org.apache.river.concurrent

Interface Referrer<T>

Type Parameters:

T - Referent

public interface Referrer<T>

The public API of package private Reference implementations, it defines the equals and hashCode contracts as well as methods identical to Reference.

Author:

Peter Firmstone

See Also:

Reference, Ref

Method Summary

Modifier and Type	Method and Description
void	clear()
boolean	enqueue()
boolean	equals(Object o) Equals is calculated on IDENTITY or EQUALITY.
T	get()
int	hashCode() Standard hashCode calculation for IDENTITY based references, where k is the referent.
boolean	isEnqueued()

Method Detail

get

T get()

See Also:

Reference.get()

clear

void clear()

See Also:

Reference.clear()

isEnqueued

boolean isEnqueued()

Returns:

true if enqueued.

See Also:

Reference.isEnqueued()

enqueue

boolean enqueue()

Returns:

true if successfully enqueued.

See Also:

Reference.enqueue()

equals

boolean equals(Object o)

Equals is calculated on IDENTITY or EQUALITY.

IDENTITY calculation:

if (this == o) return true;
if (!(o instanceof Referrer)) return false;
Object k1 = get();
Object k2 = ((Referrer) o).get();
if ( k1 != null && k1 == k2 ) return true;
return ( k1 == null && k2 == null && hashCode() == o.hashCode());


EQUALITY calculation:

if (this == o) return true; // Same reference.
if (!(o instanceof Referrer)) return false;
Object k1 = get();
Object k2 = ((Referrer) o).get();
if ( k1 != null && k1.equals(k2)) return true;
return ( k1 == null && k2 == null && hashCode() == o.hashCode());


Overrides:

equals in class Object

Parameters:

o -

Returns:

true if equal

See Also:

Ref

hashCode

int hashCode()

Standard hashCode calculation for IDENTITY based references, where k is the referent. This may be stored in a final field:

int hash = 7;
hash = 29 * hash + System.identityHashCode(k);
hash = 29 * hash + k.getClass().hashCode();


Standard hashCode calculation for EQUALITY based references, where k is the referent:

int hash = 7;
hash = 29 * hash + k.hashCode();
hash = 29 * hash + k.getClass().hashCode();


The hash must be calculated during construction and if the reference is cleared, the recorded hashCode returned. While the referent remains reachable the hashCode must be calculated each time.

Overrides:

hashCode in class Object

Returns:

hash