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Memory Pool System Project

                     THE DESIGN OF THE GENERIC FIX FUNCTION
                                 design.mps.fix
                               incomplete design
                               richard 1995-08-25

    INTRODUCTION:

    Fix is the interface through which the existence of references are communicated
    from the MPS client to the MPS.  The interface also allows the value of such
    references to be changed (this is necessary in order to implement a moving
    memory manager).

    ARCHITECTURE:

    .contract:

    .protocol.was-marked: The ScanState has a Bool wasMarked field.  This is used
    for finalization.
    .protocol.was-marked.set: All pool-specific fix methods must set the wasMarked
    field in the ScanState that they are passed.
    .protocol.was-marked.meaning: If the pool-specific fix method sets the
    wasMarked field to FALSE it is indicating the object referred to by the ref
    (the one that it is supposed to be fixing) has not previously been marked (ie,
    this is the first reference to this object that has been fixed), and that the
    object was white (in condemned space).
    .protocol.was-marked.conservative: It is always okay to set the wasMarked field
    to TRUE.
    .protocol.was-marked.finalizable: PoolMRG (design.mps.poolmrg) uses the value
    of the wasMarked field to determine whether an object is finalizable.

    IMPLEMENTATION:

    .fix.nailed: In a copying collection, a non-ambiguous fix to a broken heart
    should be snapped out _even if_ there is a RankAMBIG ref to same object (i.e.,
    even if the broken heart is nailed); the RankAMBIG reference must either be
    stale (no longer in existence) or bogus.

## A. References

## B. Document History

2002-06-21 | RB | Converted from MMInfo database design document.

## C. Copyright and License

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Ravenbrook / Projects / Memory Pool System / Version 1.111 Product Sources / Design Documents