out(5); exit(0); } void* compute_thread(void* dummy) { out(6); pthread_mutex_lock (&my_sync); out(8); x++; sleep(2); out(9); thread_done = 1; pthread_cond_signal (&rx); out(10); pthread_mutex_unlock (&my_sync); out(11); return; } void out(int sh) { printf("%d rx.__data.__lock %d\n",sh,rx.__data.__lock ); printf("%d rx.__data.__futex %d\n",sh,rx.__data.__futex ); printf("%d rx.__data.__total_seq %d\n",sh,rx.__data.__total_seq ); printf("%d rx.__data.__wakeup_seq %d\n",sh,rx.__data.__wakeup_seq ); printf("%d rx.__data.__woken_seq %d\n",sh,rx.__data.__woken_seq ); printf("%d rx.__data.__nwaiters %d\n",sh,rx.__data.__nwaiters ); printf("%d rx.__data.__mutex %d\n",sh,rx.__data.__mutex ); printf("%d rx.__data.__broadcast_seq %d\n",sh,rx.__data.__broadcast_seq ); printf("%d my_sync.__data.__lock %d\n",sh,my_sync.__data.__lock ); printf("%d my_sync.__data.__nwaiters %d\n",sh,my_sync.__data.__count ); printf("%d my_sync.__data.__mutex %d\n",sh,my_sync.__data.__owner ); printf("%d my_sync.__data.__broadcast_seq %d\n\n",sh,my_sync.__data.__nusers ); } lab_pthread_cond_timedwait(pthread_cond_t *rx,pthread_mutex_t *my_sync, unsigned int timetowait) { } [/C] Мне необходимо написать функцию , подобную pthread_cond_timedwait(), которая по истечению заданого времени (например 1 сек ) времени подымала какой либо флаг. Проблема заключается в том , что эта функция должна работать без участия выполняющихся потоков . Т.е. один поток захватывает мьютекс потом натыкается pthread_cond_wait(&rx, &my_sync ) и блокируется на этой условной переменной , после переключения другой поток начинает выполнять функцию compute_thread() . и поподает на sleep(2) , засыпает на 2 или более сек . И т.к. 2 или более сек больше чем 1 (аргумент моей функции) выставлется бит , например в __data.__woken_seq . Это можно сделать по аналогии с функцией pthread_cond_timedwait() struct _condvar_cleanup_buffer { int oldtype; pthread_cond_t *cond; pthread_mutex_t *mutex; unsigned int bc_seq; }; int __pthread_cond_timedwait (cond, mutex, abstime) pthread_cond_t *cond; pthread_mutex_t *mutex; const struct timespec *abstime; { struct _pthread_cleanup_buffer buffer; struct _condvar_cleanup_buffer cbuffer; int result = 0; /* Catch invalid parameters. */ if (abstime->tv_nsec < 0 || abstime->tv_nsec >= 1000000000) return EINVAL; int pshared = (cond->__data.__mutex == (void *) ~0l) ? LLL_SHARED : LLL_PRIVATE; /* Make sure we are alone. */ lll_lock (cond->__data.__lock, pshared); /* Now we can release the mutex. */ int err = __pthread_mutex_unlock_usercnt (mutex, 0); if (err) { lll_unlock (cond->__data.__lock, pshared); return err; } /* We have one new user of the condvar. */ ++cond->__data.__total_seq; ++cond->__data.__futex; cond->__data.__nwaiters += 1 << COND_NWAITERS_SHIFT; /* Remember the mutex we are using here. If there is already a different address store this is a bad user bug. Do not store anything for pshared condvars. */ if (cond->__data.__mutex != (void *) ~0l) cond->__data.__mutex = mutex; /* Prepare structure passed to cancellation handler. */ cbuffer.cond = cond; cbuffer.mutex = mutex; /* Before we block we enable cancellation. Therefore we have to install a cancellation handler. */ __pthread_cleanup_push (&buffer, __condvar_cleanup, &cbuffer); /* The current values of the wakeup counter. The "woken" counter must exceed this value. */ unsigned long long int val; unsigned long long int seq; val = seq = cond->__data.