[GitHub] [accumulo] keith-turner commented on issue #1764: Parallelize calls to InstanceOperations.getActiveCompactions() in listcompactions shell command

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

keith-turner commented on issue #1764:
URL: https://github.com/apache/accumulo/issues/1764#issuecomment-720685854


   One possible way to implement this is :
   
    * Move the code in ActiveCompactionItertator that converts an ActiveCompaction object to a display string into a function called `toDisplay(ActiveCompaction)`.
    * Replace this [line](https://github.com/apache/accumulo/blob/d820360b975de759b1575d68456e69c828225a85/shell/src/main/java/org/apache/accumulo/shell/commands/ListCompactionsCommand.java#L67) with a stream.
    * Remove the ActiveCompactionIterator class
   
   The code for stream could look like the following.
   
   ```java
       String finalFilterText = filterText;
       Predicate<String> textFilter = finalFilterText == null ? t -> true : t -> t.matches(finalFilterText);
       
       Iterator<String> activeCompactionIterator = tservers.stream().map(tserver -> CompletableFuture.supplyAsync(() -> {
         try {
           return instanceOps.getActiveCompactions(tserver);
         } catch (Exception e) {
           throw new RuntimeException(e);
         }
       }, executor)).flatMap(cf -> cf.join().stream()).map(ac -> toDisplay(ac)).filter(textFilter)
           .iterator();
   ```
   
   However this solution drops one thing the current code is doing. The current code sorts each tservers active compactions by age.


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