gecko-dev/image/test/gtest/TestCopyOnWrite.cpp

/* 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 "gtest/gtest.h"

#include "CopyOnWrite.h"

using namespace mozilla;
using namespace mozilla::image;

struct ValueStats {
  int32_t mCopies = 0;
  int32_t mFrees = 0;
  int32_t mCalls = 0;
  int32_t mConstCalls = 0;
  int32_t mSerial = 0;
};

struct Value {
  NS_INLINE_DECL_REFCOUNTING(Value)

  explicit Value(ValueStats& aStats)
      : mStats(aStats), mSerial(mStats.mSerial++) {}

  Value(const Value& aOther)
      : mStats(aOther.mStats), mSerial(mStats.mSerial++) {
    mStats.mCopies++;
  }

  void Go() { mStats.mCalls++; }
  void Go() const { mStats.mConstCalls++; }

  int32_t Serial() const { return mSerial; }

 protected:
  ~Value() { mStats.mFrees++; }

 private:
  ValueStats& mStats;
  int32_t mSerial;
};

TEST(ImageCopyOnWrite, Read)
{
  ValueStats stats;

  {
    CopyOnWrite<Value> cow(new Value(stats));

    EXPECT_EQ(0, stats.mCopies);
    EXPECT_EQ(0, stats.mFrees);
    EXPECT_TRUE(cow.CanRead());

    cow.Read([&](const Value* aValue) {
      EXPECT_EQ(0, stats.mCopies);
      EXPECT_EQ(0, stats.mFrees);
      EXPECT_EQ(0, aValue->Serial());
      EXPECT_TRUE(cow.CanRead());
      EXPECT_TRUE(cow.CanWrite());

      aValue->Go();

      EXPECT_EQ(0, stats.mCalls);
      EXPECT_EQ(1, stats.mConstCalls);
    });

    EXPECT_EQ(0, stats.mCopies);
    EXPECT_EQ(0, stats.mFrees);
    EXPECT_EQ(0, stats.mCalls);
    EXPECT_EQ(1, stats.mConstCalls);
  }

  EXPECT_EQ(0, stats.mCopies);
  EXPECT_EQ(1, stats.mFrees);
}

TEST(ImageCopyOnWrite, RecursiveRead)
{
  ValueStats stats;

  {
    CopyOnWrite<Value> cow(new Value(stats));

    EXPECT_EQ(0, stats.mCopies);
    EXPECT_EQ(0, stats.mFrees);
    EXPECT_TRUE(cow.CanRead());

    cow.Read([&](const Value* aValue) {
      EXPECT_EQ(0, stats.mCopies);
      EXPECT_EQ(0, stats.mFrees);
      EXPECT_EQ(0, aValue->Serial());
      EXPECT_TRUE(cow.CanRead());
      EXPECT_TRUE(cow.CanWrite());

      // Make sure that Read() inside a Read() succeeds.
      cow.Read(
          [&](const Value* aValue) {
            EXPECT_EQ(0, stats.mCopies);
            EXPECT_EQ(0, stats.mFrees);
            EXPECT_EQ(0, aValue->Serial());
            EXPECT_TRUE(cow.CanRead());
            EXPECT_TRUE(cow.CanWrite());

            aValue->Go();

            EXPECT_EQ(0, stats.mCalls);
            EXPECT_EQ(1, stats.mConstCalls);
          },
          []() {
            // This gets called if we can't read. We shouldn't get here.
            EXPECT_TRUE(false);
          });
    });

    EXPECT_EQ(0, stats.mCopies);
    EXPECT_EQ(0, stats.mFrees);
    EXPECT_EQ(0, stats.mCalls);
    EXPECT_EQ(1, stats.mConstCalls);
  }

  EXPECT_EQ(0, stats.mCopies);
  EXPECT_EQ(1, stats.mFrees);
}

TEST(ImageCopyOnWrite, Write)
{
  ValueStats stats;

  {
    CopyOnWrite<Value> cow(new Value(stats));

    EXPECT_EQ(0, stats.mCopies);
    EXPECT_EQ(0, stats.mFrees);
    EXPECT_TRUE(cow.CanRead());
    EXPECT_TRUE(cow.CanWrite());

    cow.Write([&](Value* aValue) {
      EXPECT_EQ(0, stats.mCopies);
      EXPECT_EQ(0, stats.mFrees);
      EXPECT_EQ(0, aValue->Serial());
      EXPECT_TRUE(!cow.CanRead());
      EXPECT_TRUE(!cow.CanWrite());

      aValue->Go();

      EXPECT_EQ(1, stats.mCalls);
      EXPECT_EQ(0, stats.mConstCalls);
    });

    EXPECT_EQ(0, stats.mCopies);
    EXPECT_EQ(0, stats.mFrees);
    EXPECT_EQ(1, stats.mCalls);
    EXPECT_EQ(0, stats.mConstCalls);
  }

  EXPECT_EQ(0, stats.mCopies);
  EXPECT_EQ(1, stats.mFrees);
}

TEST(ImageCopyOnWrite, WriteRecursive)
{
  ValueStats stats;

  {
    CopyOnWrite<Value> cow(new Value(stats));

    EXPECT_EQ(0, stats.mCopies);
    EXPECT_EQ(0, stats.mFrees);
    EXPECT_TRUE(cow.CanRead());
    EXPECT_TRUE(cow.CanWrite());

    cow.Read([&](const Value* aValue) {
      EXPECT_EQ(0, stats.mCopies);
      EXPECT_EQ(0, stats.mFrees);
      EXPECT_EQ(0, aValue->Serial());
      EXPECT_TRUE(cow.CanRead());
      EXPECT_TRUE(cow.CanWrite());

      // Make sure Write() inside a Read() succeeds.
      cow.Write(
          [&](Value* aValue) {
            EXPECT_EQ(1, stats.mCopies);
            EXPECT_EQ(0, stats.mFrees);
            EXPECT_EQ(1, aValue->Serial());
            EXPECT_TRUE(!cow.CanRead());
            EXPECT_TRUE(!cow.CanWrite());

            aValue->Go();

            EXPECT_EQ(1, stats.mCalls);
            EXPECT_EQ(0, stats.mConstCalls);

            // Make sure Read() inside a Write() fails.
            cow.Read(
                [](const Value* aValue) {
                  // This gets called if we can read. We shouldn't get here.
                  EXPECT_TRUE(false);
                },
                []() {
                  // This gets called if we can't read. We *should* get here.
                  EXPECT_TRUE(true);
                });

            // Make sure Write() inside a Write() fails.
            cow.Write(
                [](Value* aValue) {
                  // This gets called if we can write. We shouldn't get here.
                  EXPECT_TRUE(false);
                },
                []() {
                  // This gets called if we can't write. We *should* get here.
                  EXPECT_TRUE(true);
                });
          },
          []() {
            // This gets called if we can't write. We shouldn't get here.
            EXPECT_TRUE(false);
          });

      aValue->Go();

      EXPECT_EQ(1, stats.mCopies);
      EXPECT_EQ(0, stats.mFrees);
      EXPECT_EQ(1, stats.mCalls);
      EXPECT_EQ(1, stats.mConstCalls);
    });

    EXPECT_EQ(1, stats.mCopies);
    EXPECT_EQ(1, stats.mFrees);
    EXPECT_EQ(1, stats.mCalls);
    EXPECT_EQ(1, stats.mConstCalls);
  }

  EXPECT_EQ(1, stats.mCopies);
  EXPECT_EQ(2, stats.mFrees);
}