HDFS-17597. [ARR] RouterSnapshot supports asynchronous rpc. (#6994). …

…Contributed by Wenqi Li.

Reviewed-by: Jian Zhang <keepromise@apache.org>
Signed-off-by: He Xiaoqiao <hexiaoqiao@apache.org>

hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/RouterAsyncSnapshot.java

@@ -0,0 +1,203 @@
+/**
+ * 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
+ * <p>
+ * http://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * 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.hdfs.server.federation.router;
+
+import org.apache.hadoop.hdfs.DFSUtil;
+import org.apache.hadoop.hdfs.protocol.ClientProtocol;
+import org.apache.hadoop.hdfs.protocol.SnapshotDiffReport;
+import org.apache.hadoop.hdfs.protocol.SnapshotDiffReportListing;
+import org.apache.hadoop.hdfs.protocol.SnapshotStatus;
+import org.apache.hadoop.hdfs.protocol.SnapshottableDirectoryStatus;
+import org.apache.hadoop.hdfs.server.federation.resolver.ActiveNamenodeResolver;
+import org.apache.hadoop.hdfs.server.federation.resolver.FederationNamespaceInfo;
+import org.apache.hadoop.hdfs.server.federation.resolver.RemoteLocation;
+import org.apache.hadoop.hdfs.server.federation.router.async.ApplyFunction;
+import org.apache.hadoop.hdfs.server.namenode.NameNode;
+
+import java.io.IOException;
+import java.util.Collection;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.apache.hadoop.hdfs.server.federation.router.async.AsyncUtil.asyncApply;
+import static org.apache.hadoop.hdfs.server.federation.router.async.AsyncUtil.asyncReturn;
+
+/**
+ * Module that implements all the asynchronous RPC calls related to snapshots in
+ * {@link ClientProtocol} in the {@link RouterRpcServer}.
+ */
+public class RouterAsyncSnapshot extends RouterSnapshot {
+  /** RPC server to receive client calls. */
+  private final RouterRpcServer rpcServer;
+  /** RPC clients to connect to the Namenodes. */
+  private final RouterRpcClient rpcClient;
+  /** Find generic locations. */
+  private final ActiveNamenodeResolver namenodeResolver;
+
+  public RouterAsyncSnapshot(RouterRpcServer server) {
+    super(server);
+    this.rpcServer = server;
+    this.rpcClient = this.rpcServer.getRPCClient();
+    this.namenodeResolver = rpcServer.getNamenodeResolver();
+  }
+
+  @Override
+  public String createSnapshot(String snapshotRoot, String snapshotName) throws IOException {
+    rpcServer.checkOperation(NameNode.OperationCategory.WRITE);
+
+    final List<RemoteLocation> locations =
+        rpcServer.getLocationsForPath(snapshotRoot, true, false);
+    RemoteMethod method = new RemoteMethod("createSnapshot",
+        new Class<?>[] {String.class, String.class}, new RemoteParam(),
+        snapshotName);
+
+    if (rpcServer.isInvokeConcurrent(snapshotRoot)) {
+      rpcClient.invokeConcurrent(locations, method, String.class);
+      asyncApply((ApplyFunction<Map<RemoteLocation, String>, String>)
+          results -> {
+          Map.Entry<RemoteLocation, String> firstelement =
+              results.entrySet().iterator().next();
+          RemoteLocation loc = firstelement.getKey();
+          String result = firstelement.getValue();
+          return result.replaceFirst(loc.getDest(), loc.getSrc());
+        });
+    } else {
+      rpcClient.invokeSequential(method, locations, String.class, null);
+      asyncApply((ApplyFunction<RemoteResult<RemoteLocation, String>, String>)
+          response -> {
+          RemoteLocation loc = response.getLocation();
+          String invokedResult = response.getResult();
+          return invokedResult.replaceFirst(loc.getDest(), loc.getSrc());
+        });
+    }
+    return asyncReturn(String.class);
+  }
+
+  @Override
+  public SnapshottableDirectoryStatus[] getSnapshottableDirListing() throws IOException {
+    rpcServer.checkOperation(NameNode.OperationCategory.READ);
+
+    RemoteMethod method = new RemoteMethod("getSnapshottableDirListing");
+    Set<FederationNamespaceInfo> nss = namenodeResolver.getNamespaces();
+    rpcClient.invokeConcurrent(
+            nss, method, true, false, SnapshottableDirectoryStatus[].class);
+    asyncApply((ApplyFunction<Map<FederationNamespaceInfo, SnapshottableDirectoryStatus[]>,
+        SnapshottableDirectoryStatus[]>)
+        ret -> RouterRpcServer.merge(ret, SnapshottableDirectoryStatus.class));
+    return asyncReturn(SnapshottableDirectoryStatus[].class);
+  }
+
+  @Override
