dash/src/threadsafety.h
MarcoFalke 50daf4dce9 Merge #16034: refactoring: Rename LockAnnotation to LockAssertion and add run-time check to it
9f85e9cb3d scripted-diff: Rename LockAnnotation to LockAssertion (practicalswift)
de9b5dbca3 Make sure the compile-time locking promises given via LockAnnotation:s hold also in practice at runtime (ifdef DEBUG_LOCKORDER) (practicalswift)
3a809446b3 Move LockAnnotation to make it reflect the truth (practicalswift)
cc2588579c Move LockAnnotation from threadsafety.h (imported code) to sync.h (our code) (practicalswift)

Pull request description:

  `LockAnnotation lock(mutex);` is a guarantee to the compiler thread-analysis that `mutex` is locked (when it couldn't be determined otherwise).

  Before this PR it was possible to make the mistake of adding a `LockAnnotation` where the correct mutex is _not_ held. This in turn makes the thread-analysis reasoning being based on incorrect premises.

  This PR adds an assertion in the `LockAnnotation` ctor which checks that the guarantees given by us at compile-time are held also in practice (`ifdef DEBUG_LOCKORDER`).

  Issues like the one described in #16028 will be discovered immediately with this PR merged.

  Changes in this PR:
  * Move `LockAnnotation` from `threadsafety.h` (imported code) to `sync.h` (our code)
  * Move `LockAnnotation` in `wallet_tests` to make it reflect the truth
  * Make sure the compile-time locking promises given via `LockAnnotation`:s hold also in practice at runtime (`ifdef DEBUG_LOCKORDER`)
  * Rename `LockAnnotation` to `LockAssertion`

ACKs for commit 9f85e9:
  ryanofsky:
    utACK 9f85e9cb3d687862128ddf464d2bc2462b8627f0. No changes at all since last review except clean rebase after base PR #16033 was merged

Tree-SHA512: fb80e78fe362adfd6ea8405bcb142c09b99f834fe8be4397282b223ca2c3a2bb9719a074a47a043b44757f840b239a6fcd2f98d14771f8729204834ecf608c3a
2022-05-17 12:57:47 -04:00

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// Copyright (c) 2009-2010 Satoshi Nakamoto
// Copyright (c) 2009-2014 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() {}
};
#endif // BITCOIN_THREADSAFETY_H