diff options
Diffstat (limited to 'libpthread/nptl/sysdeps/pthread/pthread_cond_timedwait.c')
| -rw-r--r-- | libpthread/nptl/sysdeps/pthread/pthread_cond_timedwait.c | 215 |
1 files changed, 215 insertions, 0 deletions
diff --git a/libpthread/nptl/sysdeps/pthread/pthread_cond_timedwait.c b/libpthread/nptl/sysdeps/pthread/pthread_cond_timedwait.c new file mode 100644 index 000000000..4aaf5df75 --- /dev/null +++ b/libpthread/nptl/sysdeps/pthread/pthread_cond_timedwait.c @@ -0,0 +1,215 @@ +/* Copyright (C) 2003, 2004, 2007 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 <bits/kernel-features.h> + + +/* Cleanup handler, defined in pthread_cond_wait.c. */ +extern void __condvar_cleanup (void *arg) + __attribute__ ((visibility ("hidden"))); + +struct _condvar_cleanup_buffer +{ + int oldtype; + pthread_cond_t *cond; + pthread_mutex_t *mutex; + unsigned int bc_seq; +}; + +int +__pthread_cond_timedwait ( + 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 along. */ + 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_SYSCALL (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; + 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; +} + +weak_alias(__pthread_cond_timedwait, pthread_cond_timedwait) |