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  1. JDK
  2. JDK-8137055 Prepare for JEP 260
  3. JDK-8139891

Prepare Unsafe for true encapsulation



    • Sub-task
    • Resolution: Fixed
    • P2
    • 9
    • 9
    • hotspot
    • b93


      As part of the preparation for JEP 260, Unsafe needs to be separable
      from the base module, so it can be exported by a new, yet to be
      defined, jdk.unsupported module, and have a separate evolution policy
      that is not exposed. That is, the JDK needs an internal Unsafe that can
      be evolved and added to in future releases, while maintaining the
      existing Unsafe API that developers are using.

      Many uses of Unsafe are for performance reasons. Any changes made
      should preserve the current performance characteristics. To achieve this
      the existing Unsafe intrinsic candidate methods should remain intrinsic
      candidate methods. The VM can provide aliases for these intrinsics so
      they are common to both the internal and sun.misc versions of Unsafe.

      The JDK implementation will be updated to use the new internal version
      of Unsafe.

      For the purposes of making progress, this work can be split into
      several phases:

      1) Create the new internal Unsafe class and provide intrinsic support
          for both.
      2) Update existing, and possibly add new, tests to use the new
          internal Unsafe. Some tests may need to be duplicated, or reworked,
          to test both versions of Unsafe, see JDK-8140608.
      3) Update the Unsafe usages in the JDK so that there is no longer any
          dependency on sun.misc.Unsafe, see JDK-8140606.

      This bug will be used for the first phase, consisting mainly of :
        - the intrinsic aliasing,
        - the new internal Unsafe ( copy of sun.misc.Unsafe ),
        - reverting sun.misc.Unsafe to, almost, its 1.8 API,
        - minimal test and implementation updates, since there some usages
          of unaligned access that is new in the 1.9.




            chegar Chris Hegarty
            chegar Chris Hegarty
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