connectionmanager.hxx

来自「vovida的软交换」· HXX 代码 · 共 196 行

/* ====================================================================
 * The Vovida Software License, Version 1.0 
 * 
 * Copyright (c) 2000 Vovida Networks, Inc.  All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 * 
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in
 *    the documentation and/or other materials provided with the
 *    distribution.
 * 
 * 3. The names "VOCAL", "Vovida Open Communication Application Library",
 *    and "Vovida Open Communication Application Library (VOCAL)" must
 *    not be used to endorse or promote products derived from this
 *    software without prior written permission. For written
 *    permission, please contact [e-mail].
 *
 * 4. Products derived from this software may not be called "VOCAL", nor
 *    may "VOCAL" appear in their name, without prior written
 *    permission of Vovida Networks, Inc.
 * 
 * THIS SOFTWARE IS PROVIDED "AS IS" AND ANY EXPRESSED OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
 * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, TITLE AND
 * NON-INFRINGEMENT ARE DISCLAIMED.  IN NO EVENT SHALL VOVIDA
 * NETWORKS, INC. OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT DAMAGES
 * IN EXCESS OF $1,000, NOR FOR ANY INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
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 * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH
 * DAMAGE.
 * 
 * ====================================================================
 * 
 * This software consists of voluntary contributions made by Vovida
 * Networks, Inc. and many individuals on behalf of Vovida Networks,
 * Inc.  For more information on Vovida Networks, Inc., please see
 * <http://www.vovida.org/>.
 *
 */

#ifndef CONNECTIONMANAGER_HXX
#define CONNECTIONMANAGER_HXX

#include "DBConnection.hxx"
#include "Mutex.hxx"
#include "Lock.hxx"
#include <vector>

/**
 *  This class gives the Cache access to the database.
 *
 *  ConnectionManager maintains a 'pool' of database 
 *  connection info (DBConInfo) objects each of which
 *  contain a pointer to the DBConnection. 
 * 
 *  A client can obtain a DBConnection* by calling the 
 *  public accessor function "searchDBConPool()", and
 *  'free' this connection when its duty is finished.    
 * 
 *  ConnectionManager.hxx   version 1.0 -- 14 Mar 2003
 *                          Suha Cubukcuoglu
 *
 */

/** Forward Declare DBConnection class */
class DBConnection;

/** Maximum number of Database Connections
 * that are allowed in the pool. 
 */

#define MAX_CONNECTIONS 5

class ConnectionManager
{
    private:
    
        /** Pointer to the instance of this class */
        static ConnectionManager *myConManager;
    
        /** Constructor */
        ConnectionManager(void):
        // initialize an empty pool of DBConInfo objects
        DBConPool()   
        {   // initialize Pointer to DBConnection                                                                                 
            myDBConnectionP = 0;
        };

	    /** Pointer to DBConnection */
        DBConnection* myDBConnectionP;
        
        /** DBConnection objects
         *  @param myDBCon Pointer to DBConnection obj 
         *  @param used    Status of the connection 
         *  @param myTime  Timestamp for creation
         */
  
        typedef struct dbconninfo
        {
            DBConnection * myDBCon; 
            bool used;
            time_t myTime;
        
        } DBConInfo;
        
        /** Total number of connections to the database */
        static int NumDBCons;
        
        /** DBConPool vector has elements of type DBConInfo */   
        vector <DBConInfo> DBConPool;
        
        /** Number of unused DBConnections */
        static int freeDBCon;
        
	    /** Used to lock access to the DBConPool */
        static Vocal::Threads::Mutex myMutex;
        
    public:
        
        /** Returns a pointer to the existing instance
         *  of the ConnectionManager object, or creates
         *  one if none exist.
         */
        static ConnectionManager* getInstance(void);    
    
        /** Destructor */
        virtual ~ConnectionManager(void)
        {   // destroy pointer to DBConnection
            delete myDBConnectionP;
        };
    
        /** handle instructions from DBInfo */
        DBConnection* GetDBConnection(const DBInfo dbInfo);

        /**
         *  Search for existing DB connections in DBConPool.
         *  If the pool is empty, get a new connection, mark
         *  it 'used' and return it. Otherwise, find a conn
         *  which is unused, if unsuccessful, create a new  
         *  conn, mark it 'used' and pass it back to the
         *  calling environment.
         *  @param dbInfo used to set up DB connection
         *  @return DBConnection to be passed back
         */
          
        DBConnection* searchDBConPool(const DBInfo dbInfo);  

        /** 
         * Checks DBConnections in DBConPool. 
         * Removes those DBConInfo objects which have broken
         * DBConnections's.
         */

        void checkDBConns(); 
        
        /** 
         * Process a DBConnection free'd by a client.
         * @param dbconn connection to return
         * @return false if the connection does not exist.
         */
        bool returnDBCon(DBConnection * dbconn);
         
        /** 
         * Size of DBConPool.
         * @return size of pool of DBConInfo objects 
         */ 
        int dbPoolSize(){ return NumDBCons; }
        
        /**
         * Increment number of unused DBConnections.
         */
        void incrementFreeDBCon() { freeDBCon++; }

        /** 
         * Decrement number of unused DBConnections 
         */
        void decrementFreeDBCon() { freeDBCon--; }

        /**
         * Return number of unused DBConnections
         * @return free DB connctions 
         */
        int unusedDBCon(){ return freeDBCon; }   
}; 
#endif