Guards.h

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/*
        This file is part of cpp-ethereum.

        cpp-ethereum is free software: you can redistribute it and/or modify
        it under the terms of the GNU General Public License as published by
        the Free Software Foundation, either version 3 of the License, or
        (at your option) any later version.

        cpp-ethereum is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.

        You should have received a copy of the GNU General Public License
        along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
*/
#pragma once

#include <mutex>
#include <condition_variable>
#include <atomic>
#pragma warning(push)
#pragma GCC diagnostic push
#pragma GCC diagnostic ignored "-Wunused-parameter"
#include <boost/thread.hpp>
#pragma warning(pop)
#pragma GCC diagnostic pop

namespace dev
{

using Mutex = std::mutex;
using RecursiveMutex = std::recursive_mutex;
using SharedMutex = boost::shared_mutex;

using Guard = std::lock_guard<std::mutex>;
using UniqueGuard = std::unique_lock<std::mutex>;
using RecursiveGuard = std::lock_guard<std::recursive_mutex>;
using ReadGuard = boost::shared_lock<boost::shared_mutex>;
using UpgradableGuard = boost::upgrade_lock<boost::shared_mutex>;
using UpgradeGuard = boost::upgrade_to_unique_lock<boost::shared_mutex>;
using WriteGuard = boost::unique_lock<boost::shared_mutex>;

template <class GuardType, class MutexType>
struct GenericGuardBool: GuardType
{
        GenericGuardBool(MutexType& _m): GuardType(_m) {}
        bool b = true;
};
template <class MutexType>
struct GenericUnguardBool
{
        GenericUnguardBool(MutexType& _m): m(_m) { m.unlock(); }
        ~GenericUnguardBool() { m.lock(); }
        bool b = true;
        MutexType& m;
};
template <class MutexType>
struct GenericUnguardSharedBool
{
        GenericUnguardSharedBool(MutexType& _m): m(_m) { m.unlock_shared(); }
        ~GenericUnguardSharedBool() { m.lock_shared(); }
        bool b = true;
        MutexType& m;
};

class SpinLock
{
public:
        SpinLock() { m_lock.clear(); }
        void lock() { while (m_lock.test_and_set(std::memory_order_acquire)) {} }
        void unlock() { m_lock.clear(std::memory_order_release); }
private:
        std::atomic_flag m_lock;
};
using SpinGuard = std::lock_guard<SpinLock>;

template <class N>
class Notified
{
public:
        Notified() {}
        Notified(N const& _v): m_value(_v) {}
        Notified(Notified const&) = delete;
        Notified& operator=(N const& _v) { UniqueGuard l(m_mutex); m_value = _v; m_cv.notify_all(); return *this; }

        operator N() const { UniqueGuard l(m_mutex); return m_value; }

        void wait() const { N old; { UniqueGuard l(m_mutex); old = m_value; } waitNot(old); }
        void wait(N const& _v) const { UniqueGuard l(m_mutex); m_cv.wait(l, [&](){return m_value == _v;}); }
        void waitNot(N const& _v) const { UniqueGuard l(m_mutex); m_cv.wait(l, [&](){return m_value != _v;}); }
        template <class F> void wait(F const& _f) const { UniqueGuard l(m_mutex); m_cv.wait(l, _f); }

        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); }
        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;}); }
        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;}); }
        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); }

private:
        mutable Mutex m_mutex;
        mutable std::condition_variable m_cv;
        N m_value;
};

#define DEV_GUARDED(MUTEX) \
        for (GenericGuardBool<Guard, Mutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)
#define DEV_READ_GUARDED(MUTEX) \
        for (GenericGuardBool<ReadGuard, SharedMutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)
#define DEV_WRITE_GUARDED(MUTEX) \
        for (GenericGuardBool<WriteGuard, SharedMutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)
#define DEV_RECURSIVE_GUARDED(MUTEX) \
        for (GenericGuardBool<RecursiveGuard, RecursiveMutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)
#define DEV_UNGUARDED(MUTEX) \
        for (GenericUnguardBool<Mutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)
#define DEV_READ_UNGUARDED(MUTEX) \
        for (GenericUnguardSharedBool<SharedMutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)
#define DEV_WRITE_UNGUARDED(MUTEX) \
        for (GenericUnguardBool<SharedMutex> __eth_l(MUTEX); __eth_l.b; __eth_l.b = false)

}