QueryProcessingPool (druid-processing 28.0.1 API)

All Superinterfaces:

Executor, ExecutorService, com.google.common.util.concurrent.ListeningExecutorService

All Known Implementing Classes:

DirectQueryProcessingPool, ForwardingQueryProcessingPool, MetricsEmittingQueryProcessingPool
```
public interface QueryProcessingPool
extends com.google.common.util.concurrent.ListeningExecutorService
```
This class implements the logic of how units of query execution run concurrently. It is used in QueryRunnerFactory.mergeRunners(QueryProcessingPool, Iterable). In a most straightforward implementation, each unit will be submitted to an PrioritizedExecutorService. Extensions, however, can implement their own logic for picking which unit to pick first for execution.
This interface extends ListeningExecutorService as well. It has a separate method to submit query execution tasks so that implementations can differentiate those tasks from any regular async tasks. One example is GroupingEngine.mergeRunners(QueryProcessingPool, Iterable) where different kind of tasks are submitted to same processing pool.
Query execution task also includes a reference to QueryRunner so that any state required to decide the priority of a unit can be carried forward with the corresponding QueryRunner.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method	Description
`<T,V> com.google.common.util.concurrent.ListenableFuture<T>`	`submitRunnerTask(PrioritizedQueryRunnerCallable<T,V> task)`	Submits the query execution unit task for asynchronous execution.

Methods inherited from interface java.util.concurrent.Executor
execute

Methods inherited from interface java.util.concurrent.ExecutorService
awaitTermination, invokeAny, invokeAny, isShutdown, isTerminated, shutdown, shutdownNow

Methods inherited from interface com.google.common.util.concurrent.ListeningExecutorService
invokeAll, invokeAll, submit, submit, submit

- Method Detail
  - submitRunnerTask
```
<T,V> com.google.common.util.concurrent.ListenableFuture<T> submitRunnerTask(PrioritizedQueryRunnerCallable<T,V> task)
```
    Submits the query execution unit task for asynchronous execution.
    
    Type Parameters:
    
    T - - Task result type
    
    V - - Query runner sequence type
    
    Parameters:
    
    task - - Task to be submitted.
    
    Returns:
    
    - Future object for tracking the task completion.