diff options
Diffstat (limited to 'nptl/sysdeps/pthread/pthread_cond_timedwait.c')
| -rw-r--r-- | nptl/sysdeps/pthread/pthread_cond_timedwait.c | 153 |
1 files changed, 153 insertions, 0 deletions
diff --git a/nptl/sysdeps/pthread/pthread_cond_timedwait.c b/nptl/sysdeps/pthread/pthread_cond_timedwait.c new file mode 100644 index 0000000000..797d244cf7 --- /dev/null +++ b/nptl/sysdeps/pthread/pthread_cond_timedwait.c @@ -0,0 +1,153 @@ +/* Copyright (C) 2003 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Martin Schwidefsky <schwidefsky@de.ibm.com>, 2003. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Lesser General Public + License as published by the Free Software Foundation; either + version 2.1 of the License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Lesser General Public License for more details. + + You should have received a copy of the GNU Lesser General Public + License along with the GNU C Library; if not, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#include <endian.h> +#include <errno.h> +#include <sysdep.h> +#include <lowlevellock.h> +#include <pthread.h> +#include <pthreadP.h> + +#include <shlib-compat.h> + + +/* Cleanup handler, defined in pthread_cond_wait.c. */ +extern void __condvar_cleanup (void *arg) + __attribute__ ((visibility ("hidden"))); + + +int +__pthread_cond_timedwait (cond, mutex, abstime) + pthread_cond_t *cond; + pthread_mutex_t *mutex; + const struct timespec *abstime; +{ + struct _pthread_cleanup_buffer buffer; + int result = 0; + + /* Catch invalid parameters. */ + if (abstime->tv_nsec >= 1000000000) + return EINVAL; + + /* Make sure we are along. */ + lll_mutex_lock (cond->__data.__lock); + + /* Now we can release the mutex. */ + __pthread_mutex_unlock_internal (mutex); + + /* We have one new user of the condvar. */ + ++cond->__data.__total_seq; + + /* Before we block we enable cancellation. Therefore we have to + install a cancellation handler. */ + __pthread_cleanup_push (&buffer, __condvar_cleanup, cond); + + /* 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; + + /* The futex syscall operates on a 32-bit word. That is fine, we + just use the low 32 bits of the sequence counter. */ +#if BYTE_ORDER == LITTLE_ENDIAN + int *futex = ((int *) (&cond->__data.__wakeup_seq)); +#elif BYTE_ORDER == BIG_ENDIAN + int *futex = ((int *) (&cond->__data.__wakeup_seq)) + 1; +#else +# error "No valid byte order" +#endif + + while (1) + { + /* 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. */ + struct timespec rt; + rt.tv_sec = abstime->tv_sec - tv.tv_sec; + rt.tv_nsec = abstime->tv_nsec - tv.tv_usec * 1000; + if (rt.tv_nsec < 0) + { + rt.tv_nsec += 1000000000; + --rt.tv_sec; + } + /* Did we already time out? */ + if (rt.tv_sec < 0) + { + /* Yep. Adjust the sequence counter. */ + ++cond->__data.__wakeup_seq; + + /* The error value. */ + result = ETIMEDOUT; + break; + } + + /* Prepare to wait. Release the condvar futex. */ + lll_mutex_unlock (cond->__data.__lock); + + /* Enable asynchronous cancellation. Required by the standard. */ + int oldtype = __pthread_enable_asynccancel (); + + /* Wait until woken by signal or broadcast. Note that we + truncate the 'val' value to 32 bits. */ + result = lll_futex_timed_wait (futex, (unsigned int) val, &rt); + + /* Disable asynchronous cancellation. */ + __pthread_disable_asynccancel (oldtype); + + /* We are going to look at shared data again, so get the lock. */ + lll_mutex_lock(cond->__data.__lock); + + /* Check whether we are eligible for wakeup. */ + val = cond->__data.__wakeup_seq; + if (cond->__data.__woken_seq >= seq + && cond->__data.__woken_seq < val) + break; + + /* Not woken yet. Maybe the time expired? */ + if (result == -ETIMEDOUT) + { + /* Yep. Adjust the counters. */ + ++cond->__data.__wakeup_seq; + + /* The error value. */ + result = ETIMEDOUT; + break; + } + } + + /* Another thread woken up. */ + ++cond->__data.__woken_seq; + + /* We are done with the condvar. */ + lll_mutex_unlock (cond->__data.__lock); + + /* The cancellation handling is back to normal, remove the handler. */ + __pthread_cleanup_pop (&buffer, 0); + + /* Get the mutex before returning. */ + __pthread_mutex_lock_internal (mutex); + + return result; +} + +versioned_symbol (libpthread, __pthread_cond_timedwait, pthread_cond_timedwait, + GLIBC_2_3_2); |