Package org.terracotta.offheapstore.storage

Interface StorageEngine<K,V>

Type Parameters:

K - key type handled by this engine

V - value type handled by this engine

All Known Subinterfaces:

PersistentStorageEngine<K,V>

All Known Implementing Classes:

FileBackedStorageEngine, LongStorageEngine, OffHeapBufferStorageEngine, PersistentSplitStorageEngine, PortabilityBasedStorageEngine, SerializableStorageEngine, SplitStorageEngine, StringStorageEngine

public interface StorageEngine<K,V>

An object that encodes map/cache keys and values to integers.

StorageEngine instances can choose their own method of value/key encoding. Keys that are small enough to be fully encoded in the Integer return can be stored directly in the table, others could be stored in some additional data structure.

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	StorageEngine.Owner

Method Summary

Modifier and Type	Method	Description
void	attachedMapping(long encoding, int hash, int metadata)
void	bind(StorageEngine.Owner owner)
void	clear()	Called to indicate that all keys and values are now free.
void	destroy()
boolean	equalsKey(java.lang.Object key, long encoding)	Called to determine the equality of the given object against the given encoded form.
boolean	equalsValue(java.lang.Object value, long encoding)	Called to determine the equality of the given Java object value against the given encoded form.
void	freeMapping(long encoding, int hash, boolean removal)	Called to indicate that the associated encoded value is no longer needed.
long	getAllocatedMemory()	Returns a measure of the amount of memory allocated for this storage engine.
long	getDataSize()	Returns a measure of the total size of the keys and values stored in this storage engine.
long	getOccupiedMemory()	Returns a measure of the amount of memory consumed by this storage engine.
long	getVitalMemory()	Returns a measure of the amount of vital memory allocated for this storage engine.
void	invalidateCache()	Invalidate any local key/value caches.
K	readKey(long encoding, int hashCode)	Converts the supplied encoded key into its correct object form.
V	readValue(long encoding)	Converts the supplied encoded value into its correct object form.
boolean	shrink()
java.lang.Long	writeMapping(K key, V value, int hash, int metadata)	Converts the supplied key and value objects into their encoded form.

Method Detail

writeMapping

java.lang.Long writeMapping(K key,
                            V value,
                            int hash,
                            int metadata)

Converts the supplied key and value objects into their encoded form.

Parameters:

key - a key object

value - a value object

hash - the key hash

metadata - the metadata bits

Returns:

the encoded mapping

attachedMapping

void attachedMapping(long encoding,
                     int hash,
                     int metadata)

freeMapping

void freeMapping(long encoding,
                 int hash,
                 boolean removal)

Called to indicate that the associated encoded value is no longer needed.

This call can be used to free any associated resources tied to the lifecycle of the supplied encoded value.

Parameters:

encoding - encoded value

hash - hash of the freed mapping

removal - marks removal from a map

readValue

V readValue(long encoding)

Converts the supplied encoded value into its correct object form.

Parameters:

encoding - encoded value

Returns:

a decoded value object

equalsValue

boolean equalsValue(java.lang.Object value,
                    long encoding)

Called to determine the equality of the given Java object value against the given encoded form.

Simple implementations will probably perform a decode on the given encoded form in order to do a regular Object.equals(Object) comparison. This method is provided to allow implementations to optimize this comparison if possible.

Parameters:

value - a value object

encoding - encoded value

Returns:

true if the value and the encoding are equal

readKey

K readKey(long encoding,
          int hashCode)

Converts the supplied encoded key into its correct object form.

Parameters:

encoding - encoded key

hashCode - hash-code of the decoded key

Returns:

a decoded key object

equalsKey

boolean equalsKey(java.lang.Object key,
                  long encoding)

Called to determine the equality of the given object against the given encoded form.

Simple implementations will probably perform a decode on the given encoded form in order to do a regular Object.equals(Object) comparison. This method is provided to allow implementations to optimize this comparison if possible.

Parameters:

key - a key object

encoding - encoded value

Returns:

true if the key and the encoding are equal

clear

void clear()

Called to indicate that all keys and values are now free.

getAllocatedMemory

long getAllocatedMemory()

Returns a measure of the amount of memory allocated for this storage engine.

Returns:

memory allocated for this engine in bytes

getOccupiedMemory

long getOccupiedMemory()

Returns a measure of the amount of memory consumed by this storage engine.

Returns:

memory occupied by this engine in bytes

getVitalMemory

long getVitalMemory()

Returns a measure of the amount of vital memory allocated for this storage engine.

Returns:

vital memory allocated for this engine in bytes

getDataSize

long getDataSize()

Returns a measure of the total size of the keys and values stored in this storage engine.

Returns:

size of the stored keys and values in bytes

invalidateCache

void invalidateCache()

Invalidate any local key/value caches.

This is called to indicate the termination of a map write "phase". Caching is permitted within a write operation (i.e. to cache around allocation failures during eviction processes).

bind

void bind(StorageEngine.Owner owner)

destroy

void destroy()

shrink

boolean shrink()