// Copyright (c) 2009-2010 Satoshi Nakamoto

// Copyright (c) 2009-2020 The Bitcoin Core developers

// Distributed under the MIT software license, see the accompanying

// file COPYING or http://www.opensource.org/licenses/mit-license.php.

#ifndef BITCOIN_THREADSAFETY_H

#define BITCOIN_THREADSAFETY_H

#include <mutex>

#ifdef __clang__

// TL;DR Add GUARDED_BY(mutex) to member variables. The others are

// rarely necessary. Ex: int nFoo GUARDED_BY(cs_foo);

//

// See https://clang.llvm.org/docs/ThreadSafetyAnalysis.html

// for documentation.  The clang compiler can do advanced static analysis

// of locking when given the -Wthread-safety option.

#define LOCKABLE __attribute__((lockable))

#define SCOPED_LOCKABLE __attribute__((scoped_lockable))

#define GUARDED_BY(x) __attribute__((guarded_by(x)))

#define PT_GUARDED_BY(x) __attribute__((pt_guarded_by(x)))

#define ACQUIRED_AFTER(...) __attribute__((acquired_after(__VA_ARGS__)))

#define ACQUIRED_BEFORE(...) __attribute__((acquired_before(__VA_ARGS__)))

#define EXCLUSIVE_LOCK_FUNCTION(...) __attribute__((exclusive_lock_function(__VA_ARGS__)))

#define SHARED_LOCK_FUNCTION(...) __attribute__((shared_lock_function(__VA_ARGS__)))

#define EXCLUSIVE_TRYLOCK_FUNCTION(...) __attribute__((exclusive_trylock_function(__VA_ARGS__)))

#define SHARED_TRYLOCK_FUNCTION(...) __attribute__((shared_trylock_function(__VA_ARGS__)))

#define UNLOCK_FUNCTION(...) __attribute__((unlock_function(__VA_ARGS__)))

#define LOCK_RETURNED(x) __attribute__((lock_returned(x)))

#define LOCKS_EXCLUDED(...) __attribute__((locks_excluded(__VA_ARGS__)))

#define EXCLUSIVE_LOCKS_REQUIRED(...) __attribute__((exclusive_locks_required(__VA_ARGS__)))

#define SHARED_LOCKS_REQUIRED(...) __attribute__((shared_locks_required(__VA_ARGS__)))

#define NO_THREAD_SAFETY_ANALYSIS __attribute__((no_thread_safety_analysis))

#define ASSERT_EXCLUSIVE_LOCK(...) __attribute__((assert_exclusive_lock(__VA_ARGS__)))

#else

#define LOCKABLE

#define SCOPED_LOCKABLE

#define GUARDED_BY(x)

#define PT_GUARDED_BY(x)

#define ACQUIRED_AFTER(...)

#define ACQUIRED_BEFORE(...)

#define EXCLUSIVE_LOCK_FUNCTION(...)

#define SHARED_LOCK_FUNCTION(...)

#define EXCLUSIVE_TRYLOCK_FUNCTION(...)

#define SHARED_TRYLOCK_FUNCTION(...)

#define UNLOCK_FUNCTION(...)

#define LOCK_RETURNED(x)

#define LOCKS_EXCLUDED(...)

#define EXCLUSIVE_LOCKS_REQUIRED(...)

#define SHARED_LOCKS_REQUIRED(...)

#define NO_THREAD_SAFETY_ANALYSIS

#define ASSERT_EXCLUSIVE_LOCK(...)

#endif // __GNUC__

// StdMutex provides an annotated version of std::mutex for us,

// and should only be used when sync.h Mutex/LOCK/etc are not usable.

class LOCKABLE StdMutex : public std::mutex

{

public:

#ifdef __clang__

    //! For negative capabilities in the Clang Thread Safety Analysis.

    //! A negative requirement uses the EXCLUSIVE_LOCKS_REQUIRED attribute, in conjunction

    //! with the ! operator, to indicate that a mutex should not be held.

    const StdMutex& operator!() const { return *this; }

#endif // __clang__

};

// StdLockGuard provides an annotated version of std::lock_guard for us,

// and should only be used when sync.h Mutex/LOCK/etc are not usable.

class SCOPED_LOCKABLE StdLockGuard : public std::lock_guard<StdMutex>

{

public:

    explicit StdLockGuard(StdMutex& cs) EXCLUSIVE_LOCK_FUNCTION(cs) : std::lock_guard<StdMutex>(cs) {}

    ~StdLockGuard() UNLOCK_FUNCTION() = default;

};

#endif // BITCOIN_THREADSAFETY_H