org.cache2k.storage

Interface CacheStorage

All Known Subinterfaces:

EntryExpiryUpdateableStorage, FlushableStorage

All Known Implementing Classes:

ByReferenceHeapStorageImpl, ClearStorageBuffer, ImageFileStorage

public interface CacheStorage

An interface for persistent or off heap storage for a cache.

Author:

Jens Wilke; created: 2014-04-03

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	CacheStorage.EntryFilter
static interface	CacheStorage.EntryVisitor
static interface	CacheStorage.MultiThreadedContext
static interface	CacheStorage.VisitContext

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Remove all entries from the cache and free resources.
void	close() Free all resources and stop operations immediately.
boolean	contains(Object key) Returns true if there is a mapping for the key.
StorageEntry	get(Object key) Retrieve the entry from the storage.
int	getEntryCount()
void	put(StorageEntry e) Stores the entry in the storage.
boolean	remove(Object key)
void	visit(CacheStorage.VisitContext ctx, CacheStorage.EntryFilter f, CacheStorage.EntryVisitor v) Iterate over all stored entries and call the entry visitor.

Method Detail

get

StorageEntry get(Object key)
                 throws Exception

Retrieve the entry from the storage. If there is no mapping for the key, null is returned.

Depending on the cache configuration, an exception on get is not severe. The cache will try other sources or return null.

Throws:

Exception

put

void put(StorageEntry e)
         throws Exception

Stores the entry in the storage. The entry instance is solely for transferring the data, no reference may be hold within the storage to it. The callee takes care that the entry data is consistent during the put method call.

If a put operation fails an implementation should try to remove an existing entry bound to the key and then throw the exception.

Throws:

IOException - may be thrown if hope is lost

Exception

remove

boolean remove(Object key)
               throws Exception

Throws:

Exception

contains

boolean contains(Object key)
                 throws Exception

Returns true if there is a mapping for the key.

An exception on contains is not severe. The cache will try other sources or return null.

Throws:

Exception

clear

void clear()
           throws Exception

Remove all entries from the cache and free resources. This operation is called when there is no other operation concurrently executed on this storage instance.

When a Cache.clear() is initiated there is no obligation to send a CacheStorage.clear() to the persisted storage. Alternatively, all objects can be removed via remove().

Throws:

Exception

close

void close()
           throws Exception

Free all resources and stop operations immediately.

Throws:

Exception

visit

void visit(CacheStorage.VisitContext ctx,
         CacheStorage.EntryFilter f,
         CacheStorage.EntryVisitor v)
           throws Exception

Iterate over all stored entries and call the entry visitor. It is generally safe to return expired entries. If PurgeableStorage is not implemented, returning expired entries is a must, to support the generic purge algorithm.

If the ExecutorService is used, the method may return immediately without the waiting for all threads to finish. This is done by the caller, when needed.

Throws:

Exception

getEntryCount

int getEntryCount()