src/base/mutex_test.cc

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#include <string.h>
#include "base/logging.h"
#include "base/mutex.h"
#include "base/thread.h"
#include "base/util.h"
#include "testing/base/public/gunit.h"

namespace mozc {
namespace {

volatile int g_counter = 0;

class MutexTestThread : public Thread {
 public:
  MutexTestThread(Mutex *mutex, int loop, int sleep)
      : mutex_(mutex), loop_(loop), sleep_(sleep) {}

  virtual void Run() {
    for (int i = 0; i < loop_; ++i) {
      {
        scoped_lock l(mutex_);
        ++g_counter;
      }
      Util::Sleep(sleep_);
    }
  }

 private:
  Mutex *mutex_;
  int loop_;
  int sleep_;
};

class MutexTestSleepThread : public Thread {
 public:
  MutexTestSleepThread(Mutex *mutex, int sleep)
      : mutex_(mutex), sleep_(sleep) {}

  virtual void Run() {
    scoped_lock l(mutex_);
    ++g_counter;
    Util::Sleep(sleep_);
  }

 private:
  Mutex *mutex_;
  int sleep_;
};

TEST(MutexTest, MutexBasicTest) NO_THREAD_SAFETY_ANALYSIS {
  g_counter = 0;
  Mutex mutex;
  MutexTestThread t(&mutex, 1, 1000);
  t.Start();

  Util::Sleep(100);  // still g_counter is locked
  scoped_lock lockA(&mutex);  // get mutex 2nd
  ++g_counter;
  EXPECT_EQ(2, g_counter);
  scoped_lock lockB(&mutex);  // recursive lock
  ++g_counter;
  EXPECT_EQ(3, g_counter);
  t.Join();  // make sure that the thread no longer uses the mutex
}

TEST(MutexTest, TryLockTest) NO_THREAD_SAFETY_ANALYSIS {
  {  // Get a lock by TryLock.
    g_counter = 0;
    Mutex mutex;
    MutexTestSleepThread t(&mutex, 1);

    EXPECT_TRUE(mutex.TryLock());
    t.Start();
    Util::Sleep(100);
    EXPECT_EQ(0, g_counter);
    mutex.Unlock();
    t.Join();
    EXPECT_EQ(1, g_counter);

    {
      scoped_try_lock lock(&mutex);
      EXPECT_TRUE(lock.locked());
      t.Start();
      Util::Sleep(100);
      EXPECT_EQ(1, g_counter);
    }
    t.Join();
    EXPECT_EQ(2, g_counter);

    {
      scoped_try_lock lockA(&mutex);
      EXPECT_TRUE(lockA.locked());
      scoped_try_lock lockB(&mutex);
      EXPECT_TRUE(lockB.locked());
    }
  }

  {  // Cannot get a lock by TryLock since it is already locked.
    g_counter = 0;
    Mutex mutex;
    MutexTestSleepThread t(&mutex, 1000);

    uint64 start_sec;
    uint32 start_usec;
    Util::GetTimeOfDay(&start_sec, &start_usec);
    t.Start();

    Util::Sleep(100);
    EXPECT_EQ(1, g_counter);
    EXPECT_FALSE(mutex.TryLock());
    scoped_try_lock lock(&mutex);
    EXPECT_FALSE(lock.locked());

    uint64 end_sec;
    uint32 end_usec;
    Util::GetTimeOfDay(&end_sec, &end_usec);
    const uint64 elapsed_usec =
      (end_sec - start_sec) * 1000000 + end_usec - start_usec;
    EXPECT_GE(1000000, elapsed_usec);
    t.Join();
  }
}

TEST(MutexTest, MutexBatchTest) {
  const int kThreadsSize = 5;
  const int kLoopSize = 10;
  vector<MutexTestThread *> threads(kThreadsSize);

  g_counter = 0;

  Mutex mutex;
  for (int i = 0; i < kThreadsSize; ++i) {
    threads[i] = new MutexTestThread(&mutex, kLoopSize, 1);
  }

  for (int i = 0; i < kThreadsSize; ++i) {
    threads[i]->Start();
  }

  for (int i = 0; i < kThreadsSize; ++i) {
    threads[i]->Join();
  }

  for (int i = 0; i < kThreadsSize; ++i) {
    delete threads[i];
  }

  EXPECT_EQ(kThreadsSize * kLoopSize, g_counter);
}

void CallbackFunc() {
  ++g_counter;
  Util::Sleep(20);
}

class ReaderMutexTestThread : public Thread {
 public:
  explicit ReaderMutexTestThread(ReaderWriterMutex *mutex)
      : counter_(0), mutex_(mutex) {}

  static const int kStopCoutner = -1;

  virtual void Run() {
    while (g_counter != kStopCoutner) {
      Util::Sleep(1);
      scoped_reader_lock l(mutex_);
      counter_ = g_counter;
    }
  }

  int counter() const { return counter_; }

 private:
  int counter_;
  ReaderWriterMutex *mutex_;
};

// TODO(yukawa): Replace the following test with more stable one
//     which asserts deterministic conditions that will not be
//     affected by the CPU load average. b/6355447
TEST(MutexTest, ReaderWriterTest) {
  if (!ReaderWriterMutex::MultipleReadersThreadsSupported()) {
    LOG(INFO) << "ReaderWriterMutex does not support multiple "
                 "reader threads. Skipping ReaderWriterTest test.";
    return;
  }

  const size_t kThreadsSize = 3;
  vector<ReaderMutexTestThread *> threads(kThreadsSize);

  // shared variable
  g_counter = 1;

  ReaderWriterMutex mutex;
  for (size_t i = 0; i < kThreadsSize; ++i) {
    threads[i] = new ReaderMutexTestThread(&mutex);
  }

  for (size_t i = 0; i < kThreadsSize; ++i) {
    threads[i]->Start();
  }

  const uint32 kSleepTime = 500;  // 500 msec

  // every reader thread can get g_counter variable at the same time.
  Util::Sleep(kSleepTime);
  for (int i = 0; i < kThreadsSize; ++i) {
    EXPECT_EQ(g_counter, threads[i]->counter());
  }

  for (int counter = 1; counter < 10; ++counter) {
    {
      // stops the reader thread.
      scoped_writer_lock l(&mutex);

      // update counter
      g_counter = counter + 1;

      // Still the counter value is counter.
      for (size_t i = 0; i < kThreadsSize; ++i) {
        EXPECT_EQ(counter, threads[i]->counter());
      }
    }

    Util::Sleep(kSleepTime);
    // coutner value becomes the same as g_counter
    for (size_t i = 0; i < kThreadsSize; ++i) {
      EXPECT_EQ(g_counter, threads[i]->counter());
    }
  }

  {
    scoped_writer_lock l(&mutex);
    g_counter = ReaderMutexTestThread::kStopCoutner;
  }

  for (size_t i = 0; i < kThreadsSize; ++i) {
    threads[i]->Join();
    delete threads[i];
  }
}

TEST(CallOnceTest, CallOnceBasicTest) {
  g_counter = 0;
  once_t once = MOZC_ONCE_INIT;
  CallOnce(&once, CallbackFunc);
  EXPECT_EQ(1, g_counter);

  CallOnce(&once, CallbackFunc);
  EXPECT_EQ(1, g_counter);

  CallOnce(&once, CallbackFunc);
  EXPECT_EQ(1, g_counter);
}
}  // namespace
}  // namespace mozc