Package org.apache.druid.server.coordination

Class ChangeRequestHistory<T>

java.lang.Object

org.apache.druid.server.coordination.ChangeRequestHistory<T>

public class ChangeRequestHistory<T>
extends Object

This class keeps a bounded list of segment updates made on the server such as adding/dropping segments. Clients call addChangeRequest(T) or addChangeRequests(java.util.List<T>) to add updates (e. g. of segments). Clients call getRequestsSince(org.apache.druid.server.coordination.ChangeRequestHistory.Counter) to get updates since given counter.

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ChangeRequestHistory.Counter

Constructor Summary

Constructors

Constructor	Description
ChangeRequestHistory()
ChangeRequestHistory(int maxSize)

Method Summary

Modifier and Type	Method	Description
void	addChangeRequest(T request)	Add single segment change update.
void	addChangeRequests(List<T> requests)	Add batch of segment changes update.
ChangeRequestHistory.Counter	getLastCounter()
com.google.common.util.concurrent.ListenableFuture<ChangeRequestsSnapshot<T>>	getRequestsSince(ChangeRequestHistory.Counter counter)	Returns a Future that, on completion, returns list of segment updates and associated counter.
void	stop()

Methods inherited from class java.lang.Object

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

Constructor Details

ChangeRequestHistory

public ChangeRequestHistory()

ChangeRequestHistory

public ChangeRequestHistory(int maxSize)

Method Details

stop

public void stop()

addChangeRequests

public void addChangeRequests(List<T> requests)

Add batch of segment changes update.

addChangeRequest

public void addChangeRequest(T request)

Add single segment change update.

getRequestsSince

public com.google.common.util.concurrent.ListenableFuture<ChangeRequestsSnapshot<T>> getRequestsSince(ChangeRequestHistory.Counter counter)

Returns a Future that, on completion, returns list of segment updates and associated counter. If there are no update since given counter then Future completion waits till an updates is provided. If counter is older than max number of changes maintained then ChangeRequestsSnapshot is returned with ChangeRequestsSnapshot.resetCounter set to True. If there were no updates to provide immediately then a future is created and returned to caller. This future is added to the "waitingFutures" list and all the futures in the list get resolved as soon as a segment update is provided.

getLastCounter

public ChangeRequestHistory.Counter getLastCounter()