Package org.apache.druid.server.coordination

Class ChangeRequestHttpSyncer<T>

java.lang.Object

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

public class ChangeRequestHttpSyncer<T>
extends Object

This class facilitates the usage of long-polling HTTP endpoints powered by ChangeRequestHistory. For example HttpServerInventoryView uses it to keep segment state in sync with data nodes which expose the segment state via HTTP endpoint in SegmentListerResource.getSegments(long, long, long, javax.servlet.http.HttpServletRequest).

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	ChangeRequestHttpSyncer.Listener<T>	Concurrency guarantees: all calls to ChangeRequestHttpSyncer.Listener.fullSync(java.util.List<T>) and ChangeRequestHttpSyncer.Listener.deltaSync(java.util.List<T>) (that is done within the executor) are linearizable.

Field Summary

Fields

Modifier and Type	Field	Description
static final long	HTTP_TIMEOUT_EXTRA_MS

Constructor Summary

Constructors

Constructor	Description
ChangeRequestHttpSyncer(com.fasterxml.jackson.databind.ObjectMapper smileMapper, HttpClient httpClient, ScheduledExecutorService executor, URL baseServerURL, String baseRequestPath, com.fasterxml.jackson.core.type.TypeReference<ChangeRequestsSnapshot<T>> responseTypeReferences, long serverTimeoutMS, long serverUnstabilityTimeout, ChangeRequestHttpSyncer.Listener<T> listener)

Method Summary

Modifier and Type	Method	Description
boolean	awaitInitialization()	Waits for the first successful sync with this server up to maxDurationToWaitForSync.
Map<String,Object>	getDebugInfo()	Returns debugging information for printing, must not be used for any other purpose.
long	getUnstableTimeMillis()
boolean	isExecutorShutdown()
boolean	isInitialized()	Whether this server has been synced successfully at least once.
boolean	isSyncedSuccessfully()
boolean	needsReset()	Whether this syncer should be reset.
void	start()
void	stop()

Methods inherited from class java.lang.Object

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

Field Details

HTTP_TIMEOUT_EXTRA_MS

public static final long HTTP_TIMEOUT_EXTRA_MS

See Also:

• Constant Field Values

Constructor Details

ChangeRequestHttpSyncer

public ChangeRequestHttpSyncer(com.fasterxml.jackson.databind.ObjectMapper smileMapper,
 HttpClient httpClient,
 ScheduledExecutorService executor,
 URL baseServerURL,
 String baseRequestPath,
 com.fasterxml.jackson.core.type.TypeReference<ChangeRequestsSnapshot<T>> responseTypeReferences,
 long serverTimeoutMS,
 long serverUnstabilityTimeout,
 ChangeRequestHttpSyncer.Listener<T> listener)

Method Details

start

public void start()

stop

public void stop()

awaitInitialization

public boolean awaitInitialization()
                            throws InterruptedException

Waits for the first successful sync with this server up to maxDurationToWaitForSync.

Throws:

InterruptedException

isInitialized

public boolean isInitialized()

Whether this server has been synced successfully at least once.

getDebugInfo

public Map<String,Object> getDebugInfo()

Returns debugging information for printing, must not be used for any other purpose.

needsReset

public boolean needsReset()

Whether this syncer should be reset. This method returning true typically indicates a problem with the sync scheduler.

Returns:

true if the delay since the last request to the server (or since syncer start in case of no request to the server) has exceeded maxDelayBetweenSyncRequests.

getUnstableTimeMillis

public long getUnstableTimeMillis()

isSyncedSuccessfully

public boolean isSyncedSuccessfully()

Returns:

true if there have been no sync failures recently and the last successful sync was not more than maxDurationToWaitForSync ago.

isExecutorShutdown

public boolean isExecutorShutdown()