/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#include "nsThreadUtils.h"
#include "mozilla/Atomics.h"
#include "mozilla/RWLock.h"
#include "gtest/gtest.h"

using mozilla::RWLock;

static const size_t sNumThreads = 4;
static const size_t sOuterIterations = 100;
static const size_t sInnerIterations = 100;
static const size_t sWriteLockIteration = 10;

// Based on example code from _Programming with POSIX Threads_.  Not an actual
// test of correctness, but more of a "does this work at all" sort of test.

class RWLockRunnable : public mozilla::Runnable {
public:
  RWLockRunnable(RWLock* aRWLock, mozilla::Atomic<size_t>* aSharedData)
    : mozilla::Runnable("RWLockRunnable")
    , mRWLock(aRWLock)
    , mSharedData(aSharedData)
  {}

  NS_DECL_NSIRUNNABLE

private:
  ~RWLockRunnable() = default;

  RWLock* mRWLock;
  mozilla::Atomic<size_t>* mSharedData;
};

NS_IMETHODIMP
RWLockRunnable::Run()
{
  for (size_t i = 0; i < sOuterIterations; ++i) {
    if (i % sWriteLockIteration == 0) {
      mozilla::AutoWriteLock lock(*mRWLock);

      ++(*mSharedData);
    } else {
      mozilla::AutoReadLock lock(*mRWLock);

      // Loop and try to force other threads to run, but check that our
      // shared data isn't being modified by them.
      size_t initialValue = *mSharedData;
      for (size_t j = 0; j < sInnerIterations; ++j) {
        EXPECT_EQ(initialValue, *mSharedData);

        // This is a magic yield call.
        PR_Sleep(PR_INTERVAL_NO_WAIT);
      }
    }
  }

  return NS_OK;
}

TEST(RWLock, SmokeTest)
{
  nsCOMPtr<nsIThread> threads[sNumThreads];
  RWLock rwlock("test lock");
  mozilla::Atomic<size_t> data(0);

  for (size_t i = 0; i < sNumThreads; ++i) {
    nsCOMPtr<nsIRunnable> event = new RWLockRunnable(&rwlock, &data);
    NS_NewNamedThread("RWLockTester", getter_AddRefs(threads[i]), event);
  }

  // Wait for all the threads to finish.
  for (size_t i = 0; i < sNumThreads; ++i) {
    nsresult rv = threads[i]->Shutdown();
    EXPECT_TRUE(NS_SUCCEEDED(rv));
  }

  EXPECT_EQ(data, (sOuterIterations / sWriteLockIteration) * sNumThreads);
}