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Match parameterless shelf_router routes without running a regex - #544
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`RouterEntry.match` executed the compiled route pattern on every request.
For a route with no `<param>` segments that pattern is `^` plus an escaped
literal plus `$`, which matches exactly one string — the route itself — so
the regex execution was redundant.
Found in a CPU profile of `dart-lang/shelf@bottom_shelf` under load:
`_RegExp._ExecuteMatch` accounted for `0.7%` of self-time on `/plaintext`,
a fully static route, with `RouterEntry.invoke` visible alongside it. Both
shelf-based targets in that benchmark pay it; the raw `dart:io` comparison
target dispatches with `if (path == ...)` and does not.
Measured on the same machine, 5M iterations after warmup:
RegExp.firstMatch 76.9 ns/op
string == 1.2 ns/op
~66x, or roughly 0.4% of a `/plaintext` request at the profiled 48,475 RPS.
Modest, but it is pure overhead on the most common route shape.
The added test asserts equivalence rather than the optimisation: a literal
route containing `.`, `+` and `(...)` must still match only itself, with no
metacharacter behaving as a pattern. It passes both with and without the
fast path, which is the point — it pins the semantics so the shortcut
cannot silently diverge.
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Code Review
This pull request optimizes route matching in shelf_router by using direct string comparison instead of regular expression execution for parameterless routes. It also adds corresponding test cases to ensure regex metacharacters in static routes are matched literally. The reviewer suggested a further optimization to avoid compiling the regular expression altogether in the factory constructor for parameterless routes, which would save startup time and memory.
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Sep 29, 2026
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Revisions updated by `dart tools/rev_sdk_deps.dart`. core (https://github.com/dart-lang/core/compare/08e4022..4d80610): 4d80610a Thu Oct 1 22:03:38 2026 +0000 dependabot[bot] Bump the github-actions group with 5 updates (dart-lang/core#1005) dartdoc (https://github.com/dart-lang/dartdoc/compare/2a040a8..5eb0f2c): 5eb0f2c7 Thu Oct 1 19:03:48 2026 +0000 dependabot[bot] Bump github/codeql-action/upload-sarif from 4.37.9 to 4.38.2 in the github-actions group (dart-lang/dartdoc#4291) http (https://github.com/dart-lang/http/compare/d8e8e9c..585d433): 585d433 Mon Oct 5 16:12:54 2026 -0700 Brian Quinlan fix(cupertino_http): fix a websocket memory leak (dart-lang/http#1991) 337adf3 Mon Oct 5 16:03:25 2026 -0700 Brian Quinlan fix(cupertino_http): add `autoReleasePool` use to `CupertinoClient` (dart-lang/http#1990) 47c57df Tue Sep 29 14:07:01 2026 -0700 Brian Quinlan fix(ok_http): fix `NetworkOnMainThreadException` (dart-lang/http#1995) d8cde5d Tue Sep 29 14:06:44 2026 -0700 Brian Quinlan fix test (dart-lang/http#1996) 31056fe Tue Sep 29 13:57:20 2026 -0700 Brian Quinlan chore(cronet_http): prepare to release 1.10.0 (dart-lang/http#1993) 9bc3a91 Tue Sep 29 13:53:25 2026 -0700 Brian Quinlan fix(cronet_http): one global reference per `onReadCompleted` (dart-lang/http#1992) 49ecd36 Mon Sep 28 14:20:26 2026 -0700 Brian Quinlan fix(conformance): `supportsAbort` not considered in response (dart-lang/http#1994) native (https://github.com/dart-lang/native/compare/27f7678..a2a6179): a2a617910 Tue Oct 6 13:53:17 2026 +0200 Daco Harkes [jni_flutter] Bump version for publishing (dart-lang/native#3730) d3a99d66b Tue Oct 6 19:46:34 2026 +1100 Liam Appelbe [infra] Fix ffigen and jni_flutter (dart-lang/native#3724) b66d0815a Tue Oct 6 04:28:35 2026 +0300 Manar Elhabbal [ffigen] add Support passing C++ classes by value (dart-lang/native#3677) f7ffe9667 Fri Oct 2 11:33:49 2026 +0200 Moritz [native_toolchain_c] Don't pass /INCLUDE per symbol with a generated .def on Windows (dart-lang/native#3718) 77a5e4169 Thu Oct 1 10:56:45 2026 +0300 Hassnaa Mohamed [ffigen] Fix cpp method filtering (dart-lang/native#3696) cca065ca6 Thu Oct 1 10:17:12 2026 +1000 Liam Appelbe [infra] Prepare to publish everything (dart-lang/native#3716) f13623ee3 Thu Oct 1 10:16:39 2026 +1000 Liam Appelbe [jnigen] API docs (dart-lang/native#3715) be618790c Thu Oct 1 10:05:26 2026 +1000 Liam Appelbe [objective_c] API docs (dart-lang/native#3708) a18dd1148 Thu Oct 1 10:04:38 2026 +1000 Liam Appelbe [ffigen] API docs (dart-lang/native#3707) 6fd87c3b2 Tue Sep 29 19:01:11 2026 -0700 Brian Quinlan [jni] Clarify `JBuffer.asUint8List` behavior (dart-lang/native#3704) 6d5bbcfad Wed Sep 30 09:35:47 2026 +1000 Liam Appelbe [jni] API documentation (dart-lang/native#3706) fbcbc894b Wed Sep 30 09:35:34 2026 +1000 Liam Appelbe [ffigen] Document autorelease issues (dart-lang/native#3705) f99449ec9 Tue Sep 29 09:39:27 2026 +1000 Liam Appelbe [infra] Add swift2objc to the workspace (dart-lang/native#3700) 31494fa08 Tue Sep 29 09:38:59 2026 +1000 Liam Appelbe [infra] Add jni_util to the workspace (dart-lang/native#3698) shelf (https://github.com/dart-lang/shelf/compare/e5c8dc6..b2cb503): b2cb503 Wed Sep 30 22:53:07 2026 -0700 Kevin Moore Resolve shelf.io.connection_info lazily (dart-lang/shelf#542) b70fafa Tue Sep 29 13:37:08 2026 -0700 Kevin Moore Match parameterless shelf_router routes without running a regex (dart-lang/shelf#544) test (https://github.com/dart-lang/test/compare/4f92d53..d749b10): d749b104 Mon Oct 5 15:42:46 2026 -0700 Nate Bosch Fail isolate suites when the test isolate exits (dart-lang/test#2775) da2157e9 Mon Oct 5 11:12:43 2026 -0700 Nate Bosch Wait longer for the Chrome test tab to appear (dart-lang/test#2771) 00bd0c99 Mon Oct 5 18:50:03 2026 +0300 Yusuf İhsan Görgel Fix broken links in architecture.md (dart-lang/test#2774) 3be2f547 Thu Oct 1 03:46:29 2026 +0000 dependabot[bot] Bump the github-actions group with 4 updates (dart-lang/test#2773) 40a5ad90 Tue Sep 29 12:07:31 2026 -0700 Nate Bosch Delete compilation artifacts once they are no longer needed (dart-lang/test#2764) 171ad0e5 Mon Sep 28 17:29:48 2026 -0700 Jacob MacDonald export additional types from package:test_api/backend.dart (dart-lang/test#2745) 52b45064 Mon Sep 28 15:04:08 2026 -0700 Nate Bosch Tag browser and node tests, relax flaky timeouts (dart-lang/test#2770) tools (https://github.com/dart-lang/tools/compare/d87eaf7..a66d517): a66d517d Tue Oct 6 09:41:32 2026 -0700 Phil Quitslund [analytics] `DASH__SUPPRESS_ANALYTICS` env handling (dart-lang/tools#2641) 00c6e4ad Fri Oct 2 17:17:49 2026 +0530 shivytyahoo Fix VersionConstraint.intersection throwing on disjoint ranges (dart-lang/tools#2622) d523e1f8 Thu Oct 1 11:09:16 2026 +0200 Morgan :) [unified_analytics] Append to the log file instead of rewriting it (dart-lang/tools#2613) 6993cbad Wed Sep 30 14:09:32 2026 +0300 Yusuf İhsan Görgel [yaml] Improve error messages