org.apache.lens.server.api.query.constraint

Interface QueryLaunchingConstraint

All Known Implementing Classes:

MaxConcurrentDriverQueriesConstraint, MaxJDBCConnectionCheckConstraint, RetryPolicyToConstraingAdapter, TotalQueryCostCeilingConstraint

public interface QueryLaunchingConstraint

Method Summary

Modifier and Type	Method and Description
String	allowsLaunchOf(QueryContext candidateQuery, EstimatedImmutableQueryCollection launchedQueries) Returns whether this constraint allows candidate query to be launched.

Method Detail

allowsLaunchOf

String allowsLaunchOf(QueryContext candidateQuery,
                      EstimatedImmutableQueryCollection launchedQueries)

Returns whether this constraint allows candidate query to be launched.

Parameters:

candidateQuery - The query which is the next candidate to be launched.

launchedQueries - Current launched queries

Returns:

null if allowed to launch, otherwise a String containing the reason to block launch