Speed up struct encode/decode with typed field paths by kelindar · Pull Request #25 · kelindar/binary

kelindar · 2026-07-20T20:50:01Z

Summary

Fast-path addressable struct encode/decode for primitive fields using packed offset/kind metadata
Keep non-primitive fields on the existing Codec path
Clean up encoder tests (table-driven TestEncoder) and fold struct-slice cases into TestStruct
Add binary/trace-enc / binary/trace-dec benches for nested struct slices

Benchmarks

Compared struct-codec against v1.1.0 (vs v1.1.0 = delta vs tagged release):

name                 time/op      ops/s        allocs/op    vs v1.1.0
-------------------- ------------ ------------ ------------ ------------------
binary/enc           114.8 ns     8.7M         🟰 2          ✅ +7%
binary/enc-to        85.7 ns      11.7M        🟰 0          🟰 similar
binary/dec           83.4 ns      12.0M        🟰 1          ✅ +10%
binary/map-enc       8.0 µs       124.6K       🟰 209        🟰 similar
binary/map-dec       12.3 µs      81.2K        🟰 500        🟰 similar
binary/slice-enc     7.6 µs       131.9K       🟰 9          ✅ +8%
binary/slice-dec     6.2 µs       162.5K       🟰 100        ✅ +8%
binary/nest-enc      3.9 µs       253.3K       🟰 13         ✅ +8%
binary/nest-dec      3.5 µs       289.3K       🟰 63         ✅ +8%
binary/bytes-enc     848.8 ns     1.2M         🟰 3          🟰 similar
binary/bytes-dec     166.3 ns     6.0M         🟰 0          🟰 similar
binary/u64-enc       36.6 µs      27.3K        🟰 3          🟰 similar
binary/u64-dec       53.7 µs      18.6K        🟰 0          🟰 similar
binary/reuse-enc     89.4 ns      11.2M        🟰 0          🟰 similar
binary/stream-dec    130.6 ns     7.7M         🟰 1          ✅ +5%
binary/trace-enc     11.8 µs      85.0K        9            new
binary/trace-dec     12.2 µs      82.3K        640          new
nocopy/str-enc       100.8 ns     9.9M         🟰 3          🟰 similar
nocopy/str-dec       31.4 ns      31.9M        🟰 0          🟰 similar
nocopy/dict-enc      172.1 ns     5.8M         🟰 2          🟰 similar
nocopy/dict-dec      142.6 ns     7.0M         🟰 2          🟰 similar
nocopy/bmap-enc      307.1 ns     3.3M         🟰 5          🟰 similar
nocopy/bmap-dec      149.5 ns     6.7M         🟰 2          🟰 similar
nocopy/hmap-enc      300.3 ns     3.3M         🟰 5          🟰 similar
nocopy/hmap-dec      134.6 ns     7.4M         🟰 2          🟰 similar
nocopy/bytes-enc     848.7 ns     1.2M         🟰 3          🟰 similar
nocopy/bytes-dec     32.9 ns      30.4M        🟰 0          🟰 similar
nocopy/u64-enc       5.3 µs       189.4K       🟰 3          🟰 similar
nocopy/u64-dec       29.8 ns      33.5M        🟰 0          🟰 similar
nocopy/col-enc       466.5 ns     2.1M         🟰 8          🟰 similar
nocopy/col-dec       329.9 ns     3.0M         🟰 6          🟰 similar
nocopy/struct-enc    149.8 ns     6.7M         🟰 3          🟰 similar
nocopy/struct-dec    66.7 ns      15.0M        🟰 0          🟰 similar
sorted/i32-enc       76.7 µs      13.0K        🟰 5          🟰 similar
sorted/i32-dec       53.8 µs      18.6K        🟰 0          🟰 similar
sorted/u32-enc       73.1 µs      13.7K        🟰 5          🟰 similar
sorted/u32-dec       47.7 µs      20.9K        🟰 0          🟰 similar
sorted/ts-enc        47.7 µs      21.0K        🟰 6          🟰 similar
sorted/ts-dec        21.3 µs      46.9K        🟰 2          🟰 similar
sorted/tsz-enc       122.2 µs     8.2K         🟰 7          🟰 similar
sorted/tsz-dec       114.0 µs     8.8K         🟰 3          🟰 similar
sorted/tcz-enc       79.8 µs      12.5K        🟰 6          ✅ +8%
sorted/tcz-dec       73.3 µs      13.6K        🟰 3          🟰 similar
unsafe/u64-enc       479.0 ns     2.1M         🟰 3          🟰 similar
unsafe/u64-dec       452.3 ns     2.2M         🟰 2          🟰 similar

Test plan

go test ./... passes
go vet ./... is clean
cd bench && go run . -bench binary/trace runs cleanly

Pack field offset/kind into fieldCodec and write/read primitive struct fields via unsafe pointers when addressable, avoiding per-field reflect. Also tidy encoder tests and add a trace-payload bench. Co-authored-by: Cursor <cursoragent@cursor.com>

github-actions · 2026-07-20T20:50:30Z

`████████████████░░░░` 81.0% on changed lines

197 lines changed 36 uncovered 2 files

📂 2 files changed

	File	Coverage	Uncovered Lines
🟡	`codecs.go`	80.0%	342, 360, 361, 370, 371, 372, 373, 380, 381, 390 (+26 more)

| 🟢 | scanner.go | 100.0% | — |

📋 Full diff-cover report

Diff Coverage

Diff: origin/master...HEAD, staged and unstaged changes

codecs.go (80.0%): Missing lines 342,360-361,370-373,380-381,390,406,421-422,428-429,459-465,494-507
scanner.go (100%)

