com.yahoo.bard.webservice.web.handlers

Class WeightCheckRequestHandler

java.lang.Object

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

com.yahoo.bard.webservice.web.handlers.WeightCheckRequestHandler

All Implemented Interfaces:

DataRequestHandler

public class WeightCheckRequestHandler
extends BaseDataRequestHandler

Weight check request handler determines whether a request should be processed based on estimated query cost.

• If the dimensions of the query are sufficiently low cardinality, the request is allowed.
• Otherwise, send a simplified version of the query to druid asynchronously to measure the cardinality of the results.
• If the cost is too high, return an error, otherwise subsequently submit the data request.

Field Summary

Fields

Modifier and Type	Field and Description
protected DataRequestHandler	next
protected QueryWeightUtil	queryWeightUtil
protected DruidWebService	webService

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

mapper, writer

Constructor Summary

Constructors

Constructor and Description
WeightCheckRequestHandler(DataRequestHandler next, DruidWebService webService, QueryWeightUtil queryWeightUtil, com.fasterxml.jackson.databind.ObjectMapper mapper) Build a weight checking request handler.

Method Summary

Modifier and Type	Method and Description
protected SuccessCallback	buildSuccessCallback(RequestContext context, DataApiRequest request, DruidAggregationQuery<?> druidQuery, ResponseProcessor response, long queryRowLimit) Build a callback which continues the original request or refuses it with an HTTP INSUFFICIENT_STORAGE (507) status based on the cardinality of the requester 's query as measured by the weight check query.
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

next

@NotNull
protected final DataRequestHandler next

webService

@NotNull
protected final DruidWebService webService

queryWeightUtil

@NotNull
protected final QueryWeightUtil queryWeightUtil

Constructor Detail

WeightCheckRequestHandler

public WeightCheckRequestHandler(DataRequestHandler next,
                                 DruidWebService webService,
                                 QueryWeightUtil queryWeightUtil,
                                 com.fasterxml.jackson.databind.ObjectMapper mapper)

Build a weight checking request handler.

Parameters:

next - The request handler to delegate the request to.

webService - The web service to use for weight checking

queryWeightUtil - A provider which measures estimated weight against allowed weights.

mapper - A JSON object mapper, used to parse the JSON response from the weight check.

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

buildSuccessCallback

protected SuccessCallback buildSuccessCallback(RequestContext context,
                                               DataApiRequest request,
                                               DruidAggregationQuery<?> druidQuery,
                                               ResponseProcessor response,
                                               long queryRowLimit)

Build a callback which continues the original request or refuses it with an HTTP INSUFFICIENT_STORAGE (507) status based on the cardinality of the requester 's query as measured by the weight check query.

Parameters:

context - The context data from the request processing chain

request - The API request itself

druidQuery - The query being processed

response - the response handler

queryRowLimit - The number of aggregating lines allowed

Returns:

The callback handler for the weight request