Waiting for float time

Waiting for float time

[sayan]

Hi,

I am looking for a floating point version of the function Unix.sleep in
order to suspend execution of a program for 0.7s

Is there any such function in the standard library ?

Is there a solution outside of Threads, and GTK ?

I have looked at Unix.interval_timer but I'd rather not use it. From
what I understand, you have to add a signal handler to catch sigalrm,
and I do not see how to create a sleep function using it.

Is there a multiplatform solution ?

Thanks

-- 
Sébastien

Re: [Caml-list] Waiting for float time

[Karl Zilles]

sayan@crans.org wrote:
> I am looking for a floating point version of the function Unix.sleep in
> order to suspend execution of a program for 0.7s

Use select with no file_descrs.

Re: [Caml-list] Waiting for float time

[Robert Roessler]

sayan@crans.org wrote:
> I am looking for a floating point version of the function Unix.sleep in
> order to suspend execution of a program for 0.7s
> 
> Is there any such function in the standard library ?
> 
> Is there a solution outside of Threads, and GTK ?
> 
> I have looked at Unix.interval_timer but I'd rather not use it. From
> what I understand, you have to add a signal handler to catch sigalrm,
> and I do not see how to create a sleep function using it.
> 
> Is there a multiplatform solution ?

I believe the OCaml idiom for this is to use Unix.select with empty 
lists for all THREE of the descriptor lists... and this does work on 
Windows.

There may be better solutions... ;)

Robert Roessler
roessler@rftp.com
http://www.rftp.com

Re: [Caml-list] Waiting for float time

[sayan]

Robert Roessler wrote:
> sayan@crans.org wrote:
>> I am looking for a floating point version of the function Unix.sleep in
>> order to suspend execution of a program for 0.7s
>>
>> Is there any such function in the standard library ?
>>
>> Is there a solution outside of Threads, and GTK ?
>>
>> I have looked at Unix.interval_timer but I'd rather not use it. From
>> what I understand, you have to add a signal handler to catch sigalrm,
>> and I do not see how to create a sleep function using it.
>>
>> Is there a multiplatform solution ?
> 
> I believe the OCaml idiom for this is to use Unix.select with empty 
> lists for all THREE of the descriptor lists... and this does work on 
> Windows.
> 
> There may be better solutions... ;)
> 
Thanks for the suggestion, I would never have thought of polling for 
this. :)

What about wrapping usleep or nanosleep ? These are probably not 
portable, but are there obvious reasons not include them in the Unix 
library ?

-- 
Sébastien

Re: [Caml-list] Waiting for float time

[Vincent Hanquez]

On Thu, Jun 28, 2007 at 12:15:12PM +0200, sayan@crans.org wrote:
> Thanks for the suggestion, I would never have thought of polling for 
> this. :)
> 
> What about wrapping usleep or nanosleep ? These are probably not 
> portable, but are there obvious reasons not include them in the Unix 
> library ?

you have answered the question yourself;
the Unix module is unfortunately a lowest common part of what is
available on lots of unices, and also without "unsafe" stuffs (mmap).
That's why you have to do binding all the times when having specific
low level requirements.

-- 
Vincent Hanquez

Re: [Caml-list] Waiting for float time

[Matthieu Dubuget]

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2007/6/28, Karl Zilles <zilles@1969web.com>:
>
> sayan@crans.org wrote:
> > I am looking for a floating point version of the function Unix.sleep in
> > order to suspend execution of a program for 0.7s
>
> Use select with no file_descrs.


Nice! Where are this kind of tricks supposed to be collected?
FAQ, http://www.ocaml-tutorial.org/, ...?

Salutations

Matt

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Re: [Caml-list] Waiting for float time

[Bünzli Daniel]

Le 28 juin 07 à 12:18, Vincent Hanquez a écrit :

>  and also without "unsafe" stuffs (mmap).

Note that mmap is available in a safe way in the Bigarray module.

Daniel

Re: [Caml-list] Waiting for float time

[Yaron Minsky]

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On 6/27/07, Robert Roessler <roessler@rftp.com> wrote:
>
> sayan@crans.org wrote:
>
> I believe the OCaml idiom for this is to use Unix.select with empty
> lists for all THREE of the descriptor lists... and this does work on
> Windows.


Note, on Unix  at least, you need to wrap the call to select in an exception
handler, since select can be interrupted, at which point the call throws an
exception.

y

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Re: [Caml-list] Waiting for float time

[Thomas Fischbacher]

sayan@crans.org wrote:

> I am looking for a floating point version of the function Unix.sleep in
> order to suspend execution of a program for 0.7s


let sleep_float n =
   let _ = Unix.select [] [] [] n in ()
;;

Re: [Caml-list] Waiting for float time

[Bruno Verlyck, Bruno.Verlyck]

   Date: Thu, 28 Jun 2007 13:15:31 +0200
   From: "Matthieu Dubuget" <matthieu.dubuget@gmail.com>

Hi,
   2007/6/28, Karl Zilles <zilles@1969web.com>:
   > sayan@crans.org wrote:
   > > I am looking for a floating point version of the function
   > > Unix.sleep in order to suspend execution of a program for 0.7s
   > Use select with no file_descrs.
   Nice!  Where are this kind of tricks supposed to be collected?
   FAQ, http://www.ocaml-tutorial.org/, ...?
Any book / doc on Unix systems programming ?  This use of select is
standard, unix.cma is only a thin layer over libc and/or the syscalls
(at least from a non-language specific POV).  This is why the (Ocaml)
unix library's documentation starts this way:
   Chapter 21  The unix library: Unix system calls

   The unix library makes many Unix system calls and system-related
   library functions available to Objective Caml programs. This
   chapter describes briefly the functions provided.  Refer to
   sections 2 and 3 of the Unix manual for more details on the
   behavior of these functions.

