Hi Tomas,
I attach a simple non-blocking echo server. There are some functions
Nice!
Conceptually it should not block, I am not sure how to test it though.
Any ideas?
Positive testing works well:
abu:~/pico ./p dbg.l nb-ex.l
: (more *Run)
(5 (when (accept @) (task @ Sock @
Hi Konrad,
But the underlying select function also provides non blocking writes.
so that you can dely trying to write to a socket until it is ready for
more data.
Yep, this is also needed.
It would appear that task and *Run have no way of using this part of
the select function.
Right.
Hi Konrad,
train. The task and *Run mechanism (if used with enough care) give us
non blocking reads.
But the underlying select function also provides non blocking writes.
so that you can dely trying to write to a socket until it is ready for
more data.
I would say that select (in C) and
Hi Alex,
http://www.software-lab.de/refP.html#poll says:
(poll 'cnt) - cnt | NIL
Checks for the availability of data for reading on the file
descriptor cnt. See also open, in and close.
: (and (poll *Fd) (in @ (read))) # Prevent blocking
The comment is a bit misleading as it does
If the socket is set not to block, then the socket will read as much
data as is available and the underlying read call will return the
number of bytes read, right? So the poll will still be useful in an
nbio world.
John
On 10 Oct 2008, at 12:36 PM, Alexander Burger wrote:
Hi Tomas,
The
Hi Tomas,
Not necessarily. If we use the select() mechanism provided by '*Run'
and 'task', you can make input operations like 'listen', 'accept',
'read', 'rd' etc. non-blocking.
select() does not make thinks non-blocking as far as I am aware. It
just wakes up the process when
Hi Konrad,
your response to Tomas's questions dosn't seem to have made it to the list.
This is strange. I did receive it back, and it appeared in the archive.
How can that be? Is it possible that it got lost in some spam filter?
Most of the documentation I have seen seems to suggest that
On Thu, Oct 09, 2008 at 11:03:06AM +0200, Alexander Burger wrote:
I'll try this out soon. It will probably involve only the removal of the
blocking(YES, ex, sd2);
calls in src/net.c, and additional checks for EAGAIN after some read()
calls. Does anybody see a problem with that?
On Thu, Oct 09, 2008 at 08:12:28AM +0200, Alexander Burger wrote:
Under Linux, select() may report a socket file descriptor as ready
for reading, while nevertheless a subsequent read blocks. This could
for example happen when data has arrived but upon examination has
wrong checksum
Aarrgh ...
Sorry, this was complete nonsense!
I get into a busy waiting loop with that.
I have to change it back, the old version was correct.
Sorry for the confusion,
- Alex
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Hi all,
Sorry for the confusion,
Let me try to explain the situation:
In the present system, it does not help at all to put the socket into
non-blocking mode. The reason is that select() is conceptionally
separated from read().
After select() signals (correctly or incorrectly) that data are
Hi Alex,
that sends me back to the drawing board a little. Yet again I recall
seeing the fifo function but didn't realise I might need it : )
A few other things occured to me as I was working on this on the
train. The task and *Run mechanism (if used with enough care) give us
non blocking reads.
Hi Alex,
The drawback of implementing such a fully non-blocking system will
be that the present separation of event generation (select) and data
processing (read) cannot be held up any longer, and a completely
different application flow is required.
yes, indeed.
I attach a simple
Hi Konrad,
sufficently abstract the URL space from the physical disk. Most other
mature frameworks allow your to creat a completly virtual url space
which has no relation to physical files on disk. The way the forms.l
maps a full path to its javascript file and puts it in the output
Hmm,
Sounds clever, but very complicated maybe to maintain the scheduling?
You mentioned multiplayer online games as a possibility, are the big
ones with thousands of simultaneous users already operating under
these principles? It would be great if you could point me to a
resource on the basics behind
Henrik, take a look at
http://docs.python.org/library/asyncore.html
There is even a few samples. I have used this extensively,
reimplemented it directly in C a time or two.
I think it would be relatively simple to implement using 'task' and
'*Run'.
