| /** |
| * Licensed to the Apache Software Foundation (ASF) under one |
| * or more contributor license agreements. See the NOTICE file |
| * 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, 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 org.apache.aries.rsa.discovery.zookeeper.repository; |
| |
| import java.io.ByteArrayInputStream; |
| import java.io.ByteArrayOutputStream; |
| import java.io.Closeable; |
| import java.io.IOException; |
| import java.util.ArrayList; |
| import java.util.Arrays; |
| import java.util.Collection; |
| import java.util.List; |
| import java.util.Map; |
| import java.util.concurrent.ConcurrentHashMap; |
| |
| import org.apache.aries.rsa.discovery.endpoint.EndpointDescriptionParser; |
| import org.apache.zookeeper.CreateMode; |
| import org.apache.zookeeper.KeeperException; |
| import org.apache.zookeeper.KeeperException.ConnectionLossException; |
| import org.apache.zookeeper.KeeperException.NoNodeException; |
| import org.apache.zookeeper.KeeperException.NodeExistsException; |
| import org.apache.zookeeper.KeeperException.SessionExpiredException; |
| import org.apache.zookeeper.WatchedEvent; |
| import org.apache.zookeeper.Watcher; |
| import org.apache.zookeeper.Watcher.Event.EventType; |
| import org.apache.zookeeper.ZooDefs.Ids; |
| import org.apache.zookeeper.ZooKeeper; |
| import org.apache.zookeeper.data.Stat; |
| import org.osgi.service.remoteserviceadmin.EndpointDescription; |
| import org.osgi.service.remoteserviceadmin.EndpointEvent; |
| import org.osgi.service.remoteserviceadmin.EndpointEventListener; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| public class ZookeeperEndpointRepository implements Closeable, Watcher { |
| private static final Logger LOG = LoggerFactory.getLogger(ZookeeperEndpointRepository.class); |
| private final ZooKeeper zk; |
| private final EndpointDescriptionParser parser; |
| private EndpointEventListener listener; |
| public static final String PATH_PREFIX = "/osgi/service_registry"; |
| |
| private Map<String, EndpointDescription> nodes = new ConcurrentHashMap<String, EndpointDescription>(); |
| |
| public ZookeeperEndpointRepository(ZooKeeper zk) { |
| this(zk, null); |
| } |
| |
| public ZookeeperEndpointRepository(ZooKeeper zk, EndpointEventListener listener) { |
| this.zk = zk; |
| this.listener = listener; |
| this.parser = new EndpointDescriptionParser(); |
| try { |
| createPath(PATH_PREFIX); |
| } catch (Exception e) { |
| throw new IllegalStateException("Unable to create base path"); |
| } |
| this.registerWatcher(); |
| } |
| |
| public void addListener(EndpointEventListener listener) { |
| this.listener = listener; |
| } |
| |
| /** |
| * Read current endpoint stored at a znode |
| * |
| * @param path |
| * @return |
| */ |
| public EndpointDescription read(String path) { |
| return nodes.get(path); |
| } |
| |
| public void add(EndpointDescription endpoint) throws KeeperException, InterruptedException { |
| String path = getZooKeeperPath(endpoint.getId()); |
| LOG.info("Exporting endpoint to zookeeper. Endpoint: {}, Path: {}", endpoint, path); |
| createBasePath(); |
| createEphemeralNode(path, getData(endpoint)); |
| } |
| |
| public void modify(EndpointDescription endpoint) throws KeeperException, InterruptedException { |
| String path = getZooKeeperPath(endpoint.getId()); |
| LOG.info("Changing endpoint in zookeeper. Endpoint: {}, Path: {}", endpoint, path); |
| createBasePath(); |
| zk.setData(path, getData(endpoint), -1); |
| } |
| |
| public void remove(EndpointDescription endpoint) throws InterruptedException, KeeperException { |
| String path = getZooKeeperPath(endpoint.getId()); |
| LOG.info("Removing endpoint in zookeeper. Endpoint: {}, Path: {}", endpoint, path); |
| zk.delete(path, -1); |
| } |
| |
| public Collection<EndpointDescription> getAll() { |
| return nodes.values(); |
| } |
| |
| /** |
| * Removes nulls and empty strings from the given string array. |
| * |
| * @param strings an array of strings |
| * @return a new array containing the non-null and non-empty |
| * elements of the original array in the same order |
| */ |
| public static List<String> removeEmpty(List<String> strings) { |
| List<String> result = new ArrayList<String>(); |
| if (strings == null) { |
| return result; |
| } |
| for (String s : strings) { |
| if (s != null && !s.isEmpty()) { |
| result.add(s); |
| } |
| } |
| return result; |
| } |
| |
