Re: Callbacks

From: Michael Klemm (
Date: Wed Feb 23 2005 - 08:26:14 PST

  • Next message: Paul H. Hargrove: "Re: Callbacks"
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    Ulisses wrote:
    | On Wed, 2005-02-23 at 16:26 +0100, Michael Klemm wrote:
    |>Paul H. Hargrove wrote:
    |>| Micheal,
    |>|   Ulisses is correct, our design uses a single callback for
    |>| "checkpoint", "continue after taking checkpoint" and "restart from
    |>| checkpoint".  The later two cases are to be distiguished by the value
    |>| returned from cr_checkpoint().
    |>Ah... OK. After re-reading the headers and getting an example to work I
    |>understand that fact.  Afterall, I can assume that each callback routine
    |>has to call cr_checkpoint to allow BLCR to proceed to the next phase
    |>during checkpoint. If just one callback denies, the whole process is
    |>terminated. Right?
    | 	Hmm.. I don't think so. I found in include/libcr.h (I've just realized
    | that I gave you the wrong location of libcr.h in my other e-mail, sorry)
    | the following explanation:
    | // Note that if a callback returns without invoking cr_checkpoint(),
    | // then it will be invoked immediately after the return.
    There's a comment in libcr.h that states:
    Callbacks are expected to return zero on success. A callback may return
    nonzero to indicate a failure...
    In this case I assume that the checkpoint procedure gets terminated and
    no checkpoint is taken at all.
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