Build 1.0_r1(from source)

java.util.concurrent.atomic
Class AtomicIntegerFieldUpdater<T>

java.lang.Object
  extended by java.util.concurrent.atomic.AtomicIntegerFieldUpdater<T>
Type Parameters:
T - The type of the object holding the updatable field

public abstract class AtomicIntegerFieldUpdater<T>
extends Object

A reflection-based utility that enables atomic updates to designated volatile int fields of designated classes. This class is designed for use in atomic data structures in which several fields of the same node are independently subject to atomic updates.

Note that the guarantees of the compareAndSet method in this class are weaker than in other atomic classes. Because this class cannot ensure that all uses of the field are appropriate for purposes of atomic access, it can guarantee atomicity and volatile semantics only with respect to other invocations of compareAndSet and set.

Since:
1.5

Constructor Summary
protected AtomicIntegerFieldUpdater()
          Protected do-nothing constructor for use by subclasses.
 
Method Summary
 int addAndGet(T obj, int delta)
          Atomically add the given value to current value.
abstract  boolean compareAndSet(T obj, int expect, int update)
          Atomically set the value of the field of the given object managed by this Updater to the given updated value if the current value == the expected value.
 int decrementAndGet(T obj)
          Atomically decrement by one the current value.
abstract  int get(T obj)
          Get the current value held in the field by the given object.
 int getAndAdd(T obj, int delta)
          Atomically add the given value to current value.
 int getAndDecrement(T obj)
          Atomically decrement by one the current value.
 int getAndIncrement(T obj)
          Atomically increment by one the current value.
 int getAndSet(T obj, int newValue)
          Set to the given value and return the old value.
 int incrementAndGet(T obj)
          Atomically increment by one the current value.
static
<U> AtomicIntegerFieldUpdater<U>
newUpdater(Class<U> tclass, String fieldName)
          Creates an updater for objects with the given field.
abstract  void set(T obj, int newValue)
          Set the field of the given object managed by this updater.
abstract  boolean weakCompareAndSet(T obj, int expect, int update)
          Atomically set the value of the field of the given object managed by this Updater to the given updated value if the current value == the expected value.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

AtomicIntegerFieldUpdater

protected AtomicIntegerFieldUpdater()
Protected do-nothing constructor for use by subclasses.

Method Detail

newUpdater

public static <U> AtomicIntegerFieldUpdater<U> newUpdater(Class<U> tclass,
                                                          String fieldName)
Creates an updater for objects with the given field. The Class argument is needed to check that reflective types and generic types match.

Parameters:
tclass - the class of the objects holding the field
fieldName - the name of the field to be updated.
Returns:
the updater
Throws:
IllegalArgumentException - if the field is not a volatile integer type.
RuntimeException - with a nested reflection-based exception if the class does not hold field or is the wrong type.

compareAndSet

public abstract boolean compareAndSet(T obj,
                                      int expect,
                                      int update)
Atomically set the value of the field of the given object managed by this Updater to the given updated value if the current value == the expected value. This method is guaranteed to be atomic with respect to other calls to compareAndSet and set, but not necessarily with respect to other changes in the field.

Parameters:
obj - An object whose field to conditionally set
expect - the expected value
update - the new value
Returns:
true if successful.
Throws:
ClassCastException - if obj is not an instance of the class possessing the field established in the constructor.

weakCompareAndSet

public abstract boolean weakCompareAndSet(T obj,
                                          int expect,
                                          int update)
Atomically set the value of the field of the given object managed by this Updater to the given updated value if the current value == the expected value. This method is guaranteed to be atomic with respect to other calls to compareAndSet and set, but not necessarily with respect to other changes in the field, and may fail spuriously.

Parameters:
obj - An object whose field to conditionally set
expect - the expected value
update - the new value
Returns:
true if successful.
Throws:
ClassCastException - if obj is not an instance of the class possessing the field established in the constructor.

set

public abstract void set(T obj,
                         int newValue)
Set the field of the given object managed by this updater. This operation is guaranteed to act as a volatile store with respect to subsequent invocations of compareAndSet.

Parameters:
obj - An object whose field to set
newValue - the new value

get

public abstract int get(T obj)
Get the current value held in the field by the given object.

Parameters:
obj - An object whose field to get
Returns:
the current value

getAndSet

public int getAndSet(T obj,
                     int newValue)
Set to the given value and return the old value.

Parameters:
obj - An object whose field to get and set
newValue - the new value
Returns:
the previous value

getAndIncrement

public int getAndIncrement(T obj)
Atomically increment by one the current value.

Parameters:
obj - An object whose field to get and set
Returns:
the previous value;

getAndDecrement

public int getAndDecrement(T obj)
Atomically decrement by one the current value.

Parameters:
obj - An object whose field to get and set
Returns:
the previous value;

getAndAdd

public int getAndAdd(T obj,
                     int delta)
Atomically add the given value to current value.

Parameters:
obj - An object whose field to get and set
delta - the value to add
Returns:
the previous value;

incrementAndGet

public int incrementAndGet(T obj)
Atomically increment by one the current value.

Parameters:
obj - An object whose field to get and set
Returns:
the updated value;

decrementAndGet

public int decrementAndGet(T obj)
Atomically decrement by one the current value.

Parameters:
obj - An object whose field to get and set
Returns:
the updated value;

addAndGet

public int addAndGet(T obj,
                     int delta)
Atomically add the given value to current value.

Parameters:
obj - An object whose field to get and set
delta - the value to add
Returns:
the updated value;

Build 1.0_r1(from source)

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