Re: [PATCH v3 03/10] pkt-line: add packet_flush_gentle()

From: Lars Schneider <larsxschneider@gmail.com>
Date: Aug 5, 2016, 09:59 UTC
Message-ID: <3BA617E0-4DE6-46F6-B148-67265CABE707@gmail.com>
In-Reply-To: <20160802195546.GA2660@atze2.lan>

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> On 02 Aug 2016, at 21:56, Torsten Bögershausen <tboegi@web.de> wrote:
> 
> On Sun, Jul 31, 2016 at 11:45:08PM +0200, Lars Schneider wrote:
>> 
>>> On 31 Jul 2016, at 22:36, Torstem Bögershausen <tboegi@web.de> wrote:
>>> 
>>> 
>>> 
>>>> Am 29.07.2016 um 20:37 schrieb larsxschneider@gmail.com:
>>>> 
>>>> From: Lars Schneider <larsxschneider@gmail.com>
>>>> 
>>>> packet_flush() would die in case of a write error even though for some callers
>>>> an error would be acceptable.
>>> What happens if there is a write error ?
>>> Basically the protocol is out of synch.
>>> Lenght information is mixed up with payload, or the other way
>>> around.
>>> It may be, that the consequences of a write error are acceptable,
>>> because a filter is allowed to fail.
>>> What is not acceptable is a "broken" protocol.
>>> The consequence schould be to close the fd and tear down all
>>> resources. connected to it.
>>> In our case to terminate the external filter daemon in some way,
>>> and to never use this instance again.
>> 
>> Correct! That is exactly what is happening in kill_protocol2_filter()
>> here:
> 
> Wait a second.
> Is kill the same as shutdown ?
> I would expect that

No, kill is used if the filter behaved strangely or signaled an error. "Shutdown" is a graceful shutdown. However, that might not be an ideal name. See the bottom of my discussion with Peff here: http://public-inbox.org/git/74C2CEA6-EAAB-406F-8B37-969654955413%40gmail.com/

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> The process terminates itself as soon as it detects EOF.
> As there is nothing more read.
> 
> Then the next question: The combination of kill & protocol in kill_protocol(),
> what does it mean ?

I renamed that function to "kill_multi_file_filter". Initially I called the multi file filter "protocol" (bad decision I know) and named the functions accordingly.

> Is it more like a graceful shutdown_protocol() ?

Yes.

Thanks, Lars