/** * Copyright (C) 2012 10gen Inc. * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU Affero General Public License, version 3, * as published by the Free Software Foundation. * * 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 * GNU Affero General Public License for more details. * * You should have received a copy of the GNU Affero General Public License * along with this program. If not, see . * * 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 GNU Affero General 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 "mongo/base/status_with.h" #include "mongo/client/fetcher.h" #include "mongo/db/jsobj.h" #include "mongo/db/repl/optime.h" #include "mongo/executor/thread_pool_task_executor.h" #include "mongo/stdx/condition_variable.h" #include "mongo/stdx/functional.h" #include "mongo/stdx/mutex.h" #include "mongo/util/net/hostandport.h" #include "mongo/util/queue.h" namespace mongo { class DBClientBase; class OperationContext; namespace repl { class Member; class ReplicationCoordinator; // This interface exists to facilitate easier testing; // the test infrastructure implements these functions with stubs. class BackgroundSyncInterface { public: virtual ~BackgroundSyncInterface(); // Gets the head of the buffer, but does not remove it. // Returns true if an element was present at the head; // false if the queue was empty. virtual bool peek(BSONObj* op) = 0; // Deletes objects in the queue; // called by sync thread after it has applied an op virtual void consume() = 0; // wait up to 1 second for more ops to appear virtual void waitForMore() = 0; }; /** * Lock order: * 1. rslock * 2. rwlock * 3. BackgroundSync::_mutex */ class BackgroundSync : public BackgroundSyncInterface { public: // Allow index prefetching to be turned on/off enum IndexPrefetchConfig { PREFETCH_NONE = 0, PREFETCH_ID_ONLY = 1, PREFETCH_ALL = 2 }; static BackgroundSync* get(); // stop syncing (when this node becomes a primary, e.g.) void stop(); void shutdown(); void notify(OperationContext* txn); bool isPaused() const; // Blocks until _pause becomes true from a call to stop() or shutdown() void waitUntilPaused(); virtual ~BackgroundSync() {} // starts the producer thread void producerThread(); // starts the sync target notifying thread void notifierThread(); HostAndPort getSyncTarget(); // Interface implementation virtual bool peek(BSONObj* op); virtual void consume(); virtual void clearSyncTarget(); virtual void waitForMore(); // For monitoring BSONObj getCounters(); // Clears any fetched and buffered oplog entries. void clearBuffer(); /** * Cancel existing find/getMore commands on the sync source's oplog collection. */ void cancelFetcher(); bool getInitialSyncRequestedFlag(); void setInitialSyncRequestedFlag(bool value); void setIndexPrefetchConfig(const IndexPrefetchConfig cfg) { _indexPrefetchConfig = cfg; } IndexPrefetchConfig getIndexPrefetchConfig() { return _indexPrefetchConfig; } // Testing related stuff void pushTestOpToBuffer(const BSONObj& op); private: static BackgroundSync* s_instance; // protects creation of s_instance static stdx::mutex s_mutex; // Production thread BlockingQueue _buffer; // Task executor used to run find/getMore commands on sync source. executor::ThreadPoolTaskExecutor _threadPoolTaskExecutor; // _mutex protects all of the class variables except _buffer mutable stdx::mutex _mutex; OpTime _lastOpTimeFetched; // lastFetchedHash is used to match ops to determine if we need to rollback, when // a secondary. long long _lastFetchedHash; // if produce thread should be running bool _pause; stdx::condition_variable _pausedCondition; bool _appliedBuffer; stdx::condition_variable _appliedBufferCondition; HostAndPort _syncSourceHost; BackgroundSync(); BackgroundSync(const BackgroundSync& s); BackgroundSync operator=(const BackgroundSync& s); // Production thread void _producerThread(); void _produce(OperationContext* txn); /** * Processes query responses from fetcher. */ void _fetcherCallback(const StatusWith& result, BSONObjBuilder* bob, const HostAndPort& source, OpTime lastOpTimeFetched, long long lastFetchedHash, Milliseconds fetcherMaxTimeMS, Status* remoteOplogStartStatus); /** * Executes a rollback. * 'getConnection' returns a connection to the sync source. */ void _rollback(OperationContext* txn, const HostAndPort& source, stdx::function getConnection); /** * Evaluate if the current sync source is still good. * "syncSource" is the name of the current sync source, which will be used to look up the * member's heartbeat data. * "syncSourceLastOpTime" is the last OpTime the sync source has. This is passed in because the * data stored from heartbeats could be too stale and would cause unnecessary sync source * changes. * "syncSourceHasSyncSource" indicates whether our sync source is currently syncing from another * member. */ bool _shouldChangeSyncSource(const HostAndPort& syncSource, const OpTime& syncSourceLastOpTime, bool syncSourceHasSyncSource); // restart syncing void start(OperationContext* txn); long long _readLastAppliedHash(OperationContext* txn); // A pointer to the replication coordinator running the show. ReplicationCoordinator* _replCoord; // bool for indicating resync need on this node and the mutex that protects it // The resync command sets this flag; the Applier thread observes and clears it. bool _initialSyncRequestedFlag; stdx::mutex _initialSyncMutex; // This setting affects the Applier prefetcher behavior. IndexPrefetchConfig _indexPrefetchConfig; }; } // namespace repl } // namespace mongo