Re: [quicwg/base-drafts] Placeholder -1 (#2690)

Mike Bishop <notifications@github.com> Fri, 10 May 2019 18:46 UTC

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Subject: Re: [quicwg/base-drafts] Placeholder -1 (#2690)
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MikeBishop commented on this pull request.



> +cannot be reprioritized.  The structure of the dependency tree changes as
+PRIORITY frames modify the dependency links between other prioritized elements.
+
+All dependent streams are allocated an integer weight between 0 and 255
+(inclusive).
+
+Streams with the same parent SHOULD be allocated resources proportionally based
+on their weight.  Thus, if stream B depends on stream A with weight 4, stream C
+depends on stream A with weight 12, and no progress can be made on stream A,
+stream B ideally receives one-third of the resources allocated to stream C.
+
+A weight of zero indicates that no resources should be allocated to the
+indicated stream if progress can be made on other streams dependent on the same
+parent.
+
+A reference to an element which is no longer in the tree is treated as a

>From [Section 5.3.2](https://quicwg.org/base-drafts/draft-ietf-quic-http.html#priority-tree-maintenance):
> For prioritization purposes, a node in the tree is considered “inactive” when the corresponding stream has been closed for at least two round-trip times (using any reasonable estimate available on the server).

and

> Clients SHOULD assume the server is actively performing such pruning and SHOULD NOT declare a dependency on a stream it knows to have been closed.

So, yes, it is awful.  Is it more awful than saying it's the most important thing in the system because it parents directly to the root?  That's seriously context-dependent.  I'm inclined to minimize harm from a lost/delayed PRIORITY frame over minimizing harm from a misbehaving client.

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