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76 lines
2.5 KiB
C++
76 lines
2.5 KiB
C++
// @file d_writeback.h
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/**
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* Copyright (C) 2010 10gen Inc.
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Affero General Public License, version 3,
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* as published by the Free Software Foundation.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU Affero General Public License for more details.
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*
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* You should have received a copy of the GNU Affero General Public License
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* along with this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#pragma once
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#include "../pch.h"
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#include "../util/queue.h"
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namespace mongo {
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/*
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* The WriteBackManager keeps one queue of pending operations per mongos. The operations get here
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* if they were directed to a chunk that is no longer in this mongod server. The operations are
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* "written back" to the mongos server per its request (command 'writebacklisten').
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*
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* The class is thread safe.
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*/
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class WriteBackManager{
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public:
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WriteBackManager();
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~WriteBackManager();
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/*
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* @param remote server ID this operation came from
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* @param op the operation itself
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*
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* Enqueues opeartion 'op' in server 'remote's queue. The operation will be written back to
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* remote at a later stager.
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*/
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void queueWriteBack( const string& remote , const BSONObj& op );
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/*
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* @param remote server ID
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* @return the queue for operations that came from 'remote'
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*
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* Gets access to server 'remote's queue, which is synchronized.
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*/
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BlockingQueue<BSONObj>* getWritebackQueue( const string& remote );
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/*
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* @return true if there is no operation queued for write back
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*/
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bool queuesEmpty() const;
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private:
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// a map from mongos's serverIDs to queues of "rejected" operations
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// an operation is rejected if it targets data that does not live on this shard anymore
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typedef map< string , BlockingQueue<BSONObj>* > WriteBackQueuesMap;
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// '_writebackQueueLock' protects only the map itself, since each queue is syncrhonized.
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mutable mongo::mutex _writebackQueueLock;
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WriteBackQueuesMap _writebackQueues;
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};
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// TODO collect global state in a central place and init during startup
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extern WriteBackManager writeBackManager;
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} // namespace mongo
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