com.spotify.helios.testing.InMemoryLogStreamFollower Maven / Gradle / Ivy
/*-
* -\-\-
* Helios Testing Library
* --
* Copyright (C) 2016 Spotify AB
* --
* 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 com.spotify.helios.testing;
import com.spotify.docker.client.LogMessage;
import com.spotify.helios.common.descriptors.JobId;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.nio.ByteBuffer;
import java.util.Iterator;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.ConcurrentMap;
/**
* A {@link LogStreamFollower} implementation that captures all container stdout/stderr to memory.
* Provided mostly for debugging and other limited use cases, since extended container output
* will be kept in memory without bound.
*/
public class InMemoryLogStreamFollower implements LogStreamFollower {
private final ConcurrentMap streamHolders;
private InMemoryLogStreamFollower(
final ConcurrentMap streamHolders) {
this.streamHolders = streamHolders;
}
public static InMemoryLogStreamFollower create() {
return new InMemoryLogStreamFollower(new ConcurrentHashMap());
}
/**
* Get all the stdout that has been emitted by a container.
*
* @param jobId The {@link JobId} for the container in question.
*
* @return A byte array of everything written to stdout.
*/
public byte[] getStdout(final JobId jobId) {
return streamHolders.get(jobId).stdout.toByteArray();
}
/**
* Get all the stderr that has been emitted by a container.
*
* @param jobId The {@link JobId} for the container in question.
*
* @return A byte array of everything written to stderr.
*/
public byte[] getStderr(final JobId jobId) {
return streamHolders.get(jobId).stderr.toByteArray();
}
@Override
public void followLog(
final JobId jobId, final String containerId, final Iterator logStream)
throws IOException {
try (final ByteArrayOutputStream stdout = new ByteArrayOutputStream();
final ByteArrayOutputStream stderr = new ByteArrayOutputStream()) {
streamHolders.put(jobId, new StreamHolder(stdout, stderr));
while (logStream.hasNext()) {
final LogMessage message = logStream.next();
final ByteBuffer content = message.content();
switch (message.stream()) {
case STDOUT:
writeAndFlush(content, stdout);
break;
case STDERR:
writeAndFlush(content, stderr);
break;
case STDIN:
default:
break;
}
}
}
}
/** Write the contents of the given ByteBuffer to the OutputStream and flush the stream. */
private static void writeAndFlush(
final ByteBuffer buffer, final OutputStream outputStream) throws IOException {
if (buffer.hasArray()) {
outputStream.write(buffer.array(), buffer.position(), buffer.remaining());
} else {
// cannot access underlying byte array, need to copy into a temporary array
while (buffer.hasRemaining()) {
// figure out how much to read, but use an upper limit of 8kb. LogMessages should be rather
// small so we don't expect this to get hit but avoid large temporary buffers, just in case.
final int size = Math.min(buffer.remaining(), 8 * 1024);
final byte[] chunk = new byte[size];
buffer.get(chunk);
outputStream.write(chunk);
}
}
outputStream.flush();
}
private static final class StreamHolder {
final ByteArrayOutputStream stdout;
final ByteArrayOutputStream stderr;
StreamHolder(final ByteArrayOutputStream stdout, final ByteArrayOutputStream stderr) {
this.stdout = stdout;
this.stderr = stderr;
}
}
}