Re CallSite relinking

[Howard Lovatt]

I have found the following class useful for something similar, don't
know if it will be of help:

  /** A {@link MutableCallSite} that can be reset to its initial target. */
  public static class ResetableCallSite extends MutableCallSite {
    private MethodHandle reset = null;

    /**
     * Make a blank call site object with the given method type. An
default target method is
     * supplied which will throw an IllegalStateException if called
(this is not the reset (initial)
     * target, a call to setTarget is required to set the reset
(initial) target).
     *
     * @param   type  the base type of the method handles that this
call site can target
     *
     * @throws  NullPointerException  if the proposed type is null
     */
    public ResetableCallSite( final MethodType type ) throws
NullPointerException { super( type ); }

    /**
     * Make a call site object with the given target.
     *
     * @param   target  the method handle which will be the initial
target of the call site and the
     *                  memorized reset target
     *
     * @throws  NullPointerException  if the proposed target is null
     */
    public ResetableCallSite( final MethodHandle target ) throws
NullPointerException {
      super( target );
      reset = target;
    }

    /**
     * Sets the target and if it is the first call to setTarget also
memorizes the target for reset if it is the first target set.
     *
     * @param   target  the new target
     *
     * @throws  NullPointerException      if the proposed new target is null
     * @throws  WrongMethodTypeException  if the proposed new target
has a method type that differs
     *                                    from the previous target
     */
    @Override public void setTarget( final MethodHandle target )
        throws NullPointerException, WrongMethodTypeException {
      super.setTarget( target );
      if ( reset == null ) { reset = target; }
    }

    /**
     * Reset the target to its first value (may need a sync afterwards).
     *
     * @throws  IllegalStateException  if target not already set
     */
    public void reset() throws IllegalStateException {
      if ( reset == null ) {
        throw new IllegalStateException( "Target not set, therfore
can't reset" );
      }
      super.setTarget( reset );
    }

    /**
     * String representation including the reset handle.
     *
     * @return  super.toString() + "[reset = " + toString( reset ) + "]"
     */
    @Override public String toString() {
      return super.toString() + "[reset = " + toString( reset ) + "]";
    }
  }


-- 
  -- Howard.