Package io.undertow.server.handlers.cache

Class DirectBufferCache

java.lang.Object

io.undertow.server.handlers.cache.DirectBufferCache

public class DirectBufferCache
extends Object

A non-blocking buffer cache where entries are indexed by a path and are made up of a subsequence of blocks in a fixed large direct buffer. An ideal application is a file system cache, where the path corresponds to a file location.

To reduce contention, entry allocation and eviction execute in a sampling fashion (entry hits modulo N). Eviction follows an LRU approach (oldest sampled entries are removed first) when the cache is out of capacity

In order to expedite reclamation, cache entries are reference counted as opposed to garbage collected.

Author:

Jason T. Greene

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static final class	DirectBufferCache.CacheEntry

Field Summary

Fields

Modifier and Type	Field	Description
static final int	MAX_AGE_NO_CACHING	Max age 0, indicating that entries expire upon creation and are not retained;
static final int	MAX_AGE_NO_EXPIRY	Mage age -1, entries dont expire

Constructor Summary

Constructors

Constructor	Description
DirectBufferCache(int sliceSize, int slicesPerPage, int maxMemory)
DirectBufferCache(int sliceSize, int slicesPerPage, int maxMemory, org.xnio.BufferAllocator<ByteBuffer> bufferAllocator)
DirectBufferCache(int sliceSize, int slicesPerPage, int maxMemory, org.xnio.BufferAllocator<ByteBuffer> bufferAllocator, int maxAge)

Method Summary

Modifier and Type	Method	Description
DirectBufferCache.CacheEntry	add(Object key, int size)
DirectBufferCache.CacheEntry	add(Object key, int size, int maxAge)
DirectBufferCache.CacheEntry	get(Object key)
Set<Object>	getAllKeys()	Returns a set of all the keys in the cache.
void	remove(Object key)

Methods inherited from class java.lang.Object

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

Field Details

MAX_AGE_NO_CACHING

public static final int MAX_AGE_NO_CACHING

Max age 0, indicating that entries expire upon creation and are not retained;

See Also:

• Constant Field Values

MAX_AGE_NO_EXPIRY

public static final int MAX_AGE_NO_EXPIRY

Mage age -1, entries dont expire

See Also:

• Constant Field Values

Constructor Details

DirectBufferCache

public DirectBufferCache(int sliceSize,
 int slicesPerPage,
 int maxMemory)

DirectBufferCache

public DirectBufferCache(int sliceSize,
 int slicesPerPage,
 int maxMemory,
 org.xnio.BufferAllocator<ByteBuffer> bufferAllocator)

DirectBufferCache

public DirectBufferCache(int sliceSize,
 int slicesPerPage,
 int maxMemory,
 org.xnio.BufferAllocator<ByteBuffer> bufferAllocator,
 int maxAge)

Method Details

add

public DirectBufferCache.CacheEntry add(Object key,
 int size)

add

public DirectBufferCache.CacheEntry add(Object key,
 int size,
 int maxAge)

get

public DirectBufferCache.CacheEntry get(Object key)

getAllKeys

public Set<Object> getAllKeys()

Returns a set of all the keys in the cache. This is a copy of the key set at the time of method invocation.

Returns:

all the keys in this cache

remove

public void remove(Object key)