/**
 *    Copyright (C) 2013 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 <deque>

#include "mongo/bson/bsonobj.h"
#include "mongo/s/multi_command_dispatch.h"

namespace mongo {

    /**
     * A DBClientMultiCommand uses the client driver (DBClientConnections) to send and recv
     * commands to different hosts in parallel.
     *
     * See MultiCommandDispatch for more details.
     */
    class DBClientMultiCommand : public MultiCommandDispatch {
    public:

        DBClientMultiCommand() : _timeoutMillis( 0 ) {}

        ~DBClientMultiCommand();

        void addCommand( const ConnectionString& endpoint,
                         const StringData& dbName,
                         const BSONSerializable& request );

        void sendAll();

        int numPending() const;

        Status recvAny( ConnectionString* endpoint, BSONSerializable* response );

        void setTimeoutMillis( int milliSecs );

    private:

        // All info associated with an pre- or in-flight command
        struct PendingCommand {

            PendingCommand( const ConnectionString& endpoint,
                            const StringData& dbName,
                            const BSONObj& cmdObj );

            // What to send
            const ConnectionString endpoint;
            const string dbName;
            const BSONObj cmdObj;

            // Where to send it
            DBClientBase* conn;

            // If anything goes wrong
            Status status;
        };

        typedef std::deque<PendingCommand*> PendingQueue;
        PendingQueue _pendingCommands;
        int _timeoutMillis;
    };

}
