FileChangeWatcherTest.java
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* 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,
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package org.apache.zookeeper.common;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertFalse;
import static org.junit.jupiter.api.Assertions.assertTrue;
import java.io.File;
import java.io.IOException;
import java.nio.charset.StandardCharsets;
import java.nio.file.StandardWatchEventKinds;
import java.nio.file.WatchEvent;
import java.util.ArrayList;
import java.util.List;
import java.util.concurrent.atomic.AtomicInteger;
import org.apache.commons.io.FileUtils;
import org.apache.zookeeper.ZKTestCase;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.io.TempDir;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class FileChangeWatcherTest extends ZKTestCase {
@TempDir
static File tempDir;
static File tempFile;
private static final Logger LOG = LoggerFactory.getLogger(FileChangeWatcherTest.class);
private static final long FS_TIMEOUT = 30000L;
@BeforeAll
public static void createTempFile() throws IOException {
tempFile = File.createTempFile("zk_test_", "", tempDir);
}
@Test
public void testCallbackWorksOnFileChanges() throws IOException, InterruptedException {
FileChangeWatcher watcher = null;
try {
final List<WatchEvent<?>> events = new ArrayList<>();
watcher = new FileChangeWatcher(tempDir.toPath(), event -> {
LOG.info("Got an update: {} {}", event.kind(), event.context());
// Filter out the extra ENTRY_CREATE events that are
// sometimes seen at the start. Even though we create the watcher
// after the file exists, sometimes we still get a create event.
if (StandardWatchEventKinds.ENTRY_CREATE.equals(event.kind())) {
return;
}
synchronized (events) {
events.add(event);
events.notifyAll();
}
});
watcher.start();
watcher.waitForState(FileChangeWatcher.State.RUNNING);
Thread.sleep(1000L); // TODO hack
for (int i = 0; i < 3; i++) {
LOG.info("Modifying file, attempt {}", (i + 1));
FileUtils.writeStringToFile(tempFile, "Hello world " + i + "\n", StandardCharsets.UTF_8, true);
synchronized (events) {
if (events.size() < i + 1) {
events.wait(FS_TIMEOUT);
}
assertEquals(i + 1, events.size(), "Wrong number of events");
WatchEvent<?> event = events.get(i);
assertEquals(StandardWatchEventKinds.ENTRY_MODIFY, event.kind());
assertEquals(tempFile.getName(), event.context().toString());
}
}
} finally {
if (watcher != null) {
watcher.stop();
watcher.waitForState(FileChangeWatcher.State.STOPPED);
}
}
}
@Test
public void testCallbackWorksOnFileTouched() throws IOException, InterruptedException {
FileChangeWatcher watcher = null;
try {
final List<WatchEvent<?>> events = new ArrayList<>();
watcher = new FileChangeWatcher(tempDir.toPath(), event -> {
LOG.info("Got an update: {} {}", event.kind(), event.context());
// Filter out the extra ENTRY_CREATE events that are
// sometimes seen at the start. Even though we create the watcher
// after the file exists, sometimes we still get a create event.
