Provide writer preference option in rwlock.
Previous implementation of rwlock contains four atomic variables, which
is hard to maintain and change. So I make following changes in this CL:
1. Add pending flags in rwlock.state, so we don't need to synchronize
between different atomic variables. Using compare_and_swap operations
on rwlock.state is enough for all state change.
2. Add pending_lock to protect readers/writers waiting and wake up
operations. As waiting/wakeup is not performance critical, using a
lock is easier to maintain.
3. Add writer preference option.
4. Add unit tests for rwlock.
Bug: 19109156
Change-Id: Idcaa58d695ea401d64445610b465ac5cff23ec7c
diff --git a/tests/pthread_test.cpp b/tests/pthread_test.cpp
index f96ccf9..2d21e30 100644
--- a/tests/pthread_test.cpp
+++ b/tests/pthread_test.cpp
@@ -660,6 +660,37 @@
#endif // __BIONIC__
}
+TEST(pthread, pthread_rwlockattr_smoke) {
+ pthread_rwlockattr_t attr;
+ ASSERT_EQ(0, pthread_rwlockattr_init(&attr));
+
+ int pshared_value_array[] = {PTHREAD_PROCESS_PRIVATE, PTHREAD_PROCESS_SHARED};
+ for (size_t i = 0; i < sizeof(pshared_value_array) / sizeof(pshared_value_array[0]); ++i) {
+ ASSERT_EQ(0, pthread_rwlockattr_setpshared(&attr, pshared_value_array[i]));
+ int pshared;
+ ASSERT_EQ(0, pthread_rwlockattr_getpshared(&attr, &pshared));
+ ASSERT_EQ(pshared_value_array[i], pshared);
+ }
+
+ int kind_array[] = {PTHREAD_RWLOCK_PREFER_READER_NP,
+ PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP};
+ for (size_t i = 0; i < sizeof(kind_array) / sizeof(kind_array[0]); ++i) {
+ ASSERT_EQ(0, pthread_rwlockattr_setkind_np(&attr, kind_array[i]));
+ int kind;
+ ASSERT_EQ(0, pthread_rwlockattr_getkind_np(&attr, &kind));
+ ASSERT_EQ(kind_array[i], kind);
+ }
+
+ ASSERT_EQ(0, pthread_rwlockattr_destroy(&attr));
+}
+
+TEST(pthread, pthread_rwlock_init_same_as_PTHREAD_RWLOCK_INITIALIZER) {
+ pthread_rwlock_t lock1 = PTHREAD_RWLOCK_INITIALIZER;
+ pthread_rwlock_t lock2;
+ ASSERT_EQ(0, pthread_rwlock_init(&lock2, NULL));
+ ASSERT_EQ(0, memcmp(&lock1, &lock2, sizeof(lock1)));
+}
+
TEST(pthread, pthread_rwlock_smoke) {
pthread_rwlock_t l;
ASSERT_EQ(0, pthread_rwlock_init(&l, NULL));
@@ -695,7 +726,6 @@
ASSERT_EQ(0, pthread_rwlock_wrlock(&l));
ASSERT_EQ(0, pthread_rwlock_unlock(&l));
-#ifdef __BIONIC__
// EDEADLK in "read after write"
ASSERT_EQ(0, pthread_rwlock_wrlock(&l));
ASSERT_EQ(EDEADLK, pthread_rwlock_rdlock(&l));
@@ -705,7 +735,6 @@
ASSERT_EQ(0, pthread_rwlock_wrlock(&l));
ASSERT_EQ(EDEADLK, pthread_rwlock_wrlock(&l));
ASSERT_EQ(0, pthread_rwlock_unlock(&l));
-#endif
ASSERT_EQ(0, pthread_rwlock_destroy(&l));
}
@@ -807,6 +836,111 @@
ASSERT_EQ(0, pthread_rwlock_destroy(&wakeup_arg.lock));
}
+class RwlockKindTestHelper {
+ private:
+ struct ThreadArg {
+ RwlockKindTestHelper* helper;
+ std::atomic<pid_t>& tid;
+
+ ThreadArg(RwlockKindTestHelper* helper, std::atomic<pid_t>& tid)
+ : helper(helper), tid(tid) { }
+ };
+