__wakeup_seq; /* Remember the broadcast counter. */ cbuffer.bc_seq = cond->__data.__broadcast_seq; while (1) { struct timespec rt; { #ifdef __NR_clock_gettime INTERNAL_SYSCALL_DECL (err); int ret; ret = INTERNAL_VSYSCALL (clock_gettime, err, 2, (cond->__data.__nwaiters & ((1 << COND_NWAITERS_SHIFT) - 1)), &rt); # ifndef __ASSUME_POSIX_TIMERS if (__builtin_expect (INTERNAL_SYSCALL_ERROR_P (ret, err), 0)) { struct timeval tv; (void) gettimeofday (&tv, NULL); /* Convert the absolute timeout value to a relative timeout. */ rt.tv_sec = abstime->tv_sec - tv.tv_sec; rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000; } else # endif { /* Convert the absolute timeout value to a relative timeout. */ rt.tv_sec = abstime->tv_sec - rt.tv_sec; rt.tv_nsec = abstime->tv_nsec - rt.tv_nsec; } #else /* Get the current time. So far we support only one clock. */ struct timeval tv; (void) gettimeofday (&tv, NULL); /* Convert the absolute timeout value to a relative timeout. */ rt.tv_sec = abstime->tv_sec - tv.tv_sec; rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000; #endif } if (rt.tv_nsec < 0) { rt.tv_nsec += 1000000000; --rt.tv_sec; } /* Did we already time out? */ if (__builtin_expect (rt.tv_sec < 0, 0)) { if (cbuffer.bc_seq != cond->__data.__broadcast_seq) goto bc_out; goto timeout; } unsigned int futex_val = cond->__data.__futex; /* Prepare to wait. Release the condvar futex. */ lll_unlock (cond->__data.__lock, pshared); /* Enable asynchronous cancellation. Required by the standard. */ cbuffer.oldtype = __pthread_enable_asynccancel (); /* Wait until woken by signal or broadcast. */ err = lll_futex_timed_wait (&cond->__data.__futex, futex_val, &rt, pshared); /* Disable asynchronous cancellation. */ __pthread_disable_asynccancel (cbuffer.oldtype); /* We are going to look at shared data again, so get the lock. */ lll_lock (cond->__data.__lock, pshared); /* If a broadcast happened, we are done. */ if (cbuffer.bc_seq != cond->__data.__broadcast_seq) goto bc_out; /* Check whether we are eligible for wakeup. */ val = cond->__data.__wakeup_seq; cond->__data.__wakeup_seq if (val != seq && cond->__data.__woken_seq != val) break; /* Not woken yet. Maybe the time expired? */ if (__builtin_expect (err == -ETIMEDOUT, 0)) { timeout: /* Yep. Adjust the counters. */ ++cond->__data.__wakeup_seq; ++cond->__data.__futex; /* The error value. */ result = ETIMEDOUT; break; } } /* Another thread woken up. */ ++cond->__data.__woken_seq; bc_out: cond->__data.__nwaiters -= 1 << COND_NWAITERS_SHIFT; /* If pthread_cond_destroy was called on this variable already, notify the pthread_cond_destroy caller all waiters have left and it can be successfully destroyed. */ if (cond->__data.__total_seq == -1ULL && cond->__data.__nwaiters < (1 << COND_NWAITERS_SHIFT)) lll_futex_wake (&cond->__data.__nwaiters, 1, pshared); /* We are done with the condvar. */ lll_unlock (cond->__data.__lock, pshared); /* The cancellation handling is back to normal, remove the handler. */ __pthread_cleanup_pop (&buffer, 0); /* Get the mutex before returning. */ err = __pthread_mutex_cond_lock (mutex); return err ?: result; } [/C] Но я незнаю какую часть кода необходимо вытащить, есть предположения , но я не слишком силён в программирование . Спасибо заранее.
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