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authordimitri staessens <dimitri.staessens@intec.ugent.be>2016-05-13 19:34:29 +0200
committerdimitri staessens <dimitri.staessens@intec.ugent.be>2016-05-13 23:16:16 +0200
commit6fa44063041765df752cdcf81ae990e47a37681a (patch)
tree829ab9ad671b14d1244cd10b78be0a4af571416e /src/lib/rw_lock.c
parentfe4eb1fe61042a08686be54a37f72de72bef70f8 (diff)
downloadouroboros-6fa44063041765df752cdcf81ae990e47a37681a.tar.gz
ouroboros-6fa44063041765df752cdcf81ae990e47a37681a.zip
lib: implementation of read/write locks
This adds read/write locks, allowing for concurrent reads on the locked datastructure. This is needed for the fast path.
Diffstat (limited to 'src/lib/rw_lock.c')
-rw-r--r--src/lib/rw_lock.c125
1 files changed, 125 insertions, 0 deletions
diff --git a/src/lib/rw_lock.c b/src/lib/rw_lock.c
new file mode 100644
index 00000000..cf471e60
--- /dev/null
+++ b/src/lib/rw_lock.c
@@ -0,0 +1,125 @@
+/*
+ * 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)
+{
+ 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) {
+ pthread_mutex_unlock(&lock->i_lock);
+ break;
+ }
+
+ pthread_mutex_unlock(&lock->i_lock);
+
+ sched_yield();
+ }
+
+ ++(lock->i);
+
+ return pthread_mutex_lock(&lock->lock);
+}
+
+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;
+}