de.otto.synapse.state

Interface StateRepository<V>

All Superinterfaces:

java.lang.AutoCloseable

All Known Implementing Classes:

ChronicleMapStateRepository, ConcurrentHashMapStateRepository, ConcurrentMapStateRepository, DelegatingStateRepository

public interface StateRepository<V>
extends java.lang.AutoCloseable

Method Summary

Modifier and Type	Method and Description
void	clear() Removes all of the mappings from this repository (optional operation).
void	close()
java.util.Optional<V>	compute(java.lang.String key, java.util.function.BiFunction<? super java.lang.String,? super java.util.Optional<V>,? extends V> remappingFunction) Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping).
java.util.Optional<V>	get(java.lang.String key) Returns the optional value to which the specified key is mapped, or Optional.empty() if this repository contains no mapping for the key.
com.google.common.collect.ImmutableSet<java.lang.String>	keySet() /** Returns an immutable set of the keys in this repository.
java.util.Optional<V>	put(java.lang.String key, V value) Associates the specified value with the specified key in this repository.
java.util.Optional<V>	remove(java.lang.String key) Removes the mapping for a key from this repository if it is present.
long	size() Returns the number of key-value mappings in this repository.

Method Detail

compute

java.util.Optional<V> compute(java.lang.String key,
                              java.util.function.BiFunction<? super java.lang.String,? super java.util.Optional<V>,? extends V> remappingFunction)

Attempts to compute a mapping for the specified key and its current mapped value (or null if there is no current mapping). For example, to either create or append a String msg to a value mapping:

 
 repository.compute(key, (k, v) -> (v == null) ? msg : v.concat(msg))

If the function returns null, the mapping is removed (or remains absent if initially absent). If the function itself throws an (unchecked) exception, the exception is rethrown, and the current mapping is left unchanged. The default implementation is equivalent to performing the following steps for this repository, then returning the current value or null if absent:

 
 OptionalV> oldValue = repository.get(key);
 V newValue = remappingFunction.apply(key, oldValue);
 if (!oldValue.isEmpty()) {
    if (newValue != null)
       repository.put(key, newValue);
    else
       repository.remove(key);
 } else {
    if (newValue != null)
       repository.put(key, newValue);
    else
       return Optional.empty();
 }
 

Parameters:

key - key with which the specified value is to be associated

remappingFunction - the function to compute a value

Returns:

the Optional containing the new value associated with the specified key, or Optional.empty() if none

Throws:

java.lang.NullPointerException - if the specified key is null, or the remappingFunction is null

java.lang.ClassCastException - if the class of the specified value prevents it from being stored in this repository

put

java.util.Optional<V> put(java.lang.String key,
                          V value)

Associates the specified value with the specified key in this repository. If the repository previously contained a mapping for the key, the old value is replaced by the specified value. (A repository m is said to contain a mapping for a key k if and only if m.get(k) would return a non-empty value.)

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

Returns:

the previous value associated with key, or Optional.empty() if there was no mapping for key.

Throws:

java.lang.ClassCastException - if the class of the specified value prevents it from being stored in this repository

java.lang.NullPointerException - if the specified key or value is null

java.lang.IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this repository

remove

java.util.Optional<V> remove(java.lang.String key)

Removes the mapping for a key from this repository if it is present. More formally, if this repository contains a mapping from key k to value v such that (key==null ? k==null : key.equals(k)), that mapping is removed. (The repository can contain at most one such mapping.)

Returns the optional value to which this repository previously associated the key, or Optional.empty() if the repository contained no mapping for the key.

The repository will not contain a mapping for the specified key once the call returns.

Parameters:

key - key whose mapping is to be removed from the repository

Returns:

the optional previous value associated with key, or Optional.empty() if there was no mapping for key.

Throws:

java.lang.NullPointerException - if the specified key is null

clear

void clear()

Removes all of the mappings from this repository (optional operation). The repository will be empty after this call returns.

Throws:

java.lang.UnsupportedOperationException - if the clear operation is not supported by this repository

get

java.util.Optional<V> get(java.lang.String key)

Returns the optional value to which the specified key is mapped, or Optional.empty() if this repository contains no mapping for the key.

More formally, if this repository contains a mapping from a key k to a value v such that (key==null ? k==null : key.equals(k)), then this method returns Optional.of(v); otherwise it returns Optional.empty(). (There can be at most one such mapping.)

Parameters:

key - the key whose associated value is to be returned

Returns:

the Optional containing the value to which the specified key is mapped, or Optional.empty() if this repository contains no mapping for the key

Throws:

java.lang.NullPointerException - if the specified key is null

keySet

com.google.common.collect.ImmutableSet<java.lang.String> keySet()

/** Returns an immutable set of the keys in this repository.

Returns:

a set view of the keys contained in this repository

size

long size()

Returns the number of key-value mappings in this repository. If the repository contains more than Integer.MAX_VALUE elements, returns Integer.MAX_VALUE.

Returns:

the number of key-value mappings in this repository

close

void close()
    throws java.lang.Exception

Specified by:

close in interface java.lang.AutoCloseable

Throws:

java.lang.Exception