[GitHub] [hbase] bharathv commented on a change in pull request #954: HBASE-23305: Master based registry implementation

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bharathv commented on a change in pull request #954: HBASE-23305: Master based registry implementation
URL: https://github.com/apache/hbase/pull/954#discussion_r362693708
 
 

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 File path: hbase-client/src/main/java/org/apache/hadoop/hbase/client/MasterRegistry.java
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+/*
+ * 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.MASTER_ADDRS_DEFAULT;
+import static org.apache.hadoop.hbase.HConstants.MASTER_ADDRS_KEY;
+import static org.apache.hadoop.hbase.HConstants.MASTER_REGISTRY_ENABLE_HEDGED_READS_DEFAULT;
+import static org.apache.hadoop.hbase.HConstants.MASTER_REGISTRY_ENABLE_HEDGED_READS_KEY;
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.HConstants;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.RegionLocations;
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.exceptions.MasterRegistryFetchException;
+import org.apache.hadoop.hbase.ipc.HBaseRpcController;
+import org.apache.hadoop.hbase.ipc.RpcClient;
+import org.apache.hadoop.hbase.ipc.RpcClientFactory;
+import org.apache.hadoop.hbase.ipc.RpcControllerFactory;
+import org.apache.hadoop.hbase.security.User;
+import org.apache.yetus.audience.InterfaceAudience;
+import org.apache.hbase.thirdparty.com.google.common.annotations.VisibleForTesting;
+import org.apache.hbase.thirdparty.com.google.common.base.Function;
+import org.apache.hbase.thirdparty.com.google.common.base.Preconditions;
+import org.apache.hbase.thirdparty.com.google.common.net.HostAndPort;
+import org.apache.hbase.thirdparty.com.google.protobuf.RpcCallback;
+import org.apache.hadoop.hbase.shaded.protobuf.ProtobufUtil;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.ClientMetaService;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetActiveMasterRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetActiveMasterResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetClusterIdRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetClusterIdResponse;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetMetaRegionLocationsRequest;
+import org.apache.hadoop.hbase.shaded.protobuf.generated.MasterProtos.GetMetaRegionLocationsResponse;
+
+/**
+ * Master based registry implementation. Makes RPCs to the configured master addresses from config
+ * {@value org.apache.hadoop.hbase.HConstants#MASTER_ADDRS_KEY}.
+ *
+ * It supports hedged reads, which can be enabled by setting
+ * {@value org.apache.hadoop.hbase.HConstants#MASTER_REGISTRY_ENABLE_HEDGED_READS_KEY} to True. Fan
+ * out the requests batch is controlled by
+ * {@value org.apache.hadoop.hbase.HConstants#HBASE_RPCS_HEDGED_REQS_FANOUT_KEY}.
+ *
+ * TODO: Handle changes to the configuration dynamically without having to restart the client.
+ */
+@InterfaceAudience.Private
+public class MasterRegistry implements AsyncRegistry {
+  private static final String MASTER_ADDRS_CONF_SEPARATOR = ",";
+
+  // Configured list of masters to probe the meta information from.
+  private final List<ServerName> masterServers;
+
+  // RPC client used to talk to the masters.
+  private final RpcClient rpcClient;
+  private final RpcControllerFactory rpcControllerFactory;
+  private final int rpcTimeoutMs;
+
+  MasterRegistry(Configuration conf) {
+    boolean hedgedReadsEnabled = conf.getBoolean(MASTER_REGISTRY_ENABLE_HEDGED_READS_KEY,
+        MASTER_REGISTRY_ENABLE_HEDGED_READS_DEFAULT);
+    Configuration finalConf;
+    if (!hedgedReadsEnabled) {
+      // If hedged reads are disabled, it is equivalent to setting a fan out of 1. We make a copy of
+      // the configuration so that other places reusing this reference is not affected.
+      finalConf = new Configuration(conf);
+      finalConf.setInt(HConstants.HBASE_RPCS_HEDGED_REQS_FANOUT_KEY, 1);
+    } else {
+      finalConf = conf;
+    }
+    rpcTimeoutMs = (int) Math.min(Integer.MAX_VALUE, conf.getLong(HConstants.HBASE_RPC_TIMEOUT_KEY,
+        HConstants.DEFAULT_HBASE_RPC_TIMEOUT));
+    masterServers = new ArrayList<>();
+    parseMasterAddrs(finalConf);
+    rpcClient = RpcClientFactory.createClient(finalConf, HConstants.CLUSTER_ID_DEFAULT);
+    rpcControllerFactory = RpcControllerFactory.instantiate(finalConf);
+  }
+
+  /**
+   * @return Stub needed to make RPC using a hedged channel to the master end points.
+   */
+  private ClientMetaService.Interface getMasterStub() throws IOException {
+    return ClientMetaService.newStub(
+        rpcClient.createHedgedRpcChannel(masterServers, User.getCurrent(), rpcTimeoutMs));
+  }
+
+  /**
+   * Parses the list of master addresses from the provided configuration. Supported format is
+   * comma separated host[:port] values. If no port number if specified, default master port is
+   * assumed.
+   * @param conf Configuration to parse from.
+   */
+  private void parseMasterAddrs(Configuration conf) {
+    String configuredMasters = conf.get(MASTER_ADDRS_KEY, MASTER_ADDRS_DEFAULT);
+    for (String masterAddr: configuredMasters.split(MASTER_ADDRS_CONF_SEPARATOR)) {
 
 Review comment:
   There is a trim() in the next line,  you mean somewhere else? (there is also test coverage for spaces).

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