Re: [Audacity-devel] Audacity failed to read a file on C:

[Paul L. <pau...@gm...>]

On Thu, Apr 19, 2018 at 12:29 PM Steve the Fiddle <ste...@gm...>
wrote:

> On 19 April 2018 at 17:21, Paul Licameli <pau...@gm...> wrote:
> >
> >
> > On Wed, Apr 18, 2018 at 11:26 AM, Steve the Fiddle
> > <ste...@gm...> wrote:
> >>
> >> On 18 April 2018 at 13:55, Paul Licameli <pau...@gm...>
> wrote:
> >> > No clues as to operating system and appplication versions?
> >>
> >> Windows (hence "c:")
> >> I think all similar reports have been on Windows.
> >> Most recent case, Windows 10, Audacity 2.2.2
> >>
> >> >
> >> > The proximate source of that message is of course in
> >> > FileExeption::ErrorMessage() which I wrote in 2.2.0, but by the time
> you
> >> > reach the code that produes the message, and exception has "long ago"
> >> > been
> >> > thrown and caught, and you are not even in the catch-block any more,
> but
> >> > instead in a delayed handler that runs in idle time of the event loop
> to
> >> > give you a notification that there was a problem.
> >>
> >> So where is the exception thrown?
> >>
> >> >
> >> > So if you do find a way to reproduce the messages, then to debug it
> >> > further,
> >>
> >> I don't debug on Windows - I'm not sufficiently familiar with the tools.
> >>
> >> > you need to change settings of your debugger to break as soon as
> >> > exceptions
> >> > are thrown, or else find the places where an exception with
> Cause::Read
> >> > is
> >> > constructed, and put breakpoints there.
> >>
> >> OK, I see.
> >> So why do we get a "Cause::Read" error when WriteSummary() fails?
> >>
> >> Would it not be more useful to have different error messages depending
> >> on what has failed?
> >>
> >> Steve
> >
> >
> > You are looking at the use of Cause::Read in ODPCMAliasBlockFile.cpp?
> >
> > Looks like I erred and should have used Cause::Write there, to give
> better
> > information to the user.
> >
> > But this part of the code is very infrequently used.  This is for
> > "on-demand" loading of large imported files in the background.
> >
> > You can see other uses of Cause::Read in raw data import -- not a usual
> use
> > case -- and NotYetAvailableException, also special to on-demand
> loading.  I
> > think the forum users would have mentioned that they were doing one of
> those
> > unusual things?
> >
> > The direct usage of it in SimpleBlockFile::ReadData isn't reached,
> because
> > mCache.active() is always false -- this looks like an abandoned old
> > experiment with in-memory duplication of block file contents for longer
> > durations.
>
> Thanks for the explanation Paul.
> Will you fix those two bits (when you have a time)?
>

I fixed one bit at 4ba373f2d97822fb92f62ce459806e216ba8c92b (I decide
Cause::Open was more correct than Cause::Write or Cause::Read).

This may give a more correct error message to the user, "Audacity failed to
open a file in C:" though this may not shed any more light on the reasons
why.

Recall that the program does have more complete path information to the
problematic block file, but I recall we agreed it would be too overwhelming
to print it out fully.

Which is the other bit you mean?

PRL



>
> >
> > So really it's only the one use of Cause::Read in BlockFile.cpp that is
> > likely to occur.
>
> I'm hoping that the user (most recent case) will upload his project
> for us to look at - which may then cast some light on what is
> occurring.
> I'll keep you  informed.
>
> Steve
>
> >
> > PRL
> >
> >
> >
> >>
> >>
> >> >
> >> > PRL
> >> >
> >> >
> >> >
> >> > On Wed, Apr 18, 2018 at 6:35 AM, Steve the Fiddle
> >> > <ste...@gm...>
> >> > wrote:
> >> >>
> >> >> OK, so how about the specific message:
> >> >> "Audacity failed to read from a file on drive c:"
> >> >>
> >> >> My IDE does not understand the code, I don't understand the code, and
> >> >> neither myself, other support crew or the user understand what this
> >> >> message is saying.
> >> >> OK, I get that Audacity may have failed to read something on drive
> C:,
> >> >> but what, where, why, and how does the user fix it?
> >> >>
> >> >> Also, why are we seeing this problem regularly occur now? Does this
> >> >> indicate a bug in Audacity?
> >> >>
> >> >> Steve
> >> >>
> >> >> On 17 April 2018 at 21:46, Steve the Fiddle <
> ste...@gm...>
> >> >> wrote:
> >> >> > On the forum we are quite regularly hearing of problems where users
> >> >> > see error messages similar to "Audacity failed to read a file on
> C:"
> >> >> > when attempting to open a project.
> >> >> >
> >> >> > I see that this is a group of similar messages.
> >> >> > What precisely do these messages mean, and why do they occur?
> >> >> >
> >> >> > Steve
> >> >>
> >> >>
> >> >>
> >> >>
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> >> >
> >> >
> >> >
> >> >
> >> >
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> >>
> >>
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