/*******************************************************************************
* Copyright (c) 2012-2017 Codenvy, S.A.
* All rights reserved. This program and the accompanying materials
* are made available under the terms of the Eclipse Public License v1.0
* which accompanies this distribution, and is available at
* http://www.eclipse.org/legal/epl-v10.html
*
* Contributors:
* Codenvy, S.A. - initial API and implementation
*******************************************************************************/
package org.eclipse.che.plugin.maven.server.execution;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import java.io.IOException;
import java.io.Reader;
import java.util.concurrent.Future;
import java.util.function.Consumer;
/**
* Asynchronously non blocking read process output.
* Class use external executor to run read thread
*
* @author Evgen Vidolob
*/
public class OutputReader {
private static final Logger LOG = LoggerFactory.getLogger(OutputReader.class);
private static final int SLEEP_WHEN_WAS_ACTIVE = 1;
private static final int SLEEP_WHEN_IDLE = 5;
private final Executor executor;
private final Consumer<String> textConsumer;
private final Reader reader;
private final char[] buffer = new char[8192];
private final StringBuilder lineBuilder = new StringBuilder();
private Future<?> readingFuture;
private volatile boolean isStopped;
public OutputReader(Reader reader, Executor executor, Consumer<String> textConsumer) {
this.executor = executor;
this.textConsumer = textConsumer;
this.reader = reader;
}
/**
* Start reading thread
*/
public void start() {
if (readingFuture == null) {
readingFuture = executor.execute(() -> doStart());
}
}
public void stop() {
isStopped = true;
}
public void waitFor() throws InterruptedException {
try {
readingFuture.get();
} catch (java.util.concurrent.ExecutionException e) {
LOG.error(e.getMessage(), e);
}
}
private void doStart() {
try {
while (true) {
boolean active = readIfAvailable();
if (isStopped) {
break;
}
try {
Thread.sleep(getTimeToSleep(active));
} catch (InterruptedException ignored) {
}
}
} catch (Exception e) {
LOG.error(e.getMessage(), e);
} finally {
close();
}
}
private void close() {
try {
reader.close();
} catch (IOException e) {
LOG.error("Can't close stream", e);
}
}
private int getTimeToSleep(boolean active) {
return active ? SLEEP_WHEN_WAS_ACTIVE : SLEEP_WHEN_IDLE;
}
private boolean readIfAvailable() throws IOException {
boolean read = false;
int charCount;
while (reader.ready() && (charCount = reader.read(buffer)) > 1) {
read = true;
processRead(lineBuilder, buffer, charCount);
}
if (lineBuilder.length() > 0) {
consumeLine(lineBuilder);
}
return read;
}
private void consumeLine(StringBuilder lineBuilder) {
textConsumer.accept(lineBuilder.toString());
lineBuilder.setLength(0);
}
private void processRead(StringBuilder lineBuilder, char[] buffer, int charCount) {
for (int i = 0; i < charCount; i++) {
char c = buffer[i];
lineBuilder.append(c);
if (c == '\n') {
consumeLine(lineBuilder);
}
}
}
}