Summary

Total: 197 lines
Missing: 36 lines
Coverage: 81%

codecs.go

  338 		base := unsafe.Pointer(rv.UnsafeAddr())
  339 		for i := range c {
  340 			field := &c[i]
  341 			if field.Field&fieldIncluded == 0 {
! 342 				continue
  343 			}
  344 			pointer := unsafe.Add(base, field.offset())
  345 			switch field.kind() {
  346 			case reflect.String:

  356 			case reflect.Int32:
  357 				e.WriteVarint(int64(*(*int32)(pointer)))
  358 			case reflect.Int64:
  359 				e.WriteVarint(*(*int64)(pointer))
! 360 			case reflect.Uint:
! 361 				e.WriteUvarint(uint64(*(*uint)(pointer)))
  362 			case reflect.Uint8:
  363 				e.WriteUvarint(uint64(*(*uint8)(pointer)))
  364 			case reflect.Uint16:
  365 				e.WriteUvarint(uint64(*(*uint16)(pointer)))

  366 			case reflect.Uint32:
  367 				e.WriteUvarint(uint64(*(*uint32)(pointer)))
  368 			case reflect.Uint64:
  369 				e.WriteUvarint(*(*uint64)(pointer))
! 370 			case reflect.Complex64:
! 371 				e.writeComplex64(*(*complex64)(pointer))
! 372 			case reflect.Complex128:
! 373 				e.writeComplex128(*(*complex128)(pointer))
  374 			case reflect.Float32:
  375 				e.WriteFloat32(*(*float32)(pointer))
  376 			case reflect.Float64:
  377 				e.WriteFloat64(*(*float64)(pointer))

  376 			case reflect.Float64:
  377 				e.WriteFloat64(*(*float64)(pointer))
  378 			default:
  379 				if err = field.Codec.EncodeTo(e, rv.Field(i)); err != nil {
! 380 					return
! 381 				}
  382 			}
  383 		}
  384 		return
  385 	}

  386 
  387 	for i := range c {
  388 		field := &c[i]
  389 		if field.Field&fieldIncluded == 0 {
! 390 			continue
  391 		}
  392 		if err = field.Codec.EncodeTo(e, rv.Field(i)); err != nil {
  393 			return
  394 		}

  402 		base := unsafe.Pointer(rv.UnsafeAddr())
  403 		for i := range c {
  404 			field := &c[i]
  405 			if field.Field&fieldWritable == 0 {
! 406 				continue
  407 			}
  408 			pointer := unsafe.Add(base, field.offset())
  409 			switch field.kind() {
  410 			case reflect.String:

  417 			case reflect.Bool:
  418 				var value bool
  419 				value, err = d.ReadBool()
  420 				if err != nil {
! 421 					return
! 422 				}
  423 				*(*bool)(pointer) = value
  424 			case reflect.Int:
  425 				var value int64
  426 				value, err = d.ReadVarint()

  424 			case reflect.Int:
  425 				var value int64
  426 				value, err = d.ReadVarint()
  427 				if err != nil {
! 428 					return
! 429 				}
  430 				*(*int)(pointer) = int(value)
  431 			case reflect.Int8:
  432 				var value int64
  433 				value, err = d.ReadVarint()

  455 				if err != nil {
  456 					return
  457 				}
  458 				*(*int64)(pointer) = value
! 459 			case reflect.Uint:
! 460 				var value uint64
! 461 				value, err = d.ReadUvarint()
! 462 				if err != nil {
! 463 					return
! 464 				}
! 465 				*(*uint)(pointer) = uint(value)
  466 			case reflect.Uint8:
  467 				var value uint64
  468 				value, err = d.ReadUvarint()
  469 				if err != nil {

  490 				if err != nil {
  491 					return
  492 				}
  493 				*(*uint64)(pointer) = value
! 494 			case reflect.Complex64:
! 495 				var value complex64
! 496 				value, err = d.readComplex64()
! 497 				if err != nil {
! 498 					return
! 499 				}
! 500 				*(*complex64)(pointer) = value
! 501 			case reflect.Complex128:
! 502 				var value complex128
! 503 				value, err = d.readComplex128()
! 504 				if err != nil {
! 505 					return
! 506 				}
! 507 				*(*complex128)(pointer) = value
  508 			case reflect.Float32:
  509 				var value float32
  510 				value, err = d.ReadFloat32()
  511 				if err != nil {

_{🛡️ diff-cover-action}

coveralls · 2026-07-20T20:51:37Z

Coverage Report for CI Build 29778670976

Coverage decreased (-1.3%) to 90.282%

Details

Coverage decreased (-1.3%) from the base build.
Patch coverage: 36 uncovered changes across 1 file (161 of 197 lines covered, 81.73%).
2 coverage regressions across 1 file.

Uncovered Changes

File	Changed	Covered	%
codecs.go	180	144	80.0%
Total (2 files)	197	161	81.73%

Coverage Regressions

2 previously-covered lines in 1 file lost coverage.

File	Lines Losing Coverage	Coverage
codecs.go	2	88.32%

Coverage Stats


Relevant Lines:	1770
Covered Lines:	1598
Line Coverage:	90.28%
Coverage Strength:	593.93 hits per line

💛 - Coveralls

fixes

4351a25

kelindar merged commit e40235c into master Jul 20, 2026
1 check passed

kelindar deleted the struct-codec branch July 20, 2026 21:08

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Speed up struct encode/decode with typed field paths#25

Speed up struct encode/decode with typed field paths#25
kelindar merged 2 commits into
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struct-codec

kelindar commented Jul 20, 2026 •

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codecs.go

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codecs.go

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Coverage Report for CI Build 29778670976

Coverage decreased (-1.3%) to 90.282%

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kelindar commented Jul 20, 2026 •

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