WebTransport: cover the per-session datagram queue's watermark, priority, and byte-budget eviction - #3987
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WebTransport: cover the per-session datagram queue's watermark, priority, and byte-budget eviction#3987jesup wants to merge 1 commit into
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September 14, 2026 02:23
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🟡 Changes recommended
The tests reuse a datagram ID, omit HTTP/3 resume-event forwarding coverage, and retain a misleading test name.
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Pull request overview
Adds integration coverage for per-session WebTransport datagram queue behavior.
Changes:
- Tests watermark backpressure and resume signaling.
- Tests send-order priority and byte-budget eviction.
- Updates outdated connect-udp coverage and imports.
File summaries
| File | Description |
|---|---|
neqo-transport/src/connection/tests/datagram.rs |
Tests per-session resume signaling. |
neqo-http3/tests/webtransport.rs |
Updates SendGroupId import and formatting. |
neqo-http3/tests/connect_udp.rs |
Replaces obsolete connection-wide backpressure assertions. |
neqo-http3/src/features/extended_connect/tests/webtransport/mod.rs |
Adjusts test helper return type and imports. |
neqo-http3/src/features/extended_connect/tests/webtransport/datagrams.rs |
Adds watermark, priority, and eviction tests. |
Review details
Suppressed comments (1)
neqo-http3/src/features/extended_connect/tests/webtransport/datagrams.rs:206
next_idis not advanced for the datagram accepted on the first overflow, so the first “high-priority” datagram reuses both the tracking ID and payload of a still-queued low-priority datagram. Consequently,was_received(high_priority_ids[0])can be satisfied by the low-priority copy and does not prove that high-priority datagram traversed the live connection. Keep the IDs unique before leaving this loop.
low_priority_ids.push(next_id);
break;
- Files reviewed: 5/5 changed files
- Comments generated: 2
- Review effort level: Balanced
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Codecov Report✅ All modified and coverable lines are covered by tests. Additional details and impacted files@@ Coverage Diff @@
## users/jesup/expire_datagrams #3987 +/- ##
================================================================
+ Coverage 96.85% 96.89% +0.03%
================================================================
Files 119 119
Lines 41385 41385
Branches 41385 41385
================================================================
+ Hits 40083 40099 +16
+ Misses 1278 1260 -18
- Partials 24 26 +2
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Merging this PR will degrade performance by 3.57%
|
| Mode | Benchmark | BASE |
HEAD |
Efficiency | |
|---|---|---|---|---|---|
| ❌ | Simulation | coalesce_acked_from_zero 1 ranges |
2.6 µs | 2.7 µs | -4.05% |
| ❌ | Simulation | coalesce_acked_from_zero 3 ranges |
3.4 µs | 3.5 µs | -3.09% |
Tip
Investigate this regression by commenting @codspeedbot fix this regression on this PR, or directly use the CodSpeed MCP with your agent.
Comparing users/jesup/watermark_priority_eviction (bab27a4) with users/jesup/expire_datagrams (0b3378b)1
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…ity, and byte-budget eviction Adds send-order priority delivery and byte-budget eviction coverage through a live WebTransport connection, and the equivalent low-level resume-signal test directly on Connection (resume_signal_fires_once_a_blocked_queue_drains_below_watermark). Keeps a WebTransport test that the resume signal is forwarded all the way to Http3ServerEvent::OutgoingDatagramSpaceAvailable: the transport-level test only proves a ConnectionEvent is queued, and connect-udp cannot drive this at all, having no outgoingHighWaterMark equivalent. Its own copy of the old test is renamed to what it now checks.
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Benchmark resultsNo significant performance differences relative to 5df7db1. All resultstransfer/1-conn/1-100mb-resp (aka. Download)/mtu-1504: No change in performance detected. time: [132.44 ms 132.62 ms 132.82 ms]
thrpt: [752.90 MiB/s 754.04 MiB/s 755.08 MiB/s]
change:
time: [-0.2036% +0.0124% +0.2216%] (p = 0.91 > 0.05)
thrpt: [-0.2211% -0.0124% +0.2040%]
No change in performance detected.
Found 3 outliers among 100 measurements (3.00%)
1 (1.00%) high mild
2 (2.00%) high severetransfer/1-conn/10_000-parallel-1b-resp (aka. RPS)/mtu-1504: Change within noise threshold. time: [216.10 ms 216.34 ms 216.57 ms]
thrpt: [46.174 Kelem/s 46.224 Kelem/s 46.276 Kelem/s]
change:
time: [+0.6312% +0.8183% +1.0128%] (p = 0.00 < 0.05)
thrpt: [-1.0027% -0.8117% -0.6272%]
Change within noise threshold.
Found 4 outliers among 100 measurements (4.00%)
3 (3.00%) low mild
1 (1.00%) high mildtransfer/1-conn/1-1b-resp (aka. HPS)/mtu-1504: Change within noise threshold. time: [7.4105 ms 7.4146 ms 7.4188 ms]
thrpt: [134.79 B/s 134.87 B/s 134.94 B/s]
change:
time: [+0.1499% +0.2265% +0.3063%] (p = 0.00 < 0.05)
thrpt: [-0.3054% -0.2260% -0.1497%]
Change within noise threshold.transfer/1-conn/1-100mb-req (aka. Upload)/mtu-1504: No change in performance detected. time: [135.93 ms 136.37 ms 137.13 ms]
thrpt: [729.21 MiB/s 733.29 MiB/s 735.66 MiB/s]
change:
time: [-0.4522% -0.0592% +0.5934%] (p = 0.86 > 0.05)
thrpt: [-0.5899% +0.0592% +0.4542%]
No change in performance detected.