+ public:
+ pthread_rwlock_t lock;
+
+ public:
+ RwlockKindTestHelper(int kind_type) {
+ InitRwlock(kind_type);
+ }
+
+ ~RwlockKindTestHelper() {
+ DestroyRwlock();
+ }
+
+ void CreateWriterThread(pthread_t& thread, std::atomic<pid_t>& tid) {
+ tid = 0;
+ ThreadArg* arg = new ThreadArg(this, tid);
+ ASSERT_EQ(0, pthread_create(&thread, NULL,
+ reinterpret_cast<void* (*)(void*)>(WriterThreadFn), arg));
+ }
+
+ void CreateReaderThread(pthread_t& thread, std::atomic<pid_t>& tid) {
+ tid = 0;
+ ThreadArg* arg = new ThreadArg(this, tid);
+ ASSERT_EQ(0, pthread_create(&thread, NULL,
+ reinterpret_cast<void* (*)(void*)>(ReaderThreadFn), arg));
+ }
+
+ private:
+ void InitRwlock(int kind_type) {
+ pthread_rwlockattr_t attr;
+ ASSERT_EQ(0, pthread_rwlockattr_init(&attr));
+ ASSERT_EQ(0, pthread_rwlockattr_setkind_np(&attr, kind_type));
+ ASSERT_EQ(0, pthread_rwlock_init(&lock, &attr));
+ ASSERT_EQ(0, pthread_rwlockattr_destroy(&attr));
+ }
+
+ void DestroyRwlock() {
+ ASSERT_EQ(0, pthread_rwlock_destroy(&lock));
+ }
+
+ static void WriterThreadFn(ThreadArg* arg) {
+ arg->tid = gettid();
+
+ RwlockKindTestHelper* helper = arg->helper;
+ ASSERT_EQ(0, pthread_rwlock_wrlock(&helper->lock));
+ ASSERT_EQ(0, pthread_rwlock_unlock(&helper->lock));
+ delete arg;
+ }
+
+ static void ReaderThreadFn(ThreadArg* arg) {
+ arg->tid = gettid();
+
+ RwlockKindTestHelper* helper = arg->helper;
+ ASSERT_EQ(0, pthread_rwlock_rdlock(&helper->lock));
+ ASSERT_EQ(0, pthread_rwlock_unlock(&helper->lock));
+ delete arg;
+ }
+};
+
+TEST(pthread, pthread_rwlock_kind_PTHREAD_RWLOCK_PREFER_READER_NP) {
+ RwlockKindTestHelper helper(PTHREAD_RWLOCK_PREFER_READER_NP);
+ ASSERT_EQ(0, pthread_rwlock_rdlock(&helper.lock));
+
+ pthread_t writer_thread;
+ std::atomic<pid_t> writer_tid;
+ helper.CreateWriterThread(writer_thread, writer_tid);
+ WaitUntilThreadSleep(writer_tid);
+
+ pthread_t reader_thread;
+ std::atomic<pid_t> reader_tid;
+ helper.CreateReaderThread(reader_thread, reader_tid);
+ ASSERT_EQ(0, pthread_join(reader_thread, NULL));
+
+ ASSERT_EQ(0, pthread_rwlock_unlock(&helper.lock));
+ ASSERT_EQ(0, pthread_join(writer_thread, NULL));
+}
+
+TEST(pthread, pthread_rwlock_kind_PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP) {
+ RwlockKindTestHelper helper(PTHREAD_RWLOCK_PREFER_WRITER_NONRECURSIVE_NP);
+ ASSERT_EQ(0, pthread_rwlock_rdlock(&helper.lock));
+
+ pthread_t writer_thread;
+ std::atomic<pid_t> writer_tid;
+ helper.CreateWriterThread(writer_thread, writer_tid);
+ WaitUntilThreadSleep(writer_tid);
+
+ pthread_t reader_thread;
+ std::atomic<pid_t> reader_tid;
+ helper.CreateReaderThread(reader_thread, reader_tid);
+ WaitUntilThreadSleep(reader_tid);
+
+ ASSERT_EQ(0, pthread_rwlock_unlock(&helper.lock));
+ ASSERT_EQ(0, pthread_join(writer_thread, NULL));
+ ASSERT_EQ(0, pthread_join(reader_thread, NULL));
+}
+
static int g_once_fn_call_count = 0;
static void OnceFn() {
++g_once_fn_call_count;