Package com.linkedin.alpini.base.misc

Class SoftThreadLocal<T>

  • All Implemented Interfaces:
    java.util.function.Supplier<T>
    public class SoftThreadLocal<T>
extends java.lang.Object
implements java.util.function.Supplier<T>
    This class provides thread-local variables with SoftReference semantics.

    • Constructor Summary

      Constructors 
      Constructor Description
      SoftThreadLocal()  

    • Method Summary

      All Methods Static Methods Instance Methods Concrete Methods 
      Modifier and Type Method Description
      T get()
      Returns the value in the current thread's copy of this thread-local variable.
      protected T initialValue()
      Returns the current thread's "initial value" for this thread-local variable.
      void remove()
      Removes the current thread's value for this thread-local variable.
      void set​(T value)
      Sets the current thread's copy of this thread-local variable to the specified value.
      static <S> SoftThreadLocal<S> withInitial​(java.util.function.Supplier<? extends S> supplier)
      Creates a thread local variable.

      • Methods inherited from class java.lang.Object

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

    • Constructor Detail

      • SoftThreadLocal

        public SoftThreadLocal()

    • Method Detail

      • withInitial

        @Nonnull
public static <S> SoftThreadLocal<S> withInitial​(@Nonnull
                                                 java.util.function.Supplier<? extends S> supplier)
        Creates a thread local variable. The initial value of the variable is determined by invoking the get method on the Supplier.
        Type Parameters:
        S - the type of the thread local's value
        Parameters:
        supplier - the supplier to be used to determine the initial value
        Returns:
        a new thread local variable
        Throws:
        java.lang.NullPointerException - if the specified supplier is null
        Since:
        1.8

      • initialValue

        protected T initialValue()
        Returns the current thread's "initial value" for this thread-local variable. This method will be invoked the first time a thread accesses the variable with the get() method, unless the thread previously invoked the set(T) method, in which case the initialValue method will not be invoked for the thread. Normally, this method is invoked at most once per thread, but it may be invoked again in case of subsequent invocations of remove() followed by get().

        This implementation simply returns null; if the programmer desires thread-local variables to have an initial value other than null, ThreadLocal must be subclassed, and this method overridden. Typically, an anonymous inner class will be used.

        Returns:
        the initial value for this thread-local

      • get

        public T get()
        Returns the value in the current thread's copy of this thread-local variable. If the variable has no value for the current thread, it is first initialized to the value returned by an invocation of the initialValue() method.
        Specified by:
        get in interface java.util.function.Supplier<T>
        Returns:
        the current thread's value of this thread-local

      • set

        public void set​(T value)
        Sets the current thread's copy of this thread-local variable to the specified value. Most subclasses will have no need to override this method, relying solely on the initialValue() method to set the values of thread-locals.
        Parameters:
        value - the value to be stored in the current thread's copy of this thread-local.

      • remove

        public void remove()
        Removes the current thread's value for this thread-local variable. If this thread-local variable is subsequently read by the current thread, its value will be reinitialized by invoking its initialValue() method, unless its value is set by the current thread in the interim. This may result in multiple invocations of the initialValue method in the current thread.