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//===----------------------------------------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
// UNSUPPORTED: no-threads
// UNSUPPORTED: c++03, c++11
// <shared_mutex>
// template <class Mutex> class shared_lock;
// bool try_lock();
#include <atomic>
#include <cassert>
#include <mutex> // std::defer_lock
#include <shared_mutex>
#include <system_error>
#include <thread>
#include <vector>
#include "make_test_thread.h"
#include "test_macros.h"
struct Monitor {
bool try_lock_shared_called = false;
bool unlock_shared_called = false;
};
struct TrackedMutex {
Monitor* monitor = nullptr;
bool try_lock_shared() {
if (monitor != nullptr)
monitor->try_lock_shared_called = true;
return true;
}
void unlock_shared() {
if (monitor != nullptr)
monitor->unlock_shared_called = true;
}
};
template <class Mutex>
void test() {
// Basic sanity test
{
Mutex mutex;
std::vector<std::thread> threads;
std::atomic<bool> ready(false);
for (int i = 0; i != 5; ++i) {
threads.push_back(support::make_test_thread([&] {
while (!ready) {
// spin
}
std::shared_lock<Mutex> lock(mutex, std::defer_lock);
bool result = lock.try_lock();
assert(result);
assert(lock.owns_lock());
}));
}
ready = true;
for (auto& t : threads)
t.join();
}
// Make sure that we throw an exception if we try to re-lock a mutex that is
// already locked by the current thread.
{
Mutex mutex;
std::shared_lock<Mutex> lock(mutex, std::defer_lock);
assert(lock.try_lock());
assert(lock.owns_lock());
#ifndef TEST_HAS_NO_EXCEPTIONS
try {
TEST_IGNORE_NODISCARD lock.try_lock();
assert(false);
} catch (std::system_error const& e) {
assert(e.code() == std::errc::resource_deadlock_would_occur);
}
#endif
}
// Make sure that we throw an exception if we try to lock a shared_lock
// that is not associated to any mutex.
{
std::shared_lock<Mutex> lock; // not associated to a mutex
#ifndef TEST_HAS_NO_EXCEPTIONS
try {
TEST_IGNORE_NODISCARD lock.try_lock();
assert(false);
} catch (std::system_error const& e) {
assert(e.code() == std::errc::operation_not_permitted);
}
#endif
}
}
int main(int, char**) {
#if TEST_STD_VER >= 17
test<std::shared_mutex>();
#endif
test<std::shared_timed_mutex>();
test<TrackedMutex>();
// Use shared_lock with a dummy mutex class that tracks whether each
// operation has been called or not.
{
Monitor monitor;
TrackedMutex mutex{&monitor};
std::shared_lock<TrackedMutex> lock(mutex, std::defer_lock);
bool result = lock.try_lock();
assert(result);
assert(monitor.try_lock_shared_called);
assert(lock.owns_lock());
lock.unlock();
assert(monitor.unlock_shared_called);
}
return 0;
}