io.druid.query.extraction.namespace

Interface ExtractionNamespaceFunctionFactory<T extends ExtractionNamespace>

All Known Implementing Classes:

JDBCExtractionNamespaceFunctionFactory, KafkaExtractionNamespaceFactory, URIExtractionNamespaceFunctionFactory

public interface ExtractionNamespaceFunctionFactory<T extends ExtractionNamespace>

Method Summary

Methods

Modifier and Type	Method and Description
com.google.common.base.Function<String,String>	build(T extractionNamespace, Map<String,String> cache) Create a function for the given namespace which will do the manipulation requested in the extractionNamespace.
Callable<String>	getCachePopulator(T extractionNamespace, String lastVersion, Map<String,String> swap) This function is called once if `ExtractionNamespace.getUpdateMs() == 0`, or every update if `ExtractionNamespace.getUpdateMs() > 0` For ExtractionNamespace which have the NamespaceExtractionCacheManager handle regular updates, this function is used to populate the namespace cache each time.

Method Detail

build

com.google.common.base.Function<String,String> build(T extractionNamespace,
                                                   Map<String,String> cache)

Create a function for the given namespace which will do the manipulation requested in the extractionNamespace. A simple implementation would simply use the cache supplied by the `NamespaceExtractionCacheManager`. More advanced implementations may need more than just what can be cached by `NamespaceExtractionCacheManager`.

Parameters:

extractionNamespace - The ExtractionNamespace for which a manipulating function is needed.

Returns:

A function which will perform an extraction in accordance with the desires of the ExtractionNamespace

getCachePopulator

Callable<String> getCachePopulator(T extractionNamespace,
                                 String lastVersion,
                                 Map<String,String> swap)

This function is called once if `ExtractionNamespace.getUpdateMs() == 0`, or every update if `ExtractionNamespace.getUpdateMs() > 0` For ExtractionNamespace which have the NamespaceExtractionCacheManager handle regular updates, this function is used to populate the namespace cache each time. For ExtractionNamespace implementations which do not have regular updates, this function can be used to initialize resources. If the result of the Callable is the same as what is passed in as lastVersion, then no swap takes place, and the swap is discarded.

Parameters:

extractionNamespace - The ExtractionNamespace for which to populate data.

lastVersion - The version which was last cached

swap - The temporary Map into which data may be placed and will be "swapped" with the proper namespace Map in NamespaceExtractionCacheManager. Implementations which cannot offer a swappable cache of the data may ignore this but must make sure `build(...)` returns a proper Function.

Returns:

A callable that will be used to refresh resources of the namespace and return the version string used in the populating