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/**
* Copyright (C) 2020-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 <list>
#include "mongo/util/duration.h"
namespace mongo {
class OperationContext;
class OperationCPUTimer;
/**
* Allocates and tracks CPU timers for an OperationContext.
*/
class OperationCPUTimers : public std::enable_shared_from_this<OperationCPUTimers> {
public:
friend class OperationCPUTimer;
/**
* Returns `nullptr` if the platform does not support tracking of CPU consumption.
*/
static OperationCPUTimers* get(OperationContext*);
/**
* Returns a timer bound to this OperationContext and the threads that it runs on. Timers
* created from this function may safely outlive the OperationCPUTimers container and the
* OperationContext, but only to simplify destruction ordering problems.
*/
std::unique_ptr<OperationCPUTimer> makeTimer();
void onThreadAttach();
void onThreadDetach();
size_t count() const;
private:
using Iterator = std::list<mongo::OperationCPUTimer*>::iterator;
Iterator _add(OperationCPUTimer* timer);
void _remove(Iterator it);
// List of active timers on this OperationContext. When an OperationCPUTimer is constructed, it
// will add itself to this list and remove itself on destruction.
std::list<OperationCPUTimer*> _timers;
};
/**
* Implements the CPU timer for platforms that support CPU consumption tracking. Consider the
* following when using the timer:
*
* All methods may only be invoked on the thread associated with the operation.
*
* To access the timer, the operation must be associated with a client, and the client must be
* attached to the current thread.
*
* The timer is initially stopped, measures elapsed time between the invocations of `start()`
* and `stop()`, and resets on consequent invocations of `start()`.
*
* To reset a timer, it should be stopped first and then started again.
*
* The timer is paused when the operation's client is detached from the current thread, and will
* not resume until the client is reattached to a thread.
*/
class OperationCPUTimer {
public:
OperationCPUTimer(const std::shared_ptr<OperationCPUTimers>& timers);
virtual ~OperationCPUTimer();
virtual Nanoseconds getElapsed() const = 0;
virtual void start() = 0;
virtual void stop() = 0;
virtual void onThreadAttach() = 0;
virtual void onThreadDetach() = 0;
// Called by owning operation to indicate that the operation has ended and any pointers to the
// OperationCPUTimers are no longer valid. The timer will continue to function correctly.
void onOperationEnded();
private:
// Weak reference to OperationContext-owned tracked list of timers. The Timers container can be
// destructed before this Timer.
std::weak_ptr<OperationCPUTimers> _timers;
// Iterator position to speed up deletion from the list of timers for this operation.
OperationCPUTimers::Iterator _it;
};
} // namespace mongo
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