io.druid.query

Interface QueryWatcher

All Known Implementing Classes:

NoopQueryWatcher, QueryManager

public interface QueryWatcher

This interface is in a very early stage and should not be considered stable. The purpose of the QueryWatcher is to give overall visibility into queries running or pending at the QueryRunner level. This is currently used to cancel all the parts of a pending query, but may be expanded in the future to offer more direct visibility into query execution and resource usage. QueryRunners executing any computation asynchronously must register their queries with the QueryWatcher.

Method Summary

Modifier and Type	Method and Description
void	registerQuery(Query query, com.google.common.util.concurrent.ListenableFuture future) QueryRunners must use this method to register any pending queries.

Method Detail

registerQuery

void registerQuery(Query query,
                   com.google.common.util.concurrent.ListenableFuture future)

QueryRunners must use this method to register any pending queries. The given future may have cancel(true) called at any time, if cancellation of this query has been requested.

Parameters:

query - a query, which may be a subset of a larger query, as long as the underlying queryId is unchanged

future - the future holding the execution status of the query