[GitHub] [ozone] GlenGeng commented on a change in pull request #1314: HDDS-3988: DN can distinguish SCMCommand from stale leader SCM

[GitBox <gi...@apache.org>]

GlenGeng commented on a change in pull request #1314:
URL: https://github.com/apache/ozone/pull/1314#discussion_r533922178



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File path: hadoop-hdds/container-service/src/main/java/org/apache/hadoop/ozone/container/common/statemachine/StateContext.java
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@@ -470,6 +484,65 @@ public void execute(ExecutorService service, long time, TimeUnit unit)
     }
   }
 
+  /**
+   * After startup, datanode needs detect latest leader SCM before handling
+   * any SCMCommand, so that it won't be disturbed by stale leader SCM.
+   *
+   * The rule is: after majority SCMs are in HEARTBEAT state and has
+   * heard from leader SCMs (commandQueue is not empty), datanode will init
+   * termOfLeaderSCM with the max term found in commandQueue.
+   *
+   * The init process also works for non-HA mode. In that case, term of all
+   * SCMCommands will be 0.
+   */
+  void initTermOfLeaderSCM() {

Review comment:
       Sure




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