1// Copyright (c) 2009-2010 Satoshi Nakamoto
2// Copyright (c) 2009-present The Bitcoin Core developers
3// Distributed under the MIT software license, see the accompanying
4// file COPYING or http://www.opensource.org/licenses/mit-license.php.
5
6#ifndef BITCOIN_UTIL_STDMUTEX_H
7#define BITCOIN_UTIL_STDMUTEX_H
8
9// This header declares threading primitives compatible with Clang
10// Thread Safety Analysis and provides appropriate annotation macros.
11#include <threadsafety.h> // IWYU pragma: export
12
13#include <util/macros.h>
14
15#include <mutex>
16
17// StdMutex provides an annotated version of std::mutex for us,
18// and should only be used when sync.h Mutex/LOCK/etc are not usable.
19class LOCKABLE StdMutex : public std::mutex
20{
21public:
22#ifdef __clang__
23    //! For negative capabilities in the Clang Thread Safety Analysis.
24    //! A negative requirement uses the EXCLUSIVE_LOCKS_REQUIRED attribute, in conjunction
25    //! with the ! operator, to indicate that a mutex should not be held.
26    const StdMutex& operator!() const { return *this; }
27#endif // __clang__
28
29    // StdMutex::Guard provides an annotated version of std::lock_guard for us.
30    class SCOPED_LOCKABLE Guard : public std::lock_guard<StdMutex>
31    {
32    public:
33        explicit Guard(StdMutex& cs) EXCLUSIVE_LOCK_FUNCTION(cs) : std::lock_guard<StdMutex>(cs) {}
34        ~Guard() UNLOCK_FUNCTION() = default;
35    };
36
37    static inline StdMutex& CheckNotHeld(StdMutex& cs) EXCLUSIVE_LOCKS_REQUIRED(!cs) LOCK_RETURNED(cs) { return cs; }
38};
39
40// Provide STDLOCK(..) wrapper around StdMutex::Guard that checks the lock is not already held
41#define STDLOCK(cs) StdMutex::Guard BITCOIN_UNIQUE_NAME(criticalblock){StdMutex::CheckNotHeld(cs)}
42
43#endif // BITCOIN_UTIL_STDMUTEX_H
44