Package org.infinispan.functional

Interface FunctionalMap.ReadOnlyMap<K,V>

All Superinterfaces:

AutoCloseable, FunctionalMap<K,V>

All Known Implementing Classes:

ReadOnlyMapImpl

Enclosing interface:

FunctionalMap<K,V>

@Experimental
public static interface FunctionalMap.ReadOnlyMap<K,V>
extends FunctionalMap<K,V>

Exposes read-only operations that can be executed against the functional map. The information that can be read per entry in the functional map is exposed by EntryView.ReadEntryView.

Read-only operations have the advantage that no locks are acquired for the duration of the operation and so it makes sense to have them a top-level interface dedicated to them.

Browsing methods that provide a read-only view of the cached data are available via keys() and entries(). Having keys() makes sense since that way keys can be traversed without having to bring values. Having entries() makes sense since it allows traversing both keys, values and any meta parameters associated with them, but this is no extra cost to exposing just values since keys are the main index and hence will always be available. Hence, adding a method to only browse values offers nothing extra to the API.

Since:

8.0

Nested Class Summary

Nested classes/interfaces inherited from interface org.infinispan.functional.FunctionalMap

FunctionalMap.ReadOnlyMap<K,V>, FunctionalMap.ReadWriteMap<K,V>, FunctionalMap.WriteOnlyMap<K,V>

Method Summary

Modifier and Type	Method	Description
Traversable<EntryView.ReadEntryView<K,V>>	entries()	Provides a Traversable that allows clients to navigate all cached entries.
<R> CompletableFuture<R>	eval(K key, Function<EntryView.ReadEntryView<K,V>,R> f)	Evaluate a read-only function on the value associated with the key and return a CompletableFuture with the return type of the function.
default <R> CompletableFuture<R>	eval(K key, SerializableFunction<EntryView.ReadEntryView<K,V>,R> f)	Same as eval(Object, Function) except that the function must also implement Serializable
<R> Traversable<R>	evalMany(Set<? extends K> keys, Function<EntryView.ReadEntryView<K,V>,R> f)	Evaluate a read-only function on a key and potential value associated in the functional map, for each of the keys in the set passed in, and returns an Traversable to work on each computed function's result.
default <R> Traversable<R>	evalMany(Set<? extends K> keys, SerializableFunction<EntryView.ReadEntryView<K,V>,R> f)	Same as evalMany(Set, Function) except that the function must also implement Serializable
Traversable<K>	keys()	Provides a Traversable that allows clients to navigate all cached keys.
FunctionalMap.ReadOnlyMap<K,V>	withParams(Param<?>... ps)	Tweak read-only functional map executions providing Param instances.

Methods inherited from interface java.lang.AutoCloseable

close

Methods inherited from interface org.infinispan.functional.FunctionalMap

cache, getName, getStatus, isEncoded

Method Details

withParams

FunctionalMap.ReadOnlyMap<K,V> withParams(Param<?>... ps)

Tweak read-only functional map executions providing Param instances.

Specified by:

withParams in interface FunctionalMap<K,V>

eval

<R> CompletableFuture<R> eval(K key,
 Function<EntryView.ReadEntryView<K,V>,R> f)

Evaluate a read-only function on the value associated with the key and return a CompletableFuture with the return type of the function. If the user is not sure if the key is present, EntryView.ReadEntryView.find() can be used to find out for sure. Typically, function implementations would return value or MetaParam information from the cache entry in the functional map.

By returning CompletableFuture instead of the function's return type directly, the method hints at the possibility that to execute the function might require to go remote to retrieve data in persistent store or another clustered node.

This method can be used to implement read-only single-key based operations in ConcurrentMap and javax.cache.Cache such as:

• Map.get(Object)
• Map.containsKey(Object)
• javax.cache.Cache#get(Object)
• javax.cache.Cache#containsKey(Object)

The function must not mutate neither the key returned through EntryView.ReadEntryView.key() nor the internally stored value provided through EntryView.ReadEntryView.get() or EntryView.ReadEntryView.find().

Type Parameters:

R - function return type

Parameters:

key - the key associated with the EntryView.ReadEntryView to be passed to the function.

f - function that takes a EntryView.ReadEntryView associated with the key, and returns a value.

Returns:

a CompletableFuture which will be completed with the returned value from the function

eval

default <R> CompletableFuture<R> eval(K key,
 SerializableFunction<EntryView.ReadEntryView<K,V>,R> f)

Same as eval(Object, Function) except that the function must also implement Serializable

The compiler will pick this overload for lambda parameters, making them Serializable

evalMany

<R> Traversable<R> evalMany(Set<? extends K> keys,
 Function<EntryView.ReadEntryView<K,V>,R> f)

Evaluate a read-only function on a key and potential value associated in the functional map, for each of the keys in the set passed in, and returns an Traversable to work on each computed function's result.

The function passed in will be executed for as many keys present in keys collection set. Similar to eval(Object, Function), if the user is not sure whether a particular key is present, EntryView.ReadEntryView.find() can be used to find out for sure.

This method can be used to implement operations such as javax.cache.Cache#getAll(Set). DESIGN RATIONALE:

• It makes sense to expose global operation like this instead of forcing users to iterate over the keys to lookup and call get individually since Infinispan can do things more efficiently.

The function must not mutate neither the key returned through EntryView.ReadEntryView.key() nor the internally stored value provided through EntryView.ReadEntryView.get() or EntryView.ReadEntryView.find().

Type Parameters:

R - function return type

Parameters:

keys - the keys associated with each of the EntryView.ReadEntryView passed in the function callbacks

f - function that takes a EntryView.ReadEntryView associated with the key, and returns a value. It'll be invoked once for each key passed in

Returns:

a sequential Traversable that can be navigated to retrieve each function return value

evalMany

default <R> Traversable<R> evalMany(Set<? extends K> keys,
 SerializableFunction<EntryView.ReadEntryView<K,V>,R> f)

Same as evalMany(Set, Function) except that the function must also implement Serializable

The compiler will pick this overload for lambda parameters, making them Serializable

keys

Traversable<K> keys()

Provides a Traversable that allows clients to navigate all cached keys.

This method can be used to implement operations such as:

• Map.size()
• Map.keySet()
• Map.isEmpty()

Returns:

a sequential Traversable to navigate each cached key

entries

Traversable<EntryView.ReadEntryView<K,V>> entries()

Provides a Traversable that allows clients to navigate all cached entries.

This method can be used to implement operations such as:

• Map.containsValue(Object)
• Map.values()
• Map.entrySet()
• javax.cache.Cache#iterator()

Returns:

a sequential Traversable to navigate each cached entry