#107 check if various rwlocks are fair WRT multiple writers

util/tests/test-frwlock-fair-writers.cc

+// check if write locks are fair
+
+#include <stdio.h>
+#include <toku_assert.h>
+#include <unistd.h>
+#include <pthread.h>
+#include <util/frwlock.h>
+
+toku_mutex_t rwlock_mutex;
+toku::frwlock rwlock;
+volatile int killed = 0;
+
+static void *t1_func(void *arg) {
+    int i;
+    for (i = 0; !killed; i++) {
+        toku_mutex_lock(&rwlock_mutex);
+        rwlock.write_lock(false);
+        toku_mutex_unlock(&rwlock_mutex);
+        usleep(10000);
+        toku_mutex_lock(&rwlock_mutex);
+        rwlock.write_unlock();
+        toku_mutex_unlock(&rwlock_mutex);
+    }
+    printf("%lu %d\n", pthread_self(), i);
+    return arg;
+}
+
+int main(void) {
+    int r;
+
+    toku_mutex_init(&rwlock_mutex, NULL);
+    rwlock.init(&rwlock_mutex);
+    
+    const int nthreads = 2;
+    pthread_t tids[nthreads];
+    for (int i = 0; i < nthreads; i++) {
+        r = pthread_create(&tids[i], NULL, t1_func, NULL); 
+        assert(r == 0);
+    }
+    sleep(10);
+    killed = 1;
+    for (int i = 0; i < nthreads; i++) {
+        void *ret;
+        r = pthread_join(tids[i], &ret);
+        assert(r == 0);
+    }
+
+    rwlock.deinit();
+    toku_mutex_destroy(&rwlock_mutex);
+
+    return 0;
+}

util/tests/test-rwlock-unfair-writers.cc

+// check if write locks are fair
+
+#include <stdio.h>
+#include <assert.h>
+#include <unistd.h>
+#include <pthread.h>
+
+pthread_rwlock_t rwlock;
+volatile int killed = 0;
+
+static void *t1_func(void *arg) {
+    int i;
+    for (i = 0; !killed; i++) {
+        int r;
+        r = pthread_rwlock_wrlock(&rwlock); 
+        assert(r == 0);
+        usleep(10000);
+        r = pthread_rwlock_unlock(&rwlock);
+        assert(r == 0);
+    }
+    printf("%lu %d\n", pthread_self(), i);
+    return arg;
+}
+
+int main(void) {
+    int r;
+#if 0
+    rwlock = PTHREAD_RWLOCK_INITIALIZER;
+#endif
+#if 0
+    pthread_rwlockattr_t attr;
+    pthread_rwlockattr_init(&attr);
+    pthread_rwlockattr_setkind_np(&attr, PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+    r = pthread_rwlock_init(&rwlock, &attr);
+#endif
+#if 0
+    pthread_rwlockattr_t attr;
+    pthread_rwlockattr_init(&attr);
+    r = pthread_rwlock_init(&rwlock, &attr);
+#endif
+#if 1
+    r = pthread_rwlock_init(&rwlock, NULL);
+    assert(r == 0);
+#endif
+    
+    const int nthreads = 2;
+    pthread_t tids[nthreads];
+    for (int i = 0; i < nthreads; i++) {
+        r = pthread_create(&tids[i], NULL, t1_func, NULL); 
+        assert(r == 0);
+    }
+    sleep(10);
+    killed = 1;
+    for (int i = 0; i < nthreads; i++) {
+        void *ret;
+        r = pthread_join(tids[i], &ret);
+        assert(r == 0);
+    }
+    return 0;
+}