Java tutorial
/** * 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.hadoop.hbase.client; import static org.apache.hadoop.hbase.HConstants.DEFAULT_ZK_SESSION_TIMEOUT; import static org.apache.hadoop.hbase.HConstants.ZK_SESSION_TIMEOUT; import static org.apache.hadoop.hbase.HRegionInfo.DEFAULT_REPLICA_ID; import static org.apache.hadoop.hbase.HRegionInfo.FIRST_META_REGIONINFO; import static org.apache.hadoop.hbase.client.RegionReplicaUtil.getRegionInfoForDefaultReplica; import static org.apache.hadoop.hbase.client.RegionReplicaUtil.getRegionInfoForReplica; import static org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil.lengthOfPBMagic; import static org.apache.hadoop.hbase.zookeeper.RecoverableZooKeeper.removeMetaData; import java.io.IOException; import java.util.concurrent.CompletableFuture; import org.apache.commons.lang.mutable.MutableInt; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.apache.curator.framework.CuratorFramework; import org.apache.curator.framework.CuratorFrameworkFactory; import org.apache.curator.framework.api.BackgroundPathable; import org.apache.curator.framework.api.CuratorEvent; import org.apache.curator.retry.RetryNTimes; import org.apache.hadoop.conf.Configuration; import org.apache.hadoop.hbase.ClusterId; import org.apache.hadoop.hbase.HRegionLocation; import org.apache.hadoop.hbase.RegionLocations; import org.apache.hadoop.hbase.ServerName; import org.apache.hadoop.hbase.classification.InterfaceAudience; import org.apache.hadoop.hbase.exceptions.DeserializationException; import org.apache.hadoop.hbase.master.RegionState; import org.apache.hadoop.hbase.shaded.protobuf.generated.HBaseProtos; import org.apache.hadoop.hbase.shaded.protobuf.generated.ZooKeeperProtos; import org.apache.hadoop.hbase.util.Pair; import org.apache.hadoop.hbase.util.Threads; import org.apache.hadoop.hbase.zookeeper.ZKConfig; import org.apache.hadoop.hbase.zookeeper.ZNodePaths; import org.apache.zookeeper.data.Stat; /** * Fetch the registry data from zookeeper. */ @InterfaceAudience.Private class ZKAsyncRegistry implements AsyncRegistry { private static final Log LOG = LogFactory.getLog(ZKAsyncRegistry.class); private final CuratorFramework zk; private final ZNodePaths znodePaths; ZKAsyncRegistry(Configuration conf) { this.znodePaths = new ZNodePaths(conf); int zkSessionTimeout = conf.getInt(ZK_SESSION_TIMEOUT, DEFAULT_ZK_SESSION_TIMEOUT); int zkRetry = conf.getInt("zookeeper.recovery.retry", 3); int zkRetryIntervalMs = conf.getInt("zookeeper.recovery.retry.intervalmill", 1000); this.zk = CuratorFrameworkFactory.builder().connectString(ZKConfig.getZKQuorumServersString(conf)) .sessionTimeoutMs(zkSessionTimeout).retryPolicy(new RetryNTimes(zkRetry, zkRetryIntervalMs)) .threadFactory( Threads.newDaemonThreadFactory(String.format("ZKClusterRegistry-0x%08x", hashCode()))) .build(); this.zk.start(); } private interface CuratorEventProcessor<T> { T process(CuratorEvent event) throws Exception; } private static <T> CompletableFuture<T> exec(BackgroundPathable<?> opBuilder, String path, CuratorEventProcessor<T> processor) { CompletableFuture<T> future = new CompletableFuture<>(); try { opBuilder.inBackground((client, event) -> { try { future.complete(processor.process(event)); } catch (Exception e) { future.completeExceptionally(e); } }).withUnhandledErrorListener((msg, e) -> future.completeExceptionally(e)).forPath(path); } catch (Exception e) { future.completeExceptionally(e); } return future; } private static String getClusterId(CuratorEvent event) throws DeserializationException { byte[] data = event.getData(); if (data == null || data.length == 0) { return null; } data = removeMetaData(data); return ClusterId.parseFrom(data).toString(); } @Override public CompletableFuture<String> getClusterId() { return exec(zk.getData(), znodePaths.clusterIdZNode, ZKAsyncRegistry::getClusterId); } private static ZooKeeperProtos.MetaRegionServer getMetaProto(CuratorEvent event) throws IOException { byte[] data = event.getData(); if (data == null || data.length == 0) { return null; } data = removeMetaData(data); int prefixLen = lengthOfPBMagic(); return ZooKeeperProtos.MetaRegionServer.parser().parseFrom(data, prefixLen, data.length - prefixLen); } private static void tryComplete(MutableInt remaining, HRegionLocation[] locs, CompletableFuture<RegionLocations> future) { remaining.decrement(); if (remaining.intValue() > 0) { return; } future.complete(new RegionLocations(locs)); } private Pair<RegionState.State, ServerName> getStateAndServerName(ZooKeeperProtos.MetaRegionServer proto) { RegionState.State state; if (proto.hasState()) { state = RegionState.State.convert(proto.getState()); } else { state = RegionState.State.OPEN; } HBaseProtos.ServerName snProto = proto.getServer(); return Pair.newPair(state, ServerName.valueOf(snProto.getHostName(), snProto.getPort(), snProto.getStartCode())); } @Override public CompletableFuture<RegionLocations> getMetaRegionLocation() { CompletableFuture<RegionLocations> future = new CompletableFuture<>(); HRegionLocation[] locs = new HRegionLocation[znodePaths.metaReplicaZNodes.size()]; MutableInt remaining = new MutableInt(locs.length); znodePaths.metaReplicaZNodes.forEach((replicaId, path) -> { if (replicaId == DEFAULT_REPLICA_ID) { exec(zk.getData(), path, ZKAsyncRegistry::getMetaProto).whenComplete((proto, error) -> { if (error != null) { future.completeExceptionally(error); return; } if (proto == null) { future.completeExceptionally(new IOException("Meta znode is null")); return; } Pair<RegionState.State, ServerName> stateAndServerName = getStateAndServerName(proto); if (stateAndServerName.getFirst() != RegionState.State.OPEN) { future.completeExceptionally( new IOException("Meta region is in state " + stateAndServerName.getFirst())); return; } locs[DEFAULT_REPLICA_ID] = new HRegionLocation( getRegionInfoForDefaultReplica(FIRST_META_REGIONINFO), stateAndServerName.getSecond()); tryComplete(remaining, locs, future); }); } else { exec(zk.getData(), path, ZKAsyncRegistry::getMetaProto).whenComplete((proto, error) -> { if (future.isDone()) { return; } if (error != null) { LOG.warn("Failed to fetch " + path, error); locs[replicaId] = null; } else if (proto == null) { LOG.warn("Meta znode for replica " + replicaId + " is null"); locs[replicaId] = null; } else { Pair<RegionState.State, ServerName> stateAndServerName = getStateAndServerName(proto); if (stateAndServerName.getFirst() != RegionState.State.OPEN) { LOG.warn("Meta region for replica " + replicaId + " is in state " + stateAndServerName.getFirst()); locs[replicaId] = null; } else { locs[replicaId] = new HRegionLocation( getRegionInfoForReplica(FIRST_META_REGIONINFO, replicaId), stateAndServerName.getSecond()); } } tryComplete(remaining, locs, future); }); } }); return future; } private static int getCurrentNrHRS(CuratorEvent event) { Stat stat = event.getStat(); return stat != null ? stat.getNumChildren() : 0; } @Override public CompletableFuture<Integer> getCurrentNrHRS() { return exec(zk.checkExists(), znodePaths.rsZNode, ZKAsyncRegistry::getCurrentNrHRS); } private static ZooKeeperProtos.Master getMasterProto(CuratorEvent event) throws IOException { byte[] data = event.getData(); if (data == null || data.length == 0) { return null; } data = removeMetaData(data); int prefixLen = lengthOfPBMagic(); return ZooKeeperProtos.Master.parser().parseFrom(data, prefixLen, data.length - prefixLen); } @Override public CompletableFuture<ServerName> getMasterAddress() { return exec(zk.getData(), znodePaths.masterAddressZNode, ZKAsyncRegistry::getMasterProto) .thenApply(proto -> { if (proto == null) { return null; } HBaseProtos.ServerName snProto = proto.getMaster(); return ServerName.valueOf(snProto.getHostName(), snProto.getPort(), snProto.getStartCode()); }); } @Override public CompletableFuture<Integer> getMasterInfoPort() { return exec(zk.getData(), znodePaths.masterAddressZNode, ZKAsyncRegistry::getMasterProto) .thenApply(proto -> proto != null ? proto.getInfoPort() : 0); } @Override public void close() { zk.close(); } }