[GitHub] [hbase] virajjasani commented on pull request #2261: HBASE-24528 : BalancerDecision queue implementation in HMaster with Admin API

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

virajjasani commented on pull request #2261:
URL: https://github.com/apache/hbase/pull/2261#issuecomment-686667507


   I am considering to use the same filter based approach I did for the slow log method in Admin.java, where a `LogEntryFilter` can express a limit.
   `LogEntryFilter` expresses "limit" for slow/large log and similarly `BalancerDecisionRequest` expresses "limit" for balancerDecision.
   Both have built-in "limit" values and user can change it, but without constructing LogEntryFilter/BalancerDecisionRequest objects, user can not even invoke Admin.getLogEntries API. So either default or user provided "limit" will definitely reach to Admin.getLogEntries().
   
   ```
   1.
   public class BalancerDecisionRequest extends LogRequest {
   ...
     private int limit = 250;
   ...
   ...
   
   2.
   public class LogQueryFilter extends LogRequest {
   ...
   ...
     private int limit = 10;
   ...
   ...
   ```
   Admin.getLogEntries() takes one argument, which is object of either of above classes, hence we are already passing `limit` with this object.
   
   Here is how shell invokes call to Admin.getLogEntries:
   ```
       def get_balancer_decisions(args)
         balancer_decisions_req = org.apache.hadoop.hbase.client.BalancerDecisionRequest.new
         if args.key? 'LIMIT'   
           limit = args['LIMIT']
           balancer_decisions_req.setLimit(limit)   # if user provided limit in shell argument, use it, else default will be used.
         end
         balancer_decisions_responses = @admin.getLogEntries(balancer_decisions_req)
   ...
   ...
   ```


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