/*
* Copyright © 2014 Cask Data, Inc.
*
* 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 co.cask.cdap.logging.gateway.handlers;
import ch.qos.logback.classic.LoggerContext;
import ch.qos.logback.classic.PatternLayout;
import co.cask.cdap.logging.read.Callback;
import co.cask.cdap.logging.read.LogEvent;
import co.cask.http.HttpResponder;
import com.google.common.collect.ImmutableMultimap;
import org.apache.commons.lang.StringEscapeUtils;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.handler.codec.http.HttpHeaders;
import org.jboss.netty.handler.codec.http.HttpResponseStatus;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetEncoder;
import java.nio.charset.CoderResult;
/**
* LogReader callback to encode log events, and send them as chunked stream.
*/
class ChunkedLogReaderCallback implements Callback {
private final ByteBuffer chunkBuffer = ByteBuffer.allocate(8 * 1024);
private final CharsetEncoder charsetEncoder = Charset.forName("UTF-8").newEncoder();
private final HttpResponder responder;
private final PatternLayout patternLayout;
private final boolean escape;
ChunkedLogReaderCallback(HttpResponder responder, String logPattern, boolean escape) {
this.responder = responder;
this.escape = escape;
ch.qos.logback.classic.Logger rootLogger =
(ch.qos.logback.classic.Logger) LoggerFactory.getLogger(Logger.ROOT_LOGGER_NAME);
LoggerContext loggerContext = rootLogger.getLoggerContext();
this.patternLayout = new PatternLayout();
this.patternLayout.setContext(loggerContext);
this.patternLayout.setPattern(logPattern);
}
@Override
public void init() {
this.patternLayout.start();
responder.sendChunkStart(HttpResponseStatus.OK,
ImmutableMultimap.of(HttpHeaders.Names.CONTENT_TYPE, "text/plain; charset=utf-8"));
}
@Override
public void handle(LogEvent event) {
String logLine = patternLayout.doLayout(event.getLoggingEvent());
logLine = escape ? StringEscapeUtils.escapeHtml(logLine) : logLine;
// Encode logLine and send chunks
encodeSend(CharBuffer.wrap(logLine), false);
}
@Override
public void close() {
try {
// Write the last chunk
encodeSend(CharBuffer.allocate(0), true);
// Flush the encoder
CoderResult coderResult;
do {
coderResult = charsetEncoder.flush(chunkBuffer);
chunkBuffer.flip();
responder.sendChunk(ChannelBuffers.copiedBuffer(chunkBuffer));
chunkBuffer.clear();
} while (coderResult.isOverflow());
} finally {
try {
patternLayout.stop();
} finally {
responder.sendChunkEnd();
}
}
}
private void encodeSend(CharBuffer inBuffer, boolean endOfInput) {
while (true) {
CoderResult coderResult = charsetEncoder.encode(inBuffer, chunkBuffer, endOfInput);
if (coderResult.isOverflow()) {
// if reached buffer capacity then flush chunk
chunkBuffer.flip();
responder.sendChunk(ChannelBuffers.copiedBuffer(chunkBuffer));
chunkBuffer.clear();
} else if (coderResult.isError()) {
// skip characters causing error, and retry
inBuffer.position(inBuffer.position() + coderResult.length());
} else {
// log line was completely written
break;
}
}
}
}