AtomicLongFieldUpdater
public
abstract
class
AtomicLongFieldUpdater
extends Object
java.lang.Object | |
↳ | java.util.concurrent.atomic.AtomicLongFieldUpdater<T> |
A reflection-based utility that enables atomic updates to
designated volatile long
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 only with respect to other invocations of
compareAndSet
and set
on the same updater.
Object arguments for parameters of type T
that are not
instances of the class passed to newUpdater(Class, String)
will result in
a ClassCastException
being thrown.
Summary
Protected constructors | |
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AtomicLongFieldUpdater()
Protected do-nothing constructor for use by subclasses. |
Public methods | |
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final
long
|
accumulateAndGet(T obj, long x, LongBinaryOperator accumulatorFunction)
Atomically updates (with memory effects as specified by |
long
|
addAndGet(T obj, long delta)
Atomically adds the given value to the current value of the field of the given object managed by this updater. |
abstract
boolean
|
compareAndSet(T obj, long expect, long update)
Atomically sets the field of the given object managed by this updater
to the given updated value if the current value |
long
|
decrementAndGet(T obj)
Atomically decrements by one the current value of the field of the given object managed by this updater. |
abstract
long
|
get(T obj)
Returns the current value held in the field of the given object managed by this updater. |
final
long
|
getAndAccumulate(T obj, long x, LongBinaryOperator accumulatorFunction)
Atomically updates (with memory effects as specified by |
long
|
getAndAdd(T obj, long delta)
Atomically adds the given value to the current value of the field of the given object managed by this updater. |
long
|
getAndDecrement(T obj)
Atomically decrements by one the current value of the field of the given object managed by this updater. |
long
|
getAndIncrement(T obj)
Atomically increments by one the current value of the field of the given object managed by this updater. |
long
|
getAndSet(T obj, long newValue)
Atomically sets the field of the given object managed by this updater to the given value and returns the old value. |
final
long
|
getAndUpdate(T obj, LongUnaryOperator updateFunction)
Atomically updates (with memory effects as specified by |
long
|
incrementAndGet(T obj)
Atomically increments by one the current value of the field of the given object managed by this updater. |
abstract
void
|
lazySet(T obj, long newValue)
Eventually sets the field of the given object managed by this updater to the given updated value. |
static
<U>
AtomicLongFieldUpdater<U>
|
newUpdater(Class<U> tclass, String fieldName)
Creates and returns an updater for objects with the given field. |
abstract
void
|
set(T obj, long newValue)
Sets the field of the given object managed by this updater to the given updated value. |
final
long
|
updateAndGet(T obj, LongUnaryOperator updateFunction)
Atomically updates (with memory effects as specified by |
abstract
boolean
|
weakCompareAndSet(T obj, long expect, long update)
Atomically sets the field of the given object managed by this updater
to the given updated value if the current value |
Inherited methods | |
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Protected constructors
AtomicLongFieldUpdater
protected AtomicLongFieldUpdater ()
Protected do-nothing constructor for use by subclasses.
Public methods
accumulateAndGet
public final long accumulateAndGet (T obj, long x, LongBinaryOperator accumulatorFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)
) the field of the given object managed
by this updater with the results of applying the given function
to the current and given values, returning the updated value.
The function should be side-effect-free, since it may be
re-applied when attempted updates fail due to contention among
threads. The function is applied with the current value as its
first argument, and the given update as the second argument.
Parameters | |
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obj |
T : An object whose field to get and set |
x |
long : the update value |
accumulatorFunction |
LongBinaryOperator : a side-effect-free function of two arguments |
Returns | |
---|---|
long |
the updated value |
addAndGet
public long addAndGet (T obj, long delta)
Atomically adds the given value to the current value of the field of the given object managed by this updater.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
delta |
long : the value to add |
Returns | |
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long |
the updated value |
compareAndSet
public abstract boolean compareAndSet (T obj, long expect, long update)
Atomically sets 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 | |
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obj |
T : An object whose field to conditionally set |
expect |
long : the expected value |
update |
long : the new value |
Returns | |
---|---|
boolean |
true if successful |
decrementAndGet
public long decrementAndGet (T obj)
Atomically decrements by one the current value of the field of the given object managed by this updater.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
Returns | |
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long |
the updated value |
get
public abstract long get (T obj)
Returns the current value held in the field of the given object managed by this updater.
