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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;
};
class Mutex : public Latch {
public:
class LockActions;
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;
const StringData& getName() const {
return _name;
}
private:
const StringData _name;
stdx::mutex _mutex; // NOLINT
};
/**
* A set of actions to happen upon notable events on a Lockable-conceptualized type
*/
class Mutex::LockActions {
friend class Mutex;
public:
virtual ~LockActions() = default;
/**
* Action to do when a lock cannot be immediately acquired
*/
virtual void onContendedLock(const StringData& name) = 0;
/**
* Action to do when a lock is unlocked
*/
virtual void onUnlock(const StringData& name) = 0;
/**
* This function adds a LockActions subclass to the triggers for certain actions.
*
* Note that currently there is only one LockActions in use at a time. As part of SERVER-42895,
* this will change so that there is a list of LockActions maintained.
*
* LockActions can only be added and not removed. If you wish to deactivate a LockActions
* subclass, please provide the switch on that subclass to noop its functions.
*/
static void add(LockActions* actions);
private:
static auto& getState() {
struct State {
AtomicWord<LockActions*> actions{nullptr};
};
static State state;
return state;
}
};
} // 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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