org.cometd.server.transport.AsyncJSONTransport Maven / Gradle / Ivy
/*
* Copyright (c) 2008-2019 the original author or authors.
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.cometd.server.transport;
import java.io.IOException;
import java.nio.charset.Charset;
import java.text.ParseException;
import java.util.List;
import javax.servlet.AsyncContext;
import javax.servlet.ReadListener;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
import javax.servlet.ServletOutputStream;
import javax.servlet.WriteListener;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.cometd.bayeux.Channel;
import org.cometd.bayeux.server.ServerMessage;
import org.cometd.server.BayeuxServerImpl;
import org.cometd.server.ServerSessionImpl;
import org.eclipse.jetty.util.Utf8StringBuilder;
public class AsyncJSONTransport extends AbstractHttpTransport {
private static final String PREFIX = "long-polling.json";
private static final String NAME = "long-polling";
private static final int BUFFER_CAPACITY = 512;
private static final ThreadLocal buffers = new ThreadLocal() {
@Override
protected byte[] initialValue() {
return new byte[BUFFER_CAPACITY];
}
};
public AsyncJSONTransport(BayeuxServerImpl bayeux) {
super(bayeux, NAME);
setOptionPrefix(PREFIX);
}
@Override
public boolean accept(HttpServletRequest request) {
return "POST".equalsIgnoreCase(request.getMethod());
}
@Override
public void handle(HttpServletRequest request, HttpServletResponse response) throws IOException, ServletException {
String encoding = request.getCharacterEncoding();
if (encoding == null) {
encoding = "UTF-8";
}
request.setCharacterEncoding(encoding);
AsyncContext asyncContext = request.startAsync(request, response);
// Explicitly disable the timeout, to prevent
// that the timeout fires in case of slow reads.
asyncContext.setTimeout(0);
Charset charset = Charset.forName(encoding);
ReadListener reader = "UTF-8".equals(charset.name()) ? new UTF8Reader(request, response, asyncContext) :
new CharsetReader(request, response, asyncContext, charset);
ServletInputStream input = request.getInputStream();
input.setReadListener(reader);
}
@Override
protected HttpScheduler suspend(HttpServletRequest request, HttpServletResponse response, ServerSessionImpl session, ServerMessage.Mutable reply, long timeout) {
return newHttpScheduler(request, response, getAsyncContext(request), session, reply, timeout);
}
protected HttpScheduler newHttpScheduler(HttpServletRequest request, HttpServletResponse response, AsyncContext asyncContext, ServerSessionImpl session, ServerMessage.Mutable reply, long timeout) {
return new AsyncLongPollScheduler(request, response, asyncContext, session, reply, timeout);
}
@Override
protected void write(HttpServletRequest request, HttpServletResponse response, ServerSessionImpl session, boolean scheduleExpiration, List messages, ServerMessage.Mutable[] replies) {
AsyncContext asyncContext = getAsyncContext(request);
try {
// Always write asynchronously
response.setContentType("application/json;charset=UTF-8");
ServletOutputStream output = response.getOutputStream();
output.setWriteListener(new Writer(request, response, asyncContext, session, scheduleExpiration, messages, replies));
} catch (Exception x) {
if (_logger.isDebugEnabled()) {
_logger.debug("Exception while writing messages", x);
}
if (scheduleExpiration) {
scheduleExpiration(session);
}
error(request, response, asyncContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
}
protected void writeComplete(HttpServletRequest request, HttpServletResponse response, ServerSessionImpl session, List messages, ServerMessage.Mutable[] replies) {
}
protected abstract class AbstractReader implements ReadListener {
private final HttpServletRequest request;
private final HttpServletResponse response;
protected final AsyncContext asyncContext;
private int total;
protected AbstractReader(HttpServletRequest request, HttpServletResponse response, AsyncContext asyncContext) {
this.request = request;
this.response = response;
this.asyncContext = asyncContext;
}
@Override
