Motivation:
As suggested in [section 5.3.4 in http2 spec](https://datatracker.ietf.org/doc/html/rfc7540#section-5.3.4):
> When a stream is removed from the dependency tree, its dependencies can be moved to become dependent on the parent of the closed stream. The weights of new dependencies are recalculated by distributing the weight of the dependency of the closed stream proportionally based on the weights of its dependencies.
For example, we have stream A and B depend on connection stream with default weights (16), and stream C depends on A with max weight (256). When stream A was closed, we move stream C to become dependent on the connection stream, then we should distribute the weight of stream A to its children (only stream C), so the new weight of stream C will be 16. If we keep the weight of stream C unchanged, it will get more resource than stream B
Modification:
- distribute weight to its children when closing a stream
- add a unit test for the case above and fix other related unit tests
Result:
More spec-compliant and more appropriate stream reprioritization
Co-authored-by: Heng Zhang <zhangheng@imo.im>
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