folly/folly/synchronization/test/AtomicStructTest.cpp

/*
 * Copyright (c) Meta Platforms, Inc. and affiliates.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

#include <folly/synchronization/AtomicStruct.h>

#include <folly/portability/GTest.h>

using namespace folly;

struct TwoBy32 {
  uint32_t left;
  uint32_t right;
};

TEST(AtomicStruct, twoBy32) {
  AtomicStruct<TwoBy32> a(TwoBy32{10, 20});
  TwoBy32 av = a;
  EXPECT_EQ(av.left, 10);
  EXPECT_EQ(av.right, 20);
  EXPECT_TRUE(a.compare_exchange_strong(av, TwoBy32{30, 40}));
  EXPECT_FALSE(a.compare_exchange_weak(av, TwoBy32{31, 41}));
  EXPECT_EQ(av.left, 30);
  EXPECT_TRUE(a.is_lock_free());
  auto b = a.exchange(TwoBy32{50, 60});
  EXPECT_EQ(b.left, 30);
  EXPECT_EQ(b.right, 40);
  EXPECT_EQ(a.load().left, 50);
  a = TwoBy32{70, 80};
  EXPECT_EQ(a.load().right, 80);
  a.store(TwoBy32{90, 100});
  av = a;
  EXPECT_EQ(av.left, 90);
  AtomicStruct<TwoBy32> c;
  c = b;
  EXPECT_EQ(c.load().right, 40);
}

template <size_t I>
struct S {
  char x[I];
};

TEST(AtomicStruct, sizeSelection) {
  EXPECT_EQ(sizeof(AtomicStruct<S<1>>), 1);
  EXPECT_EQ(sizeof(AtomicStruct<S<2>>), 2);
  EXPECT_EQ(sizeof(AtomicStruct<S<3>>), 4);
  EXPECT_EQ(sizeof(AtomicStruct<S<4>>), 4);
  EXPECT_EQ(sizeof(AtomicStruct<S<5>>), 8);
  EXPECT_EQ(sizeof(AtomicStruct<S<6>>), 8);
  EXPECT_EQ(sizeof(AtomicStruct<S<7>>), 8);
  EXPECT_EQ(sizeof(AtomicStruct<S<8>>), 8);
}