Module java.base
Package java.util.concurrent.atomic

Class AtomicLongFieldUpdater<T>

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 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(java.lang.Class<U>, java.lang.String) will result in a ClassCastException being thrown.

Since:
1.5

  • Constructor Summary

    Constructors
    Modifier
    Constructor
    Description
    protected
    AtomicLongFieldUpdater()
    Protected do-nothing constructor for use by subclasses.

  • Method Summary

    Modifier and Type
    Method
    Description
    long
    accumulateAndGet​(T obj, long x, LongBinaryOperator accumulatorFunction)
    Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.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.
    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)
    Returns the current value held in the field of the given object managed by this updater.
    long
    getAndAccumulate​(T obj, long x, LongBinaryOperator accumulatorFunction)
    Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.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.
    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
    getAndUpdate​(T obj, LongUnaryOperator updateFunction)
    Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function, returning the previous 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.
    long
    updateAndGet​(T obj, LongUnaryOperator updateFunction)
    Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.Object...)) the field of the given object managed by this updater with the results of applying the given function, returning the 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.

    Methods declared in class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Constructor Details

    • AtomicLongFieldUpdater

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

  • Method Details

    • 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.
      Type Parameters:
      U - the type of instances of tclass
      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 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

    • 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:
      obj - An object whose field to conditionally set
      expect - the expected value
      update - the new value
      Returns:
      true if successful

    • 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 - An object whose field to conditionally set
      expect - the expected value
      update - the new value
      Returns:
      true if successful

    • 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 - An object whose field to set
      newValue - 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 set
      newValue - the new value
      Since:
      1.6

    • 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 - 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 set
      newValue - 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 set
      delta - 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 set
      delta - the value to add
      Returns:
      the updated value

    • getAndUpdate

      public final long getAndUpdate​(T obj, LongUnaryOperator updateFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.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 - An object whose field to get and set
      updateFunction - a side-effect-free function
      Returns:
      the previous value
      Since:
      1.8

    • updateAndGet

      public final long updateAndGet​(T obj, LongUnaryOperator updateFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.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 - An object whose field to get and set
      updateFunction - a side-effect-free function
      Returns:
      the updated value
      Since:
      1.8

    • getAndAccumulate

      public final long getAndAccumulate​(T obj, long x, LongBinaryOperator accumulatorFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.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 - An object whose field to get and set
      x - the update value
      accumulatorFunction - a side-effect-free function of two arguments
      Returns:
      the previous value
      Since:
      1.8

    • accumulateAndGet

      public final long accumulateAndGet​(T obj, long x, LongBinaryOperator accumulatorFunction)
      Atomically updates (with memory effects as specified by VarHandle.compareAndSet(java.lang.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:
      obj - An object whose field to get and set
      x - the update value
      accumulatorFunction - a side-effect-free function of two arguments
      Returns:
      the updated value
      Since:
      1.8