com.mysql.cj.protocol.MessageReader Maven / Gradle / Ivy
/*
* Copyright (c) 2018, 2020, Oracle and/or its affiliates.
*
* This program is free software; you can redistribute it and/or modify it under
* the terms of the GNU General Public License, version 2.0, as published by the
* Free Software Foundation.
*
* This program is also distributed with certain software (including but not
* limited to OpenSSL) that is licensed under separate terms, as designated in a
* particular file or component or in included license documentation. The
* authors of MySQL hereby grant you an additional permission to link the
* program and your derivative works with the separately licensed software that
* they have included with MySQL.
*
* Without limiting anything contained in the foregoing, this file, which is
* part of MySQL Connector/J, is also subject to the Universal FOSS Exception,
* version 1.0, a copy of which can be found at
* http://oss.oracle.com/licenses/universal-foss-exception.
*
* 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 General Public License, version 2.0,
* for more details.
*
* You should have received a copy of the GNU General Public License along with
* this program; if not, write to the Free Software Foundation, Inc.,
* 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
*/
package com.mysql.cj.protocol;
import java.io.IOException;
import java.util.Optional;
import com.mysql.cj.exceptions.CJOperationNotSupportedException;
import com.mysql.cj.exceptions.ExceptionFactory;
public interface MessageReader {
/**
* Read the next message header from server, possibly blocking indefinitely until the message is received.
*
* @return {@link MessageHeader} of the next message
* @throws IOException
* if an error occurs
*/
H readHeader() throws IOException;
/**
* Read message from server into to the given {@link Message} instance or into the new one if not present.
* For asynchronous channel it synchronously reads the next message in the stream, blocking until the message is read fully.
* Could throw CJCommunicationsException wrapping an {@link IOException} during read or parse
*
* @param reuse
* {@link Message} object to reuse. May be ignored by implementation.
* @param header
* {@link MessageHeader} instance
* @return {@link Message} instance
* @throws IOException
* if an error occurs
*/
M readMessage(Optional reuse, H header) throws IOException;
/**
* Read message from server into to the given {@link Message} instance or into the new one if not present.
* For asynchronous channel it synchronously reads the next message in the stream, blocking until the message is read fully.
* Could throw WrongArgumentException if the expected message type is not the next message (exception will be thrown in *caller* context).
*
* @param reuse
* {@link Message} object to reuse. May be ignored by implementation.
* @param expectedType
* Expected type of message.
* @return {@link Message} instance
* @throws IOException
* if an error occurs
*/
default M readMessage(Optional reuse, int expectedType) throws IOException {
throw ExceptionFactory.createException(CJOperationNotSupportedException.class, "Not supported");
}
/**
* Queue a {@link MessageListener} to receive messages delivered asynchronously.
*
* @param l
* {@link MessageListener}
*/
default void pushMessageListener(MessageListener l) {
throw ExceptionFactory.createException(CJOperationNotSupportedException.class, "Not supported");
}
/**
* Get last message sequence number, as it was stored by {@link #readHeader()}.
*
* @return number
*/
default byte getMessageSequence() {
return 0;
}
/**
* Set stored message sequence number to 0.
*/
default void resetMessageSequence() {
// no-op
}
/**
* Return a MessageReader instance free of decorators.
*
* @return {@link MessageReader}
*/
default MessageReader undecorateAll() {
return this;
}
/**
* Return the previous MessageReader instance from the decorators chain or the current MessageReader
* if it is the first entry in a chain.
*
* @return {@link MessageReader}
*/
default MessageReader undecorate() {
return this;
}
/**
* Start reading messages reader from the provided channel.
*/
default void start() {
// no-op
}
/**
* Signal to the reader that it should stop reading messages after reading the next message.
*/
default void stopAfterNextMessage() {
// no-op
}
}