io.druid.query

Interface CacheStrategy<T,CacheType,QueryType extends Query<T>>

public interface CacheStrategy<T,CacheType,QueryType extends Query<T>>

Method Summary

Modifier and Type	Method and Description
byte[]	computeCacheKey(QueryType query) Computes the cache key for the given query
com.fasterxml.jackson.core.type.TypeReference<CacheType>	getCacheObjectClazz() Returns the class type of what is used in the cache
boolean	isCacheable(QueryType query, boolean willMergeRunners) Returns the given query is cacheable or not.
com.google.common.base.Function<T,CacheType>	prepareForCache() Returns a function that converts from the QueryType's result type to something cacheable.
com.google.common.base.Function<CacheType,T>	pullFromCache() A function that does the inverse of the operation that the function prepareForCache returns

Method Detail

isCacheable

boolean isCacheable(QueryType query,
                    boolean willMergeRunners)

Returns the given query is cacheable or not. The willMergeRunners parameter can be used for distinguishing the caller is a broker or a data node.

Parameters:

query - the query to be cached

willMergeRunners - indicates that QueryRunnerFactory.mergeRunners(ExecutorService, Iterable) will be called on the cached by-segment results

Returns:

true if the query is cacheable, otherwise false.

computeCacheKey

byte[] computeCacheKey(QueryType query)

Computes the cache key for the given query

Parameters:

query - the query to compute a cache key for

Returns:

the cache key

getCacheObjectClazz

com.fasterxml.jackson.core.type.TypeReference<CacheType> getCacheObjectClazz()

Returns the class type of what is used in the cache

Returns:

Returns the class type of what is used in the cache

prepareForCache

com.google.common.base.Function<T,CacheType> prepareForCache()

Returns a function that converts from the QueryType's result type to something cacheable. The resulting function must be thread-safe.

Returns:

a thread-safe function that converts the QueryType's result type into something cacheable

pullFromCache

com.google.common.base.Function<CacheType,T> pullFromCache()

A function that does the inverse of the operation that the function prepareForCache returns

Returns:

A function that does the inverse of the operation that the function prepareForCache returns