when mixing list and key-value syntax (dart-lang/tools#2610) 068119b4 Tue Sep 29 23:21:03 2026 +0200 Lukas Klingsbo [pubspec_parse] Support tag_pattern for git dependencies (dart-lang/tools#2565) 7d859ed5 Mon Sep 28 20:28:23 2026 -0700 Kevin Moore [api_summary] Add expectApiSummaryClean and --write/--check CLI flags (dart-lang/tools#2603) web (https://github.com/dart-lang/web/compare/ec71a4c..63e6662): 63e6662 Sat Oct 3 00:23:21 2026 +0000 Natalie Weizenbaum Add a JSPair type (dart-lang/web#586) 2d68d90 Fri Oct 2 20:26:48 2026 +0000 Natalie Weizenbaum Use `js_interop` APIs in `js_interop_gen` (dart-lang/web#585) 037823c Thu Oct 1 21:59:21 2026 +0000 Natalie Weizenbaum Add JSMap, JSSet, and JSSetLike types (dart-lang/web#571) b2d1d6b Thu Oct 1 06:57:03 2026 +0000 dependabot[bot] Bump the github-actions group with 3 updates (dart-lang/web#584) 8dc8f75 Wed Sep 30 08:12:18 2026 -0700 Kevin Moore [js_interop_gen] Split union/intersection AST types and extract TypeTransformer (dart-lang/web#580) 751ccdf Wed Sep 30 08:12:18 2026 -0700 Kevin Moore [js_interop_gen] Decompose `Transformer._transformType` and deduplicate type caching (dart-lang/web#579) 6f3dd4e Wed Sep 30 08:12:17 2026 -0700 Kevin Moore [js_interop_gen] Deduplicate `UnionType` and `IntersectionType` via `UnionOrIntersectionType` (dart-lang/web#578) d9f095e Tue Sep 29 12:17:29 2026 -0700 Kevin Moore [js_interop_gen] Remove unused JS interop extension types and bindings (dart-lang/web#577) 07111ee Tue Sep 29 09:51:36 2026 -0700 Kevin Moore fix(js_interop_gen): update js_type_supertypes for Dart 3.12 (dart-lang/web#582) Change-Id: I4532049c45561fe8f8c57713ac8ec2153096fd9a Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/560660 Commit-Queue: Nate Bosch <[email protected]> Reviewed-by: Brian Quinlan <[email protected]>
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RouterEntry.matchexecutes the compiled route pattern on every request. For aroute with no
<param>segments, that pattern is^+ an escaped literal +$,which matches exactly one string — the route itself — so the regex execution is
redundant.
How it surfaced
A CPU profile of
dart-lang/shelf@bottom_shelfunderwrk -t4 -c64 -d10sshowed
_RegExp._ExecuteMatchat 0.7% of self-time on/plaintext— afully static route — with
RouterEntry.invokevisible alongside it. In thatthree-way benchmark both shelf-based targets pay this; the raw
dart:iocomparison target dispatches with
if (path == ...)and does not, so part ofthe gap on the simplest workload was router overhead rather than adapter
overhead.
Measurement
5M iterations after warmup, same machine:
RegExp.firstMatchon^/plaintext$path == '/plaintext'~66x. At the profiled 48,475 RPS (20.6 µs/request) that is roughly 0.4% of a
request — modest, but pure overhead on the most common route shape, and it
scales with route count since
Router.calltries each candidate in turn.On correctness
The literal is built with
RegExp.escape, so the compiled pattern accepts onlythe exact route string;
==accepts the same single string. The parameterisedpath is untouched.
The added test asserts equivalence, not the optimisation: a literal route
containing
.,+and(...)must still match only itself, with nometacharacter behaving as a pattern.
It passes with and without the fast path, which is deliberate — it pins the
semantics so the shortcut cannot silently diverge from the regex it replaces.
dart analyzeclean,dart formatclean, 36 tests pass inpkgs/shelf_router.