http: add upstream-request watermark callbacks to HCM#46020
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botengyao merged 3 commits intoJul 7, 2026
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Introduce UpstreamWatermarkCallbacks (envoy/http/codec.h) and the
add/removeUpstreamWatermarkCallbacks subscription API on
StreamDecoderFilterCallbacks (envoy/http/filter.h), implemented by the
FilterManager and fanned out from the connection manager's
onDecoderFilter{Above,Below}WriteBuffer{High,Low}Watermark hooks.
The downstream codec read-disable only slows the original request source.
A filter that produces request data of its own (e.g. by replaying a
buffered body via injectDecodedDataToFilterChain) does not see that
back-pressure, so it needs to subscribe here to pause/resume in step with
the upstream. A mid-stream subscriber is brought up to the current
back-pressure state on registration.
Adds stub overrides in the async client and tcp_proxy StreamDecoder
FilterCallbacks implementations, a mock, and connection-manager coverage.
Signed-off-by: Peng Gao <pengg@google.com>
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/assign @wbpcode @botengyao |
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/cc @yanjunxiang-google / @markdroth you'll likely need this for ext_proc flow control |
Merge main changes. Signed-off-by: Peng Gao <pengg@google.com>
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fixing pre-existing format in #46022 |
Merge format fix. Signed-off-by: Peng Gao <pengg@google.com>
botengyao
approved these changes
Jul 7, 2026
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/retest |
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Nice! |
Member
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/retest |
Contributor
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LGTM! Thanks for working on this! |
This was referenced Jul 25, 2026
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Commit Message:
Introduce UpstreamWatermarkCallbacks (envoy/http/codec.h) and the (add|remove)UpstreamWatermarkCallbacks subscription API on StreamDecoderFilterCallbacks (envoy/http/filter.h), implemented by the FilterManager and fanned out from the connection manager's onDecoderFilter{Above,Below}WriteBuffer{High,Low}Watermark hooks.
Useful when a filter uses injectDecodedDataToFilterChain and wants to avoid overrunning the upstream buffer. This is a spawn-off of #45899 as per review.
Also adds stub overrides in the async client and tcp_proxy StreamDecoder FilterCallbacks implementations, a mock, and connection-manager coverage.
This change is a spawn-off of #45899, which I used AI to generate. I have read and understand the code.
Additional Description:
Risk Level: Medium - new callbacks to HCM, but not yet used
Testing: unit tests
Docs Changes: n/a
Release Notes: n/a
Platform Specific Features: n/a
[Optional Runtime guard:]
[Optional Fixes #Issue]
[Optional Fixes commit #PR or SHA]
[Optional Deprecated:]
[Optional API Considerations:]