org.apache.jackrabbit.oak.plugins.observation

Class FilteringObserver

java.lang.Object

org.apache.jackrabbit.oak.plugins.observation.FilteringObserver

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, Observer

public class FilteringObserver
extends java.lang.Object
implements Observer, java.io.Closeable

An observer that implements filtering of content changes while at the same time supporting (wrapping) a BackgroundObserver underneath.

The FilteringObserver uses an explicit Filter to decide whether or not to forward a content change to the BackgroundObserver. If the Filter decides to include the change things happen as usual. If the Filter decides to exclude the change, this FilteringObserver does not forward the change, but remembers the fact that the last change was filtered. The first included change after excluded ones will cause a NOOP_CHANGE commitInfo to be passed along to the BackgroundObserver. That NOOP_CHANGE is then used by the FilteringDispatcher: if a CommitInfo is a NOOP_CHANGE then the FilteringDispatcher will not forward anything to the FilteringAwareObserver and only adjust the 'before' state accordingly (which it does also for a NOOP_CHANGE, to exactly achieve the skipping effect).

Constructor Summary

Constructors

Constructor and Description
FilteringObserver(@NotNull BackgroundObserver backgroundObserver, @NotNull Filter filter) Alternative constructor where the BackgroundObserver is created elsewhere
FilteringObserver(@NotNull java.util.concurrent.Executor executor, int queueLength, @NotNull Filter filter, @NotNull FilteringAwareObserver observer) Default constructor which creates a BackgroundObserver automatically, including creating a FilteringDispatcher.

Method Summary

Modifier and Type	Method and Description
void	close()
void	contentChanged(@NotNull NodeState root, @NotNull CommitInfo info) Observes a content change.
BackgroundObserver	getBackgroundObserver()

Methods inherited from class java.lang.Object

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

Constructor Detail

FilteringObserver

public FilteringObserver(@NotNull
                         @NotNull java.util.concurrent.Executor executor,
                         int queueLength,
                         @NotNull
                         @NotNull Filter filter,
                         @NotNull
                         @NotNull FilteringAwareObserver observer)

Default constructor which creates a BackgroundObserver automatically, including creating a FilteringDispatcher.

Parameters:

executor - the executor that should be used for the BackgroundObserver

queueLength - the queue length of the BackgroundObserver

filter - the Filter to be used for filtering

observer - the FilteringAwareObserver to which content changes ultimately are delivered after going through a chain of FilteringObserver->BackgroundObserver->FilteringDispatcher.

FilteringObserver

public FilteringObserver(@NotNull
                         @NotNull BackgroundObserver backgroundObserver,
                         @NotNull
                         @NotNull Filter filter)

Alternative constructor where the BackgroundObserver is created elsewhere

Parameters:

backgroundObserver - the BackgroundObserver to be used by this FilteringObserver

filter - the Filter to be used for filtering

Method Detail

getBackgroundObserver

public BackgroundObserver getBackgroundObserver()

contentChanged

public final void contentChanged(@NotNull
                                 @NotNull NodeState root,
                                 @NotNull
                                 @NotNull CommitInfo info)

Description copied from interface: Observer

Observes a content change. See the Observer class javadocs and relevant repository and observer registration details for more information on when and how this method gets called.

Specified by:

contentChanged in interface Observer

Parameters:

root - root state of the repository

info - commit information

close

public void close()

Specified by:

close in interface java.io.Closeable

Specified by:

close in interface java.lang.AutoCloseable