From: Konrad Meyer <konrad@...>
Date: 2007-12-03T07:29:09+09:00
Subject: Re: Trying to download first 10k

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Quoth David Beckwith:
> Hi, I'm trying to download via http only the first, say, 10k of a file.
> I'm using open-uri but even when I try to break out of the core loop
> where it's reading the buffer, I can hear my hard-drive grinding away
> downloading the entire 3MB.  When I look at the file written to the disk
> it shows only 10k, but judging by the length of time it takes to execute
> the script and the grinding sound of my hard-drive, I think it's
> downloading the entire file.
>=20
> I read the other posts about a progress bar, but that's not really what
> I'm trying to do..... or is it?
>=20
> Is there a way to interrupt the download?  As you can see I tried to
> break out of the code blocks every chance I got.
>=20
> Here is my code:
>=20
> def download_first_n_kilobytes n, file_name
>   n =3D 1024 * n
>   uri =3D file_name
>   count =3D 0
>   open(uri) do |fin|
>      open(convert_to_file_name(uri), 'w') do |fout|
>        while(buf =3D fin.read(n))
>          count +=3D 1
>          fout.write buf
>          if count > 0
>            break
>          end # if
>        end # while
>        break
>      end # open
>      break
>   end # open
> end # def
>=20
> def convert_to_file_name uri
>   "mp3/" + File.basename(uri).to_s
> end
>=20
> uri =3D "http://www.sapht.com/music/tmp/sapht_-_alvaros_messenger.mp3"
> download_first_n_kilobytes 10, uri
>=20
>=20
> Thanks a lot for looking at this!

You'll probably not want to be using open-uri but instead a custom HTTP que=
ry=20
with a "Range: bytes=3D0-10239" header.

HTH,
=2D-=20
Konrad Meyer <konrad@tylerc.org> http://konrad.sobertillnoon.com/

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