org.mandas.docker.client.LogReader Maven / Gradle / Ivy
/*-
* -\-\-
* docker-client
* --
* Copyright (C) 2016 Spotify AB
* Copyright (C) 9/2019 - 2020 Dimitris Mandalidis
* --
* 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.mandas.docker.client;
import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
import org.mandas.docker.client.LogMessage.Stream;
public class LogReader implements Closeable {
private final InputStream stream;
public static final int HEADER_SIZE = 8;
public static final int FRAME_SIZE_OFFSET = 4;
public LogReader(final InputStream stream) {
this.stream = stream;
}
public LogMessage nextMessage() throws IOException {
stream.mark(HEADER_SIZE);
// Read header
final byte[] headerBytes = new byte[HEADER_SIZE];
final int n = readAllBytes(headerBytes);
if (n == 0) {
return null;
}
final ByteBuffer header = ByteBuffer.wrap(headerBytes);
int streamId = header.get();
final int idZ = header.getInt(0);
// Read frame
final byte[] frame;
// Header format is : {STREAM_TYPE, 0, 0, 0, SIZE1, SIZE2, SIZE3, SIZE4}
if (idZ == 0 || idZ == 0x01000000 || idZ == 0x02000000) {
header.position(FRAME_SIZE_OFFSET);
final int frameSize = header.getInt();
frame = new byte[frameSize];
} else {
stream.reset();
streamId = Stream.STDOUT.id();
frame = new byte[stream.available()];
}
int total = readAllBytes(frame);
if (total < frame.length) {
throw new EOFException("EOF before reading " + frame.length + " bytes. " + total + " read instead.");
}
return new LogMessage(streamId, ByteBuffer.wrap(frame));
}
private int readAllBytes(byte[] buf) throws IOException {
int total = 0;
while (total < buf.length) {
int result = stream.read(buf, total, buf.length - total);
if (result == -1) {
break;
}
total += result;
}
return total;
}
@Override
public void close() throws IOException {
stream.close();
}
}