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

java.lang.Object
  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 on the same updater. .

Since:

1.5

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

 

Method Summary
int	addAndGet ( T           Atomically adds add the given value to the current value of the field of the given object managed by this updater. value.
abstract  boolean	compareAndSet ( T           Atomically sets set the value of the field of the given object managed by this updater Updater to the given updated value if the current value == the expected value.
int	decrementAndGet ( T           Atomically decrements decrement by one the current value of the field of the given object managed by this updater. value.
abstract  int	get ( T           Gets           Get the current value held in the field of by the given object managed by this updater. object.
int	getAndAdd ( T           Atomically adds add the given value to the current value of the field of the given object managed by this updater. value.
int	getAndDecrement ( T           Atomically decrements decrement by one the current value of the field of the given object managed by this updater. value.
int	getAndIncrement ( T           Atomically increments increment by one the current value of the field of the given object managed by this updater. value.
int	getAndSet ( T           Atomically sets the field of the given object managed by this updater           Set to the given value and returns return the old value.
int	incrementAndGet ( T           Atomically increments increment by one the current value of the field of the given object managed by this updater. value.
abstract  void	lazySet ( T           Eventually sets the field of the given object managed by this updater to the given updated value.
static <U> AtomicIntegerFieldUpdater <U>	newUpdater ( Class <U> tclass, String  fieldName)           Creates and returns an updater for objects with the given field.
abstract  void	set ( T           Sets           Set the field of the given object managed by this updater to the given updated value. updater.
abstract  boolean	weakCompareAndSet ( T           Atomically sets set the value of the field of the given object managed by this updater 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.

newUpdater

public static <U> AtomicIntegerFieldUpdater<U> newUpdater(Class<U> tclass,
                                                          String fieldName)

Creates and returns 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 updated.

Returns:

the updater

Throws:

IllegalArgumentException - if the field is not a volatile integer type type.

RuntimeException - with a nested reflection-based exception if the class does not hold field or is the wrong type type.

compareAndSet

public abstract boolean compareAndSet(T obj,
                                      int expect,
                                      int update)

Atomically sets set the value of the field of the given object managed by this updater 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 successful.

Throws:

ClassCastException - if obj is not an instance of the class possessing the field established in the constructor constructor.

weakCompareAndSet

public abstract boolean weakCompareAndSet(T obj,
                                          int expect,
                                          int update)

Atomically sets set the value of the field of the given object managed by this updater 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 successful.

Throws:

ClassCastException - if obj is not an instance of the class possessing the field established in the constructor constructor.

set

public abstract void set(T obj,
                         int newValue)

Sets Set the field of the given object managed by this updater to the given updated value. 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

lazySet

 
public abstract void lazySet ( T obj,
 int newValue) 

Eventually sets the field of the given object managed by this updater to the given updated value.

Parameters:

obj - An object whose field to set

newValue - the new value

Since:

1.6

get

public abstract int get(T obj)

Gets Get the current value held in the field of by the given object managed by this updater. object.

Parameters:

obj - An object whose field to get

Returns:

the current value

getAndSet

public int getAndSet(T obj,
                     int newValue)

Atomically sets the field of the given object managed by this updater Set to the given value and returns 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 increments by one the current value of the field of the given object managed by this updater. Atomically increment by one the current value.

Parameters:

obj - An object whose field to get and set

Returns:

the previous value value;

getAndDecrement

public int getAndDecrement(T obj)

Atomically decrements by one the current value of the field of the given object managed by this updater. Atomically decrement by one the current value.

Parameters:

obj - An object whose field to get and set

Returns:

the previous value value;

getAndAdd

public int getAndAdd(T obj,
                     int delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater. 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 value;

incrementAndGet

public int incrementAndGet(T obj)

Atomically increments by one the current value of the field of the given object managed by this updater. Atomically increment by one the current value.

Parameters:

obj - An object whose field to get and set

Returns:

the updated value value;

decrementAndGet

public int decrementAndGet(T obj)

Atomically decrements by one the current value of the field of the given object managed by this updater. Atomically decrement by one the current value.

Parameters:

obj - An object whose field to get and set

Returns:

the updated value value;

addAndGet

public int addAndGet(T obj,
                     int delta)

Atomically adds the given value to the current value of the field of the given object managed by this updater. 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 value;