test-semaphore.cc

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// Copyright 2013 the V8 project authors. All rights reserved.
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#include <stdlib.h>

#include "v8.h"

#include "platform.h"
#include "cctest.h"


using namespace ::v8::internal;


class WaitAndSignalThread V8_FINAL : public Thread {
  public:
  explicit WaitAndSignalThread(Semaphore* semaphore)
      : Thread("WaitAndSignalThread"), semaphore_(semaphore) {}
  virtual ~WaitAndSignalThread() {}

  virtual void Run() V8_OVERRIDE {
    for (int n = 0; n < 1000; ++n) {
      semaphore_->Wait();
      bool result = semaphore_->WaitFor(TimeDelta::FromMicroseconds(1));
      ASSERT(!result);
      USE(result);
      semaphore_->Signal();
    }
  }

  private:
  Semaphore* semaphore_;
};


TEST(WaitAndSignal) {
  Semaphore semaphore(0);
  WaitAndSignalThread t1(&semaphore);
  WaitAndSignalThread t2(&semaphore);

  t1.Start();
  t2.Start();

  // Make something available.
  semaphore.Signal();

  t1.Join();
  t2.Join();

  semaphore.Wait();

  bool result = semaphore.WaitFor(TimeDelta::FromMicroseconds(1));
  ASSERT(!result);
  USE(result);
}


TEST(WaitFor) {
  bool ok;
  Semaphore semaphore(0);

  // Semaphore not signalled - timeout.
  ok = semaphore.WaitFor(TimeDelta::FromMicroseconds(0));
  CHECK(!ok);
  ok = semaphore.WaitFor(TimeDelta::FromMicroseconds(100));
  CHECK(!ok);
  ok = semaphore.WaitFor(TimeDelta::FromMicroseconds(1000));
  CHECK(!ok);

  // Semaphore signalled - no timeout.
  semaphore.Signal();
  ok = semaphore.WaitFor(TimeDelta::FromMicroseconds(0));
  CHECK(ok);
  semaphore.Signal();
  ok = semaphore.WaitFor(TimeDelta::FromMicroseconds(100));
  CHECK(ok);
  semaphore.Signal();
  ok = semaphore.WaitFor(TimeDelta::FromMicroseconds(1000));
  CHECK(ok);
}


static const char alphabet[] = "XKOAD";
static const int kAlphabetSize = sizeof(alphabet) - 1;
static const int kBufferSize = 4096;  // GCD(buffer size, alphabet size) = 1
static char buffer[kBufferSize];
static const int kDataSize = kBufferSize * kAlphabetSize * 10;

static Semaphore free_space(kBufferSize);
static Semaphore used_space(0);


class ProducerThread V8_FINAL : public Thread {
  public:
  ProducerThread() : Thread("ProducerThread") {}
  virtual ~ProducerThread() {}

  virtual void Run() V8_OVERRIDE {
    for (int n = 0; n < kDataSize; ++n) {
      free_space.Wait();
      buffer[n % kBufferSize] = alphabet[n % kAlphabetSize];
      used_space.Signal();
    }
  }
};


class ConsumerThread V8_FINAL : public Thread {
  public:
  ConsumerThread() : Thread("ConsumerThread") {}
  virtual ~ConsumerThread() {}

  virtual void Run() V8_OVERRIDE {
    for (int n = 0; n < kDataSize; ++n) {
      used_space.Wait();
      ASSERT_EQ(static_cast<int>(alphabet[n % kAlphabetSize]),
                static_cast<int>(buffer[n % kBufferSize]));
      free_space.Signal();
    }
  }
};


TEST(ProducerConsumer) {
  ProducerThread producer_thread;
  ConsumerThread consumer_thread;
  producer_thread.Start();
  consumer_thread.Start();
  producer_thread.Join();
  consumer_thread.Join();
}