871549 - Use Content-Length in XHR ArrayBuffer request, maybe introduce X-Decoded-Length

Status: RESOLVED FIXED

(Core :: DOM: Core & HTML, defect)

Description

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

With bug 866431, the memory usage of ArrayBuffer XHR requests was reduced by reading directly into a growing ArrayBuffer.  We can do even better by trusting Content-Length in the header and using that as the initial allocation size, avoiding realloc fragmentation.

Using just Content-Length would be a big win, because it's unlikely that ArrayBuffer-XHR content will be served with gzip encoding.  But it might be, and there's no good way to handle that; I'd suggest introducing a new X-Decoded-Length header that we'll honor if present for that case.

Comment 1

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Attachment: use Content-Length, and fix ResetResponse

Simple patch.  Use Content-Length on ArrayBuffer loads if it's specified, up to a max of 1GB.

Also adds a missing reset() to ResetResponse(), which is a bug currently (if the arraybuffer XHR is aborted without the response being read, a subsequent load would keep appending right now).

Comment 2

[Boris Zbarsky [:bzbarsky]]

Comment on attachment 749648 [details] [diff] [review]
use Content-Length, and fix ResetResponse

r=me.

We'll need at least the reset() bits on Aurora, right?

Comment 3

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

https://hg.mozilla.org/integration/mozilla-inbound/rev/3b0d31eceef1

Comment 4

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Yeah, we'll need the reset bits on Aurora, but should just take the whole thing.

Comment 5

[Ryan VanderMeulen [:RyanVM]]

https://hg.mozilla.org/mozilla-central/rev/3b0d31eceef1

Comment 6

[Lukas Blakk [:lsblakk] use ?needinfo]

(In reply to Boris Zbarsky (:bz) from comment #2)
> Comment on attachment 749648 [details] [diff] [review]
> use Content-Length, and fix ResetResponse
> 
> r=me.
> 
> We'll need at least the reset() bits on Aurora, right?

Bug 866431 only landed on 24, so what & why do we need something for Aurora here?

Comment 7

[Boris Zbarsky [:bzbarsky]]

Ah, I thought it had landed on 23.  Vlad, do we need anything on Aurora here, or are we all good there?

Comment 8

[Vladimir Vukicevic [:vlad] [:vladv] (needinfo me, slow to respond)]

Huh, I thought it landed on 23 also.  In that case, nothing needed!