Package org.apache.lucene.search

# Class LiveFieldValues<S,T>

java.lang.Object
org.apache.lucene.search.LiveFieldValues<S,T>

All Implemented Interfaces:
  `Closeable`, `AutoCloseable`, `ReferenceManager.RefreshListener`

public abstract class LiveFieldValues<S,T> extends Object implements ReferenceManager.RefreshListener, Closeable
Tracks live field values across NRT reader reopens. This holds a map for all updated ids since the last reader reopen. Once the NRT reader is reopened, it prunes the map. This means you must reopen your NRT reader periodically otherwise the RAM consumption of this class will grow unbounded!

NOTE: you must ensure the same id is never updated at the same time by two threads, because in this case you cannot in general know which thread "won".

## Constructor Summary

Constructors
Constructor
Description
`LiveFieldValues(ReferenceManager<S> mgr, T missingValue)`
The missingValue must be non-null.

## Method Summary

Modifier and Type
Method
Description
`void`
`add(String id, T value)`
Call this after you've successfully added a document to the index, to record what value you just set the field to.
`void`
`afterRefresh(boolean didRefresh)`
Called after the attempted refresh; if the refresh did open a new reference then didRefresh will be true and `ReferenceManager.acquire()` is guaranteed to return the new reference.
`void`
`beforeRefresh()`
Called right before a refresh attempt starts.
`void`
`close()`
`void`
`delete(String id)`
Call this after you've successfully deleted a document from the index.
`T`
`get(String id)`
Returns the current value for this id, or null if the id isn't in the index or was deleted.
`protected abstract T`
`lookupFromSearcher(S s, String id)`
This is called when the id/value was already flushed and opened in an NRT IndexSearcher.
`int`
`size()`
Returns the [approximate] number of id/value pairs buffered in RAM.

### Methods inherited from class java.lang.Object

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

## Constructor Details

### LiveFieldValues

public LiveFieldValues(ReferenceManager<S> mgr, T missingValue)
The missingValue must be non-null.

## Method Details

### close

public void close()

Specified by:
  `close` in interface `AutoCloseable`
Specified by:
  `close` in interface `Closeable`

### beforeRefresh

public void beforeRefresh() throws IOException
Description copied from interface: `ReferenceManager.RefreshListener`
Called right before a refresh attempt starts.

Specified by:
  `beforeRefresh` in interface `ReferenceManager.RefreshListener`
Throws:
  `IOException`

### afterRefresh

public void afterRefresh(boolean didRefresh) throws IOException
Description copied from interface: `ReferenceManager.RefreshListener`
Called after the attempted refresh; if the refresh did open a new reference then didRefresh will be true and `ReferenceManager.acquire()` is guaranteed to return the new reference.

Specified by:
  `afterRefresh` in interface `ReferenceManager.RefreshListener`
Throws:
  `IOException`

### add

public void add(String id, T value)
Call this after you've successfully added a document to the index, to record what value you just set the field to.

### delete

public void delete(String id)
Call this after you've successfully deleted a document from the index.

### size

public int size()
Returns the [approximate] number of id/value pairs buffered in RAM.

### get

public T get(String id) throws IOException
Returns the current value for this id, or null if the id isn't in the index or was deleted.

Throws:
  `IOException`

### lookupFromSearcher

protected abstract T lookupFromSearcher(S s, String id) throws IOException
This is called when the id/value was already flushed and opened in an NRT IndexSearcher. You must implement this to go look up the value (eg, via doc values, field cache, stored fields, etc.).

Throws:
  `IOException`