Rand
Henrik Sarvell wrote:
Sounds
On Wed, Oct 08, 2008 at 09:55:16PM +1100, konrad Zielinski wrote:
I belive the issue is that I have actually installed picoLisp under
usr/local but don't use it exclusivly from that directory. As such I
Ah, yes, in that case the path gets expanded. I didn't think about that,
because I always
Konrad,
Thanks for the links and clarifications, here is another one:
http://en.wikipedia.org/wiki/Twisted_(software)
However, for really understanding what this is about this link that
you posted is very good: http://www.nightmare.com/medusa/medusa.html
From the above Medusa link: Most
For even more discussions, look at http://www.acme.com/software/ and then
mini_httpd, micro_httpd, thttpd. These are really lightweight http
servers. He did
a lot of work comparing threading, forking, and async IO. Async IO wins big
for http serving. Apache just happened to be at the right
Ahh,
I belive the issue is that I have actually installed picoLisp under
usr/local but don't use it exclusivly from that directory. As such I
get the following:
script src=http://localhost:8080//usr/local/picoLisp/lib/form.js;
type=text/javascript/script
which includes an absolure path to
Henrik,
all of the references I'm aware of are based on Python.
the standard Python library includes modules called asyncore and asynchat
(sections 17.5 and 17.6 of the Python documentation.
The original Asyncronous webserver (as far as I'm aware) is medusa
http://www.nightmare.com/medusa/
Henrik Sarvell wrote:
Thanks Randall for that! So where do we start, where do I start, am I needed?
I just don't have time now to really look into it. :-(
Is the best way to simply review the Twisted source and reimplementing
in Pico, keeping the OODB in mind all the time maybe?
I would
Hi Konrad and Henrik,
Is the best way to simply review the Twisted source and
reimplementing in Pico, keeping the OODB in mind all the time maybe?
reading from http://en.wikipedia.org/wiki/Twisted_(software)
Twisted supports an abstraction over raw threads=E2=80=94using a thread =
as
a
Hi Tomas,
I do not think Konrad could achieve single process/thread http server
without a bit of coding in C. PicoLisp I/O operations block I think
Not necessarily. If we use the select() mechanism provided by '*Run' and
'task', you can make input operations like 'listen', 'accept', 'read',
Hi Alex,
In addition, I sometimes use the 'alarm' function (in combination
with 'catch', 'throw' and 'finally') to ensure that no operation
takes too long.
I don't think alarm is good enough though. It is good for timeouts
but not for schedulling.
BTW: I found a typo in
Hi Tomas,
I don't think alarm is good enough though. It is good for timeouts
but not for schedulling.
True. I would not use if for scheduling, though, but to terminate
operations which might possibly take too long (e.g. 'connect' to another
server).
BTW: I found a typo in
Hi all,
oops, sorry! Forget what I wrote:
A .html file will
be directly sent to the client, without any forking. And also .l files
do not automatically cause the fork, but only if (app) is called during
their execution.
This was wrong. The 'server' function in lib/http.l will always fork
Hi All,
In the matter of how to begin. Twisted is I think the wrong place. It
is a very large and complicated beast which has grown in its own
unquie direction. So much so that it is incompatable with a lot of
standard python tools and libraries, uses its own logging system etc.
In copying
Hi Alex,
Not necessarily. If we use the select() mechanism provided by '*Run'
and 'task', you can make input operations like 'listen', 'accept',
'read', 'rd' etc. non-blocking.
select() does not make thinks non-blocking as far as I am aware. It
just wakes up the process when something is
Hi Alex,
thanks for the explanation!
Tomas
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Hi Alex,
your response to Tomas's questions dosn't seem to have made it to the list.
Most of the documentation I have seen seems to suggest that Sockets
need to be put into non blocking mode explicitly, ie using select() is
not sufficent. At a low level attempting to read from a nonblocking
Hi Henrik
the whole idea of an asycronous server is that you only use one
process. to handle all requests. this way session data can be stored
without using an external symbols.
Even further several clients may share state in some way, though the
only example I can think of off the top of my
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