com.spotify.docker.client.LogReader Maven / Gradle / Ivy
/*
* Copyright (c) 2014 Spotify AB.
*
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you 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 com.spotify.docker.client;
import com.google.common.io.ByteStreams;
import java.io.Closeable;
import java.io.EOFException;
import java.io.IOException;
import java.io.InputStream;
import java.nio.ByteBuffer;
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;
}
@Override
public void close() throws IOException {
stream.close();
}
public LogMessage nextMessage() throws IOException {
// Read header
final byte[] headerBytes = new byte[HEADER_SIZE];
final int n = ByteStreams.read(stream, headerBytes, 0, HEADER_SIZE);
if (n == 0) {
return null;
}
if (n != HEADER_SIZE) {
throw new EOFException();
}
final ByteBuffer header = ByteBuffer.wrap(headerBytes);
final int streamId = header.get();
header.position(FRAME_SIZE_OFFSET);
final int frameSize = header.getInt();
// Read frame
final byte[] frame = new byte[frameSize];
ByteStreams.readFully(stream, frame);
return new LogMessage(streamId, ByteBuffer.wrap(frame));
}
}