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https://issues.apache.org/jira/browse/HDFS-13522?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=17601093#comment-17601093
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ASF GitHub Bot commented on HDFS-13522:
---------------------------------------
simbadzina commented on code in PR #4311:
URL: https://github.com/apache/hadoop/pull/4311#discussion_r964308328
##########
hadoop-hdfs-project/hadoop-hdfs-rbf/src/main/java/org/apache/hadoop/hdfs/server/federation/router/FederatedNamespaceIds.java:
##########
@@ -0,0 +1,113 @@
+/**
+ * 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.hdfs.server.federation.router;
+
+import java.util.Collections;
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+import java.util.concurrent.locks.ReentrantLock;
+import org.apache.hadoop.classification.VisibleForTesting;
+import org.apache.hadoop.hdfs.NamespaceStateId;
+import org.apache.hadoop.ipc.protobuf.RpcHeaderProtos;
+import
org.apache.hadoop.hdfs.federation.protocol.proto.HdfsServerFederationProtos.RouterFederatedStateProto;
+import org.apache.hadoop.thirdparty.protobuf.InvalidProtocolBufferException;
+import org.apache.hadoop.thirdparty.protobuf.ByteString;
+
+
+/**
+ * Collection of last-seen namespace state Ids for a set of namespaces.
+ * A single NamespaceStateId is shared by all outgoing connections to a
particular namespace.
+ * Router clients share and query the entire collection.
+ */
+public class FederatedNamespaceIds {
+ private final Map<String, NamespaceStateId> namespaceIdMap = new
ConcurrentHashMap<>();
+ private final ReentrantLock lock = new ReentrantLock();
Review Comment:
You are right. I was concerned about the iterator (foreach) I have on the
map.
However, the weak consistency provided is sufficient for our needs.
https://docs.oracle.com/javase/8/docs/api/java/util/concurrent/package-summary.html#Weakly:~:text=Most%20concurrent%20Collection%20implementations%20(including%20most%20Queues)%20also%20differ%20from%20the%20usual%20java.util%20conventions%20in%20that%20their%20Iterators%20and%20Spliterators%20provide%20weakly%20consistent%20rather%20than%20fast%2Dfail%20traversal%3A
> RBF: Support observer node from Router-Based Federation
> -------------------------------------------------------
>
> Key: HDFS-13522
> URL: https://issues.apache.org/jira/browse/HDFS-13522
> Project: Hadoop HDFS
> Issue Type: Sub-task
> Components: federation, namenode
> Reporter: Erik Krogen
> Assignee: Simbarashe Dzinamarira
> Priority: Major
> Labels: pull-request-available
> Attachments: HDFS-13522.001.patch, HDFS-13522.002.patch,
> HDFS-13522_WIP.patch, RBF_ Observer support.pdf, Router+Observer RPC
> clogging.png, ShortTerm-Routers+Observer.png,
> observer_reads_in_rbf_proposal_simbadzina_v1.pdf,
> observer_reads_in_rbf_proposal_simbadzina_v2.pdf
>
> Time Spent: 20h 50m
> Remaining Estimate: 0h
>
> Changes will need to occur to the router to support the new observer node.
> One such change will be to make the router understand the observer state,
> e.g. {{FederationNamenodeServiceState}}.
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