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120 lines
3.7 KiB
120 lines
3.7 KiB
/*
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This file is part of cpp-ethereum.
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cpp-ethereum is free software: you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation, either version 3 of the License, or
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(at your option) any later version.
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cpp-ethereum is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
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*/
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/** @file Guards.h
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* @author Gav Wood <i@gavwood.com>
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* @date 2014
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*/
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#pragma once
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#include <mutex>
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#include <condition_variable>
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#include <atomic>
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namespace dev
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{
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using Mutex = std::mutex;
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using RecursiveMutex = std::recursive_mutex;
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using Guard = std::lock_guard<std::mutex>;
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using UniqueGuard = std::unique_lock<std::mutex>;
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using RecursiveGuard = std::lock_guard<std::recursive_mutex>;
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template <class GuardType, class MutexType>
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struct GenericGuardBool: GuardType
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{
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GenericGuardBool(MutexType& _m): GuardType(_m) {}
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bool b = true;
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};
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/** @brief Simple lock that waits for release without making context switch */
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class SpinLock
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{
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public:
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SpinLock() { m_lock.clear(); }
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void lock() { while (m_lock.test_and_set(std::memory_order_acquire)) {} }
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void unlock() { m_lock.clear(std::memory_order_release); }
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private:
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std::atomic_flag m_lock;
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};
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using SpinGuard = std::lock_guard<SpinLock>;
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template <class N>
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class Notified
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{
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public:
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Notified() {}
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Notified(N const& _v): m_value(_v) {}
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Notified(Notified const&) = delete;
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Notified& operator=(N const& _v) { UniqueGuard l(m_mutex); m_value = _v; m_cv.notify_all(); return *this; }
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operator N() const { UniqueGuard l(m_mutex); return m_value; }
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void wait() const { N old; { UniqueGuard l(m_mutex); old = m_value; } waitNot(old); }
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void wait(N const& _v) const { UniqueGuard l(m_mutex); m_cv.wait(l, [&](){return m_value == _v;}); }
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void waitNot(N const& _v) const { UniqueGuard l(m_mutex); m_cv.wait(l, [&](){return m_value != _v;}); }
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template <class F> void wait(F const& _f) const { UniqueGuard l(m_mutex); m_cv.wait(l, _f); }
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template <class R, class P> void wait(std::chrono::duration<R, P> _d) const { N old; { UniqueGuard l(m_mutex); old = m_value; } waitNot(_d, old); }
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template <class R, class P> void wait(std::chrono::duration<R, P> _d, N const& _v) const { UniqueGuard l(m_mutex); m_cv.wait_for(l, _d, [&](){return m_value == _v;}); }
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template <class R, class P> void waitNot(std::chrono::duration<R, P> _d, N const& _v) const { UniqueGuard l(m_mutex); m_cv.wait_for(l, _d, [&](){return m_value != _v;}); }
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template <class R, class P, class F> void wait(std::chrono::duration<R, P> _d, F const& _f) const { UniqueGuard l(m_mutex); m_cv.wait_for(l, _d, _f); }
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private:
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mutable Mutex m_mutex;
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mutable std::condition_variable m_cv;
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N m_value;
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};
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/** @brief Simple block guard.
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* The expression/block following is guarded though the given mutex.
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* Usage:
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* @code
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* Mutex m;
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* unsigned d;
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* ...
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* ETH_(m) d = 1;
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* ...
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* ETH_(m) { for (auto d = 10; d > 0; --d) foo(d); d = 0; }
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* @endcode
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*
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* There are several variants of this basic mechanism for different Mutex types and Guards.
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*
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* There is also the UNGUARD variant which allows an unguarded expression/block to exist within a
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* guarded expression. eg:
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*
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* @code
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* Mutex m;
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* int d;
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* ...
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* ETH_GUARDED(m)
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* {
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* for (auto d = 50; d > 25; --d)
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* foo(d);
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* ETH_UNGUARDED(m)
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* bar();
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* for (; d > 0; --d)
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* foo(d);
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* }
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* @endcode
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*/
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#define DEV_GUARDED(MUTEX) \
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for (GenericGuardBool<Guard, Mutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)
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}
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