Re: [RAUC] Progress indication

[Enrico Joerns <ejo@pengutronix.de>]

Hi Leif,

On 05/11/2017 12:29 PM, Middelschulte, Leif wrote:
> Hello Enrico,
>
> Am Mittwoch, den 10.05.2017, 15:22 +0200 schrieb Enrico Joerns:
>> Hi Leif,
>>
>> On 05/04/2017 04:33 PM, Middelschulte, Leif wrote:
>>>
>>> Now, about my second question: How does a custom hook script
>>> communicate its progress back to the install-handler (i.e. rauc
>>> service)?
>>>
>>> I'd go modify rauc's update_handler.c, set the
>>> G_SUBPROCESS_FLAGS_STDOUT_PIPE flag for the spawned slot
>>> script-process and read back the progress and propagate it to the
>>> DBus interface using r_context_send_progress. Is that the right
>>> direction here?
>>
>> in RAUC, the progress is generated by adding a 'step' for an action
>> you perform. When starting the action you call
>> r_context_begin_step(), when terminating the action you call
>> r_context_end_step(). It is important to know that steps have a
>> nesting depth that allows visualizers to control the granularity of
>> information they show. A step can also be marked as either
>> successful or failed.
>>
>>
>> An example is the "Determining slot states" step:
>>
>> r_context_begin_step("determine_slot_states", "Determining slot
>> states", 0); [...] r_context_end_step("determine_slot_states",
>> res);
>>
>>
>> Thus, this should be the interface to use to add new steps.
>>
>>
>> The current granularity we have does not go deeper than "Copying
>> image". This will be called for both a default install handler as
>> well as for an install hook.
>>
>> If you ask for progress from the install hook, you intend to be
>> more fine-grained with your messages?
> Yes, since some updates will take quite a while, we'd like to display
> an approximate progress (e.g. bytes written/byte to be written).
>
> I saw that there's a "send_progress" callback one can use from
> *within* the installer.

Not sure if I understand you right, but this is what I described above, 
isn't it? A `git grep send_progress` only gives me 
`r_context_send_progress`.

> But currently it's not even used to indicate any progress of raw (stream) copies, right?

No, there is currently no progress indication for raw stream copies. For
this it would work, but most other copy operations performed by binaries
(such as nandwrite) do not provide any progress, thus we did not put too
much effort on it, yet.

> I'm trying to stick to upstream code as much as possible and,
> eventually, contribute what's necessary to communicate progress
> back.

That sounds like the perfect way for me :)

> If I understood the code right, I'd go and do the following:

> 1.) make my hook script write its percentual progress to stdout
> 2.) I'd fork RAUC Service's update_handler code to read back STDOUT from the
> spawned's process (i.e. hook.sh)
 > 3.) use send_progress to publish the information to the "dumb" GUI

Basically, yes, but what you should use for indicating progress (had to 
dig in the code for that, too ;) ) is `r_context_set_step_percentage()`. 
You can read from its documentation string that its designed for such 
purposes you have, where you have a step that you want to give a number 
of nonspecific substeps. Thus like a copy progress inside a `installing 
slot` step.

There you can provide percentage steps that will also propagate to the 
global progress, meaning that you will have something like

   50% Updating rootfs0...
   51% Updating rootfs0...
   52% Updating rootfs0...
   53% Updating rootfs0...
   ...

Unfortunately, the only place in the code where this is used, already is 
the "/progress/test_explicit_percentage" test in test/progress.c.

Hope that helps you.


Best regards, Enrico

-- 
Pengutronix e.K.                           | Enrico Jörns                |
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