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

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

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.

So really it's only the one use of Cause::Read in BlockFile.cpp that is
likely to occur.

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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