Package org.apache.druid.server

Class QueryResultPusher

java.lang.Object

org.apache.druid.server.QueryResultPusher

Direct Known Subclasses:

QueryResourceQueryResultPusherFactory.QueryResourceQueryResultPusher

public abstract class QueryResultPusher
extends Object

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	QueryResultPusher.ResultsWriter
class	QueryResultPusher.StreamingHttpResponseAccumulator
static interface	QueryResultPusher.Writer

Field Summary

Fields

Modifier and Type	Field	Description
protected static final String	RESULT_TRAILER_HEADERS

Constructor Summary

Constructors

Constructor	Description
QueryResultPusher(javax.servlet.http.HttpServletRequest request, com.fasterxml.jackson.databind.ObjectMapper jsonMapper, ResponseContextConfig responseContextConfig, DruidNode selfNode, QueryResource.QueryMetricCounter counter, String queryId, javax.ws.rs.core.MediaType contentType, Map<String,String> extraHeaders)

Method Summary

Modifier and Type	Method	Description
static javax.ws.rs.core.Response	handleDruidExceptionBeforeResponseStarted(DruidException e, javax.ws.rs.core.MediaType contentType, Map<String,String> extraHeaders)	Generates a response for a DruidException that occurs prior to any query results being sent out.
javax.ws.rs.core.Response	push()	Pushes results out.
abstract QueryResultPusher.ResultsWriter	start()	Builds a ResultsWriter to start the lifecycle of the QueryResultPusher.
abstract void	writeException(Exception e, OutputStream out)

Methods inherited from class java.lang.Object

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

Field Details

RESULT_TRAILER_HEADERS

protected static final String RESULT_TRAILER_HEADERS

See Also:

• Constant Field Values

Constructor Details

QueryResultPusher

public QueryResultPusher(javax.servlet.http.HttpServletRequest request,
 com.fasterxml.jackson.databind.ObjectMapper jsonMapper,
 ResponseContextConfig responseContextConfig,
 DruidNode selfNode,
 QueryResource.QueryMetricCounter counter,
 String queryId,
 javax.ws.rs.core.MediaType contentType,
 Map<String,String> extraHeaders)

Method Details

start

public abstract QueryResultPusher.ResultsWriter start()

Builds a ResultsWriter to start the lifecycle of the QueryResultPusher. The ResultsWriter encapsulates the logic to run the query, serialize it and also report success/failure.

This response must not be null. The job of this ResultsWriter is largely to provide lifecycle management to the query running and reporting, so this object must never be null.

This start() method should do as little work as possible, it should really just make the ResultsWriter and return.

Returns:

a new ResultsWriter

writeException

public abstract void writeException(Exception e,
 OutputStream out)
                             throws IOException

Throws:

IOException

push

@Nullable
public javax.ws.rs.core.Response push()

Pushes results out. Can sometimes return a JAXRS Response object instead of actually pushing to the output stream, primarily for error handling that occurs before switching the servlet to asynchronous mode.

Returns:

null if the response has already been handled and pushed out, or a non-null Response object if it expects the container to put the bytes on the wire.

handleDruidExceptionBeforeResponseStarted

public static javax.ws.rs.core.Response handleDruidExceptionBeforeResponseStarted(DruidException e,
 javax.ws.rs.core.MediaType contentType,
 Map<String,String> extraHeaders)

Generates a response for a DruidException that occurs prior to any query results being sent out.