com.yahoo.bard.webservice.web.handlers

Class CacheRequestHandler

java.lang.Object

com.yahoo.bard.webservice.web.handlers.BaseDataRequestHandler

com.yahoo.bard.webservice.web.handlers.CacheRequestHandler

All Implemented Interfaces:

DataRequestHandler

public class CacheRequestHandler
extends BaseDataRequestHandler

Request handler to check the cache for a matching request and either return the cached result or send the next handler.

It also wraps the response processor so that valid, non-partial JSON responses are cached

Field Summary

Fields

Modifier and Type	Field and Description
static com.codahale.metrics.Meter	CACHE_HITS
static com.codahale.metrics.Meter	CACHE_MISSES
static com.codahale.metrics.Meter	CACHE_REQUESTS
protected DataCache<String>	dataCache
protected DataRequestHandler	next

Fields inherited from class com.yahoo.bard.webservice.web.handlers.BaseDataRequestHandler

mapper, writer

Constructor Summary

Constructors

Constructor and Description
CacheRequestHandler(DataRequestHandler next, DataCache<?> dataCache, com.fasterxml.jackson.databind.ObjectMapper mapper) Build a Cache request handler.

Method Summary

Modifier and Type	Method and Description
protected String	getKey(DruidAggregationQuery<?> druidQuery) Construct the cache key.
boolean	handleRequest(RequestContext context, DataApiRequest request, DruidAggregationQuery<?> druidQuery, ResponseProcessor response) Handle the response, passing the request down the chain as necessary.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

CACHE_HITS

public static final com.codahale.metrics.Meter CACHE_HITS

CACHE_MISSES

public static final com.codahale.metrics.Meter CACHE_MISSES

CACHE_REQUESTS

public static final com.codahale.metrics.Meter CACHE_REQUESTS

next

@NotNull
protected final DataRequestHandler next

dataCache

@NotNull
protected final DataCache<String> dataCache

Constructor Detail

CacheRequestHandler

public CacheRequestHandler(DataRequestHandler next,
                           @NotNull
                           DataCache<?> dataCache,
                           com.fasterxml.jackson.databind.ObjectMapper mapper)

Build a Cache request handler.

Parameters:

next - The next handler in the chain

dataCache - The cache instance

mapper - The mapper for all JSON processing

Method Detail

handleRequest

public boolean handleRequest(RequestContext context,
                             DataApiRequest request,
                             DruidAggregationQuery<?> druidQuery,
                             ResponseProcessor response)

Description copied from interface: DataRequestHandler

Handle the response, passing the request down the chain as necessary.

Parameters:

context - The context for the Request

request - The Api Request Object

druidQuery - The druid query

response - The Async response

Returns:

True if the async response has been processed or passed to a future for processing

getKey

protected String getKey(DruidAggregationQuery<?> druidQuery)
                 throws com.fasterxml.jackson.core.JsonProcessingException

Construct the cache key. Current implementation includes all the fields of the druidQuery besides the context.

Parameters:

druidQuery - The druid query.

Returns:

The cache key as a String.

Throws:

com.fasterxml.jackson.core.JsonProcessingException - if the druid query cannot be mapped to Json