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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 <deque>
#include <memory>
#include <string>
#include "mongo/base/string_data.h"
#include "mongo/s/catalog/dist_lock_catalog.h"
#include "mongo/s/catalog/dist_lock_manager.h"
#include "mongo/s/catalog/dist_lock_ping_info.h"
#include "mongo/stdx/chrono.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/stdx/mutex.h"
#include "mongo/stdx/thread.h"
#include "mongo/stdx/unordered_map.h"
namespace mongo {
class ServiceContext;
class ReplSetDistLockManager final : public DistLockManager {
public:
// How frequently should the dist lock pinger thread run and write liveness information about
// this instance of the dist lock manager
static const Seconds kDistLockPingInterval;
// How long should the lease on a distributed lock last
static const Minutes kDistLockExpirationTime;
ReplSetDistLockManager(ServiceContext* globalContext,
StringData processID,
std::unique_ptr<DistLockCatalog> catalog,
Milliseconds pingInterval,
Milliseconds lockExpiration);
virtual ~ReplSetDistLockManager();
void startUp() override;
void shutDown(OperationContext* opCtx) override;
std::string getProcessID() override;
StatusWith<DistLockHandle> lockWithSessionID(OperationContext* opCtx,
StringData name,
StringData whyMessage,
const OID& lockSessionID,
Milliseconds waitFor) override;
StatusWith<DistLockHandle> tryLockWithLocalWriteConcern(OperationContext* opCtx,
StringData name,
StringData whyMessage,
const OID& lockSessionID) override;
void unlock(OperationContext* opCtx, const DistLockHandle& lockSessionID) override;
void unlock(OperationContext* opCtx,
const DistLockHandle& lockSessionID,
StringData name) override;
void unlockAll(OperationContext* opCtx, const std::string& processID) override;
protected:
Status checkStatus(OperationContext* opCtx, const DistLockHandle& lockSessionID) override;
private:
/**
* Queue a lock to be unlocked asynchronously with retry until it doesn't error.
*/
void queueUnlock(const DistLockHandle& lockSessionID, const boost::optional<std::string>& name);
/**
* Periodically pings and checks if there are locks queued that needs unlocking.
*/
void doTask();
/**
* Returns true if shutDown was called.
*/
bool isShutDown();
/**
* Returns true if the current process that owns the lock has no fresh pings since
* the lock expiration threshold.
*/
StatusWith<bool> isLockExpired(OperationContext* opCtx,
const LocksType lockDoc,
const Milliseconds& lockExpiration);
//
// All member variables are labeled with one of the following codes indicating the
// synchronization rules for accessing them.
//
// (F) Self synchronizing.
// (M) Must hold _mutex for access.
// (I) Immutable, no synchronization needed.
// (S) Can only be called inside startUp/shutDown.
//
ServiceContext* const _serviceContext; // (F)
const std::string _processID; // (I)
const std::unique_ptr<DistLockCatalog> _catalog; // (I)
const Milliseconds _pingInterval; // (I)
const Milliseconds _lockExpiration; // (I)
stdx::mutex _mutex;
std::unique_ptr<stdx::thread> _execThread; // (S)
// Contains the list of locks queued for unlocking. Cases when unlock operation can
// be queued include:
// 1. First attempt on unlocking resulted in an error.
// 2. Attempting to grab or overtake a lock resulted in an error where we are uncertain
// whether the modification was actually applied or not, and call unlock to make
// sure that it was cleaned up.
std::deque<std::pair<DistLockHandle, boost::optional<std::string>>> _unlockList; // (M)
bool _isShutDown = false; // (M)
stdx::condition_variable _shutDownCV; // (M)
// Map of lockName to last ping information.
stdx::unordered_map<std::string, DistLockPingInfo> _pingHistory; // (M)
};
} // namespace mongo
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