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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 <string>
#include "mongo/base/status.h"
#include "mongo/db/catalog/index_catalog.h"
#include "mongo/db/catalog/multi_index_block.h"
#include "mongo/db/concurrency/d_concurrency.h"
#include "mongo/db/jsobj.h"
#include "mongo/platform/atomic_word.h"
#include "mongo/util/background.h"
namespace mongo {
class Collection;
class Database;
class OperationContext;
/**
* A helper class for replication to use for building indexes.
* In standalone mode, we use the client connection thread for building indexes in the
* background. In replication mode, secondaries must spawn a new thread to build background
* indexes, since there are no client connection threads to use for such purpose. IndexBuilder
* is a subclass of BackgroundJob to enable this use.
* This class is also used for building indexes in the foreground on secondaries, for
* code convenience. buildInForeground() is directly called by the replication applier to
* build an index in the foreground; the properties of BackgroundJob are not used for this use
* case.
* For background index builds, BackgroundJob::go() is called on the IndexBuilder instance,
* which begins a new thread at this class's run() method. After go() is called in the
* parent thread, waitForBgIndexStarting() must be called by the same parent thread,
* before any other thread calls go() on any other IndexBuilder instance. This is
* ensured by the replication system, since commands are effectively run single-threaded
* by the replication applier.
* The argument "constraints" specifies whether we should honor or ignore index constraints,
* The ignoring of constraints is for replication due to idempotency reasons.
* The argument "replicatedWrites" specifies whether or not this operation should replicate
* oplog entries associated with this index build.
* The argument "initIndexTs" specifies the timestamp to be used to make the initial catalog write.
*/
class IndexBuilder : public BackgroundJob {
public:
/**
* Indicates whether or not to ignore indexing errors.
*/
enum class IndexConstraints { kEnforce, kRelax };
/**
* Indicates whether or not to replicate writes.
*/
enum class ReplicatedWrites { kReplicated, kUnreplicated };
IndexBuilder(const BSONObj& index,
IndexConstraints constraints,
ReplicatedWrites replicatedWrites,
Timestamp initIndexTs = Timestamp::min());
virtual ~IndexBuilder();
virtual void run();
/**
* name of the builder, not the index
*/
virtual std::string name() const;
/**
* Instead of building the index in a background thread, build on the current thread.
*/
Status buildInForeground(OperationContext* opCtx, Database* db) const;
/**
* Waits for a background index build to register itself. This function must be called
* after starting a background index build via a BackgroundJob and before starting a
* subsequent one.
*/
static void waitForBgIndexStarting();
static bool canBuildInBackground();
private:
Status _buildAndHandleErrors(OperationContext* opCtx,
Database* db,
bool buildInBackground,
Lock::DBLock* dbLock) const;
Status _build(OperationContext* opCtx,
bool buildInBackground,
Collection* coll,
MultiIndexBlock& indexer,
Lock::DBLock* dbLock) const;
const BSONObj _index;
const IndexConstraints _indexConstraints;
const ReplicatedWrites _replicatedWrites;
const Timestamp _initIndexTs;
std::string _name; // name of this builder, not related to the index
static AtomicWord<unsigned> _indexBuildCount;
};
}
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