| /** |
| * 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.distributedlog.impl.subscription; |
| |
| import com.google.common.base.Charsets; |
| import java.io.IOException; |
| import java.util.concurrent.CompletableFuture; |
| import java.util.concurrent.atomic.AtomicReference; |
| import org.apache.distributedlog.DLSN; |
| import org.apache.distributedlog.ZooKeeperClient; |
| import org.apache.distributedlog.exceptions.DLInterruptedException; |
| import org.apache.distributedlog.api.subscription.SubscriptionStateStore; |
| import org.apache.distributedlog.common.concurrent.FutureUtils; |
| import org.apache.distributedlog.util.Utils; |
| import org.apache.zookeeper.AsyncCallback; |
| import org.apache.zookeeper.CreateMode; |
| import org.apache.zookeeper.KeeperException; |
| import org.apache.zookeeper.data.Stat; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| public class ZKSubscriptionStateStore implements SubscriptionStateStore { |
| |
| static final Logger logger = LoggerFactory.getLogger(ZKSubscriptionStateStore.class); |
| |
| private final ZooKeeperClient zooKeeperClient; |
| private final String zkPath; |
| private AtomicReference<DLSN> lastCommittedPosition = new AtomicReference<DLSN>(null); |
| |
| public ZKSubscriptionStateStore(ZooKeeperClient zooKeeperClient, String zkPath) { |
| this.zooKeeperClient = zooKeeperClient; |
| this.zkPath = zkPath; |
| } |
| |
| @Override |
| public void close() throws IOException { |
| } |
| |
| /** |
| * Get the last committed position stored for this subscription |
| */ |
| @Override |
| public CompletableFuture<DLSN> getLastCommitPosition() { |
| if (null != lastCommittedPosition.get()) { |
| return FutureUtils.value(lastCommittedPosition.get()); |
| } else { |
| return getLastCommitPositionFromZK(); |
| } |
| } |
| |
| CompletableFuture<DLSN> getLastCommitPositionFromZK() { |
| final CompletableFuture<DLSN> result = new CompletableFuture<DLSN>(); |
| try { |
| logger.debug("Reading last commit position from path {}", zkPath); |
| zooKeeperClient.get().getData(zkPath, false, new AsyncCallback.DataCallback() { |
| @Override |
| public void processResult(int rc, String path, Object ctx, byte[] data, Stat stat) { |
| logger.debug("Read last commit position from path {}: rc = {}", zkPath, rc); |
| if (KeeperException.Code.NONODE.intValue() == rc) { |
| result.complete(DLSN.NonInclusiveLowerBound); |
| } else if (KeeperException.Code.OK.intValue() != rc) { |
| result.completeExceptionally(KeeperException.create(KeeperException.Code.get(rc), path)); |
| } else { |
| try { |
| DLSN dlsn = DLSN.deserialize(new String(data, Charsets.UTF_8)); |
| result.complete(dlsn); |
| } catch (Exception t) { |
| logger.warn("Invalid last commit position found from path {}", zkPath, t); |
| // invalid dlsn recorded in subscription state store |
| result.complete(DLSN.NonInclusiveLowerBound); |
| } |
| } |
| } |
| }, null); |
| } catch (ZooKeeperClient.ZooKeeperConnectionException zkce) { |
| result.completeExceptionally(zkce); |
| } catch (InterruptedException ie) { |
| result.completeExceptionally(new DLInterruptedException("getLastCommitPosition was interrupted", ie)); |
| } |
| return result; |
| } |
| |
| /** |
| * Advances the position associated with the subscriber |
| * |
| * @param newPosition - new commit position |
| */ |
| @Override |
| public CompletableFuture<Void> advanceCommitPosition(DLSN newPosition) { |
| if (null == lastCommittedPosition.get() || |
| (newPosition.compareTo(lastCommittedPosition.get()) > 0)) { |
| lastCommittedPosition.set(newPosition); |
| return Utils.zkAsyncCreateFullPathOptimisticAndSetData(zooKeeperClient, |
| zkPath, newPosition.serialize().getBytes(Charsets.UTF_8), |
| zooKeeperClient.getDefaultACL(), |
| CreateMode.PERSISTENT); |
| } else { |
| return FutureUtils.Void(); |
| } |
| } |
| } |