io.boodskap.iot.ext.fs.bin.rules.FSWatcherService Maven / Gradle / Ivy
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Simple file system poller for Boodskap IoT Platform
package io.boodskap.iot.ext.fs.bin.rules;
import static java.nio.file.StandardWatchEventKinds.ENTRY_CREATE;
import static java.nio.file.StandardWatchEventKinds.ENTRY_DELETE;
import static java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY;
import java.io.File;
import java.io.IOException;
import java.nio.file.FileSystems;
import java.nio.file.FileVisitResult;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.SimpleFileVisitor;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;
import java.nio.file.attribute.BasicFileAttributes;
import java.util.HashMap;
import java.util.Map;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
public class FSWatcherService implements Runnable {
private static final Logger LOG = LoggerFactory.getLogger(FSWatcherService.class);
public static interface Handler{
public void handle(String inout, String rule, Path path);
}
private final Handler handler;
private final WatchService watcher;
private final Map keys;
/**
* Creates a WatchService and registers the given directory
*/
FSWatcherService(Path dir, Handler handler) throws IOException {
this.handler = handler;
this.watcher = FileSystems.getDefault().newWatchService();
this.keys = new HashMap();
walkAndRegisterDirectories(dir);
}
/**
* Register the given directory with the WatchService; This function will be
* called by FileVisitor
*/
private void registerDirectory(Path dir) throws IOException {
WatchKey key = dir.register(watcher, ENTRY_CREATE, ENTRY_DELETE, ENTRY_MODIFY);
keys.put(key, dir);
}
/**
* Register the given directory, and all its sub-directories, with the
* WatchService.
*/
private void walkAndRegisterDirectories(final Path start) throws IOException {
// register directory and sub-directories
Files.walkFileTree(start, new SimpleFileVisitor() {
@Override
public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
LOG.info(String.format("Registering dir:%s for input", dir));
registerDirectory(dir);
return FileVisitResult.CONTINUE;
}
@Override
public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
final File bfile = file.toFile();
final String inout = bfile.getParentFile().getParentFile().getName();
final String rule = bfile.getParentFile().getName();
LOG.debug(String.format("Existing file type:%s rule:%s file:%s", inout, rule, file));
handler.handle(inout, rule, file);
return FileVisitResult.CONTINUE;
}
});
}
/**
* Process all events for keys queued to the watcher
*/
public void run() {
while (!Thread.currentThread().isInterrupted()) {
// wait for key to be signalled
WatchKey key;
try {
key = watcher.take();
} catch (InterruptedException x) {
return;
}
Path dir = keys.get(key);
if (dir == null) {
System.err.println("WatchKey not recognized!!");
continue;
}
for (WatchEvent> event : key.pollEvents()) {
@SuppressWarnings("rawtypes")
WatchEvent.Kind kind = event.kind();
// Context for directory entry event is the file name of entry
@SuppressWarnings("unchecked")
Path name = ((WatchEvent) event).context();
Path child = dir.resolve(name);
// print out event
LOG.debug(String.format("%s: %s\n", kind.name(), child));
// if directory is created, and watching recursively, then register it and its
// sub-directories
if (kind == ENTRY_CREATE) {
try {
if (Files.isDirectory(child)) {
walkAndRegisterDirectories(child);
}else {
final File bfile = child.toFile();
final String inout = bfile.getParentFile().getParentFile().getName();
final String rule = bfile.getParentFile().getName();
LOG.debug(String.format("New file type:%s rule:%s file:%s", inout, rule, child));
handler.handle(inout, rule, child);
}
} catch (IOException x) {
LOG.error("Processing Failed", x);
}
}
}
// reset key and remove from set if directory no longer accessible
boolean valid = key.reset();
if (!valid) {
keys.remove(key);
// all directories are inaccessible
if (keys.isEmpty()) {
break;
}
}
}
}
}