Benchmarks

Philosophy

gogenfilter is designed for linters and static analysis tools where detection overhead must be negligible. The two-phase architecture (filename first, content only when needed) ensures most checks complete with zero I/O.

Results

Benchmarked on Go 1.26, Apple M2. Results may vary by hardware.

Summary

	Benchmark	ns/op	B/op	allocs/op
Filter (enabled)	307	64	2
Filter (disabled)	5.0	0	0
Filename detection (Phase 1)	14	0	0
Per-generator check (avg)	~15	0	0
MatchPattern (doublestar **)	121	0	0
DetectReason (filename)	648	696	6
DetectReason (content)	1324	744	7
Error construction	3	0	0
errors.Is matching	10	0	0

Filter

The primary API. Full end-to-end detection including filesystem access.

Filter/enabled    307 ns/op    64 B/op    2 allocs/op
Filter/disabled   5.0 ns/op    0 B/op    0 allocs/op

A disabled filter is essentially a branch prediction — 5 nanoseconds. An enabled filter with a known-generated file completes in ~307ns with 2 small allocations.

Phase 1: Filename Detection

Phase 1: filename-based detection (zero I/O). This is the fast path — a single scan of the filename against the detector table. No file reads, no content parsing.

Filename phase    14 ns/op    0 B/op    0 allocs/op

This benchmarks the internal filename-only check. Results are exact-matched against known generated-file patterns (e.g., models.go, *.sql.go, _templ.go, .pb.go, wire_gen.go, _moq.go, _mock.go, mock_*.go).

Per-Generator Checks

Individual Is*Generated functions. Several check both filename patterns and content markers (IsSQLCGenerated, IsTemplGenerated, IsGoEnumGenerated, IsProtobufGenerated, IsMockgenGenerated, IsMockeryGenerated, IsCounterfeiterGenerated, IsGqlgenGenerated, IsEasyjsonGenerated). The rest check content only.

IsGenericGenerated    8.2 ns/op    0 B/op    0 allocs/op
IsSQLCGenerated       23.3 ns/op    0 B/op    0 allocs/op
IsProtobufGenerated   17.4 ns/op    0 B/op    0 allocs/op

All under 25 nanoseconds with zero allocations.

DetectReason

Variadic detection across multiple filter options:

DetectReason/filename_only    648 ns/op    696 B/op    6 allocs/op
DetectReason/content_based    1324 ns/op    744 B/op    7 allocs/op
DetectReason/not_filtered     1031 ns/op    680 B/op    5 allocs/op

Higher cost than the per-generator checks because it iterates all enabled detectors and performs content matching. Still sub-microsecond.

DetectReasonReader

Same as DetectReason but reads from an io.Reader:

DetectReasonReader/sqlc_filename    880 ns/op   1352 B/op    10 allocs/op
DetectReasonReader/not_filtered      1283 ns/op   1272 B/op    9 allocs/op

Includes the cost of reading content from the reader.

Pattern Matching

MatchPattern with different glob patterns via doublestar:

MatchPattern/question     58 ns/op    0 B/op    0 allocs/op
MatchPattern/exact        78 ns/op    0 B/op    0 allocs/op
MatchPattern/wildcard     113 ns/op    0 B/op    0 allocs/op
MatchPattern/doublestar   121 ns/op    0 B/op    0 allocs/op
MatchPattern/no_match     170 ns/op    0 B/op    0 allocs/op

All zero-allocation. ** globs are the most expensive at ~121ns — still negligible.

Error System

Error construction and inspection:

NewSQLCConfigError        2.8 ns/op     0 B/op    0 allocs/op
NewProjectRootError       4.1 ns/op     0 B/op    0 allocs/op
ProjectRootErrorIs        9.3 ns/op     0 B/op    0 allocs/op
SQLCConfigErrorIs         9.9 ns/op     0 B/op    0 allocs/op
ProjectRootErrorError     348 ns/op     144 B/op    3 allocs/op
SQLCConfigErrorError      413 ns/op     176 B/op    5 allocs/op

Error construction and errors.Is matching are essentially free. Error() string formatting allocates but is only called when displaying errors.

Reproducing

Run the benchmarks yourself:

go test -bench=. -benchmem ./...

For stable results, run on a quiet system with CPU frequency scaling disabled.

Live Dashboard

Historical benchmark trends are tracked automatically on every push to master:

View Live Benchmark Dashboard

The dashboard shows:

• Time-series charts for all 17 benchmarks
• Commit-level granularity with tooltips showing commit messages
• Automatic regression highlighting when performance degrades >150%

Results above are a point-in-time snapshot (Go 1.26, Apple M2). The dashboard provides continuous, hardware-consistent tracking from CI.