Re: dd SIGUSR1 race

[Pádraig Brady]

On 09/26/2014 06:39 PM, Federico Simoncelli wrote:
> ----- Original Message -----
>> From: "Pádraig Brady" <address@hidden>
>> To: "Federico Simoncelli" <address@hidden>
>> Cc: "Bernhard Voelker" <address@hidden>, "Coreutils" <address@hidden>
>> Sent: Friday, September 26, 2014 6:05:33 PM
>> Subject: Re: dd SIGUSR1 race
>>
>>> Many other commands are providing an explicit flag: wget, curl,
>>> qemu-img, etc.
>>
>> Yes, I see qemu-img supports both.
>> If not too invasive, we could accept a status=progress patch to output
>> stats every approx 1s (noting the caveats of being blocked behind large
>> reads/writes)
> 
> I'll try to investigate if I can easily use sigusr1 with your new patch,
> meanwhile I came up with a patch adding status=progress.
> 
> It's a simple draft and I am open to hear all comments about it,
> especially on what's the format to report the progress.
> 
> For example qemu-img uses '\r' so that the output is always on the same
> line.
> 
> Patch in attachment.

I like the idea of '\r', but it involved a little adjustment to deal with.
I've updated your patch (attached) with the following changes:

 - Augmented the texinfo and NEWS entries
 - Added documentation to --help/man
 - Adjusted periodic output to use \r rather than \n
 - Used gethrxtime() rather than clock_gettime() which is not generally 
available
 - Avoided a race and CPU spinning in the test

thanks,
Pádraig.

dd-progress.patch
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