Package org.apache.jackrabbit.oak.segment

Class CheckpointCompactor

java.lang.Object

org.apache.jackrabbit.oak.segment.Compactor

org.apache.jackrabbit.oak.segment.CheckpointCompactor

public class CheckpointCompactor
extends Compactor

This compactor implementation is aware of the checkpoints in the repository. It uses this information to further optimise the compaction result by

• Rebasing the checkpoints and subsequently the root on top of each other in chronological order. This results minimises the deltas that need to be processed and stored.
• Caching the compacted checkpoints and root states for deduplication should the same checkpoint or root state occur again in a later compaction retry cycle.

Field Summary

Fields

Modifier and Type	Field	Description
protected @NotNull ClassicCompactor	compactor
protected @NotNull GCMonitor	gcListener

Constructor Summary

Constructors

Constructor	Description
CheckpointCompactor(@NotNull GCMonitor gcListener, @NotNull ClassicCompactor compactor)	Create a new instance based on the passed arguments.

Method Summary

Modifier and Type	Method	Description
@Nullable CompactedNodeState	compact(@NotNull NodeState before, @NotNull NodeState after, @NotNull NodeState onto, @NotNull Canceller canceller)	compact the differences between after and before on top of onto.
@Nullable CompactedNodeState	compactDown(@NotNull NodeState before, @NotNull NodeState after, @NotNull Canceller hardCanceller, @NotNull Canceller softCanceller)	compact the differences between after and before on top of after.

Methods inherited from class org.apache.jackrabbit.oak.segment.Compactor

compactDown, compactUp, compactUp

Methods inherited from class java.lang.Object

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

Field Detail

gcListener

@NotNull
protected final @NotNull GCMonitor gcListener

compactor

@NotNull
protected final @NotNull ClassicCompactor compactor

Constructor Detail

CheckpointCompactor

public CheckpointCompactor(@NotNull
                           @NotNull GCMonitor gcListener,
                           @NotNull
                           @NotNull ClassicCompactor compactor)

Create a new instance based on the passed arguments.

Parameters:

gcListener - listener receiving notifications about the garbage collection process

compactor - the delegate compactor to use for the actual compaction work

Method Detail

compactDown

@Nullable
public @Nullable CompactedNodeState compactDown(@NotNull
                                                @NotNull NodeState before,
                                                @NotNull
                                                @NotNull NodeState after,
                                                @NotNull
                                                @NotNull Canceller hardCanceller,
                                                @NotNull
                                                @NotNull Canceller softCanceller)
                                         throws IOException

Description copied from class: Compactor

compact the differences between after and before on top of after.

Specified by:

compactDown in class Compactor

Parameters:

before - the node state to diff against from after

after - the node state diffed against before

hardCanceller - the trigger for hard cancellation, will abandon compaction if cancelled

softCanceller - the trigger for soft cancellation, will return partially compacted state if cancelled

Returns:

the compacted node state or null if hard-cancelled

Throws:

IOException - will throw exception if any errors occur during compaction

compact

@Nullable
public @Nullable CompactedNodeState compact(@NotNull
                                            @NotNull NodeState before,
                                            @NotNull
                                            @NotNull NodeState after,
                                            @NotNull
                                            @NotNull NodeState onto,
                                            @NotNull
                                            @NotNull Canceller canceller)
                                     throws IOException

Description copied from class: Compactor

compact the differences between after and before on top of onto.

Specified by:

compact in class Compactor

Parameters:

before - the node state to diff against from after

after - the node state diffed against before

onto - the node state to compact to apply the diff to

canceller - the trigger for hard cancellation, will abandon compaction if cancelled

Returns:

the compacted node state or null if hard-cancelled

Throws:

IOException - will throw exception if any errors occur during compaction