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

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

On 19 April 2018 at 17:29, 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)?

Do I need to log it as a bug?

>
>>
>> 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.

No additional useful information yet. He's just wanting to know why he
can't open his project and we're running out of guesses.

Steve

>
> 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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>>
>>
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