Parameters | |
---|---|
obj |
T : An object whose field to get |
Returns | |
---|---|
long |
the current value |
getAndAccumulate
public final long getAndAccumulate (T obj, long x, LongBinaryOperator accumulatorFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)
) the field of the given object managed
by this updater with the results of applying the given function
to the current and given values, returning the previous value.
The function should be side-effect-free, since it may be
re-applied when attempted updates fail due to contention among
threads. The function is applied with the current value as its
first argument, and the given update as the second argument.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
x |
long : the update value |
accumulatorFunction |
LongBinaryOperator : a side-effect-free function of two arguments |
Returns | |
---|---|
long |
the previous value |
getAndAdd
public long getAndAdd (T obj, long delta)
Atomically adds the given value to the current value of the field of the given object managed by this updater.
Parameters | |
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obj |
T : An object whose field to get and set |
delta |
long : the value to add |
Returns | |
---|---|
long |
the previous value |
getAndDecrement
public long getAndDecrement (T obj)
Atomically decrements by one the current value of the field of the given object managed by this updater.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
Returns | |
---|---|
long |
the previous value |
getAndIncrement
public long getAndIncrement (T obj)
Atomically increments by one the current value of the field of the given object managed by this updater.
Parameters | |
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obj |
T : An object whose field to get and set |
Returns | |
---|---|
long |
the previous value |
getAndSet
public long getAndSet (T obj, long newValue)
Atomically sets the field of the given object managed by this updater to the given value and returns the old value.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
newValue |
long : the new value |
Returns | |
---|---|
long |
the previous value |
getAndUpdate
public final long getAndUpdate (T obj, LongUnaryOperator updateFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)
) the field of the given object managed
by this updater with the results of applying the given
function, returning the previous value. The function should be
side-effect-free, since it may be re-applied when attempted
updates fail due to contention among threads.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
updateFunction |
LongUnaryOperator : a side-effect-free function |
Returns | |
---|---|
long |
the previous value |
incrementAndGet
public long incrementAndGet (T obj)
Atomically increments by one the current value of the field of the given object managed by this updater.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
Returns | |
---|---|
long |
the updated value |
lazySet
public abstract void lazySet (T obj, long newValue)
Eventually sets the field of the given object managed by this updater to the given updated value.
Parameters | |
---|---|
obj |
T : An object whose field to set |
newValue |
long : the new value |
newUpdater
public static AtomicLongFieldUpdater<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 | |
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tclass |
Class : the class of the objects holding the field |
fieldName |
String : the name of the field to be updated |
Returns | |
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AtomicLongFieldUpdater<U> |
the updater |
Throws | |
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IllegalArgumentException |
if the field is not a volatile long type |
RuntimeException |
with a nested reflection-based exception if the class does not hold field or is the wrong type, or the field is inaccessible to the caller according to Java language access control |
set
public abstract void set (T obj, long newValue)
Sets the field of the given object managed by this updater to the
given updated value. This operation is guaranteed to act as a volatile
store with respect to subsequent invocations of compareAndSet
.
Parameters | |
---|---|
obj |
T : An object whose field to set |
newValue |
long : the new value |
updateAndGet
public final long updateAndGet (T obj, LongUnaryOperator updateFunction)
Atomically updates (with memory effects as specified by VarHandle.compareAndSet(Object)
) the field of the given object managed
by this updater with the results of applying the given
function, returning the updated value. The function should be
side-effect-free, since it may be re-applied when attempted
updates fail due to contention among threads.
Parameters | |
---|---|
obj |
T : An object whose field to get and set |
updateFunction |
LongUnaryOperator : a side-effect-free function |
Returns | |
---|---|
long |
the updated value |
weakCompareAndSet
public abstract boolean weakCompareAndSet (T obj, long expect, long update)
Atomically sets 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.
This operation may fail spuriously and does not provide
ordering guarantees, so is only rarely an appropriate
alternative to compareAndSet
.
Parameters | |
---|---|
obj |
T : An object whose field to conditionally set |
expect |
long : the expected value |
update |
long : the new value |
Returns | |
---|---|
boolean |
true if successful |