/* -*- 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 "nsISupportsImpl.h"

#include "mozilla/Atomics.h"

#include "nsThreadUtils.h"

#include "gtest/gtest.h"

using namespace mozilla;

class nsThreadSafeAutoRefCntRunner final : public nsIRunnable

{

public:

  NS_DECL_THREADSAFE_ISUPPORTS

  NS_IMETHOD Run() final

  {

    for (int i = 0; i < 10000; i++) {

      if (++sRefCnt == 1) {

        sIncToOne++;

      }

      if (--sRefCnt == 0) {

        sDecToZero++;

      }

    }

    return NS_OK;

  }

  static ThreadSafeAutoRefCnt sRefCnt;

  static Atomic<uint32_t, Relaxed> sIncToOne;

  static Atomic<uint32_t, Relaxed> sDecToZero;

private:

  ~nsThreadSafeAutoRefCntRunner() {}

};

NS_IMPL_ISUPPORTS(nsThreadSafeAutoRefCntRunner, nsIRunnable)

ThreadSafeAutoRefCnt nsThreadSafeAutoRefCntRunner::sRefCnt;

Atomic<uint32_t, Relaxed> nsThreadSafeAutoRefCntRunner::sIncToOne(0);

Atomic<uint32_t, Relaxed> nsThreadSafeAutoRefCntRunner::sDecToZero(0);

// When a refcounted object is actually owned by a cache, we may not

// want to release the object after last reference gets released. In

// this pattern, the cache may rely on the balance of increment to one

// and decrement to zero, so that it can maintain a counter for GC.

TEST(AutoRefCnt, ThreadSafeAutoRefCntBalance)

{

  static const size_t kThreadCount = 4;

  nsCOMPtr<nsIThread> threads[kThreadCount];

  for (size_t i = 0; i < kThreadCount; i++) {

    nsresult rv = NS_NewThread(getter_AddRefs(threads[i]),

                               new nsThreadSafeAutoRefCntRunner);

    EXPECT_TRUE(NS_SUCCEEDED(rv));

  }

  for (size_t i = 0; i < kThreadCount; i++) {

    threads[i]->Shutdown();

  }

  EXPECT_EQ(nsThreadSafeAutoRefCntRunner::sRefCnt, nsrefcnt(0));

  EXPECT_EQ(nsThreadSafeAutoRefCntRunner::sIncToOne,

            nsThreadSafeAutoRefCntRunner::sDecToZero);

}