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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 <iosfwd>
#include <list>
#include <string>
#include <vector>
#include "mongo/base/status.h"
#include "mongo/bson/bsonobj.h"
#include "mongo/client/fetcher.h"
#include "mongo/db/namespace_string.h"
#include "mongo/db/repl/base_cloner.h"
#include "mongo/db/repl/collection_cloner.h"
#include "mongo/executor/task_executor.h"
#include "mongo/platform/mutex.h"
#include "mongo/stdx/condition_variable.h"
#include "mongo/util/concurrency/thread_pool.h"
#include "mongo/util/net/hostandport.h"
namespace mongo {
namespace repl {
class StorageInterface;
class DatabaseCloner : public BaseCloner {
DatabaseCloner(const DatabaseCloner&) = delete;
DatabaseCloner& operator=(const DatabaseCloner&) = delete;
public:
struct Stats {
std::string dbname;
Date_t start;
Date_t end;
size_t collections{0};
size_t clonedCollections{0};
std::vector<CollectionCloner::Stats> collectionStats;
std::string toString() const;
BSONObj toBSON() const;
void append(BSONObjBuilder* builder) const;
};
/**
* Predicate used on the collection info objects returned by listCollections.
* Each collection info is represented by a document in the following format:
* {
* name: <collection name>,
* options: <collection options>
* }
*
* Returns true if the collection described by the info object should be cloned.
* Returns false if the collection should be ignored.
*/
using ListCollectionsPredicateFn = std::function<bool(const BSONObj&)>;
/**
* Callback function to report progress of collection cloning. Arguments are:
* - status from the collection cloner's 'onCompletion' callback.
* - source namespace of the collection cloner that completed (or failed).
*
* Called exactly once for every collection cloner started by the the database cloner.
*/
using CollectionCallbackFn = std::function<void(const Status&, const NamespaceString&)>;
/**
* Type of function to start a collection cloner.
*/
using StartCollectionClonerFn = std::function<Status(CollectionCloner&)>;
using ScheduleDbWorkFn = std::function<StatusWith<executor::TaskExecutor::CallbackHandle>(
executor::TaskExecutor::CallbackFn)>;
/**
* Creates DatabaseCloner task in inactive state. Use start() to activate cloner.
*
* The cloner calls 'onCompletion' when the database cloning has completed or failed.
*
* 'onCompletion' will be called exactly once.
*
* Takes ownership of the passed StorageInterface object.
*
* 'listCollectionsFilter' will be extended to include collections only, filtering out views.
*/
DatabaseCloner(executor::TaskExecutor* executor,
ThreadPool* dbWorkThreadPool,
const HostAndPort& source,
const std::string& dbname,
const BSONObj& listCollectionsFilter,
const ListCollectionsPredicateFn& listCollectionsPredicate,
StorageInterface* storageInterface,
const CollectionCallbackFn& collectionWork,
CallbackFn onCompletion);
virtual ~DatabaseCloner();
/**
* Returns collection info objects read from listCollections result and will not include views.
*/
const std::vector<BSONObj>& getCollectionInfos_forTest() const;
bool isActive() const override;
Status startup() noexcept override;
void shutdown() override;
void join() override;
DatabaseCloner::Stats getStats() const;
std::string getDBName() const;
//
// Testing only functions below.
//
/**
* Overrides how executor schedules database work.
*
* For testing only.
*/
void setScheduleDbWorkFn_forTest(const ScheduleDbWorkFn& scheduleDbWorkFn);
/**
* Overrides how executor starts a collection cloner.
*
* For testing only
*/
void setStartCollectionClonerFn(const StartCollectionClonerFn& startCollectionCloner);
// State transitions:
// PreStart --> Running --> ShuttingDown --> Complete
// It is possible to skip intermediate states. For example,
// Calling shutdown() when the cloner has not started will transition from PreStart directly
// to Complete.
// This enum class is made public for testing.
enum class State { kPreStart, kRunning, kShuttingDown, kComplete };
/**
* Returns current database cloner state.
* For testing only.
*/
State getState_forTest() const;
private:
bool _isActive_inlock() const;
/**
* Returns whether the DatabaseCloner is in shutdown.
*/
bool _isShuttingDown() const;
/**
* Read collection names and options from listCollections result.
*/
void _listCollectionsCallback(const StatusWith<Fetcher::QueryResponse>& fetchResult,
Fetcher::NextAction* nextAction,
BSONObjBuilder* getMoreBob);
/**
* Forwards collection cloner result to client.
* Starts a new cloner on a different collection.
*/
void _collectionClonerCallback(const Status& status, const NamespaceString& nss);
/**
* Reports completion status.
* Sets cloner to inactive.
*/
void _finishCallback(const Status& status);
/**
* Calls the above method after unlocking.
*/
void _finishCallback_inlock(stdx::unique_lock<Latch>& lk, const Status& status);
//
// All member variables are labeled with one of the following codes indicating the
// synchronization rules for accessing them.
//
// (R) Read-only in concurrent operation; no synchronization required.
// (M) Reads and writes guarded by _mutex
// (S) Self-synchronizing; access in any way from any context.
// (RT) Read-only in concurrent operation; synchronized externally by tests
//
mutable Mutex _mutex = MONGO_MAKE_LATCH("DatabaseCloner::_mutex");
mutable stdx::condition_variable _condition; // (M)
executor::TaskExecutor* _executor; // (R)
ThreadPool* _dbWorkThreadPool; // (R)
const HostAndPort _source; // (R)
const std::string _dbname; // (R)
const BSONObj _listCollectionsFilter; // (R)
const ListCollectionsPredicateFn _listCollectionsPredicate; // (R)
StorageInterface* _storageInterface; // (R)
CollectionCallbackFn
_collectionWork; // (R) Invoked once for every successfully started collection cloner.
CallbackFn _onCompletion; // (R) Invoked once when cloning completes or fails.
Fetcher _listCollectionsFetcher; // (R) Fetcher instance for running listCollections command.
// Collection info objects returned from listCollections.
// Format of each document:
// {
// name: <collection name>,
// options: <collection options>
// }
// Holds all collection infos from listCollections.
std::vector<BSONObj> _collectionInfos; // (M)
std::vector<NamespaceString> _collectionNamespaces; // (M)
std::list<CollectionCloner> _collectionCloners; // (M)
std::list<CollectionCloner>::iterator _currentCollectionClonerIter; // (M)
ScheduleDbWorkFn
_scheduleDbWorkFn; // (RT) Function for scheduling database work using the executor.
StartCollectionClonerFn _startCollectionCloner; // (RT)
Stats _stats; // (M) Stats about what this instance did.
// Current database cloner state. See comments for State enum class for details.
State _state = State::kPreStart; // (M)
};
/**
* Insertion operator for DatabaseCloner::State. Formats database cloner state for output stream.
* For testing only.
*/
std::ostream& operator<<(std::ostream& os, const DatabaseCloner::State& state);
} // namespace repl
} // namespace mongo
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