359 lines
10 KiB
C++
359 lines
10 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_SYNC_H
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#define BITCOIN_SYNC_H
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#include <threadsafety.h>
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#include <util/macros.h>
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#include <condition_variable>
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#include <mutex>
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#include <string>
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#include <thread>
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////////////////////////////////////////////////
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// //
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// THE SIMPLE DEFINITION, EXCLUDING DEBUG CODE //
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// //
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////////////////////////////////////////////////
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/*
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RecursiveMutex mutex;
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std::recursive_mutex mutex;
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LOCK(mutex);
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std::unique_lock<std::recursive_mutex> criticalblock(mutex);
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LOCK2(mutex1, mutex2);
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std::unique_lock<std::recursive_mutex> criticalblock1(mutex1);
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std::unique_lock<std::recursive_mutex> criticalblock2(mutex2);
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TRY_LOCK(mutex, name);
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std::unique_lock<std::recursive_mutex> name(mutex, std::try_to_lock_t);
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ENTER_CRITICAL_SECTION(mutex); // no RAII
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mutex.lock();
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LEAVE_CRITICAL_SECTION(mutex); // no RAII
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mutex.unlock();
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*/
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///////////////////////////////
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// //
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// THE ACTUAL IMPLEMENTATION //
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// //
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///////////////////////////////
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#ifdef DEBUG_LOCKORDER
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void EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false);
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void LeaveCritical();
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void CheckLastCritical(void* cs, std::string& lockname, const char* guardname, const char* file, int line);
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std::string LocksHeld();
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template <typename MutexType>
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void AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, MutexType* cs) ASSERT_EXCLUSIVE_LOCK(cs);
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void AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs);
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void DeleteLock(void* cs);
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/**
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* Call abort() if a potential lock order deadlock bug is detected, instead of
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* just logging information and throwing a logic_error. Defaults to true, and
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* set to false in DEBUG_LOCKORDER unit tests.
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*/
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extern bool g_debug_lockorder_abort;
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#else
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void static inline EnterCritical(const char* pszName, const char* pszFile, int nLine, void* cs, bool fTry = false) {}
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void static inline LeaveCritical() {}
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void static inline CheckLastCritical(void* cs, std::string& lockname, const char* guardname, const char* file, int line) {}
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template <typename MutexType>
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void static inline AssertLockHeldInternal(const char* pszName, const char* pszFile, int nLine, MutexType* cs) ASSERT_EXCLUSIVE_LOCK(cs) {}
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void static inline AssertLockNotHeldInternal(const char* pszName, const char* pszFile, int nLine, void* cs) {}
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void static inline DeleteLock(void* cs) {}
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#endif
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#define AssertLockHeld(cs) AssertLockHeldInternal(#cs, __FILE__, __LINE__, &cs)
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#define AssertLockNotHeld(cs) AssertLockNotHeldInternal(#cs, __FILE__, __LINE__, &cs)
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/**
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* Template mixin that adds -Wthread-safety locking annotations and lock order
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* checking to a subset of the mutex API.
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*/
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template <typename PARENT>
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class LOCKABLE AnnotatedMixin : public PARENT
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{
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public:
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~AnnotatedMixin() {
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DeleteLock((void*)this);
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}
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void lock() EXCLUSIVE_LOCK_FUNCTION()
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{
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PARENT::lock();
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}
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void unlock() UNLOCK_FUNCTION()
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{
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PARENT::unlock();
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}
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bool try_lock() EXCLUSIVE_TRYLOCK_FUNCTION(true)
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{
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return PARENT::try_lock();
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}
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using UniqueLock = std::unique_lock<PARENT>;
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};
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/**
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* Wrapped mutex: supports recursive locking, but no waiting
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* TODO: We should move away from using the recursive lock by default.
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*/
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using RecursiveMutex = AnnotatedMixin<std::recursive_mutex>;
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/** Wrapped mutex: supports waiting but not recursive locking */
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typedef AnnotatedMixin<std::mutex> Mutex;
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#ifdef DEBUG_LOCKCONTENTION
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void PrintLockContention(const char* pszName, const char* pszFile, int nLine);
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#endif
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/** Wrapper around std::unique_lock style lock for Mutex. */
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template <typename Mutex, typename Base = typename Mutex::UniqueLock>
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class SCOPED_LOCKABLE UniqueLock : public Base
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{
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private:
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void Enter(const char* pszName, const char* pszFile, int nLine)
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{
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EnterCritical(pszName, pszFile, nLine, (void*)(Base::mutex()));
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#ifdef DEBUG_LOCKCONTENTION
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if (!Base::try_lock()) {
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PrintLockContention(pszName, pszFile, nLine);
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#endif
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Base::lock();
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#ifdef DEBUG_LOCKCONTENTION
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}
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#endif
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}
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bool TryEnter(const char* pszName, const char* pszFile, int nLine)
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{
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EnterCritical(pszName, pszFile, nLine, (void*)(Base::mutex()), true);
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Base::try_lock();
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if (!Base::owns_lock())
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LeaveCritical();
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return Base::owns_lock();
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}
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public:
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UniqueLock(Mutex& mutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(mutexIn) : Base(mutexIn, std::defer_lock)
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{
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if (fTry)
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TryEnter(pszName, pszFile, nLine);
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else
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Enter(pszName, pszFile, nLine);
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}
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UniqueLock(Mutex* pmutexIn, const char* pszName, const char* pszFile, int nLine, bool fTry = false) EXCLUSIVE_LOCK_FUNCTION(pmutexIn)
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{
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if (!pmutexIn) return;
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*static_cast<Base*>(this) = Base(*pmutexIn, std::defer_lock);
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if (fTry)
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TryEnter(pszName, pszFile, nLine);
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else
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Enter(pszName, pszFile, nLine);
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}
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~UniqueLock() UNLOCK_FUNCTION()
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{
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if (Base::owns_lock())
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LeaveCritical();
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}
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operator bool()
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{
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return Base::owns_lock();
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}
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protected:
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// needed for reverse_lock
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UniqueLock() { }
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public:
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/**
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* An RAII-style reverse lock. Unlocks on construction and locks on destruction.
