Module org.apache.lucene.core

Package org.apache.lucene.index

Class FlushPolicy

java.lang.Object

org.apache.lucene.index.FlushPolicy

Direct Known Subclasses:

FlushByRamOrCountsPolicy

abstract class FlushPolicy
extends Object

FlushPolicy controls when segments are flushed from a RAM resident internal data-structure to the IndexWriters Directory.

Segments are traditionally flushed by:

• RAM consumption - configured via IndexWriterConfig.setRAMBufferSizeMB(double)
• Number of RAM resident documents - configured via IndexWriterConfig.setMaxBufferedDocs(int)

IndexWriter consults the provided FlushPolicy to control the flushing process. The policy is informed for each added or updated document as well as for each delete term. Based on the FlushPolicy, the information provided via DocumentsWriterPerThread and DocumentsWriterFlushControl, the FlushPolicy decides if a DocumentsWriterPerThread needs flushing and mark it as flush-pending via DocumentsWriterFlushControl.setFlushPending(org.apache.lucene.index.DocumentsWriterPerThread), or if deletes need to be applied.

See Also:

• DocumentsWriterFlushControl
• DocumentsWriterPerThread
• IndexWriterConfig.setFlushPolicy(FlushPolicy)

Field Summary

Fields

Modifier and Type	Field	Description
protected LiveIndexWriterConfig	indexWriterConfig
protected InfoStream	infoStream

Constructor Summary

Constructors

Constructor	Description
FlushPolicy()

Method Summary

Modifier and Type	Method	Description
private boolean	assertMessage(String s)
protected DocumentsWriterPerThread	findLargestNonPendingWriter(DocumentsWriterFlushControl control, DocumentsWriterPerThread perThread)	Returns the current most RAM consuming non-pending DocumentsWriterPerThread with at least one indexed document.
protected void	init(LiveIndexWriterConfig indexWriterConfig)	Called by DocumentsWriter to initialize the FlushPolicy
abstract void	onChange(DocumentsWriterFlushControl control, DocumentsWriterPerThread perThread)	Called for each delete, insert or update.

Methods inherited from class java.lang.Object

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

Field Details

indexWriterConfig

protected LiveIndexWriterConfig indexWriterConfig

infoStream

protected InfoStream infoStream

Constructor Details

FlushPolicy

FlushPolicy()

Method Details

onChange

public abstract void onChange(DocumentsWriterFlushControl control,
 DocumentsWriterPerThread perThread)

Called for each delete, insert or update. For pure deletes, the given DocumentsWriterPerThread may be null.

Note: This method is called synchronized on the given DocumentsWriterFlushControl and it is guaranteed that the calling thread holds the lock on the given DocumentsWriterPerThread

init

protected void init(LiveIndexWriterConfig indexWriterConfig)

Called by DocumentsWriter to initialize the FlushPolicy

findLargestNonPendingWriter

protected DocumentsWriterPerThread findLargestNonPendingWriter(DocumentsWriterFlushControl control,
 DocumentsWriterPerThread perThread)

Returns the current most RAM consuming non-pending DocumentsWriterPerThread with at least one indexed document.

This method will never return null

assertMessage

private boolean assertMessage(String s)