java.util.concurrent.atomic

Class AtomicIntegerFieldUpdater<T- >

Table des matières
  • 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 only with respect to other invocations of compareAndSet and set on the same updater.

    Since:
    1.5

    • Constructor Summary

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

        

    • Method Summary

      Methods 
      Modifier and Type Method and Description
      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.
      abstract boolean compareAndSet(T obj, int expect, int 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.
      int decrementAndGet(T obj)
      Atomically decrements by one the current value of the field of the given object managed by this updater.
      abstract int get(T obj)
      Gets the current value held in the field of the given object managed by this updater.
      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.
      int getAndDecrement(T obj)
      Atomically decrements by one the current value of the field of the given object managed by this updater.
      int getAndIncrement(T obj)
      Atomically increments by one the current value of the field of the given object managed by this updater.
      int getAndSet(T obj, int newValue)
      Atomically sets the field of the given object managed by this updater to the given value and returns the old value.
      int 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, int newValue)
      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 obj, int newValue)
      Sets the field of the given object managed by this updater to the given updated value.
      abstract boolean weakCompareAndSet(T obj, int expect, int 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.

        

    • 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 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
        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 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
        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 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.

        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
        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)
        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,
           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 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 int getAndSet(T obj,
            int 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 int 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 int 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 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.
        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 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 int 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 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.
        Parameters:
        obj - An object whose field to get and set
        delta - the value to add
        Returns:
        the updated value

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Document créé le 07/12/2006, dernière modification le 04/03/2020
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