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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/>.
*/
/** @file Guards.h
* @author Gav Wood <i@gavwood.com>
* @date 2014
*/
#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;
};
/** @brief Simple lock that waits for release without making context switch */
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;
};
/** @brief Simple block guard.
* The expression/block following is guarded though the given mutex.
* Usage:
* @code
* Mutex m;
* unsigned d;
* ...
* ETH_(m) d = 1;
* ...
* ETH_(m) { for (auto d = 10; d > 0; --d) foo(d); d = 0; }
* @endcode
*
* There are several variants of this basic mechanism for different Mutex types and Guards.
*
* There is also the UNGUARD variant which allows an unguarded expression/block to exist within a
* guarded expression. eg:
*
* @code
* Mutex m;
* int d;
* ...
* ETH_GUARDED(m)
* {
* for (auto d = 50; d > 25; --d)
* foo(d);
* ETH_UNGUARDED(m)
* bar();
* for (; d > 0; --d)
* foo(d);
* }
* @endcode
*/
#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)
}