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/**
* Copyright (C) 2017 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 <vector>
#include "mongo/base/disallow_copying.h"
#include "mongo/base/status_with.h"
#include "mongo/base/string_data.h"
#include "mongo/s/catalog/type_chunk.h"
#include "mongo/s/catalog/type_collection.h"
#include "mongo/s/chunk_version.h"
#include "mongo/util/concurrency/notification.h"
namespace mongo {
class NamespaceString;
class OperationContext;
/**
* Interface through which the sharding catalog cache requests the set of changed chunks to be
* retrieved from the persisted metadata store.
*/
class CatalogCacheLoader {
public:
virtual ~CatalogCacheLoader() = default;
/**
* Used as a return value for getChunksSince.
*/
struct CollectionAndChangedChunks {
CollectionAndChangedChunks();
CollectionAndChangedChunks(const OID& collEpoch,
const BSONObj& collShardKeyPattern,
const BSONObj& collDefaultCollation,
bool collShardKeyIsUnique,
std::vector<ChunkType> chunks);
// Information about the entire collection
OID epoch;
BSONObj shardKeyPattern;
BSONObj defaultCollation;
bool shardKeyIsUnique{false};
// The chunks which have changed sorted by their chunkVersion. This list might potentially
// contain all the chunks in the collection.
std::vector<ChunkType> changedChunks;
};
/**
* Initializes internal state. Must be called only once when sharding state is initialized.
*/
virtual void initializeReplicaSetRole(bool isPrimary) = 0;
/**
* Changes internal state on step down.
*/
virtual void onStepDown() = 0;
/**
* Changes internal state on step up.
*/
virtual void onStepUp() = 0;
/**
* Notifies the loader that the persisted collection version for 'nss' has been updated.
*/
virtual void notifyOfCollectionVersionUpdate(OperationContext* opCtx,
const NamespaceString& nss,
const ChunkVersion& version) = 0;
/**
* Waits for the persisted collection version to be GTE to 'version', or an epoch change.
*/
virtual Status waitForCollectionVersion(OperationContext* opCtx,
const NamespaceString& nss,
const ChunkVersion& version) = 0;
/**
* Non-blocking call, which requests the chunks changed since the specified version to be
* fetched from the persistent metadata store and invokes the callback function with the result.
* The callback function must never throw - it is a fatal error to do so.
*
* If for some reason the asynchronous fetch operation cannot be dispatched (for example on
* shutdown), throws a DBException. Otherwise it is guaranteed that the callback function will
* be invoked even on error and the returned notification will be signalled.
*
* The callbackFn object must not be destroyed until it has been called. The returned
* Notification object can be waited on in order to ensure that.
*/
virtual std::shared_ptr<Notification<void>> getChunksSince(
const NamespaceString& nss,
ChunkVersion version,
stdx::function<void(OperationContext*, StatusWith<CollectionAndChangedChunks>)>
callbackFn) = 0;
protected:
CatalogCacheLoader() = default;
};
} // namespace mongo
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