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*/
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class reverse_lock {
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public:
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explicit reverse_lock(UniqueLock& _lock, const char* _guardname, const char* _file, int _line) : lock(_lock), file(_file), line(_line) {
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CheckLastCritical((void*)lock.mutex(), lockname, _guardname, _file, _line);
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lock.unlock();
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LeaveCritical();
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lock.swap(templock);
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}
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~reverse_lock() {
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templock.swap(lock);
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EnterCritical(lockname.c_str(), file.c_str(), line, (void*)lock.mutex());
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lock.lock();
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}
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private:
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reverse_lock(reverse_lock const&);
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reverse_lock& operator=(reverse_lock const&);
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UniqueLock& lock;
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UniqueLock templock;
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std::string lockname;
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const std::string file;
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const int line;
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};
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friend class reverse_lock;
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};
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#define REVERSE_LOCK(g) typename std::decay<decltype(g)>::type::reverse_lock PASTE2(revlock, __COUNTER__)(g, #g, __FILE__, __LINE__)
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template<typename MutexArg>
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using DebugLock = UniqueLock<typename std::remove_reference<typename std::remove_pointer<MutexArg>::type>::type>;
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#define LOCK(cs) DebugLock<decltype(cs)> PASTE2(criticalblock, __COUNTER__)(cs, #cs, __FILE__, __LINE__)
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#define LOCK2(cs1, cs2) \
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DebugLock<decltype(cs1)> criticalblock1(cs1, #cs1, __FILE__, __LINE__); \
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DebugLock<decltype(cs2)> criticalblock2(cs2, #cs2, __FILE__, __LINE__);
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#define TRY_LOCK(cs, name) DebugLock<decltype(cs)> name(cs, #cs, __FILE__, __LINE__, true)
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#define WAIT_LOCK(cs, name) DebugLock<decltype(cs)> name(cs, #cs, __FILE__, __LINE__)
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#define ENTER_CRITICAL_SECTION(cs) \
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{ \
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EnterCritical(#cs, __FILE__, __LINE__, (void*)(&cs)); \
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(cs).lock(); \
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}
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#define LEAVE_CRITICAL_SECTION(cs) \
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{ \
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(cs).unlock(); \
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LeaveCritical(); \
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}
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//! Run code while locking a mutex.
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//!
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//! Examples:
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//!
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//! WITH_LOCK(cs, shared_val = shared_val + 1);
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//!
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//! int val = WITH_LOCK(cs, return shared_val);
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//!
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#define WITH_LOCK(cs, code) [&] { LOCK(cs); code; }()
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class CSemaphore
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{
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private:
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std::condition_variable condition;
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std::mutex mutex;
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int value;
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public:
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explicit CSemaphore(int init) : value(init) {}
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void wait()
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{
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std::unique_lock<std::mutex> lock(mutex);
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condition.wait(lock, [&]() { return value >= 1; });
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value--;
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}
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bool try_wait()
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{
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std::lock_guard<std::mutex> lock(mutex);
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if (value < 1)
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return false;
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value--;
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return true;
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}
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void post()
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{
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{
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std::lock_guard<std::mutex> lock(mutex);
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value++;
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}
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condition.notify_one();
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}
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};
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/** RAII-style semaphore lock */
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class CSemaphoreGrant
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{
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private:
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CSemaphore* sem;
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bool fHaveGrant;
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public:
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void Acquire()
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{
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if (fHaveGrant)
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return;
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sem->wait();
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fHaveGrant = true;
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}
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void Release()
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{
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if (!fHaveGrant)
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return;
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sem->post();
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fHaveGrant = false;
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}
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bool TryAcquire()
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{
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if (!fHaveGrant && sem->try_wait())
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fHaveGrant = true;
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return fHaveGrant;
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}
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void MoveTo(CSemaphoreGrant& grant)
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{
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grant.Release();
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grant.sem = sem;
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grant.fHaveGrant = fHaveGrant;
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fHaveGrant = false;
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}
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CSemaphoreGrant() : sem(nullptr), fHaveGrant(false) {}
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explicit CSemaphoreGrant(CSemaphore& sema, bool fTry = false) : sem(&sema), fHaveGrant(false)
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{
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if (fTry)
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TryAcquire();
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else
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Acquire();
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}
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~CSemaphoreGrant()
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{
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Release();
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}
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operator bool() const
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{
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return fHaveGrant;
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}
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};
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// Utility class for indicating to compiler thread analysis that a mutex is
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// locked (when it couldn't be determined otherwise).
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struct SCOPED_LOCKABLE LockAssertion
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{
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template <typename Mutex>
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explicit LockAssertion(Mutex& mutex) EXCLUSIVE_LOCK_FUNCTION(mutex)
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{
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#ifdef DEBUG_LOCKORDER
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AssertLockHeld(mutex);
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#endif
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}
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~LockAssertion() UNLOCK_FUNCTION() {}
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};
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#endif // BITCOIN_SYNC_H
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