help / color / mirror / Atom feed
From: Emmanuel Briot <>
Subject: Re: Broadcast / iterate to all Connection objects via Simple Components?
Date: Mon, 13 Feb 2023 00:44:01 -0800 (PST)	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <tscseu$23ce9$>

> sockets (socket select). 

Have you taken a look at epoll(), on linux ?  It is so much more natural to use, and so much more efficient in practice.
The example I mentioned above (a server with 25_000 concurrent connections) cannot work with select (which only
accepts file descriptors up to 1024), and is slow with poll (since the result of the latter is the number of events, and we
need to iterate over all registered sockets every time).

> P.S. This poses difficulties for users, who see all communication turned 
> upside down being driven by arbitrary socket events rather than by the 
> protocol logic. This was a reason I argued for introducing co-routines 
> with task interface in Ada.

In my own code, I basically provide an epoll-based generic framework.  One of the formal parameters is a `Job_Type`
with one primitive operation `Execute`.
The latter is initially called when a new connection is established, and is expected to do as much non-blocking work
as it can (Execute is run in one of the worker tasks).  When it cannot make progress, it returns a tuple (file_descriptor, type_of_event_to_wait_for)
to indicate when it needs to be called again in the future, for instance some data became available to read on the
specified file_descriptor.
The intent is that the `Job_Type` is implemented as a state machine internally.

Of course, a state machine is one of the two ways I know (along with a task) to implement the equivalent of
a co-routine in Ada.  So I 100% agree with you that co-routines would be very useful in simplifying user code,
in particular in the scenario we are discussing here !

  reply	other threads:[~2023-02-13  8:44 UTC|newest]

Thread overview: 22+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-02-07 20:29 Broadcast / iterate to all Connection objects via Simple Components? A.J.
2023-02-08  8:55 ` Dmitry A. Kazakov
2023-02-08  9:55 ` Jeffrey R.Carter
2023-02-13  7:28   ` Emmanuel Briot
2023-02-13  8:30     ` Dmitry A. Kazakov
2023-02-13  8:44       ` Emmanuel Briot [this message]
2023-02-13 10:55         ` Dmitry A. Kazakov
2023-02-13 11:07           ` Emmanuel Briot
2023-02-13 11:57             ` Dmitry A. Kazakov
2023-02-13 13:22               ` Niklas Holsti
2023-02-13 15:10                 ` Dmitry A. Kazakov
2023-02-13 16:26                   ` Niklas Holsti
2023-02-13 19:48                     ` Dmitry A. Kazakov
2023-02-15  9:54                       ` Niklas Holsti
2023-02-15 10:57                         ` Dmitry A. Kazakov
2023-02-15 18:37                           ` Niklas Holsti
2023-02-19  1:27                             ` A.J.
2023-02-19  8:29                               ` Dmitry A. Kazakov
2023-02-19 14:37                               ` Niklas Holsti
2023-02-13 15:43                 ` J-P. Rosen
2023-02-13 16:40             ` Jeremy Grosser <>
2023-02-13 20:33 ` Daniel Norte de Moraes
replies disabled

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox