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authorSander Vrijders <sander.vrijders@intec.ugent.be>2016-05-14 18:36:23 +0200
committerSander Vrijders <sander.vrijders@intec.ugent.be>2016-05-14 18:36:23 +0200
commit0cbf6e091c66b7d5004a4fc3b368fc2fcdd4fe8a (patch)
treeada50d609614a0942bfd7a07ad06533e7bb5c9ac /src/lib/rw_lock.c
parentaf1dff6fc06f55d6565589282ac4ebacc53b4d29 (diff)
parentaf4097f51b7bd4f37212c2d49f0596779d79c36e (diff)
downloadouroboros-0cbf6e091c66b7d5004a4fc3b368fc2fcdd4fe8a.tar.gz
ouroboros-0cbf6e091c66b7d5004a4fc3b368fc2fcdd4fe8a.zip
Merge remote-tracking branch 'upstream/be' into be
Diffstat (limited to 'src/lib/rw_lock.c')
-rw-r--r--src/lib/rw_lock.c127
1 files changed, 127 insertions, 0 deletions
diff --git a/src/lib/rw_lock.c b/src/lib/rw_lock.c
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--- /dev/null
+++ b/src/lib/rw_lock.c
@@ -0,0 +1,127 @@
+/*
+ * Ouroboros - Copyright (C) 2016
+ *
+ * Read/Write locks
+ *
+ * Dimitri Staessens <dimitri.staessens@intec.ugent.be>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <ouroboros/rw_lock.h>
+
+int rw_lock_init(rw_lock_t * lock)
+{
+ if (lock == NULL)
+ return -1;
+
+ pthread_mutex_init(&lock->lock, NULL);
+ pthread_mutex_init(&lock->i_lock, NULL);
+ lock->i = 0;
+
+ return 0;
+}
+
+void rw_lock_destroy(rw_lock_t * lock)
+{
+ if (lock == NULL)
+ return;
+
+ pthread_mutex_destroy(&lock->lock);
+ pthread_mutex_destroy(&lock->i_lock);
+ lock->i = -1;
+}
+
+int rw_lock_rdlock(rw_lock_t * lock)
+{
+ int ret = 0;
+
+ if (lock == NULL)
+ return -1;
+
+ pthread_mutex_lock(&lock->i_lock);
+
+ if (lock->i < 0) {
+ pthread_mutex_unlock(&lock->i_lock);
+ return -1;
+ }
+
+ if (lock->i == 0)
+ ret = pthread_mutex_lock(&lock->lock);
+
+ ++(lock->i);
+
+ pthread_mutex_unlock(&lock->i_lock);
+
+ return ret;
+}
+
+int rw_lock_wrlock(rw_lock_t * lock)
+{
+ int ret = 0;
+
+ if (lock == NULL)
+ return -1;
+
+ pthread_mutex_lock(&lock->i_lock);
+
+ if (lock->i < 0) {
+ pthread_mutex_unlock(&lock->i_lock);
+ return -1;
+ }
+
+ pthread_mutex_unlock(&lock->i_lock);
+
+ while (1) {
+ pthread_mutex_lock(&lock->i_lock);
+
+ if (lock->i == 0) {
+ ++(lock->i);
+ ret = pthread_mutex_lock(&lock->lock);
+ pthread_mutex_unlock(&lock->i_lock);
+ break;
+ }
+
+ pthread_mutex_unlock(&lock->i_lock);
+
+ sched_yield();
+ }
+
+ return ret;
+}
+
+int rw_lock_unlock(rw_lock_t * lock)
+{
+ int ret = 0;
+
+ if (lock == NULL)
+ return -1;
+
+ pthread_mutex_lock(&lock->i_lock);
+
+ if (lock->i < 0) {
+ pthread_mutex_unlock(&lock->i_lock);
+ return -1;
+ }
+
+ --(lock->i);
+
+ if (lock->i == 0)
+ ret = pthread_mutex_unlock(&lock->lock);
+
+ pthread_mutex_unlock(&lock->i_lock);
+
+ return ret;
+}