org.hibernate.search.backend.impl.lucene

Class NRTWorkspaceImpl

java.lang.Object

org.hibernate.search.backend.impl.lucene.AbstractWorkspaceImpl

org.hibernate.search.backend.impl.lucene.NRTWorkspaceImpl

All Implemented Interfaces:

DirectoryBasedReaderProvider, ReaderProvider, Workspace

public class NRTWorkspaceImpl
extends AbstractWorkspaceImpl
implements DirectoryBasedReaderProvider

A Workspace implementation taking advantage of NRT Lucene features. IndexReader instances are obtained directly from the IndexWriter, which is not forced to flush all pending changes to the Directory structure.

Lucene requires in its current version to flush delete operations, or the IndexReaders retrieved via NRT will include deleted Document instances in queries; flushing delete operations happens to be quite expensive so this Workspace implementation attempts to detect when such a flush operation is needed.

Applying write operations flags "indexReader requirements" with needs for either normal flush or flush including deletes, but does not update IndexReader instances. The IndexReaders are updated only if and when a fresh IndexReader is requested via openIndexReader(). This method will check if it can return the last opened IndexReader or in case of the reader being stale open a fresh reader from the current IndexWriter.

Generation counters are used to track need-at-least version versus last-updated-at version: shared state is avoided between index writers and reader threads to avoid high complexity. The method afterTransactionApplied(boolean, boolean) might trigger multiple times flagging the index to be dirty without triggering an actual IndexReader refresh, so the version counters can have gaps: method refreshReaders() will always jump to latest seen version, as it will refresh the index to satisfy both kinds of flush requirements (writes and deletes).

We keep a reference IndexReader in the currentReader atomic reference as a fast path for multiple read events when the index is not dirty.

This class implements both Workspace and ReaderProvider.

Author:

Sanne Grinovero (C) 2011 Red Hat Inc.

Field Summary

Fields inherited from class org.hibernate.search.backend.impl.lucene.AbstractWorkspaceImpl

writerHolder

Constructor Summary

Constructors

Constructor and Description
NRTWorkspaceImpl(DirectoryBasedIndexManager indexManager, WorkerBuildContext buildContext, Properties cfg)

Method Summary

Methods

Modifier and Type	Method and Description
void	afterTransactionApplied(boolean someFailureHappened, boolean streaming) Invoked after all changes of a transaction are applied.
void	closeIndexReader(IndexReader reader)
void	flush() Makes sure eventually pending changes are made visible to IndexReaders.
void	initialize(DirectoryBasedIndexManager indexManager, Properties props)
void	notifyWorkApplied(LuceneWork work) Some workspaces need this to determine for example the kind of flush operations which are safe to apply.
IndexReader	openIndexReader()
void	stop()

Methods inherited from class org.hibernate.search.backend.impl.lucene.AbstractWorkspaceImpl

areSingleTermDeletesSafe, getAnalyzer, getDocumentBuilder, getEntitiesInIndexManager, getIndexWriter, getIndexWriter, incrementModificationCounter, optimizerPhase, performOptimization, shutDownNow

Methods inherited from class java.lang.Object

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

Constructor Detail

NRTWorkspaceImpl

public NRTWorkspaceImpl(DirectoryBasedIndexManager indexManager,
                WorkerBuildContext buildContext,
                Properties cfg)

Method Detail

afterTransactionApplied

public void afterTransactionApplied(boolean someFailureHappened,
                           boolean streaming)

Description copied from interface: Workspace

Invoked after all changes of a transaction are applied. Must be invoked strictly once after every Workspace.getIndexWriter() in a finally block as implementations might rely on counters to release the IndexWriter.

Specified by:

afterTransactionApplied in interface Workspace

Specified by:

afterTransactionApplied in class AbstractWorkspaceImpl

Parameters:

someFailureHappened - usually false, set to true if errors where caught while using the IndexWriter

streaming - if no immediate visibility of the change is required (hint for performance)

openIndexReader

public IndexReader openIndexReader()

Specified by:

openIndexReader in interface ReaderProvider

closeIndexReader

public void closeIndexReader(IndexReader reader)

Specified by:

closeIndexReader in interface ReaderProvider

initialize

public void initialize(DirectoryBasedIndexManager indexManager,
              Properties props)

Specified by:

initialize in interface DirectoryBasedReaderProvider

stop

public void stop()

Specified by:

stop in interface DirectoryBasedReaderProvider

flush

public void flush()

Description copied from interface: Workspace

Makes sure eventually pending changes are made visible to IndexReaders.

Specified by:

flush in interface Workspace

notifyWorkApplied

public void notifyWorkApplied(LuceneWork work)

Description copied from interface: Workspace

Some workspaces need this to determine for example the kind of flush operations which are safe to apply. Generally used for statistics.

Specified by:

notifyWorkApplied in interface Workspace

Parameters:

work - the LuceneWork which was just processed