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https://issues.apache.org/jira/browse/DRILL-4286?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16252575#comment-16252575
 ] 

ASF GitHub Bot commented on DRILL-4286:
---------------------------------------

Github user paul-rogers commented on a diff in the pull request:

    https://github.com/apache/drill/pull/921#discussion_r150971745
  
    --- Diff: 
exec/java-exec/src/main/java/org/apache/drill/exec/coord/zk/ZKClusterCoordinator.java
 ---
    @@ -200,11 +206,50 @@ public void unregister(RegistrationHandle handle) {
         }
       }
     
    +  /**
    +   * Update drillbit endpoint state. Drillbit advertises its
    +   * state in Zookeeper when a shutdown request of drillbit is
    +   * triggered. State information is used during planning and
    +   * initial client connection phases.
    +   */
    +  public RegistrationHandle update(RegistrationHandle handle, State state) 
{
    +    ZKRegistrationHandle h = (ZKRegistrationHandle) handle;
    +      try {
    +        endpoint = h.endpoint.toBuilder().setState(state).build();
    +        ServiceInstance<DrillbitEndpoint> serviceInstance = 
ServiceInstance.<DrillbitEndpoint>builder()
    +                .name(serviceName)
    +                .id(h.id)
    +                .payload(endpoint).build();
    +        discovery.updateService(serviceInstance);
    +      } catch (Exception e) {
    +        e.printStackTrace();
    +      }
    +      return handle;
    +  }
    +
       @Override
       public Collection<DrillbitEndpoint> getAvailableEndpoints() {
         return this.endpoints;
       }
     
    +  /*
    +   * Get a collection of ONLINE Drillbit endpoints by excluding the 
drillbits
    +   * that are in QUIESCENT state (drillbits shutting down). Primarily used 
by the planner
    +   * to plan queries only on ONLINE drillbits and used by the client 
during initial connection
    +   * phase to connect to a drillbit (foreman)
    +   * @return A collection of ONLINE endpoints
    +   */
    +  @Override
    +  public Collection<DrillbitEndpoint> getOnlineEndPoints() {
    +    Collection<DrillbitEndpoint> runningEndPoints = new ArrayList<>();
    +    for (DrillbitEndpoint endpoint: endpoints){
    +      if(!endpoint.hasState() || endpoint.getState().equals(State.ONLINE)) 
{
    --- End diff --
    
    This stanza appears multiple times. Can we define a static function that 
does the double check to avoid redundant code?
    
    ```
    boolean isInState(State state) {
    ...
    ```
    Choose an appropriate name, maybe `isDrillbitInState` or whatever.


> Have an ability to put server in quiescent mode of operation
> ------------------------------------------------------------
>
>                 Key: DRILL-4286
>                 URL: https://issues.apache.org/jira/browse/DRILL-4286
>             Project: Apache Drill
>          Issue Type: New Feature
>          Components: Execution - Flow
>            Reporter: Victoria Markman
>            Assignee: Venkata Jyothsna Donapati
>
> I think drill will benefit from mode of operation that is called "quiescent" 
> in some databases. 
> From IBM Informix server documentation:
> {code}
> Change gracefully from online to quiescent mode
> Take the database server gracefully from online mode to quiescent mode to 
> restrict access to the database server without interrupting current 
> processing. After you perform this task, the database server sets a flag that 
> prevents new sessions from gaining access to the database server. The current 
> sessions are allowed to finish processing. After you initiate the mode 
> change, it cannot be canceled. During the mode change from online to 
> quiescent, the database server is considered to be in Shutdown mode.
> {code}
> This is different from shutdown, when processes are terminated. 



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