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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 "mongo/db/commands/fsync.h"
#include "mongo/db/commands/server_status_metric.h"
#include "mongo/db/concurrency/replication_state_transition_lock_guard.h"
#include "mongo/db/repl/initial_syncer.h"
#include "mongo/db/repl/oplog_applier.h"
#include "mongo/db/repl/replication_consistency_markers.h"
#include "mongo/db/repl/replication_coordinator.h"
#include "mongo/db/repl/replication_metrics.h"
#include "mongo/db/repl/session_update_tracker.h"
#include "mongo/db/repl/storage_interface.h"
namespace mongo {
namespace repl {
/**
* Applies oplog entries.
* Primarily used to apply batches of operations fetched from a sync source during steady state
* replication and initial sync.
*
* When used for steady state replication, runs a thread that reads batches of operations from
* an oplog buffer populated through the BackgroundSync interface, writes them into the oplog
* collection, and applies the batch of operations.
*/
class OplogApplierImpl : public OplogApplier {
OplogApplierImpl(const OplogApplierImpl&) = delete;
OplogApplierImpl& operator=(const OplogApplierImpl&) = delete;
public:
/**
* Constructs this OplogApplier with specific options.
* During steady state replication, _run() obtains batches of operations to apply
* from the oplogBuffer. During the oplog application phase, the batch of operations is
* distributed across writer threads in 'writerPool'. Each writer thread applies its own vector
* of operations using 'func'. The writer thread pool is not owned by us.
*/
OplogApplierImpl(executor::TaskExecutor* executor,
OplogBuffer* oplogBuffer,
Observer* observer,
ReplicationCoordinator* replCoord,
ReplicationConsistencyMarkers* consistencyMarkers,
StorageInterface* storageInterface,
const Options& options,
ThreadPool* writerPool);
private:
/**
* Runs oplog application in a loop until shutdown() is called.
* Retrieves operations from the OplogBuffer in batches that will be applied in parallel using
* applyOplogBatch().
*/
void _run(OplogBuffer* oplogBuffer) override;
/**
* Applies a batch of oplog entries by writing the oplog entries to the local oplog and then
* using a set of threads to apply the operations. It writes all entries to the oplog, but only
* applies entries with timestamp >= beginApplyingTimestamp.
*
* If the batch application is successful, returns the optime of the last op applied, which
* should be the last op in the batch.
* Returns ErrorCodes::CannotApplyOplogWhilePrimary if the node has become primary.
*
* To provide crash resilience, this function will advance the persistent value of 'minValid'
* to at least the last optime of the batch. If 'minValid' is already greater than or equal
* to the last optime of this batch, it will not be updated.
*/
StatusWith<OpTime> _applyOplogBatch(OperationContext* opCtx, std::vector<OplogEntry> ops);
void _deriveOpsAndFillWriterVectors(OperationContext* opCtx,
std::vector<OplogEntry>* ops,
std::vector<std::vector<const OplogEntry*>>* writerVectors,
std::vector<std::vector<OplogEntry>>* derivedOps,
SessionUpdateTracker* sessionUpdateTracker) noexcept;
// Not owned by us.
ReplicationCoordinator* const _replCoord;
// Pool of worker threads for writing ops to the databases.
// Not owned by us.
ThreadPool* const _writerPool;
StorageInterface* _storageInterface;
ReplicationConsistencyMarkers* const _consistencyMarkers;
// Used to determine which operations should be applied during initial sync. If this is null,
// we will apply all operations that were fetched.
OpTime _beginApplyingOpTime = OpTime();
void fillWriterVectors(OperationContext* opCtx,
std::vector<OplogEntry>* ops,
std::vector<std::vector<const OplogEntry*>>* writerVectors,
std::vector<std::vector<OplogEntry>>* derivedOps) noexcept;
protected:
// Marked as protected for use in unit tests.
/**
* This function is used by the thread pool workers to write ops to the db.
* It modifies the passed-in vector, and callers should not make any assumptions about the
* state of the vector after calling. The OplogEntry objects themselves are not modified.
*
* This function has been marked as virtual to allow certain unit tests to skip oplog
* application.
*/
virtual Status applyOplogBatchPerWorker(OperationContext* opCtx,
std::vector<const OplogEntry*>* ops,
WorkerMultikeyPathInfo* workerMultikeyPathInfo);
};
/**
* Applies either a single oplog entry or a set of grouped insert operations.
*/
Status applyOplogEntryOrGroupedInserts(OperationContext* opCtx,
const OplogEntryOrGroupedInserts& entryOrGroupedInserts,
OplogApplication::Mode oplogApplicationMode);
} // namespace repl
} // namespace mongo
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