Watch file changes in distribution and log

Author: jozala

test/test-clusters/src/main/java/org/elasticsearch/test/cluster/local/AbstractLocalClusterFactory.java

@@ -94,6 +94,7 @@ public H create(S spec) {
         Path baseWorkingDir;
         try {
             baseWorkingDir = Files.createTempDirectory(spec.getName());
+            DebugUtils.watchDirectory(baseWorkingDir);
         } catch (IOException e) {
             throw new UncheckedIOException(e);
         }

test/test-clusters/src/main/java/org/elasticsearch/test/cluster/util/DebugUtils.java

@@ -14,8 +14,15 @@
 
 import java.io.File;
 import java.io.IOException;
+import java.nio.file.FileSystems;
 import java.nio.file.Files;
 import java.nio.file.Path;
+import java.nio.file.StandardWatchEventKinds;
+import java.nio.file.WatchEvent;
+import java.nio.file.WatchKey;
+import java.nio.file.WatchService;
+import java.util.HashMap;
+import java.util.Map;
 import java.util.stream.Stream;
 
 public class DebugUtils {
@@ -69,4 +76,67 @@ private static void listFilesRecursively(Path directoryPath) {
             e.printStackTrace();
         }
     }
+
+    public static void watchDirectory(Path directoryPath) {
+
+        Thread thread = new Thread(() -> {
+            try {
+                WatchService watchService = FileSystems.getDefault().newWatchService();
+                Map<WatchKey, Path> keyPathMap = new HashMap<>();
+
+                // Register the directory and all its subdirectories
+                registerAll(directoryPath, watchService, keyPathMap);
+
+                LOGGER.warn("Watching directory: {}", directoryPath);
+
+                while (true) {
+                    WatchKey key = watchService.take();
+                    Path dir = keyPathMap.get(key);
+
+                    for (WatchEvent<?> event : key.pollEvents()) {
+                        WatchEvent.Kind<?> kind = event.kind();
+                        Path name = (Path) event.context();
+                        Path child = dir.resolve(name);
+
+                        LOGGER.warn("Event kind: {}. File affected: {}", kind, child);
+
+                        if (kind == StandardWatchEventKinds.ENTRY_CREATE) {
+                            if (Files.isDirectory(child)) {
+                                registerAll(child, watchService, keyPathMap);
+                            }
+                        }
+                    }
+
+                    boolean valid = key.reset();
+                    if (valid == false) {
+                        keyPathMap.remove(key);
+                        if (keyPathMap.isEmpty()) {
+                            break;
+                        }
+                    }
+                }
+            } catch (IOException | InterruptedException e) {
+                e.printStackTrace();
+            }
+        });
+
+        thread.start();
+
+    }
+
+    private static void registerAll(Path start, WatchService watchService, Map<WatchKey, Path> keyPathMap) throws IOException {
+        Files.walk(start).filter(Files::isDirectory).forEach(path -> {
+            try {
+                WatchKey key = path.register(
+                    watchService,
+                    StandardWatchEventKinds.ENTRY_CREATE,
+                    StandardWatchEventKinds.ENTRY_DELETE,
+                    StandardWatchEventKinds.ENTRY_MODIFY
+                );
+                keyPathMap.put(key, path);
+            } catch (IOException e) {
+                e.printStackTrace();
+            }
+        });
+    }
 }