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236 | // Copyright (C) 2020-2024 Internet Systems Consortium, Inc. ("ISC")
//
// 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 <config.h>
#include <gtest/gtest.h><--- Include file: not found. Please note: Cppcheck does not need standard library headers to get proper results.
#include <util/unlock_guard.h>
#include <exceptions/exceptions.h>
#include <mutex><--- Include file: not found. Please note: Cppcheck does not need standard library headers to get proper results.
#include <thread><--- Include file: not found. Please note: Cppcheck does not need standard library headers to get proper results.
using namespace isc::util;
using namespace std;
namespace {
/// @brief test mutex class used to check the internal state of a 'fictional'
/// mutex so that the functionality of the UnlockGuard can be tested
/// @note the test mutex can be recursive which means that a lock can be called
/// on the same thread and not resulting in a dead lock
class TestMutex {
public:
/// @brief Constructor
///
/// @param recursive sets the mutex as recursive mutex
TestMutex(bool recursive = false) : lock_(0), dead_lock_(false),
lock_count_(0), unlock_count_(0), recursive_(recursive) {
}
/// @brief lock the mutex
void lock() {
lock_guard<mutex> lk(mutex_);
if (lock_ >= 1) {
// mutex is already locked
if (!recursive_) {
// lock on a non-recursive mutex resulting in a dead lock
dead_lock_ = true;
isc_throw(isc::InvalidOperation,
"recursive lock on already locked mutex resulting in "
"dead lock");
} else {
// lock on a recursive mutex
if (this_thread::get_id() != id_) {
// lock on a recursive mutex on a different thread resulting
// in a dead lock
dead_lock_ = true;
isc_throw(isc::InvalidOperation,
"recursive lock on a different thread on already "
"locked mutex resulting in dead lock");
}
}
}
// increment the total number of locks
lock_count_++;
// increment the lock state
lock_++;
// save the thread id
id_ = this_thread::get_id();
}
/// @brief unlock the mutex
void unlock() {
lock_guard<mutex> lk(mutex_);
if (lock_ <= 0) {
// unlock an unlocked mutex
isc_throw(isc::InvalidOperation, "unlock on non locked mutex "
"resulting in undefined behavior");
}
if (lock_ == 1) {
// only one thread has the lock
// self healing mutex resetting the dead lock flag
dead_lock_ = false;
// reset the thread id
id_ = std::thread::id();
}
// increment the total number of unlocks
unlock_count_++;
// decrement the lock state
lock_--;
}
/// @brief get the mutex lock state
///
/// @return the mutex lock state
int32_t getLock() {
lock_guard<mutex> lk(mutex_);
return lock_;
}
/// @brief get the mutex dead lock state
///
/// @return the mutex dead lock state
bool getDeadLock() {
lock_guard<mutex> lk(mutex_);
return dead_lock_;
}
/// @brief get the number of locks performed on mutex
///
/// @return the mutex number of locks
uint32_t getLockCount() {
lock_guard<mutex> lk(mutex_);
return lock_count_;
}
/// @brief get the number of unlocks performed on mutex
///
/// @return the mutex number of unlocks
uint32_t getUnlockCount() {
lock_guard<mutex> lk(mutex_);
return unlock_count_;
}
/// @brief test the internal state of the mutex
///
/// @param expected_lock check equality of this value with lock state
/// @param expected_lock_count check equality of this value with lock count
/// @param expected_unlock_count check equality of this value with unlock count
/// @param expected_dead_lock check equality of this value with dead lock state
void testMutexState(int32_t expected_lock,
uint32_t expected_lock_count,
uint32_t expected_unlock_count,
bool expected_dead_lock) {
ASSERT_EQ(getLock(), expected_lock);
ASSERT_EQ(getLockCount(), expected_lock_count);
