Package EDU.oswego.cs.dl.util.concurrent
Class SynchronizedRef
- java.lang.Object
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- EDU.oswego.cs.dl.util.concurrent.SynchronizedVariable
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- EDU.oswego.cs.dl.util.concurrent.SynchronizedRef
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- All Implemented Interfaces:
Executor
- Direct Known Subclasses:
WaitableRef
public class SynchronizedRef extends SynchronizedVariable
A simple class maintaining a single reference variable that is always accessed and updated under synchronization.
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Field Summary
Fields Modifier and Type Field Description protected java.lang.Object
value_
The maintained reference-
Fields inherited from class EDU.oswego.cs.dl.util.concurrent.SynchronizedVariable
lock_
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Constructor Summary
Constructors Constructor Description SynchronizedRef(java.lang.Object initialValue)
Create a SynchronizedRef initially holding the given reference and using its own internal lock.SynchronizedRef(java.lang.Object initialValue, java.lang.Object lock)
Make a new SynchronizedRef with the given initial value, and using the supplied lock.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description boolean
commit(java.lang.Object assumedValue, java.lang.Object newValue)
Set value to newValue only if it is currently assumedValue.java.lang.Object
get()
Return the current valuejava.lang.Object
set(java.lang.Object newValue)
Set to newValue.java.lang.Object
swap(SynchronizedRef other)
Atomically swap values with another SynchronizedRef.-
Methods inherited from class EDU.oswego.cs.dl.util.concurrent.SynchronizedVariable
execute, getLock
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Constructor Detail
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SynchronizedRef
public SynchronizedRef(java.lang.Object initialValue)
Create a SynchronizedRef initially holding the given reference and using its own internal lock.
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SynchronizedRef
public SynchronizedRef(java.lang.Object initialValue, java.lang.Object lock)
Make a new SynchronizedRef with the given initial value, and using the supplied lock.
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Method Detail
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get
public final java.lang.Object get()
Return the current value
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set
public java.lang.Object set(java.lang.Object newValue)
Set to newValue.- Returns:
- the old value
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commit
public boolean commit(java.lang.Object assumedValue, java.lang.Object newValue)
Set value to newValue only if it is currently assumedValue.- Returns:
- true if successful
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swap
public java.lang.Object swap(SynchronizedRef other)
Atomically swap values with another SynchronizedRef. Uses identityHashCode to avoid deadlock when two SynchronizedRefs attempt to simultaneously swap with each other. (Note: Ordering via identyHashCode is not strictly guaranteed by the language specification to return unique, orderable values, but in practice JVMs rely on them being unique.)- Returns:
- the new value
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