HBASE-26181 Region server and master could use itself as ConnectionRegistry (#3603)

Signed-off-by: Bharath Vissapragada <bharathv@apache.org>

hbase-server/src/main/java/org/apache/hadoop/hbase/client/ClusterConnectionFactory.java

@@ -18,9 +18,11 @@
 package org.apache.hadoop.hbase.client;
 
 import java.io.IOException;
+import java.net.InetSocketAddress;
 import java.net.SocketAddress;
 import java.security.PrivilegedExceptionAction;
 import org.apache.hadoop.conf.Configuration;
+import org.apache.hadoop.hbase.regionserver.HRegionServer;
 import org.apache.hadoop.hbase.security.User;
 import org.apache.hadoop.hbase.util.FutureUtils;
 import org.apache.hadoop.hbase.util.ReflectionUtils;
@@ -38,18 +40,8 @@ public final class ClusterConnectionFactory {
   private ClusterConnectionFactory() {
   }
 
-  /**
-   * Create a new {@link AsyncClusterConnection} instance.
-   * <p/>
-   * Unlike what we have done in {@link ConnectionFactory}, here we just return an
-   * {@link AsyncClusterConnection} instead of a {@link java.util.concurrent.CompletableFuture},
-   * which means this method could block on fetching the cluster id. This is just used to simplify
-   * the implementation, as when starting new region servers, we do not need to be event-driven. Can
-   * change later if we want a {@link java.util.concurrent.CompletableFuture} here.
-   */
-  public static AsyncClusterConnection createAsyncClusterConnection(Configuration conf,
-      SocketAddress localAddress, User user) throws IOException {
-    ConnectionRegistry registry = ConnectionRegistryFactory.getRegistry(conf);
+  private static AsyncClusterConnection createAsyncClusterConnection(Configuration conf,
+    ConnectionRegistry registry, SocketAddress localAddress, User user) throws IOException {
     String clusterId = FutureUtils.get(registry.getClusterId());
     Class<? extends AsyncClusterConnection> clazz =
       conf.getClass(HBASE_SERVER_CLUSTER_CONNECTION_IMPL, AsyncClusterConnectionImpl.class,
@@ -62,4 +54,32 @@ public final class ClusterConnectionFactory {
       throw new IOException(e);
     }
   }
+
+  /**
+   * Create a new {@link AsyncClusterConnection} instance.
+   * <p/>
+   * Unlike what we have done in {@link ConnectionFactory}, here we just return an
+   * {@link AsyncClusterConnection} instead of a {@link java.util.concurrent.CompletableFuture},
+   * which means this method could block on fetching the cluster id. This is just used to simplify
+   * the implementation, as when starting new region servers, we do not need to be event-driven. Can
+   * change later if we want a {@link java.util.concurrent.CompletableFuture} here.
+   */
+  public static AsyncClusterConnection createAsyncClusterConnection(Configuration conf,
+    SocketAddress localAddress, User user) throws IOException {
+    return createAsyncClusterConnection(conf, ConnectionRegistryFactory.getRegistry(conf),
+      localAddress, user);
+  }
+
+  /**
+   * Create a new {@link AsyncClusterConnection} instance for a region server.
+   */
+  public static AsyncClusterConnection createAsyncClusterConnection(HRegionServer regionServer)
+    throws IOException {
+    RegionServerRegistry registry = new RegionServerRegistry(regionServer);
+    Configuration conf = regionServer.getConfiguration();
+    InetSocketAddress localAddress =
+      new InetSocketAddress(regionServer.getRSRpcServices().getSocketAddress().getAddress(), 0);
+    User user = regionServer.getUserProvider().getCurrent();
+    return createAsyncClusterConnection(conf, registry, localAddress, user);
+  }
 }

hbase-server/src/main/java/org/apache/hadoop/hbase/client/RegionServerRegistry.java

