'stream handling' in scratchhandler needs improvement

[heppg]

In current scratchHandler, the length information is discarded. This leads to lost sync when data are not contained in one chunk of bytes arriving from socket.
Here a working sample out of my scratchClient.

while not self.stopped():
try:
#
# get the bytes from the socket
# This is not necessarily a full record, just some bytes.
#
chunk = self.scratch_socket.recv(BUFFER_SIZE)
#
# no data arriving means: connection closed
#
if len(chunk) == 0:
scratchClient.event_disconnect()
break

            data += chunk
            #
            # there are multiple records possible in one
            # received chunk
            # ... as well as the data could not be long enough for a full record.
            #
            # need at least 4 bytes to identify length of record.
            #
            while  len(data) >= 4:
                recordLen = (ord(data[0]) << 24) +     \
                            (ord(data[1]) << 16) +     \
                            (ord(data[2]) <<  8) +     \
                            (ord(data[3]) <<  0 )               
                #           
                if recordLen > 512:
                    logger.debug("unusual large record length received: {len:%d}".format(len=recordLen))   
                #
                # are there enough bytes in data for a full record ?
                # if not, leave the loop here and wait for more chunks to arrive.
                #
                if len(data) < 4+recordLen:
                    break   

                record = data[4: 4+recordLen]
                logger.debug( 'data recvd from scratch-Length: %d, Data: %s' , len(record), record)
                self.processRecord ( record )
                #
                # cut off the record from the received data
                #               
                data = data[4+recordLen:]
                #
        except socket.timeout:
            # if logger.isEnabledFor(logging.DEBUG):
            #    logger.debug( "No data received: socket timeout")
            continue
        except Exception as e:
            logger.warn(e)
            scratchClient.event_disconnect()
            self.stop()
            continue