[GitHub] [ozone] GlenGeng commented on a change in pull request #2116: HDDS-5050. Add retry policy for ratis requests in SCM HA.

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

GlenGeng commented on a change in pull request #2116:
URL: https://github.com/apache/ozone/pull/2116#discussion_r608321313



##########
File path: hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/RetriableWithNoFailoverException.java
##########
@@ -0,0 +1,26 @@
+/*
+ * 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.hdds.scm.ha;
+
+import java.io.IOException;
+
+public class RetriableWithNoFailoverException  extends IOException {

Review comment:
       one space before `extends`

##########
File path: hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/SCMHAUtils.java
##########
@@ -50,6 +55,14 @@ private SCMHAUtils() {
     // not used
   }
 
+  private static final List<Class<? extends Exception>> EXCEPTION_LIST =
+      ImmutableList.<Class<? extends Exception>>builder()
+          .add(LeaderNotReadyException.class)
+          .add(ReconfigurationInProgressException.class)
+          .add(ResourceUnavailableException.class)
+          .add(ReconfigurationTimeoutException.class)

Review comment:
       move `ReconfigurationTimeoutException` ahead of `ResourceUnavailableException`.
   
   Move `EXCEPTION_LIST` ahead of the private Ctor, better declare all member variables ahead of all member functions.

##########
File path: hadoop-hdds/framework/src/main/java/org/apache/hadoop/hdds/scm/proxy/SCMBlockLocationFailoverProxyProvider.java
##########
@@ -257,8 +249,11 @@ public RetryPolicy getSCMBlockLocationRetryPolicy(String newLeader) {
       @Override
       public RetryAction shouldRetry(Exception e, int retry,
                                      int failover, boolean b) {
-        performFailoverToAssignedLeader(newLeader);
-        return getRetryAction(failover);
+        if (!SCMHAUtils.isRetriableWithNoFailoverException(e)) {
+          performFailoverToAssignedLeader(newLeader);
+        }
+        return SCMHAUtils.getRetryAction(failover, retry, e, maxRetryCount,

Review comment:
       It is weird here that `SCMHAUtils.getRetryAction` does not handle conditions that `SCMHAUtils.isRetriableWithNoFailoverException(e)` is true.

##########
File path: hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/SCMHAUtils.java
##########
@@ -50,6 +55,14 @@ private SCMHAUtils() {
     // not used
   }
 
+  private static final List<Class<? extends Exception>> EXCEPTION_LIST =

Review comment:
       `EXCEPTION_LIST` -> `RETRIABLE_WITH_NO_FAILOVER_EXCEPTION_LIST`
   
   and update function name `getExceptionList` too.

##########
File path: hadoop-hdds/common/src/main/java/org/apache/hadoop/hdds/scm/ha/SCMHAUtils.java
##########
@@ -184,4 +197,42 @@ public static OzoneConfiguration removeSelfId(
     String scmServiceId = getScmServiceId(configuration);
     return getSCMNodeIds(configuration, scmServiceId);
   }
+
+  // This will return the underlying exception after unwrapping
+  // the exception to see if it matches with expected exception
+  // list , returns true otherwise will return false.
+  public static boolean isRetriableWithNoFailoverException(Exception e) {
+    Throwable t = e;
+    while (t != null && t.getCause() != null) {
+      for (Class<? extends Exception> cls : getExceptionList()) {

Review comment:
       better use `clazz` instead of `cls`.

##########
File path: hadoop-hdds/framework/src/main/java/org/apache/hadoop/hdds/scm/proxy/SCMContainerLocationFailoverProxyProvider.java
##########
@@ -180,14 +181,22 @@ public synchronized void close() throws IOException {
     }
   }
 
-  public synchronized RetryPolicy.RetryAction getRetryAction(int failovers) {
-    if (failovers >= maxRetryCount) {
+  public RetryPolicy.RetryAction getRetryAction(int failovers, int retry,
+      Exception e) {
+    if (SCMHAUtils.isRetriableWithNoFailoverException(e)) {
+      if (retry < maxRetryCount) {
+        return new RetryPolicy.RetryAction(
+            RetryPolicy.RetryAction.RetryDecision.RETRY, getRetryInterval());
+      } else {
+        return RetryPolicy.RetryAction.FAIL;
+      }
+    } else if (failovers < maxRetryCount) {

Review comment:
       as above. let's wrap `FAILOVER_AND_RETRY` and `FAIL` together for failover exception.




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