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authorUlrich Drepper <drepper@redhat.com>2006-10-28 05:15:26 +0000
committerUlrich Drepper <drepper@redhat.com>2006-10-28 05:15:26 +0000
commiteb0a3d0cab507fecefe390a340f74ab8e5cf7831 (patch)
treec97ac1c33a78c454c0aeb520624af29c724355d2 /nptl/pthread_rwlock_timedrdlock.c
parent006a8f6f626e6e4d30b73c2ee20377b6a8cce1b7 (diff)
downloadglibc-eb0a3d0cab507fecefe390a340f74ab8e5cf7831.tar.gz
* sysdeps/pthread/pthread_barrier_wait.c: Move to...
* pthread_barrier_wait.c: ...here. * sysdeps/pthread/pthread_cond_broadcast.c: Move to... * pthread_cond_broadcast.c: ...here. * sysdeps/pthread/pthread_cond_signal.c: Move to... * pthread_cond_signal.c: ...here. * sysdeps/pthread/pthread_cond_timedwait.c: Move to... * pthread_cond_timedwait.c: ...here. * sysdeps/pthread/pthread_cond_wait.c: Move to... * pthread_cond_wait.c: ...here. * sysdeps/pthread/pthread_once.c: Move to... * pthread_once.c: ...here. * sysdeps/pthread/pthread_rwlock_rdlock.c: Move to... * pthread_rwlock_rdlock.c: ...here. * sysdeps/pthread/pthread_rwlock_timedrdlock.c: Move to... * pthread_rwlock_timedrdlock.c: ...here. * sysdeps/pthread/pthread_rwlock_timedwrlock.c: Move to... * pthread_rwlock_timedwrlock.c: ...here. * sysdeps/pthread/pthread_rwlock_unlock.c: Move to... * pthread_rwlock_unlock.c: ...here. * sysdeps/pthread/pthread_rwlock_wrlock.c: Move to... * pthread_rwlock_wrlock.c: ...here. * sysdeps/pthread/pthread_spin_destroy.c: Move to... * pthread_spin_destroy.c: ...here. * sysdeps/pthread/pthread_spin_init.c: Move to... * pthread_spin_init.c: ...here. * sysdeps/pthread/pthread_spin_unlock.c: Move to... * pthread_spin_unlock.c: ...here. * sysdeps/pthread/pthread_getcpuclockid.c: Move to... * pthread_getcpuclockid.c: ...here.
Diffstat (limited to 'nptl/pthread_rwlock_timedrdlock.c')
-rw-r--r--nptl/pthread_rwlock_timedrdlock.c137
1 files changed, 137 insertions, 0 deletions
diff --git a/nptl/pthread_rwlock_timedrdlock.c b/nptl/pthread_rwlock_timedrdlock.c
new file mode 100644
index 0000000000..80ea83a3dd
--- /dev/null
+++ b/nptl/pthread_rwlock_timedrdlock.c
@@ -0,0 +1,137 @@
+/* Copyright (C) 2003, 2004 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 <errno.h>
+#include <sysdep.h>
+#include <lowlevellock.h>
+#include <pthread.h>
+#include <pthreadP.h>
+
+
+/* Try to acquire read lock for RWLOCK or return after specfied time. */
+int
+pthread_rwlock_timedrdlock (rwlock, abstime)
+ pthread_rwlock_t *rwlock;
+ const struct timespec *abstime;
+{
+ int result = 0;
+
+ /* Make sure we are along. */
+ lll_mutex_lock(rwlock->__data.__lock);
+
+ while (1)
+ {
+ int err;
+
+ /* Get the rwlock if there is no writer... */
+ if (rwlock->__data.__writer == 0
+ /* ...and if either no writer is waiting or we prefer readers. */
+ && (!rwlock->__data.__nr_writers_queued
+ || rwlock->__data.__flags == 0))
+ {
+ /* Increment the reader counter. Avoid overflow. */
+ if (++rwlock->__data.__nr_readers == 0)
+ {
+ /* Overflow on number of readers. */
+ --rwlock->__data.__nr_readers;
+ result = EAGAIN;
+ }
+
+ break;
+ }
+
+ /* Make sure we are not holding the rwlock as a writer. This is
+ a deadlock situation we recognize and report. */
+ if (__builtin_expect (rwlock->__data.__writer
+ == THREAD_GETMEM (THREAD_SELF, tid), 0))
+ {
+ result = EDEADLK;
+ break;
+ }
+
+ /* Make sure the passed in timeout value is valid. Ideally this
+ test would be executed once. But since it must not be
+ performed if we would not block at all simply moving the test
+ to the front is no option. Replicating all the code is
+ costly while this test is not. */
+ if (__builtin_expect (abstime->tv_nsec >= 1000000000
+ || abstime->tv_nsec < 0, 0))
+ {
+ result = EINVAL;
+ break;
+ }
+
+ /* 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, return with an appropriate error. */
+ result = ETIMEDOUT;
+ break;
+ }
+
+ /* Remember that we are a reader. */
+ if (++rwlock->__data.__nr_readers_queued == 0)
+ {
+ /* Overflow on number of queued readers. */
+ --rwlock->__data.__nr_readers_queued;
+ result = EAGAIN;
+ break;
+ }
+
+ int waitval = rwlock->__data.__readers_wakeup;
+
+ /* Free the lock. */
+ lll_mutex_unlock (rwlock->__data.__lock);
+
+ /* Wait for the writer to finish. */
+ err = lll_futex_timed_wait (&rwlock->__data.__readers_wakeup,
+ waitval, &rt);
+
+ /* Get the lock. */
+ lll_mutex_lock (rwlock->__data.__lock);
+
+ --rwlock->__data.__nr_readers_queued;
+
+ /* Did the futex call time out? */
+ if (err == -ETIMEDOUT)
+ {
+ /* Yep, report it. */
+ result = ETIMEDOUT;
+ break;
+ }
+ }
+
+ /* We are done, free the lock. */
+ lll_mutex_unlock (rwlock->__data.__lock);
+
+ return result;
+}