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/**
* Copyright (C) 2014 MongoDB 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 <http://www.gnu.org/licenses/>.
*
* 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 <boost/optional.hpp>
#include <cstddef>
#include "mongo/base/disallow_copying.h"
#include "mongo/bson/timestamp.h"
#include "mongo/db/repl/member_state.h"
#include "mongo/db/repl/multiapplier.h"
#include "mongo/db/repl/oplog_buffer.h"
#include "mongo/db/repl/optime.h"
#include "mongo/stdx/functional.h"
#include "mongo/util/time_support.h"
namespace mongo {
class BSONObj;
class OID;
class OldThreadPool;
class OperationContext;
class ServiceContext;
class SnapshotName;
class Status;
struct HostAndPort;
template <typename T>
class StatusWith;
namespace repl {
class LastVote;
class ReplSettings;
class ReplicationCoordinator;
class ReplicationExecutor;
using OnInitialSyncFinishedFn = stdx::function<void(OperationContext* opCtx)>;
using StartInitialSyncFn = stdx::function<void(OnInitialSyncFinishedFn callback)>;
using StartSteadyReplicationFn = stdx::function<void()>;
/**
* This class represents the interface the ReplicationCoordinator uses to interact with the
* rest of the system. All functionality of the ReplicationCoordinatorImpl that would introduce
* dependencies on large sections of the server code and thus break the unit testability of
* ReplicationCoordinatorImpl should be moved here.
*/
class ReplicationCoordinatorExternalState {
MONGO_DISALLOW_COPYING(ReplicationCoordinatorExternalState);
public:
ReplicationCoordinatorExternalState();
virtual ~ReplicationCoordinatorExternalState();
/**
* Starts the journal listener, and snapshot threads
*
* NOTE: Only starts threads if they are not already started,
*/
virtual void startThreads(const ReplSettings& settings) = 0;
/**
* Starts an initial sync, and calls "finished" when done,
* for replica set member.
*
* NOTE: Use either this (and below function) or the Master/Slave version, but not both.
*/
virtual void startInitialSync(OnInitialSyncFinishedFn finished) = 0;
/**
* Returns true if an incomplete initial sync is detected.
*/
virtual bool isInitialSyncFlagSet(OperationContext* opCtx) = 0;
/**
* Starts steady state sync for replica set member.
*
* NOTE: Use either this or the Master/Slave version, but not both.
*/
virtual void startSteadyStateReplication(OperationContext* opCtx,
ReplicationCoordinator* replCoord) = 0;
virtual void runOnInitialSyncThread(stdx::function<void(OperationContext* opCtx)> run) = 0;
/**
* Stops the data replication threads = bgsync, applier, reporter.
*/
virtual void stopDataReplication(OperationContext* opCtx) = 0;
/**
* Starts the Master/Slave threads and sets up logOp
*/
virtual void startMasterSlave(OperationContext* opCtx) = 0;
/**
* Performs any necessary external state specific shutdown tasks, such as cleaning up
* the threads it started.
*/
virtual void shutdown(OperationContext* opCtx) = 0;
/**
* Returns task executor for scheduling tasks to be run asynchronously.
*/
virtual executor::TaskExecutor* getTaskExecutor() const = 0;
/**
* Returns shared db worker thread pool for collection cloning.
*/
virtual OldThreadPool* getDbWorkThreadPool() const = 0;
/**
* Runs the repair database command on the "local" db, if the storage engine is MMapV1.
* Note: Used after initial sync to compact the database files.
*/
virtual Status runRepairOnLocalDB(OperationContext* opCtx) = 0;
/**
* Creates the oplog, writes the first entry and stores the replica set config document.
*/
virtual Status initializeReplSetStorage(OperationContext* opCtx, const BSONObj& config) = 0;
/**
* Called when a node on way to becoming a primary is ready to leave drain mode. It is called
* outside of the global X lock and the replication coordinator mutex.
*
* Throws on errors.
*/
virtual void onDrainComplete(OperationContext* opCtx) = 0;
/**
* Called as part of the process of transitioning to primary and run with the global X lock and
* the replication coordinator mutex acquired, so no majoirty writes are allowed while in this
* state. See the call site in ReplicationCoordinatorImpl for details about when and how it is
* called.
*
* Among other things, this writes a message about our transition to primary to the oplog if
* isV1 and and returns the optime of that message. If !isV1, returns the optime of the last op
* in the oplog.
*
* Throws on errors.
*/
virtual OpTime onTransitionToPrimary(OperationContext* opCtx, bool isV1ElectionProtocol) = 0;
/**
* Simple wrapper around SyncSourceFeedback::forwardSlaveProgress. Signals to the
* SyncSourceFeedback thread that it needs to wake up and send a replSetUpdatePosition
* command upstream.
*/
virtual void forwardSlaveProgress() = 0;
/**
* Queries the singleton document in local.me. If it exists and our hostname has not
* changed since we wrote, returns the RID stored in the object. If the document does not
* exist or our hostname doesn't match what was recorded in local.me, generates a new OID
* to use as our RID, stores it in local.me, and returns it.
*/
virtual OID ensureMe(OperationContext*) = 0;
/**
* Returns true if "host" is one of the network identities of this node.
*/
virtual bool isSelf(const HostAndPort& host, ServiceContext* service) = 0;
/**
* Gets the replica set config document from local storage, or returns an error.
*/
virtual StatusWith<BSONObj> loadLocalConfigDocument(OperationContext* opCtx) = 0;
/**
* Stores the replica set config document in local storage, or returns an error.