Found 8 outliers among 100 measurements (8.00%)
7 (7.00%) high mild
1 (1.00%) high severestreams/walltime/1-streams/each-1000-bytes: Change within noise threshold. time: [552.84 µs 554.67 µs 556.79 µs]
thrpt: [1.7128 MiB/s 1.7194 MiB/s 1.7251 MiB/s]
change:
time: [+0.2900% +0.8153% +1.3237%] (p = 0.00 < 0.05)
thrpt: [-1.3064% -0.8087% -0.2891%]
Change within noise threshold.
Found 11 outliers among 100 measurements (11.00%)
11 (11.00%) high severestreams/walltime/1000-streams/each-1-bytes: No change in performance detected. time: [10.538 ms 10.552 ms 10.566 ms]
thrpt: [92.421 KiB/s 92.545 KiB/s 92.667 KiB/s]
change:
time: [-0.0083% +0.1833% +0.3715%] (p = 0.06 > 0.05)
thrpt: [-0.3701% -0.1830% +0.0083%]
No change in performance detected.streams/walltime/1000-streams/each-1000-bytes: Change within noise threshold. time: [33.992 ms 34.026 ms 34.061 ms]
thrpt: [27.999 MiB/s 28.028 MiB/s 28.056 MiB/s]
change:
time: [+0.5737% +0.7203% +0.8698%] (p = 0.00 < 0.05)
thrpt: [-0.8623% -0.7151% -0.5704%]
Change within noise threshold.streams-flow-controlled/walltime/1-streams/each-4194304-bytes: No change in performance detected. time: [25.828 ms 25.861 ms 25.895 ms]
thrpt: [154.47 MiB/s 154.67 MiB/s 154.87 MiB/s]
change:
time: [-0.2133% +0.1742% +0.4661%] (p = 0.36 > 0.05)
thrpt: [-0.4639% -0.1739% +0.2138%]
No change in performance detected.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high mildstreams-flow-controlled/walltime/10-streams/each-1048576-bytes: Change within noise threshold. time: [71.758 ms 71.841 ms 71.926 ms]
thrpt: [139.03 MiB/s 139.20 MiB/s 139.36 MiB/s]
change:
time: [+0.7659% +0.9292% +1.0899%] (p = 0.00 < 0.05)
thrpt: [-1.0782% -0.9206% -0.7601%]
Change within noise threshold.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high mildtransfer/walltime/pacing-false/varying-seeds: No change in performance detected. time: [17.537 ms 17.556 ms 17.585 ms]
thrpt: [227.47 MiB/s 227.84 MiB/s 228.09 MiB/s]
change:
time: [-0.1261% +0.0070% +0.1793%] (p = 0.94 > 0.05)
thrpt: [-0.1790% -0.0070% +0.1263%]
No change in performance detected.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high severetransfer/walltime/pacing-true/varying-seeds: Change within noise threshold. time: [17.822 ms 17.834 ms 17.846 ms]
thrpt: [224.14 MiB/s 224.29 MiB/s 224.44 MiB/s]
change:
time: [+0.0277% +0.1252% +0.2231%] (p = 0.01 < 0.05)
thrpt: [-0.2226% -0.1251% -0.0277%]
Change within noise threshold.
Found 4 outliers among 100 measurements (4.00%)
4 (4.00%) high mildtransfer/walltime/pacing-false/same-seed: Change within noise threshold. time: [17.461 ms 17.485 ms 17.522 ms]
thrpt: [228.29 MiB/s 228.76 MiB/s 229.08 MiB/s]
change:
time: [-0.9201% -0.7422% -0.5038%] (p = 0.00 < 0.05)
thrpt: [+0.5064% +0.7477% +0.9286%]
Change within noise threshold.
Found 1 outliers among 100 measurements (1.00%)
1 (1.00%) high severetransfer/walltime/pacing-true/same-seed: Change within noise threshold. time: [17.885 ms 17.896 ms 17.907 ms]
thrpt: [223.38 MiB/s 223.52 MiB/s 223.65 MiB/s]
change:
time: [+0.3643% +0.4610% +0.5593%] (p = 0.00 < 0.05)
thrpt: [-0.5562% -0.4589% -0.3630%]
Change within noise threshold.
Found 5 outliers among 100 measurements (5.00%)
1 (1.00%) low mild
4 (4.00%) high mildInstructions per cycleCriterion reported no significant timing changes. All benchmarks
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Performance profiles for profiler.firefox.comBenchmarks (14)
|
Contributor
Failed Interop TestsQUIC Interop Runner, client vs. server, differences relative to
All resultsSucceeded Interop TestsQUIC Interop Runner, client vs. server neqo-pr as client
neqo-pr as server
Unsupported Interop TestsQUIC Interop Runner, client vs. server neqo-pr as client
neqo-pr as server
|
Contributor
Client/server transfer resultsPerformance differences relative to 5df7db1. Transfer of 33554432 bytes over loopback, min. 100 runs. All unit-less numbers are in milliseconds.
Table above only shows statistically significant changes. See all results below. All resultsTransfer of 33554432 bytes over loopback, min. 100 runs. All unit-less numbers are in milliseconds.
Download data for |
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As far as I can tell, this mostly adds tests. Can these tests be folded into the pull requests that add their corresponding features? |
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