Bruno.

Re: [Caml-list] Waiting for float time

[Matthieu Dubuget]

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2007/6/28, Bruno Verlyck <Bruno.Verlyck@inria.fr>:
>
>    Date: Thu, 28 Jun 2007 13:15:31 +0200
>    From: "Matthieu Dubuget" <matthieu.dubuget@gmail.com>
>
> Hi,
>    2007/6/28, Karl Zilles <zilles@1969web.com>:
>    > sayan@crans.org wrote:
>    > > I am looking for a floating point version of the function
>    > > Unix.sleep in order to suspend execution of a program for 0.7s
>    > Use select with no file_descrs.
>    Nice!  Where are this kind of tricks supposed to be collected?
>    FAQ, http://www.ocaml-tutorial.org/, ...?
> Any book / doc on Unix systems programming ?


Fair answer. But I'm sure you understood my question, didn't you?

I faced exactly the same problem as Sébastien.

I had some OCaml code using Thread module, and, Thread.delay. Because of one
bug in ocaml compilers, I can not use Thread module (
http://caml.inria.fr/mantis/view.php?id=4173).
Not a very big problem after some thought, because the use of Thread was not
absolutely necessary when using my Ocaml code wrapped inside a shared
library. I then looked for a replacement for Thread.delay. I still needed to
wait some (small amount of time) without pooling.

Sorry if I'm not a unix guru, but the fact is that I did not find the
Unix.select solution.

So. Suppose there is some short tricks/recipes list about OCaml somewhere:
it may save time to beginners looking for such things. I asked the question,
because maybe, there is already such a place? (the caml-list archive since
today, at least...)

Salutations

Matthieu Dubuget

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Re: [Caml-list] Waiting for float time

[Bruno Verlyck, Bruno.Verlyck]

   Date: Thu, 28 Jun 2007 17:29:46 +0200
   From: "Matthieu Dubuget" <matthieu.dubuget@gmail.com>

   2007/6/28, Bruno Verlyck <Bruno.Verlyck@inria.fr>:
   >    Date: Thu, 28 Jun 2007 13:15:31 +0200
   >    From: "Matthieu Dubuget" <matthieu.dubuget@gmail.com>

   >    2007/6/28, Karl Zilles <zilles@1969web.com>:
   >    > sayan@crans.org wrote:
   >    > > I am looking for a floating point version of the function Unix.sleep in
   >    > > order to suspend execution of a program for 0.7s
   >    > Use select with no file_descrs.
   >    Nice!  Where are this kind of tricks supposed to be collected?  FAQ,
   >    http://www.ocaml-tutorial.org/, ...?
   > Any book / doc on Unix systems programming ?
   Fair answer.  But I'm sure you understood my question, didn't you?
I try :-)

   Sorry if I'm not a unix guru, but the fact is that I did not find the
   Unix.select solution.
My point was: it's not an OCaml-related issue (which obviously is not
the answer you expect).

   So.  Suppose there is some short tricks/recipes list about OCaml
About Unix.  I found "The Single UNIX® Specification" worth reading
(as a reference, not as an intro).

   somewhere: it may save time to beginners looking for such things.
   I asked the question, because maybe, there is already such a place?
   (The caml-list archive since today, at least...)
In the caml-list, Xavier often recommends «the books by W. Richard
Stevens ("Advanced Programming in the Unix Environment", "Unix Network
Programming", etc)»; e.g., in
 http://groups.google.com/group/fa.caml/browse_thread/thread/e591ab18a8397a2f/c19874b0c2d5209a?lnk=gst&q=system+programming+book+leroy&rnum=1#c19874b0c2d5209a

Sorry for these frustrating answers :-)
Bruno (who doesn't HTH anymore...)

Re: [Caml-list] Waiting for float time

[Robert Roessler]

Yaron Minsky wrote:
> On 6/27/07, *Robert Roessler* <roessler@rftp.com 
> <mailto:roessler@rftp.com>> wrote:
> 
>     sayan@crans.org <mailto:sayan@crans.org> wrote:
> 
>     I believe the OCaml idiom for this is to use Unix.select with empty
>     lists for all THREE of the descriptor lists... and this does work on
>     Windows.
> 
> 
> Note, on Unix  at least, you need to wrap the call to select in an 
> exception handler, since select can be interrupted, at which point the 
> call throws an exception.

Thanks for the reminder - I am too familiar with OCaml's Windows 
version of Unix.select, which recognizes and special-cases the 
"sleep-only" use of select by transforming it into a non-alertable 
[Win32] Sleep() call. ;)

Robert Roessler
roessler@rftp.com
http://www.rftp.com