org.wikidata.query.rdf.blazegraph.throttling

Class Throttler<B>

java.lang.Object

org.wikidata.query.rdf.blazegraph.throttling.Throttler<B>

Type Parameters:

B - type of the bucket used to differentiate clients

public class Throttler<B>
extends Object

Implement throttling logic.

See Also:

for a more complete description of how throttling works.

Field Summary

Fields

Modifier and Type	Field and Description
String	alwaysThrottleParam This parameter in query will cause throttling no matter what.

Constructor Summary

Constructors

Constructor and Description
Throttler(Duration requestTimeThreshold, Bucketing<B> bucketing, Callable<ThrottlingState> createThrottlingState, com.google.common.cache.Cache<B,ThrottlingState> stateStore, String enableThrottlingIfHeader, String alwaysThrottleParam) Constructor.

Method Summary

Modifier and Type	Method and Description
void	failure(javax.servlet.http.HttpServletRequest request, Duration elapsed) Notify this throttler that a request has completed in error.
Duration	getBackoffDelay(javax.servlet.http.HttpServletRequest request) How long should this client wait before his next request.
long	getStateSize() The size (in number of entries) of the throttling state.
boolean	isThrottled(javax.servlet.http.HttpServletRequest request) Should this request be throttled.
void	success(javax.servlet.http.HttpServletRequest request, Duration elapsed) Notify this throttler that a request has been completed successfully.

Methods inherited from class java.lang.Object

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

Field Detail

alwaysThrottleParam

public final String alwaysThrottleParam

This parameter in query will cause throttling no matter what. This can be used for testing.

Constructor Detail

Throttler

public Throttler(Duration requestTimeThreshold,
                 Bucketing<B> bucketing,
                 Callable<ThrottlingState> createThrottlingState,
                 com.google.common.cache.Cache<B,ThrottlingState> stateStore,
                 String enableThrottlingIfHeader,
                 String alwaysThrottleParam)

Constructor. Note that a bucket represent our approximation of a single client.

Parameters:

requestTimeThreshold - requests longer than this will trigger tracking resource consumption

bucketing - how to associate a request with a specific bucket

createThrottlingState - how to create the initial throttling state when we start tracking a specific client

stateStore - the cache in which we store the per client state of throttling

enableThrottlingIfHeader - throttling is only enabled if this header is present

alwaysThrottleParam - this query parameter will cause throttling no matter what

Method Detail

getStateSize

public long getStateSize()

The size (in number of entries) of the throttling state. This correspond to the number of clients currently being tracked.

Returns:

the number of entries in state size

isThrottled

public boolean isThrottled(javax.servlet.http.HttpServletRequest request)

Should this request be throttled.

Parameters:

request - the request to check

Returns:

true if the request should be throttled

success

public void success(javax.servlet.http.HttpServletRequest request,
                    Duration elapsed)

Notify this throttler that a request has been completed successfully.

Parameters:

request - the request

elapsed - how long that request took

failure

public void failure(javax.servlet.http.HttpServletRequest request,
                    Duration elapsed)

Notify this throttler that a request has completed in error.

Parameters:

request - the request

elapsed - how long that request took

getBackoffDelay

public Duration getBackoffDelay(javax.servlet.http.HttpServletRequest request)

How long should this client wait before his next request.

Parameters:

request - the request

Returns:

0 if no throttling, the backoff delay otherwise