com.hazelcast.spi.hotrestart.impl.gc.tracker

Class Tracker

java.lang.Object

com.hazelcast.spi.hotrestart.impl.gc.tracker.Tracker

public abstract class Tracker
extends Object

Tracks the GC state for a single key handle in the Hot Restart store: which chunk holds the live record, whether it's a tombstone, and the global garbage count for the key handle. The tracker may also refer to a key handle with no live record, if its global garbage count is still non-zero. This condition can occur when the record is interred by a prefix tombstone.

The global garbage count is the number of all garbage records with the given key handle still present in value chunks, excluding those records which are known to be interred by a prefix tombstone. This count reaching zero means that, if the currently live record is a tombstone, it can be declared garbage since there are no more records left that it must protect from resurrection.

Constructor Summary

Constructors

Constructor and Description
Tracker()

Method Summary

Modifier and Type	Method and Description
long	chunkSeq()
abstract long	garbageCount()
void	incrementGarbageCount() Increments the global garbage count for this tracker.
boolean	isAlive()
boolean	isTombstone()
void	moveToChunk(long destChunkSeq) Makes this tracker point to a new chunk seq as the location of the live record.
void	newLiveRecord(long chunkSeq, boolean freshIsTombstone, TrackerMap owner, boolean restarting) Signals that a new live record with this tracker's key handle for has entered the system.
boolean	reduceGarbageCount(int amount) Reduces the global garbage count for this tracker by the specified amount.
void	retire(TrackerMap owner) Signals that the live record that this tracker points to was retired.

Methods inherited from class java.lang.Object

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

Constructor Detail

Tracker

public Tracker()

Method Detail

isAlive

public final boolean isAlive()

Returns:

whether there is a live record for this tracker's key handle

chunkSeq

public final long chunkSeq()

Returns:

the chunk seq of the live record corresponding to this tracker

isTombstone

public final boolean isTombstone()

Returns:

whether the live record corresponding to this tracker is a tombstone

moveToChunk

public final void moveToChunk(long destChunkSeq)

Makes this tracker point to a new chunk seq as the location of the live record.

Parameters:

destChunkSeq - seq of the chunk holding the live record

newLiveRecord

public final void newLiveRecord(long chunkSeq,
                                boolean freshIsTombstone,
                                TrackerMap owner,
                                boolean restarting)

Signals that a new live record with this tracker's key handle for has entered the system.

Parameters:

chunkSeq - seq of the chunk where the record was written

freshIsTombstone - whether the new record is a tombstone

owner - the TrackerMap owning this tracker (needed to notify its callback)

restarting - whether this is called during Hot Restart, used only for an assertion

retire

public final void retire(TrackerMap owner)

Signals that the live record that this tracker points to was retired.

Parameters:

owner - the TrackerMap owning this tracker (needed to notify its callback)

incrementGarbageCount

public final void incrementGarbageCount()

Increments the global garbage count for this tracker.

reduceGarbageCount

public final boolean reduceGarbageCount(int amount)

Reduces the global garbage count for this tracker by the specified amount.

garbageCount

public abstract long garbageCount()

Returns:

this tracker's global garbage count