com.sleepycat.je.tree

Class VLSNCache

java.lang.Object

com.sleepycat.je.tree.VLSNCache

Direct Known Subclasses:

VLSNCache.DefaultCache

public abstract class VLSNCache
extends java.lang.Object

Caches the VLSN sequence for the LN entries in a BIN, when VLSN preservation and caching are configured. A VLSN is added to the cache when an LN is evicted from a BIN. When the LN is resident, there is no need for caching because the LN contains the VLSN. See BIN.setTarget. This strategy works because an LN is always cached during a read or write operation, and only evicted after that based on eviction policies.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	VLSNCache.DefaultCache

Field Summary

Fields

Modifier and Type	Field and Description
static VLSNCache	EMPTY_CACHE An EMPTY_CACHE is used initially for each BIN until the need arises to add to the cache.

Constructor Summary

Constructors

Constructor and Description
VLSNCache()

Method Summary

Modifier and Type	Method and Description
abstract VLSNCache	copy(int from, int to, int n)
abstract long	get(int idx)
abstract long	getMemorySize()
abstract VLSNCache	set(int idx, long val, IN parent)

Methods inherited from class java.lang.Object

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

Field Detail

EMPTY_CACHE

public static VLSNCache EMPTY_CACHE

An EMPTY_CACHE is used initially for each BIN until the need arises to add to the cache. The cache will remain empty if LNs are never evicted or version caching is not configured, which is always the case for standalone JE.

Constructor Detail

VLSNCache

public VLSNCache()

Method Detail

get

public abstract long get(int idx)

set

public abstract VLSNCache set(int idx,
                              long val,
                              IN parent)

copy

public abstract VLSNCache copy(int from,
                               int to,
                               int n)

getMemorySize

public abstract long getMemorySize()