+  public SnapshotStatus[] getSnapshotListing(String snapshotRoot) throws IOException {
+    rpcServer.checkOperation(NameNode.OperationCategory.READ);
+    final List<RemoteLocation> locations =
+        rpcServer.getLocationsForPath(snapshotRoot, true, false);
+    RemoteMethod remoteMethod = new RemoteMethod("getSnapshotListing",
+        new Class<?>[]{String.class},
+        new RemoteParam());
+    if (rpcServer.isInvokeConcurrent(snapshotRoot)) {
+      rpcClient.invokeConcurrent(
+          locations, remoteMethod, true, false, SnapshotStatus[].class);
+      asyncApply((ApplyFunction<Map<RemoteLocation, SnapshotStatus[]>, SnapshotStatus[]>)
+          ret -> {
+          SnapshotStatus[] response = ret.values().iterator().next();
+          String src = ret.keySet().iterator().next().getSrc();
+          String dst = ret.keySet().iterator().next().getDest();
+          for (SnapshotStatus s : response) {
+            String mountPath = DFSUtil.bytes2String(s.getParentFullPath()).
+                replaceFirst(src, dst);
+            s.setParentFullPath(DFSUtil.string2Bytes(mountPath));
+          }
+          return response;
+        });
+    } else {
+      rpcClient
+          .invokeSequential(remoteMethod, locations, SnapshotStatus[].class,
+              null);
+      asyncApply((ApplyFunction<RemoteResult<RemoteLocation, SnapshotStatus[]>, SnapshotStatus[]>)
+          invokedResponse -> {
+          RemoteLocation loc = invokedResponse.getLocation();
+          SnapshotStatus[] response = invokedResponse.getResult();
+          for (SnapshotStatus s : response) {
+            String mountPath = DFSUtil.bytes2String(s.getParentFullPath()).
+                replaceFirst(loc.getDest(), loc.getSrc());
+            s.setParentFullPath(DFSUtil.string2Bytes(mountPath));
+          }
+          return response;
+        });
+    }
+    return asyncReturn(SnapshotStatus[].class);
+  }
+
+  @Override
+  public SnapshotDiffReport getSnapshotDiffReport(
+      String snapshotRoot, String earlierSnapshotName,
+      String laterSnapshotName) throws IOException {
+    rpcServer.checkOperation(NameNode.OperationCategory.READ);
+
+    final List<RemoteLocation> locations =
+        rpcServer.getLocationsForPath(snapshotRoot, true, false);
+    RemoteMethod remoteMethod = new RemoteMethod("getSnapshotDiffReport",
+        new Class<?>[] {String.class, String.class, String.class},
+        new RemoteParam(), earlierSnapshotName, laterSnapshotName);
+
+    if (rpcServer.isInvokeConcurrent(snapshotRoot)) {
+      rpcClient.invokeConcurrent(
+          locations, remoteMethod, true, false, SnapshotDiffReport.class);
+      asyncApply((ApplyFunction<Map<RemoteLocation, SnapshotDiffReport>, SnapshotDiffReport>)
+          ret -> ret.values().iterator().next());
+      return asyncReturn(SnapshotDiffReport.class);
+    } else {
+      return rpcClient.invokeSequential(
+          locations, remoteMethod, SnapshotDiffReport.class, null);
+    }
+  }
+
+  @Override
+  public SnapshotDiffReportListing getSnapshotDiffReportListing(
+      String snapshotRoot, String earlierSnapshotName, String laterSnapshotName,
+      byte[] startPath, int index) throws IOException {
+    rpcServer.checkOperation(NameNode.OperationCategory.READ);
+
+    final List<RemoteLocation> locations =
+        rpcServer.getLocationsForPath(snapshotRoot, true, false);
+    Class<?>[] params = new Class<?>[] {
+        String.class, String.class, String.class,
+        byte[].class, int.class};
+    RemoteMethod remoteMethod = new RemoteMethod(
+        "getSnapshotDiffReportListing", params,
+        new RemoteParam(), earlierSnapshotName, laterSnapshotName,
+        startPath, index);
+
+    if (rpcServer.isInvokeConcurrent(snapshotRoot)) {
+      rpcClient.invokeConcurrent(locations, remoteMethod, false, false,
+              SnapshotDiffReportListing.class);
+      asyncApply((ApplyFunction<Map<RemoteLocation, SnapshotDiffReportListing>,
+          SnapshotDiffReportListing>) ret -> {
+          Collection<SnapshotDiffReportListing> listings = ret.values();
+          SnapshotDiffReportListing listing0 = listings.iterator().next();
+          return listing0;
+        });
+      return asyncReturn(SnapshotDiffReportListing.class);
+    } else {
+      return rpcClient.invokeSequential(
+          locations, remoteMethod, SnapshotDiffReportListing.class, null);
+    }
+  }
+}