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/*
* Copyright © Canonical Ltd.
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 or 3,
* as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mir/recursive_read_write_mutex.h"
#include "mir/test/barrier.h"
#include <gtest/gtest.h>
#include <gmock/gmock.h>
namespace mt = mir::test;
using namespace testing;
namespace
{
/* These tests are not ideal as they may fail by hanging. But I don't know a good
* way to kill a thread within the process (i.e. without leaking resources and
* causing "undefined behavior"). That is having a "watchdog" timeout just leads
* to other issues and running in a separate process seems OTT.
*/
struct RecursiveReadWriteMutex : public Test
{
int const recursion_depth{1729};
unsigned const reader_threads{42};
mt::Barrier readonly_barrier{reader_threads};
mt::Barrier read_and_write_barrier{reader_threads+1};
std::vector<std::thread> threads;
mir::RecursiveReadWriteMutex mutex;
void SetUp()
{
threads.reserve(reader_threads+1);
}
void TearDown()
{
for (auto& thread : threads)
if (thread.joinable()) thread.join();
}
MOCK_METHOD0(notify_read_locked, void());
MOCK_METHOD0(notify_read_unlocking, void());
MOCK_METHOD0(notify_write_locked, void());
MOCK_METHOD0(notify_write_unlocking, void());
};
}
TEST_F(RecursiveReadWriteMutex, can_be_recursively_read_locked)
{
for (int i = 0; i != recursion_depth; ++i)
mutex.read_lock();
}
TEST_F(RecursiveReadWriteMutex, can_be_recursively_write_locked)
{
for (int i = 0; i != recursion_depth; ++i)
mutex.write_lock();
}
TEST_F(RecursiveReadWriteMutex, can_be_write_locked_on_thread_with_read_lock)
{
mutex.read_lock();
mutex.write_lock();
}
TEST_F(RecursiveReadWriteMutex, can_be_read_locked_on_thread_with_write_lock)
{
mutex.write_lock();
mutex.read_lock();
}
TEST_F(RecursiveReadWriteMutex, can_be_read_locked_on_multiple_threads)
{
auto const reader_function =
[&]{
mutex.read_lock();
notify_read_locked();
readonly_barrier.ready();
notify_read_unlocking();
mutex.read_unlock();
};
InSequence seq;
EXPECT_CALL(*this, notify_read_locked()).Times(reader_threads);
EXPECT_CALL(*this, notify_read_unlocking()).Times(reader_threads);
for (auto i = 0U; i != reader_threads; ++i)
threads.push_back(std::thread{reader_function});
}
TEST_F(RecursiveReadWriteMutex, write_lock_waits_for_read_locks_on_other_threads)
{
auto const reader_function =
[&]{
mutex.read_lock();
notify_read_locked();
read_and_write_barrier.ready();
notify_read_unlocking();
mutex.read_unlock();
};
auto const writer_function =
[&]{
read_and_write_barrier.ready();
mutex.write_lock();
notify_write_locked();
};
InSequence seq;
EXPECT_CALL(*this, notify_read_locked()).Times(reader_threads);
EXPECT_CALL(*this, notify_read_unlocking()).Times(reader_threads);
EXPECT_CALL(*this, notify_write_locked()).Times(1);
for (auto i = 0U; i != reader_threads; ++i)
threads.push_back(std::thread{reader_function});
threads.push_back(std::thread{writer_function});
}
TEST_F(RecursiveReadWriteMutex, read_lock_waits_for_write_locks_on_other_threads)
{
auto const reader_function =
[&]{
read_and_write_barrier.ready();
mutex.read_lock();
notify_read_locked();
};
auto const writer_function =
[&]{
mutex.write_lock();
notify_write_locked();
read_and_write_barrier.ready();
notify_write_unlocking();
mutex.write_unlock();
};
InSequence seq;
EXPECT_CALL(*this, notify_write_locked()).Times(1);
EXPECT_CALL(*this, notify_write_unlocking()).Times(1);
EXPECT_CALL(*this, notify_read_locked()).Times(reader_threads);
for (auto i = 0U; i != reader_threads; ++i)
threads.push_back(std::thread{reader_function});
threads.push_back(std::thread{writer_function});
}
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