[Python-ideas] PEP 3156: Transport.sendfile

[Guido van Rossum]

On Fri, Jan 25, 2013 at 10:11 AM, Nikolay Kim <fafhrd91 at gmail.com> wrote:

>
> On Jan 25, 2013, at 10:08 AM, Guido van Rossum <guido at python.org> wrote:
>
> On Fri, Jan 25, 2013 at 10:03 AM, Nikolay Kim <fafhrd91 at gmail.com> wrote:
>
>>
>> I think Transport needs 'sendfile' api, something like:
>>
>>    @tasks.coroutine
>>    def sendfile(self, fd, offset, nbytes):
>>       ….
>>
>> otherwise it is impossible to implement sendfile without breaking
>> transport encapsulation
>
>
> Really? Can't the user write this themselves? What's wrong with this:
>
> while True:
>   data = os.read(fd, 16*1024)
>   if not data: break
>   transport.write(data)
>
> (Perhaps augmented with a way to respond to pause() requests.)
>
>
> i mean 'os.sendfile()', zero-copy sendfile.
>

I see (http://docs.python.org/dev/library/os.html#os.sendfile).

Hm, that function is so platform-specific that we might as well force users
to do it this way:

sock = transport.get_extra_info("socket")
if sock is not None:
  os.sendfile(sock.fileno(), ......)
else:
  <use write() like I suggested above>

-- 
--Guido van Rossum (python.org/~guido)
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