connect-cli-latency.md
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In docs/operations/At c3d562fCopy the commit ID
In docs/operations/At c3d562fCopy the commit ID
The CLI routes Connect repository operations through ClientSource and
mkit-client. The native channel keeps one idle connection per origin for ten
seconds on its owned current-thread runtime. Reads and signed writes, including
streamed transfers, reuse that connection. TCP_NODELAY matches the previous
adapter. No runtime scheduler thread, dependency, or feature is added.
The cli_https_latency_comparison fixture drives separately built real CLI
binaries against the same Connect service and a TLS proxy with certificate-chain
and hostname verification enabled. It delays encrypted bytes by 25 ms in each
direction, including TLS handshake flights: 50 ms injected RTT, with local TCP
connection establishment. The server advertises HTTP/2 and HTTP/1.1. The old
adapter negotiates HTTP/2; the native channel negotiates HTTP/1.1.
Each comparison uses five samples per row, alternating binary order. Clone follows six independently published packmap nodes. The small push publishes a seventh commit; the following pull receives that commit. Every measured command starts a fresh CLI process. The fixture verifies exact normalized stdout, stderr, exit codes, refs, canonical object bytes, and pack/packmap ids and bytes. The server and repositories are recreated for each sample. This is a small repository latency comparison, not a throughput benchmark or a remote service measurement. Shared-host timing noise is shown in the ranges.
The old-path source is merged #1438 (e1dff395); its CLI, adapter, native channel
and lockfile match the separately built approved parent tree. The switch before
reuse is 7df65e1b. The second comparison changes only native connection reuse
and TCP_NODELAY in production. This task launched no concurrent builds during
either measurement; unrelated work on the shared host was uncontrolled.
Before the fix, median milliseconds (min–max), and new TLS connections:
| Operation | Old adapter | Switch before reuse | Old / switch connections |
|---|---|---|---|
| Clone, six-node chain | 2493 (2388–2614) | 2250 (2161–2318) | 13 / 14 |
| Pull, no-op | 294 (280–312) | 313 (312–318) | 1 / 2 |
| Pull, one commit | 687 (651–802) | 729 (716–837) | 3 / 4 |
| Push, small commit | 1863 (1834–1908) | 1835 (1816–1937) | 9 / 13 |
After the fix, rerunning both binaries with the same fixture:
| Operation | Old adapter | Switch with reuse | Improvement | Old / switch connections |
|---|---|---|---|---|
| Clone, six-node chain | 2452 (2435–2635) | 1186 (1028–1361) | 51.6% | 13 / 1 |
| Pull, no-op | 301 (282–311) | 240 (226–351) | 20.3% | 1 / 1 |
| Pull, one commit | 759 (677–800) | 442 (392–648) | 41.8% | 3 / 1 |
| Push, small commit | 1873 (1761–1940) | 897 (822–1236) | 52.1% | 9 / 1 |
Every median is lower than the old path. The old adapter pooled unary calls but opened fresh connections for streamed transfers, accounting for its clone, one-commit pull, and push counts. The restored pool includes transfers; it does not introduce a separate read or write protocol implementation.
Hyper's automatic cancellation retry recovers only an untouched request from a reused connection before writing starts. It does not clone or reconstruct the request. Buffered bodies and streaming receivers, signed headers, nonces and idempotency keys remain unchanged. Once the request starts writing, hyper returns failures to the existing host recovery policy. Signed writes therefore reuse connections under the same pre-start guarantee as reads; fresh write connections are unnecessary.
The implementation was audited against hyper-util 0.1.20's
send_request
and hyper 1.11.1's
HTTP/1 dispatcher.
The pool builder
documents that retry boundary. Pool checkout rejects elapsed idle connections
even when runtime tasks paused between calls; a Tokio pool timer also removes
idle entries when the runtime is driven. Response bodies are consumed before
reuse; partial or canceled exchanges do not contribute a reusable connection.
Native tests pin same-connection sequential reads and signed writes, expiration while the runtime is paused, server closure between calls, exact streamed bytes after an idle close, refusal to replay a fully received signed mutation that loses its reply, and clean exchange after a truncated response. Existing streaming, deadline, typed failure, Send/Sync, and host recovery tests remain.
Build the old and new CLI binaries in separate worktrees using
CARGO_BUILD_JOBS=3 just cargo-cached build -p mkit-cli --bin mkit; retain each
binary separately. Set MKIT_HTTPS_BENCH_OLD_BIN and
MKIT_HTTPS_BENCH_NEW_BIN to those binaries, optionally set
MKIT_HTTPS_BENCH_SAMPLES (default five), then run from the new checkout:
CARGO_BUILD_JOBS=3 just cargo-cached test -p mkit-cli \
--test remote_dispatch_connect cli_https_latency_comparison \
-- --exact --nocaptureThe latency fixture is opt-in because noisy wall-clock comparisons are unsuitable as shared-runner assertions. Normal CI retains the verified-TLS byte-parity matrix and deterministic native connection/replay regressions.