public void onDataAvailable() throws IOException {
ServletInputStream input = request.getInputStream();
if (_logger.isDebugEnabled()) {
_logger.debug("Asynchronous read start from {}", input);
}
int maxMessageSize = getMaxMessageSize();
byte[] buffer = buffers.get();
while (input.isReady()) {
int read = input.read(buffer);
if (_logger.isDebugEnabled()) {
_logger.debug("Asynchronous read {} bytes from {}", read, input);
}
if (read < 0) {
break;
} else {
if (maxMessageSize > 0) {
total += read;
if (total > maxMessageSize) {
throw new IOException("Max message size " + maxMessageSize + " exceeded");
}
}
append(buffer, 0, read);
}
}
if (!input.isFinished()) {
if (_logger.isDebugEnabled()) {
_logger.debug("Asynchronous read pending from {}", input);
}
}
}
protected abstract void append(byte[] buffer, int offset, int length);
@Override
public void onAllDataRead() throws IOException {
ServletInputStream input = request.getInputStream();
String json = finish();
if (_logger.isDebugEnabled()) {
_logger.debug("Asynchronous read end from {}: {}", input, json);
}
process(json);
}
protected abstract String finish();
protected void process(String json) throws IOException {
getBayeux().setCurrentTransport(AsyncJSONTransport.this);
setCurrentRequest(request);
try {
ServerMessage.Mutable[] messages = parseMessages(json);
if (_logger.isDebugEnabled()) {
_logger.debug("Parsed {} messages", messages == null ? -1 : messages.length);
}
if (messages != null) {
processMessages(request, response, messages);
} else {
asyncContext.complete();
}
} catch (ParseException x) {
handleJSONParseException(request, response, json, x);
asyncContext.complete();
} finally {
setCurrentRequest(null);
getBayeux().setCurrentTransport(null);
}
}
@Override
public void onError(Throwable throwable) {
error(request, response, asyncContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
}
protected class UTF8Reader extends AbstractReader {
private final Utf8StringBuilder content = new Utf8StringBuilder(BUFFER_CAPACITY);
protected UTF8Reader(HttpServletRequest request, HttpServletResponse response, AsyncContext asyncContext) {
super(request, response, asyncContext);
}
@Override
protected void append(byte[] buffer, int offset, int length) {
content.append(buffer, offset, length);
}
@Override
protected String finish() {
return content.toString();
}
}
protected class CharsetReader extends AbstractReader {
private byte[] content = new byte[BUFFER_CAPACITY];
private final Charset charset;
private int count;
public CharsetReader(HttpServletRequest request, HttpServletResponse response, AsyncContext asyncContext, Charset charset) {
super(request, response, asyncContext);
this.charset = charset;
}
@Override
protected void append(byte[] buffer, int offset, int length) {
int size = content.length;
int newSize = size;
while (newSize - count < length) {
newSize <<= 1;
}
if (newSize < 0) {
throw new IllegalArgumentException("Message too large");
}
if (newSize != size) {
byte[] newContent = new byte[newSize];
System.arraycopy(content, 0, newContent, 0, count);
content = newContent;
}
System.arraycopy(buffer, offset, content, count, length);
count += length;
}
@Override
protected String finish() {
return new String(content, 0, count, charset);
}
}
protected class Writer implements WriteListener {
private final HttpServletRequest request;
private final HttpServletResponse response;
private final AsyncContext asyncContext;
private final ServerSessionImpl session;
private final boolean scheduleExpiration;
private final List messages;
private final ServerMessage.Mutable[] replies;
private int messageIndex;
private int replyIndex;
private boolean needsComma;
private State state = State.BEGIN;
protected Writer(HttpServletRequest request, HttpServletResponse response, AsyncContext asyncContext, ServerSessionImpl session, boolean scheduleExpiration, List messages, ServerMessage.Mutable[] replies) {
this.request = request;
this.response = response;
this.asyncContext = asyncContext;
this.session = session;
this.scheduleExpiration = scheduleExpiration;
