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

On 02 Aug 2016, at 21:56, Torsten Bögershausen [off-list ref] wrote:

On Sun, Jul 31, 2016 at 11:45:08PM +0200, Lars Schneider wrote:

quoted

quoted

On 31 Jul 2016, at 22:36, Torstem Bögershausen [off-list ref] wrote:

quoted

Am 29.07.2016 um 20:37 schrieb larsxschneider@gmail.com:

From: Lars Schneider <redacted>

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/

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