[GitHub] [ozone] adoroszlai commented on a diff in pull request #3615: HDDS-7023. Add CLI for reseting the expired deleted block txn

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

adoroszlai commented on code in PR #3615:
URL: https://github.com/apache/ozone/pull/3615#discussion_r928714072


##########
hadoop-hdds/server-scm/src/main/java/org/apache/hadoop/hdds/scm/block/DeletedBlockLogImpl.java:
##########
@@ -181,6 +181,31 @@ public void incrementCount(List<Long> txIDs)
     }
   }
 
+  /**
+   * {@inheritDoc}
+   *
+   * @throws IOException
+   */
+  @Override
+  public int resetCount(List<Long> txIDs) throws IOException {
+    List<Long> failedTransactions = getFailedTransactions().stream()
+        .map(DeletedBlocksTransaction::getTxID).collect(Collectors.toList());
+    if (txIDs != null && !txIDs.isEmpty()) {
+      failedTransactions = failedTransactions.stream().filter(txIDs::contains)
+          .collect(Collectors.toList());
+    }

Review Comment:
   > why the second stream is not allowed? These two streams are independent processes I think
   
   It is allowed, but unnecessary.  Stream pipelines support multiple non-terminal operations (`filter()`, `map()`, etc.):
   
   ```suggestion
       Stream<Long> stream = getFailedTransactions().stream()
           .map(DeletedBlocksTransaction::getTxID);
       if (txIDs != null && !txIDs.isEmpty()) {
         stream = stream.filter(txIDs::contains);
       }
       List<Long> failedTransactions = stream.collect(Collectors.toList());
   ```
   
   This is better than the one with `Set` if the filter is expected to drop many items.  We save the cost of materializing the bigger collection.
   
   However, since this command is not performance-critical, both solutions are fine.



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