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/**
* Copyright (C) 2018-present MongoDB, Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the Server Side Public License, version 1,
* as published by MongoDB, Inc.
*
* This program 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
* Server Side Public License for more details.
*
* You should have received a copy of the Server Side Public License
* along with this program. If not, see
* <http://www.mongodb.com/licensing/server-side-public-license>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the Server Side Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include <type_traits>
#include "mongo/base/error_codes.h"
#include "mongo/base/string_data.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/stdx/mutex.h"
#include "mongo/util/duration.h"
namespace mongo {
class Latch {
public:
virtual ~Latch() = default;
virtual void lock() = 0;
virtual void unlock() = 0;
virtual bool try_lock() = 0;
virtual StringData getName() const {
return "AnonymousLatch"_sd;
}
};
class Mutex : public Latch {
class LockNotifier;
public:
class LockListener;
static constexpr auto kAnonymousMutexStr = "AnonymousMutex"_sd;
Mutex() : Mutex(kAnonymousMutexStr) {}
// Note that StringData is a view type, thus the underlying string for _name must outlive any
// given Mutex
explicit Mutex(const StringData& name) : _name(name) {}
void lock() override;
void unlock() override;
bool try_lock() override;
StringData getName() const override {
return _name;
}
/**
* This function adds a LockListener subclass to the triggers for certain actions.
*
* LockListeners can only be added and not removed. If you wish to deactivate a LockListeners
* subclass, please provide the switch on that subclass to noop its functions. It is only safe
* to add a LockListener during a MONGO_INITIALIZER.
*/
static void addLockListener(LockListener* listener);
private:
static auto& _getListenerState() noexcept {
struct State {
std::vector<LockListener*> list;
};
// Note that state should no longer be mutated after init-time (ala MONGO_INITIALIZERS). If
// this changes, than this state needs to be synchronized.
static State state;
return state;
}
static void _onContendedLock(const StringData& name) noexcept;
static void _onQuickLock(const StringData& name) noexcept;
static void _onSlowLock(const StringData& name) noexcept;
static void _onUnlock(const StringData& name) noexcept;
const StringData _name;
stdx::mutex _mutex; // NOLINT
};
/**
* A set of actions to happen upon notable events on a Lockable-conceptualized type
*/
class Mutex::LockListener {
friend class Mutex;
public:
virtual ~LockListener() = default;
/**
* Action to do when a lock cannot be immediately acquired
*/
virtual void onContendedLock(const StringData& name) = 0;
/**
* Action to do when a lock was acquired without blocking
*/
virtual void onQuickLock(const StringData& name) = 0;
/**
* Action to do when a lock was acquired after blocking
*/
virtual void onSlowLock(const StringData& name) = 0;
/**
* Action to do when a lock is unlocked
*/
virtual void onUnlock(const StringData& name) = 0;
};
} // namespace mongo
/**
* Define a mongo::Mutex with all arguments passed through to the ctor
*/
#define MONGO_MAKE_LATCH(...) \
mongo::Mutex { \
__VA_ARGS__ \
}
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