| /* |
| * 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.solr.handler; |
| |
| import java.lang.invoke.MethodHandles; |
| |
| import org.apache.solr.common.cloud.ClusterState; |
| import org.apache.solr.common.cloud.SolrZkClient; |
| import org.apache.solr.common.cloud.ZkNodeProps; |
| import org.apache.solr.core.SolrCore; |
| import org.apache.zookeeper.KeeperException; |
| import org.apache.zookeeper.WatchedEvent; |
| import org.apache.zookeeper.Watcher; |
| import org.slf4j.Logger; |
| import org.slf4j.LoggerFactory; |
| |
| /** |
| * <p> |
| * Manage the leader state of the CDCR nodes. |
| * </p> |
| * <p> |
| * It takes care of notifying the {@link CdcrReplicatorManager} in case |
| * of a leader state change. |
| * </p> |
| * @deprecated since 8.6 |
| */ |
| @Deprecated(since = "8.6") |
| class CdcrLeaderStateManager extends CdcrStateManager { |
| |
| private boolean amILeader = false; |
| |
| private LeaderStateWatcher wrappedWatcher; |
| private Watcher watcher; |
| |
| private SolrCore core; |
| |
| private static final Logger log = LoggerFactory.getLogger(MethodHandles.lookup().lookupClass()); |
| |
| CdcrLeaderStateManager(final SolrCore core) { |
| this.core = core; |
| |
| // Fetch leader state and register the watcher at startup |
| try { |
| SolrZkClient zkClient = core.getCoreContainer().getZkController().getZkClient(); |
| ClusterState clusterState = core.getCoreContainer().getZkController().getClusterState(); |
| |
| watcher = this.initWatcher(zkClient); |
| // if the node does not exist, it means that the leader was not yet registered. This can happen |
| // when the cluster is starting up. The core is not yet fully loaded, and the leader election process |
| // is waiting for it. |
| if (this.isLeaderRegistered(zkClient, clusterState)) { |
| this.checkIfIAmLeader(); |
| } |
| } catch (KeeperException | InterruptedException e) { |
| log.warn("Failed fetching initial leader state and setting watch", e); |
| } |
| } |
| |
| /** |
| * Checks if the leader is registered. If it is not registered, we are probably at the |
| * initialisation phase of the cluster. In this case, we must attach a watcher to |
| * be notified when the leader is registered. |
| */ |
| private boolean isLeaderRegistered(SolrZkClient zkClient, ClusterState clusterState) |
| throws KeeperException, InterruptedException { |
| // First check if the znode exists, and register the watcher at the same time |
| return zkClient.exists(this.getZnodePath(), watcher, true) != null; |
| } |
| |
| /** |
| * SolrZkClient does not guarantee that a watch object will only be triggered once for a given notification |
| * if we does not wrap the watcher - see SOLR-6621. |
| */ |
| private Watcher initWatcher(SolrZkClient zkClient) { |
| wrappedWatcher = new LeaderStateWatcher(); |
| return zkClient.wrapWatcher(wrappedWatcher); |
| } |
| |
| private void checkIfIAmLeader() throws KeeperException, InterruptedException { |
| SolrZkClient zkClient = core.getCoreContainer().getZkController().getZkClient(); |
| ZkNodeProps props = ZkNodeProps.load(zkClient.getData(CdcrLeaderStateManager.this.getZnodePath(), null, null, true)); |
| if (props != null) { |
| CdcrLeaderStateManager.this.setAmILeader(props.get("core").equals(core.getName())); |
| } |
| } |
| |
| private String getZnodePath() { |
| String myShardId = core.getCoreDescriptor().getCloudDescriptor().getShardId(); |
| String myCollection = core.getCoreDescriptor().getCloudDescriptor().getCollectionName(); |
| return "/collections/" + myCollection + "/leaders/" + myShardId + "/leader"; |
| } |
| |
| void setAmILeader(boolean amILeader) { |
| if (this.amILeader != amILeader) { |
| this.amILeader = amILeader; |
| this.callback(); // notify the observers of a state change |
| } |
| } |
| |
| boolean amILeader() { |
| return amILeader; |
| } |
| |
| void shutdown() { |
| if (wrappedWatcher != null) { |
| wrappedWatcher.cancel(); // cancel the watcher to avoid spurious warn messages during shutdown |
| } |
| } |
| |
| private class LeaderStateWatcher implements Watcher { |
| |
| private boolean isCancelled = false; |
| |
| /** |
| * Cancel the watcher to avoid spurious warn messages during shutdown. |
| */ |
| void cancel() { |
| isCancelled = true; |
| } |
| |
| @Override |
| public void process(WatchedEvent event) { |
| if (isCancelled) return; // if the watcher is cancelled, do nothing. |
| String collectionName = core.getCoreDescriptor().getCloudDescriptor().getCollectionName(); |
| String shard = core.getCoreDescriptor().getCloudDescriptor().getShardId(); |
| |
| log.debug("The leader state has changed: {} @ {}:{}", event, collectionName, shard); |
| // session events are not change events, and do not remove the watcher |
| if (Event.EventType.None.equals(event.getType())) { |
| return; |
| } |
| |
| try { |
| log.info("Received new leader state @ {}:{}", collectionName, shard); |
| SolrZkClient zkClient = core.getCoreContainer().getZkController().getZkClient(); |
| ClusterState clusterState = core.getCoreContainer().getZkController().getClusterState(); |
| if (CdcrLeaderStateManager.this.isLeaderRegistered(zkClient, clusterState)) { |
| CdcrLeaderStateManager.this.checkIfIAmLeader(); |
| } |
| } catch (KeeperException | InterruptedException e) { |
| log.warn("Failed updating leader state and setting watch @ {}: {}", collectionName, shard, e); |
| } |
| } |
| |
| } |
| |
| } |
| |