this.messages = messages;
this.replies = replies;
}
@Override
public void onWritePossible() throws IOException {
ServletOutputStream output = response.getOutputStream();
if (_logger.isDebugEnabled()) {
_logger.debug("Messages/replies {}/{} to write for session {}", messages.size(), replies.length, session);
}
while (true) {
switch (state) {
case BEGIN: {
state = State.HANDSHAKE;
if (!writeBegin(output)) {
return;
}
break;
}
case HANDSHAKE: {
state = State.MESSAGES;
if (!writeHandshakeReply(output)) {
return;
}
break;
}
case MESSAGES: {
if (!writeMessages(output)) {
return;
}
state = State.REPLIES;
break;
}
case REPLIES: {
if (!writeReplies(output)) {
return;
}
state = State.END;
break;
}
case END: {
state = State.COMPLETE;
if (!writeEnd(output)) {
return;
}
break;
}
case COMPLETE: {
if (asyncContext != null) {
asyncContext.complete();
}
writeComplete(request, response, session, messages, replies);
return;
}
default: {
throw new IllegalStateException();
}
}
}
}
private boolean writeBegin(ServletOutputStream output) throws IOException {
output.write('[');
return output.isReady();
}
private boolean writeHandshakeReply(ServletOutputStream output) throws IOException {
if (replies.length > 0) {
ServerMessage.Mutable reply = replies[0];
if (Channel.META_HANDSHAKE.equals(reply.getChannel())) {
if (allowMessageDeliveryDuringHandshake(session) && !messages.isEmpty()) {
reply.put("x-messages", messages.size());
}
getBayeux().freeze(reply);
output.write(toJSONBytes(reply, "UTF-8"));
needsComma = true;
++replyIndex;
}
}
return output.isReady();
}
private boolean writeMessages(ServletOutputStream output) throws IOException {
try {
int size = messages.size();
while (output.isReady()) {
if (messageIndex == size) {
// Start the interval timeout after writing the
// messages since they may take time to be written.
startExpiration();
return true;
} else {
if (needsComma) {
output.write(',');
needsComma = false;
} else {
ServerMessage message = messages.get(messageIndex);
output.write(toJSONBytes(message, "UTF-8"));
needsComma = messageIndex < size;
++messageIndex;
}
}
}
return false;
} catch (Throwable x) {
// Start the interval timeout also in case of
// exceptions to ensure the session can be swept.
startExpiration();
throw x;
}
}
private void startExpiration() {
if (scheduleExpiration) {
scheduleExpiration(session);
}
}
private boolean writeReplies(ServletOutputStream output) throws IOException {
int size = replies.length;
while (output.isReady()) {
if (replyIndex == size) {
return true;
} else {
ServerMessage.Mutable reply = replies[replyIndex];
if (reply != null) {
if (needsComma) {
output.write(',');
needsComma = false;
} else {
getBayeux().freeze(reply);
output.write(toJSONBytes(reply, "UTF-8"));
needsComma = replyIndex < size;
++replyIndex;
}
} else {
++replyIndex;
}
}
}
return false;
}
private boolean writeEnd(ServletOutputStream output) throws IOException {
output.write(']');
return output.isReady();
}
@Override
public void onError(Throwable throwable) {
if (_logger.isDebugEnabled()) {
_logger.debug("Failure writing messages", throwable);
}
// Start the interval timeout also in case of
// errors to ensure the session can be swept.
startExpiration();
error(request, response, asyncContext, HttpServletResponse.SC_INTERNAL_SERVER_ERROR);
}
}
private enum State {
BEGIN, HANDSHAKE, MESSAGES, REPLIES, END, COMPLETE
}
private class AsyncLongPollScheduler extends LongPollScheduler {
private AsyncLongPollScheduler(HttpServletRequest request, HttpServletResponse response, AsyncContext asyncContext, ServerSessionImpl session, ServerMessage.Mutable reply, long timeout) {
super(request, response, asyncContext, session, reply, timeout);
}
@Override
protected void dispatch() {
// Direct call to resume() to write the messages in the queue and the replies.
// Since the write is async, we will never block here and thus never delay other sessions.
resume(getRequest(), getResponse(), getAsyncContext(), getServerSession(), getMetaConnectReply());
}
}
}
© 2015 - 2025 Weber Informatics LLC | Privacy Policy