cern.entwined

Interface OpaqueMap<K,V>

Type Parameters:

K - The map key type.

V - The map value type.

All Known Implementing Classes:

TransactionalMap

public interface OpaqueMap<K,V>

A map like interface to facilitate implementation of TransactionalMap.

Author:

Ivan Koblik

Method Summary

Methods

Modifier and Type	Method and Description
void	clear() Removes all of the mappings from this map (optional operation).
boolean	containsKey(K key) Returns true if this map contains a mapping for the specified key.
V	get(K key) Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.
boolean	isEmpty() Returns true if this map contains no key-value mappings.
Set<K>	keySet() Returns a Set view of the keys contained in this map.
V	put(K key, V value) Associates the specified value with the specified key in this map (optional operation).
void	putAll(Map<? extends K,? extends V> m) Copies all of the mappings from the specified map to this map (optional operation).
V	remove(K key) Removes the mapping for a key from this map if it is present (optional operation).
int	size() Returns the number of key-value mappings in this map.

Method Detail

size

int size()

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

To preserve transactional consistency this operation marks the entire universe of keys as accessed, this means that commits to an updated global state will be rejected.

Returns:

the number of key-value mappings in this map

isEmpty

boolean isEmpty()

Returns true if this map contains no key-value mappings.

To preserve transactional consistency this operation marks the entire universe of keys as accessed in cases when map is empty but was not cleared with call clear() method, this means that commits to an updated global state will be rejected.

Returns:

true if this map contains no key-value mappings

containsKey

boolean containsKey(K key)

Returns true if this map contains a mapping for the specified key. More formally, returns true if and only if this map contains a mapping for a key k such that (key==null ? k==null : key.equals(k)). (There can be at most one such mapping.)

Parameters:

key - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

Throws:

NullPointerException - if the specified key is null and this map does not permit null keys (optional)

get

V get(K key)

Returns the value to which the specified key is mapped, or null if this map contains no mapping for the key.

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

If this map permits null values, then a return value of null does not necessarily indicate that the map contains no mapping for the key; it's also possible that the map explicitly maps the key to null. The containsKey operation may be used to distinguish these two cases.

Parameters:

key - the key whose associated value is to be returned

Returns:

the value to which the specified key is mapped, or null if this map contains no mapping for the key

Throws:

NullPointerException - if the specified key is null and this map does not permit null keys (optional)

put

V put(K key,
    V value)

Associates the specified value with the specified key in this map (optional operation). If the map previously contained a mapping for the key, the old value is replaced by the specified value. (A map m is said to contain a mapping for a key k if and only if m.containsKey(k) would return true.)

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 null if there was no mapping for key. (A null return can also indicate that the map previously associated null with key, if the implementation supports null values.)

Throws:

UnsupportedOperationException - if the put operation is not supported by this map

ClassCastException - if the class of the specified key or value prevents it from being stored in this map

NullPointerException - if the specified key or value is null and this map does not permit null keys or values

IllegalArgumentException - if some property of the specified key or value prevents it from being stored in this map

remove

V remove(K key)

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

Returns the value to which this map previously associated the key, or null if the map contained no mapping for the key.

If this map permits null values, then a return value of null does not necessarily indicate that the map contained no mapping for the key; it's also possible that the map explicitly mapped the key to null.

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

Parameters:

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

Returns:

the previous value associated with key, or null if there was no mapping for key.

Throws:

UnsupportedOperationException - if the remove operation is not supported by this map

NullPointerException - if the specified key is null and this map does not permit null keys (optional)

putAll

void putAll(Map<? extends K,? extends V> m)

Copies all of the mappings from the specified map to this map (optional operation). The effect of this call is equivalent to that of calling put(k, v) on this map once for each mapping from key k to value v in the specified map. The behavior of this operation is undefined if the specified map is modified while the operation is in progress.

Parameters:

m - mappings to be stored in this map

Throws:

UnsupportedOperationException - if the putAll operation is not supported by this map

ClassCastException - if the class of a key or value in the specified map prevents it from being stored in this map

IllegalArgumentException - if the specified map is null, or if this map does not permit null keys or values, and the specified map contains null keys or values

clear

void clear()

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

Throws:

UnsupportedOperationException - if the clear operation is not supported by this map

keySet

Set<K> keySet()

Returns a Set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. If the map is modified while an iteration over the set is in progress (except through the iterator's own remove operation), the results of the iteration are undefined. The set supports element removal, which removes the corresponding mapping from the map, via the Iterator.remove, Set.remove, removeAll, retainAll, and clear operations. It does not support the add or addAll operations.

In cases when the map hasn't been cleared within the running transaction it is highly probable that any interaction with the resulting set will mark the entire universe of keys as accessed, this means that commits to an updated global state will be rejected. Following actions are highly advised to be done in read-only transactions:

• Iterating over the entire set.
• Checking size of the collection.
• Invoking isEmpty on empty map.

Returns:

a set view of the keys contained in this map