| public static String getZooKeeperPath(String name) { |
| String escaped = name.replace('/', '#'); |
| return name == null || name.isEmpty() ? PATH_PREFIX : PATH_PREFIX + '/' + escaped; |
| } |
| |
| @Override |
| public void process(WatchedEvent event) { |
| LOG.info("Received event {}", event); |
| if (event.getType() == EventType.NodeDeleted) { |
| handleRemoved(event.getPath()); |
| return; |
| } |
| watchRecursive(event.getPath()); |
| } |
| |
| @Override |
| public void close() throws IOException { |
| nodes.clear(); |
| } |
| |
| private void createBasePath() throws KeeperException, InterruptedException { |
| String path = ZookeeperEndpointRepository.getZooKeeperPath(PATH_PREFIX); |
| createPath(path); |
| } |
| |
| private void registerWatcher() { |
| try { |
| watchRecursive(ZookeeperEndpointRepository.PATH_PREFIX); |
| } catch (Exception e) { |
| LOG.info(e.getMessage(), e); |
| } |
| } |
| |
| /** |
| * TODO Check if we handle connection losses correctly |
| * @param path |
| */ |
| private void watchRecursive(String path) { |
| LOG.debug("Watching {}", path); |
| try { |
| handleZNodeChanged(path); |
| List<String> children = zk.getChildren(path, this); |
| if (children == null) { |
| return; |
| } |
| for (String child : children) { |
| String childPath = (path.endsWith("/") ? path : path + "/") + child; |
| watchRecursive(childPath); |
| } |
| } catch (NoNodeException e) { |
| // Happens when a node was removed |
| LOG.debug(e.getMessage(), e); |
| } catch (ConnectionLossException e) { |
| LOG.debug(e.getMessage(), e); |
| } catch (SessionExpiredException e) { |
| LOG.debug(e.getMessage(), e); |
| } catch (Exception e) { |
| LOG.info(e.getMessage(), e); |
| } |
| } |
| |
| private byte[] getData(EndpointDescription epd) { |
| ByteArrayOutputStream bos = new ByteArrayOutputStream(); |
| parser.writeEndpoint(epd, bos); |
| return bos.toByteArray(); |
| } |
| |
| private void createEphemeralNode(String fullPath, byte[] data) throws KeeperException, InterruptedException { |
| try { |
| zk.create(fullPath, data, Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); |
| } catch (NodeExistsException nee) { |
| // this sometimes happens after a ZooKeeper node dies and the ephemeral node |
| // that belonged to the old session was not yet deleted. We need to make our |
| // session the owner of the node so it won't get deleted automatically - |
| // we do this by deleting and recreating it ourselves. |
| LOG.info("node for endpoint already exists, recreating: {}", fullPath); |
| try { |
| zk.delete(fullPath, -1); |
| } catch (NoNodeException nne) { |
| // it's a race condition, but as long as it got deleted - it's ok |
| } |
| zk.create(fullPath, data, Ids.OPEN_ACL_UNSAFE, CreateMode.EPHEMERAL); |
| } |
| } |
| |
| private void createPath(String path) throws KeeperException, InterruptedException { |
| StringBuilder current = new StringBuilder(); |
| List<String> parts = ZookeeperEndpointRepository.removeEmpty(Arrays.asList(path.split("/"))); |
| for (String part : parts) { |
| current.append('/'); |
| current.append(part); |
| try { |
| if (zk.exists(current.toString(), false) == null) { |
| zk.create(current.toString(), new byte[0], Ids.OPEN_ACL_UNSAFE, CreateMode.PERSISTENT); |
| } |
| } catch (NodeExistsException nee) { |
| // it's not the first node with this path to ever exist - that's normal |
| } |
| } |
| } |
| |
| private void handleZNodeChanged(String path) throws KeeperException, InterruptedException { |
| Stat stat = new Stat(); |
| byte[] data = zk.getData(path, false, stat); |
| if (data == null || data.length == 0) { |
| return; |
| } |
| EndpointDescription endpoint = parser.readEndpoint(new ByteArrayInputStream(data)); |
| if (endpoint != null) { |
| handleChanged(path, endpoint); |
| } |
| } |
| |
| private void handleRemoved(String path) { |
| EndpointDescription endpoint = nodes.remove(path); |
| EndpointEvent event = new EndpointEvent(EndpointEvent.REMOVED, endpoint); |
| if (listener != null) { |
| listener.endpointChanged(event, null); |
| } |
| } |
| |
| private void handleChanged(String path, EndpointDescription endpoint) { |
| EndpointDescription old = nodes.put(path, endpoint); |
| int type = old == null ? EndpointEvent.ADDED : EndpointEvent.MODIFIED; |
| EndpointEvent event = new EndpointEvent(type, endpoint); |
| if (listener != null) { |
| listener.endpointChanged(event, null); |
| } |
| } |
| |
| } |