if (StandardWatchEventKinds.ENTRY_CREATE.equals(event.kind())) {
return;
}
synchronized (events) {
events.add(event);
events.notifyAll();
}
});
watcher.start();
watcher.waitForState(FileChangeWatcher.State.RUNNING);
Thread.sleep(1000L); // TODO hack
LOG.info("Touching file");
FileUtils.touch(tempFile);
synchronized (events) {
if (events.isEmpty()) {
events.wait(FS_TIMEOUT);
}
assertFalse(events.isEmpty());
WatchEvent<?> event = events.get(0);
assertEquals(StandardWatchEventKinds.ENTRY_MODIFY, event.kind());
assertEquals(tempFile.getName(), event.context().toString());
}
} finally {
if (watcher != null) {
watcher.stop();
watcher.waitForState(FileChangeWatcher.State.STOPPED);
}
}
}
@Test
public void testCallbackWorksOnFileAdded() throws IOException, InterruptedException {
FileChangeWatcher watcher = null;
try {
final List<WatchEvent<?>> events = new ArrayList<>();
watcher = new FileChangeWatcher(tempDir.toPath(), event -> {
LOG.info("Got an update: {} {}", event.kind(), event.context());
synchronized (events) {
events.add(event);
events.notifyAll();
}
});
watcher.start();
watcher.waitForState(FileChangeWatcher.State.RUNNING);
Thread.sleep(1000L); // TODO hack
File tempFile2 = File.createTempFile("zk_test_", "", tempDir);
tempFile2.deleteOnExit();
synchronized (events) {
if (events.isEmpty()) {
events.wait(FS_TIMEOUT);
}
assertFalse(events.isEmpty());
WatchEvent<?> event = events.get(0);
assertEquals(StandardWatchEventKinds.ENTRY_CREATE, event.kind());
assertEquals(tempFile2.getName(), event.context().toString());
}
} finally {
if (watcher != null) {
watcher.stop();
watcher.waitForState(FileChangeWatcher.State.STOPPED);
}
}
}
@Test
public void testCallbackWorksOnFileDeleted() throws IOException, InterruptedException {
FileChangeWatcher watcher = null;
try {
final List<WatchEvent<?>> events = new ArrayList<>();
watcher = new FileChangeWatcher(tempDir.toPath(), event -> {
LOG.info("Got an update: {} {}", event.kind(), event.context());
// Filter out the extra ENTRY_CREATE events that are
// sometimes seen at the start. Even though we create the watcher
// after the file exists, sometimes we still get a create event.
if (StandardWatchEventKinds.ENTRY_CREATE.equals(event.kind())) {
return;
}
synchronized (events) {
events.add(event);
events.notifyAll();
}
});
watcher.start();
watcher.waitForState(FileChangeWatcher.State.RUNNING);
Thread.sleep(1000L); // TODO hack
tempFile.delete();
synchronized (events) {
if (events.isEmpty()) {
events.wait(FS_TIMEOUT);
}
assertFalse(events.isEmpty());
WatchEvent<?> event = events.get(0);
assertEquals(StandardWatchEventKinds.ENTRY_DELETE, event.kind());
assertEquals(tempFile.getName(), event.context().toString());
}
} finally {
if (watcher != null) {
watcher.stop();
watcher.waitForState(FileChangeWatcher.State.STOPPED);
}
}
}
@Test
public void testCallbackErrorDoesNotCrashWatcherThread() throws IOException, InterruptedException {
FileChangeWatcher watcher = null;
try {
final AtomicInteger callCount = new AtomicInteger(0);
watcher = new FileChangeWatcher(tempDir.toPath(), event -> {
LOG.info("Got an update: {} {}", event.kind(), event.context());
int oldValue;
synchronized (callCount) {
oldValue = callCount.getAndIncrement();
callCount.notifyAll();
}
if (oldValue == 0) {
throw new RuntimeException("This error should not crash the watcher thread");
}
});
watcher.start();
watcher.waitForState(FileChangeWatcher.State.RUNNING);
Thread.sleep(1000L); // TODO hack
LOG.info("Modifying file");
FileUtils.writeStringToFile(tempFile, "Hello world\n", StandardCharsets.UTF_8, true);
synchronized (callCount) {
while (callCount.get() == 0) {
callCount.wait(FS_TIMEOUT);
}
}
LOG.info("Modifying file again");
FileUtils.writeStringToFile(tempFile, "Hello world again\n", StandardCharsets.UTF_8, true);
synchronized (callCount) {
if (callCount.get() == 1) {
callCount.wait(FS_TIMEOUT);
}
}
// The value of callCount can exceed 1 only if the callback thread
// survives the exception thrown by the first callback.
assertTrue(callCount.get() > 1);
} finally {
if (watcher != null) {
watcher.stop();
watcher.waitForState(FileChangeWatcher.State.STOPPED);
}
}
}
}