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

[Steve t. F. <ste...@gm...>]

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)?

>
> 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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