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/**
* Copyright (C) 2015 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
namespace mongo {
class OperationContext;
class Status;
/**
* Manages the persistence and recovery of the sharding config metadata's min opTime.
*
* The opTime recovery document resides in the admin.system.version collection and has the
* following format:
*
* { _id: "minOpTimeRecovery",
* minOpTime: { ts: Timestamp 1443820968000|1, t: 11 },
* minOptimeUpdaters: 1 }
*/
class ShardingStateRecovery {
public:
/**
* Marks the beginning of a sharding metadata operation which requires recovery of the config
* server's minOpTime after node failure. It is only safe to commence the operation after this
* method returns an OK status.
*/
static Status startMetadataOp(OperationContext* opCtx);
/**
* Marks the end of a sharding metadata operation, persisting the latest config server opTime at
* the time of the call.
*/
static void endMetadataOp(OperationContext* opCtx);
/**
* Recovers the minimal config server opTime that the instance should be using for reading
* sharding metadata so that the instance observes all metadata modifications it did the last
* time it was active (or PRIMARY, if replica set).
*
* NOTE: This method will block until recovery completes.
*
* Returns OK if the minOpTime was successfully recovered or failure status otherwise. It is
* unsafe to read and rely on any sharding metadata before this method has returned success.
*/
static Status recover(OperationContext* opCtx);
};
} // namespace mongo
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