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832c57a534
Clang added new "capability"-based thread-safety attributes years ago, but the old ones remain supported for backwards-compatibility. However, while adding annotations for our reverse_lock, I noticed that there is a difference between the unlock_function and release_capability attributes. unlock_function actually maps to release_generic_capability, which does not work properly when implementing a scoped unlocker. To be consistent, the other capability-based attributes are updated here as well. To avoid having to update our macro usage throughout the codebase, I reused our existing ones. Additionally, SHARED_UNLOCK_FUNCTION is added here, as a subsequent PR will introduce annotations for shared_mutex and shared_lock.
80 lines
3.5 KiB
C++
80 lines
3.5 KiB
C++
// Copyright (c) 2009-2010 Satoshi Nakamoto
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// Copyright (c) 2009-2020 The Bitcoin Core developers
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// Distributed under the MIT software license, see the accompanying
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// file COPYING or http://www.opensource.org/licenses/mit-license.php.
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#ifndef BITCOIN_THREADSAFETY_H
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#define BITCOIN_THREADSAFETY_H
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#include <mutex>
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#ifdef __clang__
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// TL;DR Add GUARDED_BY(mutex) to member variables. The others are
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// rarely necessary. Ex: int nFoo GUARDED_BY(cs_foo);
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//
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// See https://clang.llvm.org/docs/ThreadSafetyAnalysis.html
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// for documentation. The clang compiler can do advanced static analysis
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// of locking when given the -Wthread-safety option.
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#define LOCKABLE __attribute__((capability("")))
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#define SCOPED_LOCKABLE __attribute__((scoped_lockable))
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#define GUARDED_BY(x) __attribute__((guarded_by(x)))
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#define PT_GUARDED_BY(x) __attribute__((pt_guarded_by(x)))
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#define ACQUIRED_AFTER(...) __attribute__((acquired_after(__VA_ARGS__)))
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#define ACQUIRED_BEFORE(...) __attribute__((acquired_before(__VA_ARGS__)))
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#define EXCLUSIVE_LOCK_FUNCTION(...) __attribute__((acquire_capability(__VA_ARGS__)))
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#define SHARED_LOCK_FUNCTION(...) __attribute__((acquire_shared_capability(__VA_ARGS__)))
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#define EXCLUSIVE_TRYLOCK_FUNCTION(...) __attribute__((try_acquire_capability(__VA_ARGS__)))
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#define SHARED_TRYLOCK_FUNCTION(...) __attribute__((try_acquire_shared_capability(__VA_ARGS__)))
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#define UNLOCK_FUNCTION(...) __attribute__((release_capability(__VA_ARGS__)))
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#define SHARED_UNLOCK_FUNCTION(...) __attribute__((release_shared_capability(__VA_ARGS__)))
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#define LOCK_RETURNED(x) __attribute__((lock_returned(x)))
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#define LOCKS_EXCLUDED(...) __attribute__((locks_excluded(__VA_ARGS__)))
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#define EXCLUSIVE_LOCKS_REQUIRED(...) __attribute__((requires_capability(__VA_ARGS__)))
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#define SHARED_LOCKS_REQUIRED(...) __attribute__((requires_shared_capability(__VA_ARGS__)))
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#define NO_THREAD_SAFETY_ANALYSIS __attribute__((no_thread_safety_analysis))
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#define ASSERT_EXCLUSIVE_LOCK(...) __attribute__((assert_capability(__VA_ARGS__)))
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#else
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#define LOCKABLE
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#define SCOPED_LOCKABLE
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#define GUARDED_BY(x)
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#define PT_GUARDED_BY(x)
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#define ACQUIRED_AFTER(...)
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#define ACQUIRED_BEFORE(...)
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#define EXCLUSIVE_LOCK_FUNCTION(...)
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#define SHARED_LOCK_FUNCTION(...)
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#define EXCLUSIVE_TRYLOCK_FUNCTION(...)
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#define SHARED_TRYLOCK_FUNCTION(...)
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#define UNLOCK_FUNCTION(...)
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#define SHARED_UNLOCK_FUNCTION(...)
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#define LOCK_RETURNED(x)
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#define LOCKS_EXCLUDED(...)
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#define EXCLUSIVE_LOCKS_REQUIRED(...)
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#define SHARED_LOCKS_REQUIRED(...)
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#define NO_THREAD_SAFETY_ANALYSIS
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#define ASSERT_EXCLUSIVE_LOCK(...)
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#endif // __GNUC__
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// StdMutex provides an annotated version of std::mutex for us,
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// and should only be used when sync.h Mutex/LOCK/etc are not usable.
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class LOCKABLE StdMutex : public std::mutex
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{
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public:
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#ifdef __clang__
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//! For negative capabilities in the Clang Thread Safety Analysis.
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//! A negative requirement uses the EXCLUSIVE_LOCKS_REQUIRED attribute, in conjunction
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//! with the ! operator, to indicate that a mutex should not be held.
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const StdMutex& operator!() const { return *this; }
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#endif // __clang__
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};
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// StdLockGuard provides an annotated version of std::lock_guard for us,
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// and should only be used when sync.h Mutex/LOCK/etc are not usable.
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class SCOPED_LOCKABLE StdLockGuard : public std::lock_guard<StdMutex>
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{
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public:
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explicit StdLockGuard(StdMutex& cs) EXCLUSIVE_LOCK_FUNCTION(cs) : std::lock_guard<StdMutex>(cs) {}
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~StdLockGuard() UNLOCK_FUNCTION() = default;
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};
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#endif // BITCOIN_THREADSAFETY_H
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