1 files changed, 181 insertions, 0 deletions
diff --git a/third_party/libwebrtc/rtc_base/synchronization/mutex_unittest.cc b/third_party/libwebrtc/rtc_base/synchronization/mutex_unittest.cc
new file mode 100644
index 0000000000..fcca78d18b
--- /dev/null
+++ b/third_party/libwebrtc/rtc_base/synchronization/mutex_unittest.cc
@@ -0,0 +1,181 @@
+/*
+ *  Copyright 2020 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "rtc_base/synchronization/mutex.h"
+
+#include <stddef.h>
+#include <stdint.h>
+
+#include <atomic>
+#include <memory>
+#include <type_traits>
+#include <utility>
+#include <vector>
+
+#include "benchmark/benchmark.h"
+#include "rtc_base/checks.h"
+#include "rtc_base/event.h"
+#include "rtc_base/location.h"
+#include "rtc_base/message_handler.h"
+#include "rtc_base/platform_thread.h"
+#include "rtc_base/synchronization/yield.h"
+#include "rtc_base/thread.h"
+#include "test/gtest.h"
+
+namespace webrtc {
+namespace {
+
+using ::rtc::Event;
+using ::rtc::Message;
+using ::rtc::MessageHandler;
+using ::rtc::Thread;
+
+constexpr int kNumThreads = 16;
+
+template <class MutexType>
+class RTC_LOCKABLE RawMutexLocker {
+ public:
+  explicit RawMutexLocker(MutexType& mutex) : mutex_(mutex) {}
+  void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION() { mutex_.Lock(); }
+  void Unlock() RTC_UNLOCK_FUNCTION() { mutex_.Unlock(); }
+
+ private:
+  MutexType& mutex_;
+};
+
+class RTC_LOCKABLE RawMutexTryLocker {
+ public:
+  explicit RawMutexTryLocker(Mutex& mutex) : mutex_(mutex) {}
+  void Lock() RTC_EXCLUSIVE_LOCK_FUNCTION() {
+    while (!mutex_.TryLock()) {
+      YieldCurrentThread();
+    }
+  }
+  void Unlock() RTC_UNLOCK_FUNCTION() { mutex_.Unlock(); }
+
+ private:
+  Mutex& mutex_;
+};
+
+template <class MutexType, class MutexLockType>
+class MutexLockLocker {
+ public:
+  explicit MutexLockLocker(MutexType& mutex) : mutex_(mutex) {}
+  void Lock() { lock_ = std::make_unique<MutexLockType>(&mutex_); }
+  void Unlock() { lock_ = nullptr; }
+
+ private:
+  MutexType& mutex_;
+  std::unique_ptr<MutexLockType> lock_;
+};
+
+template <class MutexType, class MutexLocker>
+class LockRunner : public rtc::MessageHandlerAutoCleanup {
+ public:
+  template <typename... Args>
+  explicit LockRunner(Args... args)
+      : threads_active_(0),
+        start_event_(true, false),
+        done_event_(true, false),
+        shared_value_(0),
+        mutex_(args...),
+        locker_(mutex_) {}
+
+  bool Run() {
+    // Signal all threads to start.
+    start_event_.Set();
+
+    // Wait for all threads to finish.
+    return done_event_.Wait(kLongTime);
+  }
+
+  void SetExpectedThreadCount(int count) { threads_active_ = count; }
+
+  int shared_value() {
+    int shared_value;
+    locker_.Lock();
+    shared_value = shared_value_;
+    locker_.Unlock();
+    return shared_value;
+  }
+
+  void OnMessage(Message* msg) override {
+    ASSERT_TRUE(start_event_.Wait(kLongTime));
+    locker_.Lock();
+
+    EXPECT_EQ(0, shared_value_);
+    int old = shared_value_;
+
+    // Use a loop to increase the chance of race. If the `locker_`
+    // implementation is faulty, it would be improbable that the error slips
+    // through.
+    for (int i = 0; i < kOperationsToRun; ++i) {
+      benchmark::DoNotOptimize(++shared_value_);
+    }
+    EXPECT_EQ(old + kOperationsToRun, shared_value_);
+    shared_value_ = 0;
+
+    locker_.Unlock();
+    if (threads_active_.fetch_sub(1) == 1) {
+      done_event_.Set();
+    }
+  }
+
+ private:
+  static constexpr int kLongTime = 10000;  // 10 seconds
+  static constexpr int kOperationsToRun = 1000;
+
+  std::atomic<int> threads_active_;
+  Event start_event_;
+  Event done_event_;
+  int shared_value_;
+  MutexType mutex_;
+  MutexLocker locker_;
+};
+
+void StartThreads(std::vector<std::unique_ptr<Thread>>& threads,
+                  MessageHandler* handler) {
+  for (int i = 0; i < kNumThreads; ++i) {
+    std::unique_ptr<Thread> thread(Thread::Create());
+    thread->Start();
+    thread->Post(RTC_FROM_HERE, handler);
+    threads.push_back(std::move(thread));
+  }
+}
+
+TEST(MutexTest, ProtectsSharedResourceWithMutexAndRawMutexLocker) {
+  std::vector<std::unique_ptr<Thread>> threads;
+  LockRunner<Mutex, RawMutexLocker<Mutex>> runner;
+  StartThreads(threads, &runner);
+  runner.SetExpectedThreadCount(kNumThreads);
+  EXPECT_TRUE(runner.Run());
+  EXPECT_EQ(0, runner.shared_value());
+}
+
+TEST(MutexTest, ProtectsSharedResourceWithMutexAndRawMutexTryLocker) {
+  std::vector<std::unique_ptr<Thread>> threads;
+  LockRunner<Mutex, RawMutexTryLocker> runner;
+  StartThreads(threads, &runner);
+  runner.SetExpectedThreadCount(kNumThreads);
+  EXPECT_TRUE(runner.Run());
+  EXPECT_EQ(0, runner.shared_value());
+}
+
+TEST(MutexTest, ProtectsSharedResourceWithMutexAndMutexLocker) {
+  std::vector<std::unique_ptr<Thread>> threads;
+  LockRunner<Mutex, MutexLockLocker<Mutex, MutexLock>> runner;
+  StartThreads(threads, &runner);
+  runner.SetExpectedThreadCount(kNumThreads);
+  EXPECT_TRUE(runner.Run());
+  EXPECT_EQ(0, runner.shared_value());
+}
+
+}  // namespace
+}  // namespace webrtc