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// Copyright 2020 Google LLC
//
// 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
//
// https://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 "rwmutex.h"
#include "gmock/gmock.h"
#include "gtest/gtest.h"
#include <array>
#include <thread>
#include <vector>
namespace {
constexpr const size_t NumThreads = 8;
}
// Check that WLock behaves like regular mutex.
TEST(RWMutex, WLock) {
dap::RWMutex rwmutex;
int counter = 0;
std::vector<std::thread> threads;
for (size_t i = 0; i < NumThreads; i++) {
threads.emplace_back([&] {
for (int j = 0; j < 1000; j++) {
dap::WLock lock(rwmutex);
counter++;
EXPECT_EQ(counter, 1);
counter--;
}
});
}
for (auto& thread : threads) {
thread.join();
}
EXPECT_EQ(counter, 0);
}
TEST(RWMutex, NoRLockWithWLock) {
dap::RWMutex rwmutex;
std::vector<std::thread> threads;
std::array<int, NumThreads> counters = {};
{ // With WLock held...
dap::WLock wlock(rwmutex);
for (size_t i = 0; i < counters.size(); i++) {
int* counter = &counters[i];
threads.emplace_back([&rwmutex, counter] {
dap::RLock lock(rwmutex);
for (int j = 0; j < 1000; j++) {
(*counter)++;
}
});
}
// RLocks should block
for (int counter : counters) {
EXPECT_EQ(counter, 0);
}
}
for (auto& thread : threads) {
thread.join();
}
for (int counter : counters) {
EXPECT_EQ(counter, 1000);
}
}
TEST(RWMutex, NoWLockWithRLock) {
dap::RWMutex rwmutex;
std::vector<std::thread> threads;
size_t counter = 0;
{ // With RLocks held...
dap::RLock rlockA(rwmutex);
dap::RLock rlockB(rwmutex);
dap::RLock rlockC(rwmutex);
for (size_t i = 0; i < NumThreads; i++) {
threads.emplace_back(std::thread([&] {
dap::WLock lock(rwmutex);
counter++;
}));
}
// ... WLocks should block
EXPECT_EQ(counter, 0U);
}
for (auto& thread : threads) {
thread.join();
}
EXPECT_EQ(counter, NumThreads);
}
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