@@ -0,0 +1,81 @@
+/**
+ * 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 java.io.IOException;
+import java.util.List;
+import java.util.Optional;
+import java.util.concurrent.CompletableFuture;
+import org.apache.hadoop.hbase.HRegionLocation;
+import org.apache.hadoop.hbase.RegionLocations;
+import org.apache.hadoop.hbase.ServerName;
+import org.apache.hadoop.hbase.regionserver.HRegionServer;
+import org.apache.yetus.audience.InterfaceAudience;
+
+/**
+ * Connection registry implementation for region server.
+ */
+@InterfaceAudience.Private
+public class RegionServerRegistry implements ConnectionRegistry {
+
+  private final HRegionServer regionServer;
+
+  public RegionServerRegistry(HRegionServer regionServer) {
+    this.regionServer = regionServer;
+  }
+
+  @Override
+  public CompletableFuture<RegionLocations> getMetaRegionLocations() {
+    CompletableFuture<RegionLocations> future = new CompletableFuture<>();
+    Optional<List<HRegionLocation>> locs =
+      regionServer.getMetaRegionLocationCache().getMetaRegionLocations();
+    if (locs.isPresent()) {
+      List<HRegionLocation> list = locs.get();
+      if (list.isEmpty()) {
+        future.completeExceptionally(new IOException("no meta location available"));
+      } else {
+        future.complete(new RegionLocations(list));
+      }
+    } else {
+      future.completeExceptionally(new IOException("no meta location available"));
+    }
+    return future;
+  }
+
+  @Override
+  public CompletableFuture<String> getClusterId() {
+    return CompletableFuture.completedFuture(regionServer.getClusterId());
+  }
+
+  @Override
+  public CompletableFuture<ServerName> getActiveMaster() {
+    CompletableFuture<ServerName> future = new CompletableFuture<>();
+    Optional<ServerName> activeMaster = regionServer.getActiveMaster();
+    if (activeMaster.isPresent()) {
+      future.complete(activeMaster.get());
+    } else {
+      future.completeExceptionally(new IOException("no active master available"));
+    }
+    return future;
+  }
+
+  @Override
+  public void close() {
+    // nothing
+  }
+}

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/HRegionServer.java

@@ -863,26 +863,6 @@ public class HRegionServer extends Thread implements
     return true;
   }
 
-  private Configuration cleanupConfiguration() {
-    Configuration conf = this.conf;
-    // We use ZKConnectionRegistry for all the internal communication, primarily for these reasons:
-    // - Decouples RS and master life cycles. RegionServers can continue be up independent of
-    //   masters' availability.
-    // - Configuration management for region servers (cluster internal) is much simpler when adding
-    //   new masters or removing existing masters, since only clients' config needs to be updated.
-    // - We need to retain ZKConnectionRegistry for replication use anyway, so we just extend it for
-    //   other internal connections too.
-    conf.set(HConstants.CLIENT_CONNECTION_REGISTRY_IMPL_CONF_KEY,
-        HConstants.ZK_CONNECTION_REGISTRY_CLASS);
-    if (conf.get(HConstants.CLIENT_ZOOKEEPER_QUORUM) != null) {
-      // Use server ZK cluster for server-issued connections, so we clone
-      // the conf and unset the client ZK related properties
-      conf = new Configuration(this.conf);
-      conf.unset(HConstants.CLIENT_ZOOKEEPER_QUORUM);
-    }
-    return conf;
-  }
-
   /**
    * Run test on configured codecs to make sure supporting libs are in place.
    */
@@ -907,11 +887,7 @@ public class HRegionServer extends Thread implements
    */
   protected final synchronized void setupClusterConnection() throws IOException {
     if (asyncClusterConnection == null) {
-      Configuration conf = cleanupConfiguration();
-      InetSocketAddress localAddress = new InetSocketAddress(this.rpcServices.isa.getAddress(), 0);
-      User user = userProvider.getCurrent();
-      asyncClusterConnection =
-        ClusterConnectionFactory.createAsyncClusterConnection(conf, localAddress, user);
+      asyncClusterConnection = ClusterConnectionFactory.createAsyncClusterConnection(this);
     }
   }
 
@@ -4022,4 +3998,8 @@ public class HRegionServer extends Thread implements
   public MetaRegionLocationCache getMetaRegionLocationCache() {
     return this.metaRegionLocationCache;
   }
+
+  public UserProvider getUserProvider() {
+    return userProvider;
+  }
 }