Add a checkCancelled public method to ContextIndexSearcher · elastic/elasticsearch#121349

(5 comments) (0 reactions) (0 assignees)Java (76,700 stars) (25,882 forks)batch import

:Search Foundations/Search>enhancementTeam:Search Foundationshelp wanted

Description

The ContextIndexSearcher has some API to deal with cancelled tasks, see for example hasCancellations() below. Acting on cancelled tasks can be useful in ValueFetchers (which can be implemented by plugins via custom runtime fields), where resources can be released in such a case. Although the method hasCancellations() is public and accessible to plugins, there is however no access point to its counterpart checkCancelled() (see below): that method would be needed to check if the search's task got cancelled (and act upon it).

Would it be possible to add a public access method to checkCancelled(), in order to allow plugins to handle cancellations in custom runtime fields ?
Related question: are IndexSearchers used in Elasticsearch all ContextIndexSearcher instances ?

https://github.com/elastic/elasticsearch/blob/0d2db063ec4d8e95941e3b92dc150e294e5f0689/server/src/main/java/org/elasticsearch/search/internal/ContextIndexSearcher.java#L193

https://github.com/elastic/elasticsearch/blob/0d2db063ec4d8e95941e3b92dc150e294e5f0689/server/src/main/java/org/elasticsearch/index/mapper/MappedFieldType.java#L118

https://github.com/elastic/elasticsearch/blob/0d2db063ec4d8e95941e3b92dc150e294e5f0689/server/src/main/java/org/elasticsearch/search/internal/ContextIndexSearcher.java#L594

Contributor guide

Tech stack: java
Domain: backend
Issue type: feature
Difficulty: 3
Estimated time: 1-3 hours
Activity status: fresh
Clarity: clear
Prerequisites: JavaElasticsearch search internals
Newbie friendliness: 60
Research direction: Examine ContextIndexSearcher.java (lines 193 and 594) to understand the existing private checkCancelled method and its relationship to hasCancellations. Check the linked MappedFieldType.java to understand how ValueFetchers use cancellation. Review comments in the issue #121349 for maintainer feedback on whether all IndexSearcher instances are ContextIndexSearcher, and whether a public method is acceptable. The change may involve adding a simple public wrapper that delegates to the private checkCancelled, following existing patterns.