range requests and multipart responses
jftucker at gmail.com
Tue Jul 20 05:21:15 EDT 2010
On 20 Jul 2010, at 07:18, Eric Wong wrote:
> Hi all,
> Does anybody have real-world use cases of clients using Range: requests
> with multiple comma-delimited byte ranges (and thus expecting multipart
> responses)? If not, I'm not going to bloat Rainbows! with it for now.
> While being able to specify a single range is very useful for resuming
> failed downloads and for things who want to "peek" at magic patterns
> before requesting the rest of a file, I can't think of good use cases
> for having to deal with multipart responses.
> Even if you were writing a FUSE-based filesystem over HTTP, it wouldn't
> even be useful for implementing preadv(2) since you can only specify a
> single offset there.
> Maybe if you mmap() a FUSE-ed file and two threads access the same file
> in different parts at the *exact*same*time* the FUSE layer could be
> smart enough to make a single HTTP request instead of two? :)
>  - For the performance-minded, it's also tough to implement multipart
> responses efficiently using any sendfile() implementation.
> Our TCP_CORK support is far from optimal under Linux right now,
> and not using TCP_CORK would be even less efficient with extra
> multipart headers. AFAIK, sendfilev() isn't available outside of
> Solaris, either.
Does cork even help in real world use cases?
> Eric Wong
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