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　　DBPort 是表示數據庫端口的類，分別用 call 和 say 方法實現讀取和寫入操作。
　　這兩個方法都調用了 go 方法。

    // 讀取操作
    Response call( OutMessage msg , DBCollection coll )
        throws IOException {
        return go( msg , coll );
    }

    // 寫入操作
    void say( OutMessage msg )
        throws IOException {
        go( msg , null );
    }

    // 執行操作
    private synchronized Response go( OutMessage msg , DBCollection coll )
        throws IOException {
        return go( msg , coll , false );
    }

    // 執行操作
    private synchronized Response go( OutMessage msg , DBCollection coll , boolean forceReponse )
        throws IOException {

        // 正在處理請求
        if ( _processingResponse ){
            if ( coll == null ){
                // this could be a pipeline and should be safe
            }
            else {
                // this could cause issues since we're reading data off the wire
                throw new IllegalStateException( "DBPort.go called and expecting a response while processing another response" );
            }
        }

        // 增加調用次數計數
        _calls++;
    
        // _sorket 為空，打開連接
        if ( _socket == null )
            _open();
        
        if ( _out == null )
            throw new IllegalStateException( "_out shouldn't be null" );

        try {
            // 準備消息
            msg.prepare();

            // 輸出
            msg.pipe( _out );
            
            if ( _pool != null )
                _pool._everWorked = true;
            
            if ( coll == null && ! forceReponse )
                return null;
            
            _processingResponse = true;

            // 返回結果
            return new Response( _sa , coll , _in , _decoder);
        }
        catch ( IOException ioe ){
            close();
            throw ioe;
        }
        finally {
            _processingResponse = false;
        }
    }

　　DBProt 的 go 方法調用了 OutMessage 的 prepare、pipe 等方法，實際上這些方法又是間接地通過 PoolOutputBuffer 實現的，這將在后面的文章中提到。

　　另外 DBPort 的 open 方法用于打開數據連接：

    // 打開連接
    boolean _open()
        throws IOException {
        
        long sleepTime = 100;

        final long start = System.currentTimeMillis();
        while ( true ){
            
            IOException lastError = null;

            try {
                // 創建 socket 并連接
                _socket = new Socket();
                _socket.connect( _addr , _options.connectTimeout );
                
                // 設置 socket 參數
                _socket.setTcpNoDelay( ! USE_NAGLE );
                _socket.setKeepAlive( _options.socketKeepAlive );
                _socket.setSoTimeout( _options.socketTimeout );

                // 獲取輸入輸出流
                _in = new BufferedInputStream( _socket.getInputStream() );
                _out = _socket.getOutputStream();
                return true;
            }
            catch ( IOException ioe ){
               // ...
            }
            
            if ( ! _options.autoConnectRetry || ( _pool != null && ! _pool._everWorked ) )
                throw lastError;


            // 超時處理
            
            long sleptSoFar = System.currentTimeMillis() - start;

            if ( sleptSoFar >= CONN_RETRY_TIME_MS )
                throw lastError;
            
            if ( sleepTime + sleptSoFar > CONN_RETRY_TIME_MS )
                sleepTime = CONN_RETRY_TIME_MS - sleptSoFar;

            //  等待重試
            _logger.severe( "going to sleep and retry.  total sleep time after = " + ( sleptSoFar + sleptSoFar ) + "ms  this time:" + sleepTime + "ms" );
            ThreadUtil.sleep( sleepTime );
            sleepTime *= 2;
        }
    }