First work on threaded version.

[idzebra-moved-to-github.git] / util / zebra-lock.c

diff --git a/util/zebra-lock.c b/util/zebra-lock.c
new file mode 100644 (file)
index 0000000..6739a18
--- /dev/null
+++ b/util/zebra-lock.c
@@ -0,0 +1,102 @@
+
+#include <assert.h>
+
+#include <zebra-lock.h>
+
+int zebra_mutex_init (Zebra_mutex *p)
+{
+    pthread_mutex_init (&p->mutex, 0);
+    return 0;
+}
+
+int zebra_mutex_destroy (Zebra_mutex *p)
+{
+    pthread_mutex_destroy (&p->mutex);
+    return 0;
+}
+
+int zebra_mutex_lock (Zebra_mutex *p)
+{
+    pthread_mutex_lock (&p->mutex);
+    return 0;
+}
+
+int zebra_mutex_unlock (Zebra_mutex *p)
+{
+    pthread_mutex_unlock (&p->mutex);
+    return 0;
+}
+
+int zebra_lock_rdwr_init (Zebra_lock_rdwr *p)
+{
+    p->readers_reading = 0;
+    p->writers_writing = 0;
+    pthread_mutex_init (&p->mutex, 0);
+    pthread_cond_init (&p->lock_free, 0);
+    return 0;
+}
+
+int zebra_lock_rdwr_destroy (Zebra_lock_rdwr *p)
+{
+    assert (p->readers_reading == 0);
+    assert (p->writers_writing == 0);
+    pthread_mutex_destroy (&p->mutex);
+    pthread_cond_destroy (&p->lock_free);
+    return 0;
+}
+
+int zebra_lock_rdwr_rlock (Zebra_lock_rdwr *p)
+{
+    pthread_mutex_lock (& p->mutex);
+    while (p->writers_writing)
+       pthread_cond_wait (&p->lock_free, &p->mutex);
+    p->readers_reading++;
+    pthread_mutex_unlock(&p->mutex);
+    return 0;
+}
+
+int zebra_lock_rdwr_wlock (Zebra_lock_rdwr *p)
+{
+    pthread_mutex_lock (&p->mutex);
+    while (p->writers_writing || p->readers_reading)
+       pthread_cond_wait (&p->lock_free, &p->mutex);
+    p->writers_writing++;
+    pthread_mutex_unlock (&p->mutex);
+    return 0;
+}
+
+int zebra_lock_rdwr_runlock (Zebra_lock_rdwr *p)
+{
+    pthread_mutex_lock (&p->mutex);
+    if (p->readers_reading == 0)
+    {
+       pthread_mutex_unlock (&p->mutex);
+       return -1;
+    } 
+    else
+    {
+       p->readers_reading--;
+       if (p->readers_reading == 0)
+           pthread_cond_signal (&p->lock_free);
+       pthread_mutex_unlock (&p->mutex);
+    }
+    return 0;
+}
+
+int zebra_lock_rdwr_wunlock (Zebra_lock_rdwr *p)
+{
+    pthread_mutex_lock (&p->mutex);
+    if (p->writers_writing == 0)
+    {
+       pthread_mutex_unlock (&p->mutex);
+       return -1;
+    }
+    else
+    {
+       p->writers_writing--;
+       pthread_cond_broadcast(&p->lock_free);
+       pthread_mutex_unlock(&p->mutex);
+    }
+    return 0;
+}
+