org.apache.cassandra.hints

Class HintsService

java.lang.Object

org.apache.cassandra.hints.HintsService

All Implemented Interfaces:

HintsServiceMBean

public final class HintsService
extends java.lang.Object
implements HintsServiceMBean

A singleton-ish wrapper over various hints components: - a catalog of all hints stores - a single-threaded write executor - a multi-threaded dispatch executor - the buffer pool for writing hints into The front-end for everything hints related.

Field Summary

Fields

Modifier and Type	Field and Description
static HintsService	instance
HintedHandoffMetrics	metrics

Method Summary

Modifier and Type	Method and Description
void	deleteAllHints() Deletes all hints for all destinations.
void	deleteAllHintsForEndpoint(java.net.InetAddress target) Deletes all hints for the provided destination.
void	deleteAllHintsForEndpoint(java.lang.String address) Deletes all hints for the provided destination.
void	excise(java.util.UUID hostId) Cleans up hints-related state after a node with id = hostId left.
void	flushAndFsyncBlockingly(java.lang.Iterable<java.util.UUID> hostIds) Flush the buffer pool for the selected target nodes, then fsync their writers.
boolean	isShutDown() Returns true in case service is shut down.
void	pauseDispatch() Pause dispatch of all hints.
void	registerMBean()
void	resumeDispatch() Resume dispatch of all hints.
void	shutdownBlocking() Gracefully and blockingly shut down the service.
void	startDispatch()
java.util.concurrent.Future	transferHints(java.util.function.Supplier<java.util.UUID> hostIdSupplier) Transfer all local hints to the hostId supplied by hostIdSupplier Flushes the buffer to make sure all hints are on disk and closes the hint writers so we don't leave any hint files around.
void	write(java.lang.Iterable<java.util.UUID> hostIds, Hint hint) Write a hint for a iterable of nodes.
void	write(java.util.UUID hostId, Hint hint) Write a hint for a single node.

Methods inherited from class java.lang.Object

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

Field Detail

instance

public static HintsService instance

metrics

public final HintedHandoffMetrics metrics

Method Detail

registerMBean

public void registerMBean()

write

public void write(java.lang.Iterable<java.util.UUID> hostIds,
                  Hint hint)

Write a hint for a iterable of nodes.

Parameters:

hostIds - host ids of the hint's target nodes

hint - the hint to store

write

public void write(java.util.UUID hostId,
                  Hint hint)

Write a hint for a single node.

Parameters:

hostId - host id of the hint's target node

hint - the hint to store

flushAndFsyncBlockingly

public void flushAndFsyncBlockingly(java.lang.Iterable<java.util.UUID> hostIds)

Flush the buffer pool for the selected target nodes, then fsync their writers.

Parameters:

hostIds - host ids of the nodes to flush and fsync hints for

startDispatch

public void startDispatch()

pauseDispatch

public void pauseDispatch()

Description copied from interface: HintsServiceMBean

Pause dispatch of all hints. Does not affect the creation of hints.

Specified by:

pauseDispatch in interface HintsServiceMBean

resumeDispatch

public void resumeDispatch()

Description copied from interface: HintsServiceMBean

Resume dispatch of all hints. Does not affect the creation of hints.

Specified by:

resumeDispatch in interface HintsServiceMBean

shutdownBlocking

public void shutdownBlocking()
                      throws java.util.concurrent.ExecutionException,
                             java.lang.InterruptedException

Gracefully and blockingly shut down the service. Will abort dispatch sessions that are currently in progress (which is okay, it's idempotent), and make sure the buffers are flushed, hints files written and fsynced.

Throws:

java.util.concurrent.ExecutionException

java.lang.InterruptedException

deleteAllHints

public void deleteAllHints()

Deletes all hints for all destinations. Doesn't make snapshots - should be used with care.

Specified by:

deleteAllHints in interface HintsServiceMBean

deleteAllHintsForEndpoint

public void deleteAllHintsForEndpoint(java.lang.String address)

Deletes all hints for the provided destination. Doesn't make snapshots - should be used with care.

Specified by:

deleteAllHintsForEndpoint in interface HintsServiceMBean

Parameters:

address - inet address of the target node - encoded as a string for easier JMX consumption

deleteAllHintsForEndpoint

public void deleteAllHintsForEndpoint(java.net.InetAddress target)

Deletes all hints for the provided destination. Doesn't make snapshots - should be used with care.

Parameters:

target - inet address of the target node

excise

public void excise(java.util.UUID hostId)

Cleans up hints-related state after a node with id = hostId left. Dispatcher can not stop itself (isHostAlive() can not start returning false for the leaving host because this method is called by the same thread as gossip, which blocks gossip), so we can't simply wait for completion. We should also flush the buffer if there are any hints for the node there, and close the writer (if any), so that we don't leave any hint files lying around. Once that is done, we can simply delete all hint files and remove the host id from the catalog. The worst that can happen if we don't get everything right is a hints file (or two) remaining undeleted.

Parameters:

hostId - id of the node being excised

transferHints

public java.util.concurrent.Future transferHints(java.util.function.Supplier<java.util.UUID> hostIdSupplier)

Transfer all local hints to the hostId supplied by hostIdSupplier Flushes the buffer to make sure all hints are on disk and closes the hint writers so we don't leave any hint files around. After that, we serially dispatch all the hints in the HintsCatalog. If we fail delivering all hints, we will ask the hostIdSupplier for a new target host and retry delivering any remaining hints there, once, with a delay of 10 seconds before retrying.

Parameters:

hostIdSupplier - supplier of stream target host ids. This is generally the closest one according to the DynamicSnitch

Returns:

When this future is done, it either has streamed all hints to remote nodes or has failed with a proper log message

isShutDown

public boolean isShutDown()

Returns true in case service is shut down.