以下代码在我使用 clang thread annotations 时生成一个警告.我正在尝试包装 boost::shared_mutex
和 boost::shared_lock
.如何使用线程注释表示此锁是共享锁?
源代码:
#include <mutex>
#include "boost/thread/shared_mutex.hpp"
class __attribute__((shared_capability("mutex"))) BoostSharedMutex {
public:
boost::shared_mutex &getNativeHandle() { return m_mutex; }
private:
mutable boost::shared_mutex m_mutex;
};
class __attribute__((scoped_lockable)) MutexSharedLock {
public:
explicit MutexSharedLock(BoostSharedMutex &mutex) __attribute__((acquire_shared_capability(mutex)))
: m_lock(mutex.getNativeHandle()) {}
~MutexSharedLock() __attribute__((release_shared_capability())) = default;
private:
boost::shared_lock<boost::shared_mutex> m_lock;
};
int main() {
BoostSharedMutex mutex;
MutexSharedLock lock(mutex);
}
叮当输出:
clang++-3.6 --std=c++11 -Wall -Wthread-safety /tmp/foo.cpp -lboost_system
/tmp/foo.cpp:25:5: warning: releasing mutex 'lock' using shared access, expected exclusive access [-Wthread-safety-analysis]
}
^
1 warning generated.
编辑:这可以编译但似乎是错误的。这是我这边的问题吗?
#include <mutex>
#include "boost/thread/shared_mutex.hpp"
class __attribute__((shared_capability("mutex"))) BoostSharedMutex {
public:
boost::shared_mutex &getNativeHandle() { return m_mutex; }
private:
mutable boost::shared_mutex m_mutex;
};
class __attribute__((scoped_lockable)) MutexSharedLock {
public:
explicit MutexSharedLock(BoostSharedMutex &mutex) __attribute__((acquire_capability(mutex))) // changed from acquired_shared_capability
: m_lock(mutex.getNativeHandle()) {}
~MutexSharedLock() __attribute__((release_capability())) = default; // changed from release_shared_capability
private:
boost::shared_lock<boost::shared_mutex> m_lock;
};
BoostSharedMutex mutex;
int locked_variable __attribute__((guarded_by(mutex)));
int main() {
MutexSharedLock lock(mutex);
std::cout << locked_variable << std::endl; // ok, guarded variable is only read
locked_variable = 42; // no warning while writing in the guarded variable while only holding a non-exclusive lock?
}
最佳答案
在尝试了几种组合后,这似乎有效:
#include <mutex>
#include "boost/thread/shared_mutex.hpp"
class __attribute__((capability("mutex"))) BoostSharedMutex {
public:
boost::shared_mutex &getNativeHandle() { return m_mutex; }
private:
mutable boost::shared_mutex m_mutex;
};
class __attribute__((scoped_lockable)) MutexSharedLock {
public:
explicit MutexSharedLock(BoostSharedMutex &mutex) __attribute__((acquire_shared_capability(mutex)))
: m_lock(mutex.getNativeHandle()) {}
~MutexSharedLock() __attribute__((release_capability())) = default;
private:
boost::shared_lock<boost::shared_mutex> m_lock;
};
class __attribute__((scoped_lockable)) MutexLock {
public:
explicit MutexLock(BoostSharedMutex &mutex) __attribute__((acquire_capability(mutex)))
: m_lock(mutex.getNativeHandle()) {}
~MutexLock() __attribute__((release_capability())) = default;
private:
std::unique_lock<boost::shared_mutex> m_lock;
};
BoostSharedMutex mutex;
int locked_variable __attribute__((guarded_by(mutex)));
int main() {
{
MutexSharedLock lock(mutex);
std::cout << locked_variable << std::endl;
// locked_variable = 42; -- triger a error as expected
}
{
MutexLock lock(mutex);
std::cout << locked_variable << std::endl;
locked_variable = 42;
}
}
我很想知道为什么
MutexSharedLock
应该使用 acquire_shared_capability
但通过 release_capability
发布...(如果有人现在可以确认代码是正确的,我会打开问题)
关于multithreading - Clang 线程安全注解和共享功能,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/33608378/