[GitHub] [accumulo] ctubbsii commented on a change in pull request #1744: Use newer map methods in TabletGroupWatcher

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

ctubbsii commented on a change in pull request #1744:
URL: https://github.com/apache/accumulo/pull/1744#discussion_r508861282



##########
File path: server/manager/src/main/java/org/apache/accumulo/master/TabletGroupWatcher.java
##########
@@ -214,14 +214,8 @@ public void run() {
           TableId tableId = tls.extent.tableId();
           TableConfiguration tableConf = this.master.getContext().getTableConfiguration(tableId);
 
-          MergeStats mergeStats = mergeStatsCache.get(tableId);
-          if (mergeStats == null) {
-            mergeStats = currentMerges.get(tableId);
-            if (mergeStats == null) {
-              mergeStats = new MergeStats(new MergeInfo());
-            }
-            mergeStatsCache.put(tableId, mergeStats);
-          }
+          MergeStats mergeStats = mergeStatsCache.computeIfAbsent(tableId,
+              k -> currentMerges.getOrDefault(k, new MergeStats(new MergeInfo())));

Review comment:
       This always constructs the the 'default' `new MergeStats(new MergeInfo()))`, even if already exists in `currentMerges`. To avoid that, you could use the following instead of `getOrDefault`:
   
   ```suggestion
                 k -> {
                   var mergeStats = currentMerges.get(k);
                   return mergeStats != null ? mergeStats : new MergeStats(new MergeInfo());
                 });
   ```




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