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JDBC Type 4 driver for MySQL
/*
* Copyright (c) 2015, 2018, Oracle and/or its affiliates. All rights reserved.
*
* 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.x;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;
import java.util.Optional;
import java.util.concurrent.BlockingQueue;
import java.util.concurrent.LinkedBlockingQueue;
import java.util.concurrent.TimeUnit;
import com.google.protobuf.GeneratedMessageV3;
import com.google.protobuf.InvalidProtocolBufferException;
import com.google.protobuf.Parser;
import com.mysql.cj.exceptions.CJCommunicationsException;
import com.mysql.cj.exceptions.WrongArgumentException;
import com.mysql.cj.protocol.FullReadInputStream;
import com.mysql.cj.protocol.MessageListener;
import com.mysql.cj.protocol.MessageReader;
import com.mysql.cj.x.protobuf.Mysqlx.Error;
import com.mysql.cj.x.protobuf.Mysqlx.ServerMessages;
/**
* Synchronous-only implementation of {@link MessageReader}. This implementation wraps an {@link java.io.InputStream}.
*/
public class SyncMessageReader implements MessageReader {
/** Stream as a source of messages. */
private FullReadInputStream inputStream;
private XMessageHeader header;
/** Queue of MessageListeners waiting to process messages. */
BlockingQueue> messageListenerQueue = new LinkedBlockingQueue<>();
/** Lock to protect the pending message. */
Object dispatchingThreadMonitor = new Object();
/** Lock to protect async reads from sync ones. */
Object waitingSyncOperationMonitor = new Object();
Thread dispatchingThread = null;
public SyncMessageReader(FullReadInputStream inputStream) {
this.inputStream = inputStream;
}
@Override
public XMessageHeader readHeader() throws IOException {
// waiting for ListenersDispatcher completion to perform sync call
synchronized (this.waitingSyncOperationMonitor) {
if (this.header == null) {
this.header = readHeaderLocal();
}
if (this.header.getMessageType() == ServerMessages.Type.ERROR_VALUE) {
throw new XProtocolError(readMessageLocal(Error.class));
}
return this.header;
}
}
private XMessageHeader readHeaderLocal() throws IOException {
try {
/*
* Note that the "header" per-se is the size of all data following the header. This currently includes the message type tag (1 byte) and the
* message bytes. However since we know the type tag is present we also read it as part of the header. This may change in the future if session
* multiplexing is supported by the protocol. The protocol will be able to accommodate it but we will have to separate reading data after the
* header (size).
*/
byte[] len = new byte[5];
this.inputStream.readFully(len);
this.header = new XMessageHeader(len);
} catch (IOException ex) {
// TODO close socket?
throw new CJCommunicationsException("Cannot read packet header", ex);
}
return this.header;
}
@SuppressWarnings("unchecked")
private T readMessageLocal(Class messageClass) {
Parser parser = (Parser) MessageConstants.MESSAGE_CLASS_TO_PARSER.get(messageClass);
byte[] packet = new byte[this.header.getMessageSize()];
try {
this.inputStream.readFully(packet);
} catch (IOException ex) {
// TODO close socket?
throw new CJCommunicationsException("Cannot read packet payload", ex);
}
try {
return parser.parseFrom(packet);
} catch (InvalidProtocolBufferException ex) {
throw new WrongArgumentException(ex);
} finally {
// This must happen if we *successfully* read a packet. CJCommunicationsException will be thrown above if not
this.header = null;
}
}
@Override
public XMessage readMessage(Optional reuse, XMessageHeader hdr) throws IOException {
return readMessage(reuse, hdr.getMessageType());
}
@Override
public XMessage readMessage(Optional reuse, int expectedType) throws IOException {
// waiting for ListenersDispatcher completion to perform sync call
synchronized (this.waitingSyncOperationMonitor) {
try {
Class expectedClass = MessageConstants.getMessageClassForType(expectedType);
List notices = null;
XMessageHeader hdr;
while ((hdr = readHeader()).getMessageType() == ServerMessages.Type.NOTICE_VALUE && expectedType != ServerMessages.Type.NOTICE_VALUE) {
if (notices == null) {
notices = new ArrayList<>();
}
notices.add(Notice.getInstance(new XMessage(readMessageLocal(MessageConstants.getMessageClassForType(ServerMessages.Type.NOTICE_VALUE)))));
}
Class messageClass = MessageConstants.getMessageClassForType(hdr.getMessageType());
// ensure that parsed message class matches incoming tag
if (expectedClass != messageClass) {
throw new WrongArgumentException("Unexpected message class. Expected '" + expectedClass.getSimpleName() + "' but actually received '"
+ messageClass.getSimpleName() + "'");
}
return new XMessage(readMessageLocal(messageClass)).addNotices(notices);
} catch (IOException e) {
throw new XProtocolError(e.getMessage(), e);
}
}
}
public void pushMessageListener(final MessageListener listener) {
try {
this.messageListenerQueue.put(listener);
} catch (InterruptedException e) {
throw new CJCommunicationsException("Cannot queue message listener.", e);
}
synchronized (this.dispatchingThreadMonitor) {
if (this.dispatchingThread == null) {
ListenersDispatcher ld = new ListenersDispatcher();
this.dispatchingThread = new Thread(ld, "Message listeners dispatching thread");
this.dispatchingThread.start();
// We must ensure that ListenersDispatcher is really started before leaving
// the synchronized block. Otherwise the race condition is possible: if next
// operation is executed synchronously it could consume results of the previous
// asynchronous operation.
int millis = 5000; // TODO expose via properties ?
while (!ld.started) {
try {
Thread.sleep(10);
millis = millis - 10;
} catch (InterruptedException e) {
throw new XProtocolError(e.getMessage(), e);
}
if (millis <= 0) {
throw new XProtocolError("Timeout for starting ListenersDispatcher exceeded.");
}
}
}
}
}
private class ListenersDispatcher implements Runnable {
/**
* The timeout value for queue.poll(timeout, unit) defining the time after that we close and unregister the dispatching thread.
* On the other hand, the bigger timeout value allows to keep dispatcher thread running while multiple concurrent asynchronous
* read operations are pending, thus avoiding the delays for new dispatching threads creation.
*/
private static final long POLL_TIMEOUT = 100; // TODO expose via connection property
boolean started = false;
public ListenersDispatcher() {
}
@Override
public void run() {
synchronized (SyncMessageReader.this.waitingSyncOperationMonitor) {
this.started = true;
try {
while (true) {
MessageListener l;
if ((l = SyncMessageReader.this.messageListenerQueue.poll(POLL_TIMEOUT, TimeUnit.MILLISECONDS)) == null) {
synchronized (SyncMessageReader.this.dispatchingThreadMonitor) {
if (SyncMessageReader.this.messageListenerQueue.peek() == null) {
SyncMessageReader.this.dispatchingThread = null;
break;
}
}
} else {
try {
XMessage msg = null;
do {
XMessageHeader hdr = readHeader();
msg = readMessage(null, hdr);
} while (!l.createFromMessage(msg));
} catch (Throwable t) {
l.error(t);
}
}
}
} catch (InterruptedException e) {
throw new CJCommunicationsException("Read operation interrupted.", e);
}
}
}
}
}