Roll forward to cl/338482889

Signed-off-by: Alexey Polyudov <apolyudov@google.com>
Change-Id: I9850950db8bd84f0904ea1a413151887f52098cf

cpp/platform/public/mutex_test.cc

@@ -0,0 +1,103 @@
+#include "platform/public/mutex.h"
+
+#include "platform/public/condition_variable.h"
+#include "platform/public/single_thread_executor.h"
+#include "gtest/gtest.h"
+#include "absl/synchronization/mutex.h"
+#include "absl/time/clock.h"
+#include "absl/time/time.h"
+
+namespace location {
+namespace nearby {
+namespace {
+
+class MutexTest : public testing::Test {
+ public:
+  void VerifyStepReached(int expected) {
+    absl::MutexLock lock(&step_mutex_);
+    absl::Time deadline = absl::Now() + kTimeToWait;
+    while (step_ != expected) {
+      if (step_cond_.WaitWithDeadline(&step_mutex_, deadline)) break;
+    }
+    EXPECT_EQ(step_, expected);
+    // Make sure we are not progressing further.
+    absl::SleepFor(kTimeToWait);
+    EXPECT_EQ(step_, expected);
+  }
+
+ protected:
+  SingleThreadExecutor executor_;
+  const absl::Duration kTimeToWait = absl::Milliseconds(500);
+  std::atomic_int step_ = 0;
+  absl::Mutex step_mutex_;
+  absl::CondVar step_cond_;
+};
+
+TEST_F(MutexTest, ConstructorDestructorWorks) {
+  Mutex test_mutex;
+  SUCCEED();
+}
+
+TEST_F(MutexTest, BasicLockingWorks) {
+  Mutex test_mutex;
+  test_mutex.Lock();
+  executor_.Execute([this, &test_mutex]() {
+    step_ = 1;
+    step_cond_.Signal();
+    test_mutex.Lock();
+    test_mutex.Unlock();
+    step_ = 2;
+    step_cond_.Signal();
+  });
+  VerifyStepReached(1);
+  test_mutex.Unlock();
+  VerifyStepReached(2);
+}
+
+#ifdef THREAD_SANITIZER
+TEST_F(MutexTest, DISABLED_DoubleLockIsDeadlock)
+ABSL_NO_THREAD_SAFETY_ANALYSIS {
+#else
+TEST_F(MutexTest, DoubleLockIsDeadlock) ABSL_NO_THREAD_SAFETY_ANALYSIS {
+#endif
+  Mutex test_mutex{/*check=*/false};  // Disable run-time deadlock detection.
+  test_mutex.Lock();
+  executor_.Execute([this, &test_mutex]() ABSL_NO_THREAD_SAFETY_ANALYSIS {
+    step_ = 1;
+    step_cond_.Signal();  // We entered executor.
+    test_mutex.Lock();
+    step_ = 2;
+    step_cond_.Signal();  // We acquired the test lock.
+    test_mutex.Lock();    // Deadlock. (Main thread should save us).
+    step_ = 3;
+    step_cond_.Signal();  // We are done.
+  });
+  VerifyStepReached(1);
+  test_mutex.Unlock();  // Let executor proceed to step 2.
+  VerifyStepReached(2);
+  test_mutex.Unlock();  // Bring executor out of deadlock.
+  VerifyStepReached(3);
+  test_mutex.Unlock();  // Unlock before shutdown.
+}
+
+TEST_F(MutexTest, DoubleLockIsNotDeadlock) {
+  RecursiveMutex test_mutex;
+  test_mutex.Lock();
+  executor_.Execute([this, &test_mutex]() ABSL_NO_THREAD_SAFETY_ANALYSIS {
+    step_ = 1;
+    step_cond_.Signal();  // We entered executor.
+    test_mutex.Lock();
+    test_mutex.Lock();
+    test_mutex.Unlock();
+    test_mutex.Unlock();
+    step_ = 2;
+    step_cond_.Signal();  // We are done.
+  });
+  VerifyStepReached(1);
+  test_mutex.Unlock();  // Let executor continue.
+  VerifyStepReached(2);
+}
+
+}  // namespace
+}  // namespace nearby
+}  // namespace location