Package org.infinispan.functional

Interface MetaParam<T>

Type Parameters:

T - type of MetaParam instance, implementations should assign it to the implementation's type.

All Known Subinterfaces:

MetaParam.Writable<T>

All Known Implementing Classes:

CounterConfigurationMetaParam, MetaParam.MetaBoolean, MetaParam.MetaCreated, MetaParam.MetaEntryVersion, MetaParam.MetaLastUsed, MetaParam.MetaLifespan, MetaParam.MetaLoadedFromPersistence, MetaParam.MetaLong, MetaParam.MetaMaxIdle, MetaParam.MetaUpdateCreationTime

@Experimental
public interface MetaParam<T>

An easily extensible metadata parameter that's stored along with the value in the the functional map.

Some metadata parameters can be provided by the user in which case they need to implement MetaParam.Writable. Examples of writable metadata parameters are version information, lifespan of the cached value...etc.

Those metadata parameters not extending MetaParam.Writable are created by internal logic and hence can only be queried, for example: time when value was added into the functional map, or last time value was accessed or modified.

What makes MetaParam different from Param is that MetaParam values are designed to be stored along with key/value pairs in the functional map, to provide extra information. On the other hand, Param instances merely act as ways to tweak how operations are executed, and their contents are never stored permanently.

This interface replaces Infinispan's Metadata interface providing a more flexible way to add new metadata parameters to be stored with the cached entries.

MetaParam design has been geared towards making a clear separation between the metadata that can be provided by the user on per-entry basis, e.g. lifespan, maxIdle, version...etc, as opposed to metadata that's produced by the internal logic that cannot be modified directly by the user, e.g. cache entry created time, last time cache entry was modified or accessed ...etc.

Since:

8.0

Nested Class Summary

Nested Classes

Modifier and Type	Interface	Description
static interface	MetaParam.Lookup	Provides metadata parameter lookup capabilities using Class as lookup key.
static class	MetaParam.MetaBoolean
static final class	MetaParam.MetaCreated	Read only metadata parameter representing a cached entry's created time in milliseconds.
static class	MetaParam.MetaEntryVersion	Writable metadata parameter representing a cached entry's generic version.
static final class	MetaParam.MetaLastUsed	Read only metadata parameter representing a cached entry's last used time in milliseconds.
static final class	MetaParam.MetaLifespan	Writable metadata parameter representing a cached entry's millisecond lifespan.
static final class	MetaParam.MetaLoadedFromPersistence	Non-writable parameter telling if the entry was loaded from a persistence tier (CacheLoader) or not.
static class	MetaParam.MetaLong	Abstract class for numeric long-based metadata parameter instances.
static final class	MetaParam.MetaMaxIdle	Writable metadata parameter representing a cached entry's millisecond max idle time.
static final class	MetaParam.MetaUpdateCreationTime	A parameter to tell if the creation timestamp should be updated for modified entries.
static interface	MetaParam.Writable<T>	Writable MetaParam instances are those that the user can provide to be stored as part of the cache entry.

Method Summary

Modifier and Type	Method	Description
T	get()	Returns the value of the meta parameter.

Method Details

get

T get()

Returns the value of the meta parameter.