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improving performance of writing into a pipe

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  improving performance of writing into a pipe mikprog@gmail.com - 2013-02-18 07:12 -0800
    Re: improving performance of writing into a pipe Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-02-18 15:21 +0000
      Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-18 08:31 -0800
        Re: improving performance of writing into a pipe Thomas Rachel <nutznetz-0c1b6768-bfa9-48d5-a470-7603bd3aa915@spamschutz.glglgl.de> - 2013-02-18 17:49 +0100
          Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-18 09:00 -0800
            Re: improving performance of writing into a pipe Michael Torrie <torriem@gmail.com> - 2013-02-18 11:12 -0700
              Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 01:24 -0800
                Re: improving performance of writing into a pipe Peter Otten <__peter__@web.de> - 2013-02-19 10:55 +0100
                  Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 02:27 -0800
                    Re: improving performance of writing into a pipe Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-02-19 11:15 +0000
                  Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 02:27 -0800
                Re: improving performance of writing into a pipe Michael Torrie <torriem@gmail.com> - 2013-02-19 10:47 -0700
                  Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-20 09:54 -0800
                    Re: improving performance of writing into a pipe John Gordon <gordon@panix.com> - 2013-02-20 18:39 +0000
                    Re: improving performance of writing into a pipe Oscar Benjamin <oscar.j.benjamin@gmail.com> - 2013-02-20 22:05 +0000
                  Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-20 09:54 -0800
              Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 01:24 -0800
      Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-18 08:31 -0800
    Re: improving performance of writing into a pipe Serhiy Storchaka <storchaka@gmail.com> - 2013-02-18 21:29 +0200
      Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 04:10 -0800
      Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 04:10 -0800
      Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 05:39 -0800
        Re: improving performance of writing into a pipe Peter Otten <__peter__@web.de> - 2013-02-19 14:57 +0100
          Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 06:38 -0800
          Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 06:38 -0800
      Re: improving performance of writing into a pipe mikprog@gmail.com - 2013-02-19 05:39 -0800

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#39210

On Monday, February 18, 2013 7:29:09 PM UTC, Serhiy Storchaka wrote:
> On 18.02.13 17:12, mikprog@gmail.com wrote:
> 
> > on an embedded linux system (BeagleBoard) I am writing data coming from bluetooth dongle into a pipe.
> 
> > The function is the following one:
> 
> >
> 
> >
> 
> > def write_to_pipe(line):
> 
> >
> 
> >      # next line ensures that bytes like '0x09' are not translated into '\t' for
> 
> >      #example, and they are sent as such
> 
> >      hexbytes = "\\x" + "\\x".join([hex(ord(c))[2:].zfill(2) for c in line])
> 
> >      wrap = ["echo -en '", "' > /tmp/mypipe"]
> 
> >      msg = hexbytes.join(wrap)
> 
> >      print "DBG: sending: ", msg
> 
> >
> 
> >      try:
> 
> >          os.popen( msg )
> 
> >      except:
> 
> >          print "Error: write_to_pipe has failed!"
> 
> >
> 
> >
> 
> > Now I typically receive 4 bytes from the bluetooth dongle and that is fine.
> 
> > However when I receive many more than that it seems that the writing into the pipe is too slow.
> 
> >
> 
> > Is there any clever/obvious way to improve the code above?
> 
> > (I am quite sure there is to be honest).
> 
> 
> 
> def write_to_pipe(line):
> 
>      hexbytes = ''.join('\\x%02x' % ord(c) for c in line)
> 
>      with open('/tmp/mypipe', 'w') as f:
> 
>          f.write(hexbytes)


I'll take your hexbytes = '' line (which is surely more efficient than mine).
However whit this approach open + write it seems the pipe doesn't get the data...
I am not sure what is going on. 
At this point I suspect it could be a problem on the pipe itself (which I inherited). 

It is just weird that the pipe accept this correctly:
wrap = ["echo -en '", "' > /tmp/midi"]
msg = hexbytes.join(wrap)
os.popen( msg )

but seems to be careless of approach open + write.

I need to investigate there.

Thanks a lot, to you and to everyone else.
Mik

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#39218

> 
> def write_to_pipe(line):
> 
>      hexbytes = ''.join('\\x%02x' % ord(c) for c in line)
> 
>      with open('/tmp/mypipe', 'w') as f:
> 
>          f.write(hexbytes)


Update:
with a fix in the pipe THIS was the right way to do it, and it now works.
Thanks a lot Serhiy to you and to everyone else.

Mik

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#39223

mikprog@gmail.com wrote:

>> def write_to_pipe(line):
>>      hexbytes = ''.join('\\x%02x' % ord(c) for c in line)

I thought this was only needed to have 'echo' except your data.

>>      with open('/tmp/mypipe', 'w') as f:
>>          f.write(hexbytes)

> Update:
> with a fix in the pipe THIS was the right way to do it, and it now works.
> Thanks a lot Serhiy to you and to everyone else.

Do you mind telling us what fix you applied?

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#39225

> > Thanks a lot Serhiy to you and to everyone else.
> 
> 
> Do you mind telling us what fix you applied?


Oh, apologies Peter, I thought it was clear as I posted it after the lines written by Serhiy.
So it was what Serhiy suggest in addition to some (?minor?) modification to the pipe itself, which I cannot comment about as I don't have access to it.
But apparently the problem of not being able to open it was due to it.
(It does not help much I am afraid... but that's all I know).

Mik

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#39226

> > Thanks a lot Serhiy to you and to everyone else.
> 
> 
> Do you mind telling us what fix you applied?


Oh, apologies Peter, I thought it was clear as I posted it after the lines written by Serhiy.
So it was what Serhiy suggest in addition to some (?minor?) modification to the pipe itself, which I cannot comment about as I don't have access to it.
But apparently the problem of not being able to open it was due to it.
(It does not help much I am afraid... but that's all I know).

Mik

[toc] | [prev] | [next] | [standalone]

#39219

> 
> def write_to_pipe(line):
> 
>      hexbytes = ''.join('\\x%02x' % ord(c) for c in line)
> 
>      with open('/tmp/mypipe', 'w') as f:
> 
>          f.write(hexbytes)


Update:
with a fix in the pipe THIS was the right way to do it, and it now works.
Thanks a lot Serhiy to you and to everyone else.

Mik

[toc] | [prev] | [standalone]

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