[Sugar-devel] new journal and datastore maintainer

[Martin Langhoff]

On Fri, Sep 18, 2009 at 2:10 AM, James Cameron <quozl at laptop.org> wrote:
> By branching at the 0.82 point as deployed, determining from evidence

Good theoretical re-statement. You post may clarify things for other
readers -- as for me, I know very well what I am requesting. And I do
respect that it is not easy.

It is just... very important.

> I've reviewed the changes just now from 0.82 to 0.84.  It was certainly
> an entire rewrite, so what you are in effect asking is for someone to
> support the 0.82 DS to fix a problem that is not yet well defined.

The _root cause_ is not well defined, although Tomeu has pointed out
likely culprits. The results are very well known, and it is possible
recover the situation without surgery. Read:

  http://lists.laptop.org/pipermail/devel/2008-May/014601.html

And here you can find "steps to repro" and a workaround if you want to
see it in action:

  http://dev.laptop.org/ticket/7719

(Uy users probably triggering the DS problem in a different way)

As for the code that controls this?

in shell/view/Shell.py:

    def _start_journal_idle(self):
        # Mount the datastore in internal flash
        ds_path = env.get_profile_path('datastore')
        try:
            datastore.mount(ds_path, [], timeout=120 * \
                                         DBUS_PYTHON_TIMEOUT_UNITS_PER_SECOND)
        except:
            # Don't explode if there's corruption; move the data out of the way
            # and attempt to create a store from scratch.
            shutil.move(ds_path, os.path.abspath(ds_path) + str(time.time()))
            datastore.mount(ds_path, [], timeout=120 * \
                                         DBUS_PYTHON_TIMEOUT_UNITS_PER_SECOND)


The good news: if recent Sugars have retained this logic, even if we
hit issues with newer datastore code (hope not! :-) ), the same
"recovery" tool will help for newer Sugar.




m
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 martin at laptop.org -- School Server Architect
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