ASSERT_EQ(getUnlockCount(), expected_unlock_count);
ASSERT_EQ(getDeadLock(), expected_dead_lock);
}
private:
/// @brief internal lock state of the mutex
int32_t lock_;
/// @brief state which indicates that the mutex is in dead lock
bool dead_lock_;
/// @brief total number of locks performed on the mutex
uint32_t lock_count_;
/// @brief total number of unlocks performed on the mutex
uint32_t unlock_count_;
/// @brief flag to indicate if the mutex is recursive or not
bool recursive_;
/// @brief mutex used to keep the internal state consistent
mutex mutex_;
/// @brief the id of the thread holding the mutex
std::thread::id id_;
};
/// @brief Test Fixture for testing isc::util::UnlockGuard
class UnlockGuardTest : public ::testing::Test {
};
/// @brief test TestMutex functionality with non-recursive mutex, and recursive
/// mutex
TEST_F(UnlockGuardTest, testMutex) {<--- syntax error
shared_ptr<TestMutex> test_mutex;
// test non-recursive lock
test_mutex = make_shared<TestMutex>();
test_mutex->testMutexState(0, 0, 0, false);
{
// call lock_guard constructor which locks mutex
lock_guard<TestMutex> lock(*test_mutex.get());
// expect lock 1 lock_count 1 unlock_count 0 dead_lock false
test_mutex->testMutexState(1, 1, 0, false);
{
// call lock_guard constructor which locks mutex resulting in an
// exception as the mutex is already locked (dead lock)
EXPECT_THROW(lock_guard<TestMutex> lock2(*test_mutex.get()),
isc::InvalidOperation);
// expect lock 1 lock_count 1 unlock_count 0 dead_lock true
// you should not be able to get here...using a real mutex
test_mutex->testMutexState(1, 1, 0, true);
}
// expect lock 1 lock_count 1 unlock_count 0 dead_lock true
// you should not be able to get here...using a real mutex
test_mutex->testMutexState(1, 1, 0, true);
}
// expect lock 0 lock_count 1 unlock_count 1 dead_lock false
// the implementation is self healing when completely unlocking the mutex
test_mutex->testMutexState(0, 1, 1, false);
// test recursive lock
test_mutex = make_shared<TestMutex>(true);
test_mutex->testMutexState(0, 0, 0, false);
{
// call lock_guard constructor which locks mutex
lock_guard<TestMutex> lock(*test_mutex.get());
// expect lock 1 lock_count 1 unlock_count 0 dead_lock false
test_mutex->testMutexState(1, 1, 0, false);
{
// call lock_guard constructor which locks mutex but does not block
// as this is done on the same thread and the mutex is recursive
EXPECT_NO_THROW(lock_guard<TestMutex> lock2(*test_mutex.get()));
// expect lock 1 lock_count 2 unlock_count 1 dead_lock false
// the destructor was already called in EXPECT_NO_THROW scope
test_mutex->testMutexState(1, 2, 1, false);
}
// expect lock 1 lock_count 2 unlock_count 1 dead_lock false
test_mutex->testMutexState(1, 2, 1, false);
}
// expect lock 0 lock_count 2 unlock_count 2 dead_lock false
test_mutex->testMutexState(0, 2, 2, false);
}
/// @brief test UnlockGuard functionality with non-recursive mutex
TEST_F(UnlockGuardTest, testUnlockGuard) {
shared_ptr<TestMutex> test_mutex;
// test non-recursive lock
test_mutex = make_shared<TestMutex>();
test_mutex->testMutexState(0, 0, 0, false);
{
// call lock_guard constructor which locks mutex
lock_guard<TestMutex> lock(*test_mutex.get());
// expect lock 1 lock_count 1 unlock_count 0 dead_lock false
test_mutex->testMutexState(1, 1, 0, false);
{
UnlockGuard<TestMutex> unlock_guard(*test_mutex.get());
// expect lock 0 lock_count 1 unlock_count 1 dead_lock false
test_mutex->testMutexState(0, 1, 1, false);
}
// expect lock 1 lock_count 2 unlock_count 1 dead_lock false
test_mutex->testMutexState(1, 2, 1, false);
}
// expect lock 0 lock_count 2 unlock_count 2 dead_lock false
test_mutex->testMutexState(0, 2, 2, false);
}
} // namespace
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