- java.lang.Object
-
- java.util.concurrent.atomic.AtomicLongFieldUpdater<T>
-
- Type Parameters:
T
- The type of the object holding the updatable field
public abstract class AtomicLongFieldUpdater<T> extends Object
A reflection-based utility that enables atomic updates to designatedvolatile 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 ofcompareAndSet
andset
on the same updater.- Since:
- 1.5
-
-
Constructor Summary
Constructors Modifier Constructor and Description protected
AtomicLongFieldUpdater()
Protected do-nothing constructor for use by subclasses.
-
Method Summary
Methods Modifier and Type Method and Description 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==
the expected 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)
Gets the current value held in the field of the given object managed by this updater.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.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.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.
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-
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Constructor Detail
-
AtomicLongFieldUpdater
protected AtomicLongFieldUpdater()
Protected do-nothing constructor for use by subclasses.
-
-
Method Detail
-
newUpdater
public static <U> 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:
tclass
- the class of the objects holding the fieldfieldName
- the name of the field to be updated.- Returns:
- the updater
- Throws:
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.
-
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 tocompareAndSet
andset
, but not necessarily with respect to other changes in the field.- Parameters:
obj
- An object whose field to conditionally setexpect
- the expected valueupdate
- the new value- Returns:
- true if successful.
- Throws:
ClassCastException
- ifobj
is not an instance of the class possessing the field established in the constructor.
-
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 tocompareAndSet
andset
, but not necessarily with respect to other changes in the field.May fail spuriously and does not provide ordering guarantees, so is only rarely an appropriate alternative to
compareAndSet
.- Parameters:
obj
- An object whose field to conditionally setexpect
- the expected valueupdate
- the new value- Returns:
- true if successful.
- Throws:
ClassCastException
- ifobj
is not an instance of the class possessing the field established in the constructor.
-
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 ofcompareAndSet
.- Parameters:
obj
- An object whose field to setnewValue
- the new 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
- An object whose field to setnewValue
- the new value- Since:
- 1.6
-
get
public abstract long get(T obj)
Gets the current value held in the field of the given object managed by this updater.- Parameters:
obj
- An object whose field to get- Returns:
- the current 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
- An object whose field to get and setnewValue
- the new value- Returns:
- 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:
obj
- An object whose field to get and set- Returns:
- 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
- An object whose field to get and set- Returns:
- 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:
obj
- An object whose field to get and setdelta
- the value to add- Returns:
- 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
- An object whose field to get and set- Returns:
- the updated value
-
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
- An object whose field to get and set- Returns:
- 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
- An object whose field to get and setdelta
- the value to add- Returns:
- the updated value
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Vielen Dank im Voraus.
Dokument erstellt 11/06/2005, zuletzt geändert 04/03/2020
Quelle des gedruckten Dokuments:https://www.gaudry.be/de/java-api-rf-java/util/concurrent/atomic/atomiclongfieldupdater.html
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