*/
virtual Status storeLocalConfigDocument(OperationContext* opCtx, const BSONObj& config) = 0;
/**
* Gets the replica set lastVote document from local storage, or returns an error.
*/
virtual StatusWith<LastVote> loadLocalLastVoteDocument(OperationContext* opCtx) = 0;
/**
* Stores the replica set lastVote document in local storage, or returns an error.
*/
virtual Status storeLocalLastVoteDocument(OperationContext* opCtx,
const LastVote& lastVote) = 0;
/**
* Sets the global opTime to be 'newTime'.
*/
virtual void setGlobalTimestamp(ServiceContext* service, const Timestamp& newTime) = 0;
/**
* Gets the last optime of an operation performed on this host, from stable
* storage.
*/
virtual StatusWith<OpTime> loadLastOpTime(OperationContext* opCtx) = 0;
/**
* Cleaning up the oplog, by potentially truncating:
* If we are recovering from a failed batch then minvalid.start though minvalid.end need
* to be removed from the oplog before we can start applying operations.
*/
virtual void cleanUpLastApplyBatch(OperationContext* opCtx) = 0;
/**
* Returns the HostAndPort of the remote client connected to us that initiated the operation
* represented by "opCtx".
*/
virtual HostAndPort getClientHostAndPort(const OperationContext* opCtx) = 0;
/**
* Closes all connections in the given TransportLayer except those marked with the
* keepOpen property, which should just be connections used for heartbeating.
* This is used during stepdown, and transition out of primary.
*/
virtual void closeConnections() = 0;
/**
* Kills all operations that have a Client that is associated with an incoming user
* connection. Used during stepdown.
*/
virtual void killAllUserOperations(OperationContext* opCtx) = 0;
/**
* Resets any active sharding metadata on this server and stops any sharding-related threads
* (such as the balancer). It is called after stepDown to ensure that if the node becomes
* primary again in the future it will recover its state from a clean slate.
*/
virtual void shardingOnStepDownHook() = 0;
/**
* Notifies the bgsync and syncSourceFeedback threads to choose a new sync source.
*/
virtual void signalApplierToChooseNewSyncSource() = 0;
/**
* Notifies the bgsync to stop fetching data.
*/
virtual void stopProducer() = 0;
/**
* Start bgsync's producer if it's stopped.
*/
virtual void startProducerIfStopped() = 0;
/**
* Drops all snapshots and clears the "committed" snapshot.
*/
virtual void dropAllSnapshots() = 0;
/**
* Updates the committed snapshot to the newCommitPoint, and deletes older snapshots.
*
* It is illegal to call with a newCommitPoint that does not name an existing snapshot.
*/
virtual void updateCommittedSnapshot(SnapshotName newCommitPoint) = 0;
/**
* Creates a new snapshot.
*/
virtual void createSnapshot(OperationContext* opCtx, SnapshotName name) = 0;
/**
* Signals the SnapshotThread, if running, to take a forced snapshot even if the global
* timestamp hasn't changed.
*
* Does not wait for the snapshot to be taken.
*/
virtual void forceSnapshotCreation() = 0;
/**
* Returns whether or not the SnapshotThread is active.
*/
virtual bool snapshotsEnabled() const = 0;
virtual void notifyOplogMetadataWaiters() = 0;
/**
* Returns multiplier to apply to election timeout to obtain upper bound
* on randomized offset.
*/
virtual double getElectionTimeoutOffsetLimitFraction() const = 0;
/**
* Returns true if the current storage engine supports read committed.
*/
virtual bool isReadCommittedSupportedByStorageEngine(OperationContext* opCtx) const = 0;
/**
* Applies the operations described in the oplog entries contained in "ops" using the
* "applyOperation" function.
*/
virtual StatusWith<OpTime> multiApply(OperationContext* opCtx,
MultiApplier::Operations ops,
MultiApplier::ApplyOperationFn applyOperation) = 0;
/**
* Used by multiApply() to writes operations to database during steady state replication.
*/
virtual Status multiSyncApply(MultiApplier::OperationPtrs* ops) = 0;
/**
* Used by multiApply() to writes operations to database during initial sync. `fetchCount` is a
* pointer to a counter that is incremented every time we fetch a missing document.
*
*/
virtual Status multiInitialSyncApply(MultiApplier::OperationPtrs* ops,
const HostAndPort& source,
AtomicUInt32* fetchCount) = 0;
/**
* This function creates an oplog buffer of the type specified at server startup.
*/
virtual std::unique_ptr<OplogBuffer> makeInitialSyncOplogBuffer(
OperationContext* opCtx) const = 0;
/**
* Creates an oplog buffer suitable for steady state replication.
*/
virtual std::unique_ptr<OplogBuffer> makeSteadyStateOplogBuffer(
OperationContext* opCtx) const = 0;
/**
* Returns true if the user specified to use the new version for initial sync.
*/
virtual bool shouldUseDataReplicatorInitialSync() const = 0;
/**
* Returns maximum number of times that the oplog fetcher will consecutively restart the oplog
* tailing query on non-cancellation errors.
*/
virtual std::size_t getOplogFetcherMaxFetcherRestarts() const = 0;
/*
* Creates noop writer instance. Setting the _noopWriter member is not protected by a guard,
* hence it must be called before multi-threaded operations start.
*/
virtual void setupNoopWriter(Seconds waitTime) = 0;
/*
* Starts periodic noop writes to oplog.
*/
virtual void startNoopWriter(OpTime) = 0;
/*
* Stops periodic noop writes to oplog.
*/
virtual void stopNoopWriter() = 0;
};
} // namespace repl
} // namespace mongo
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