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Merged
merged 3 commits into from
Jun 5, 2025
+49 −23
Merged

s2: check for cap, not len of buffer in EncodeBetter/Best #1080

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19d624d
Consistently check for capacity of provided buffer
vdarulis Jun 3, 2025
41124a6
Make sure benchmarks reuse memory
vdarulis Jun 4, 2025
ea02415
Fix snapref, too
vdarulis Jun 4, 2025
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4 changes: 3 additions & 1 deletion internal/snapref/encode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -20,8 +20,10 @@ import (
func Encode(dst, src []byte) []byte {
if n := MaxEncodedLen(len(src)); n < 0 {
panic(ErrTooLarge)
} else if len(dst) < n {
} else if cap(dst) < n {
dst = make([]byte, n)
} else {
dst = dst[:n]
}

// The block starts with the varint-encoded length of the decompressed bytes.
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8 changes: 6 additions & 2 deletions s2/encode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -117,8 +117,10 @@ func EstimateBlockSize(src []byte) (d int) {
func EncodeBetter(dst, src []byte) []byte {
if n := MaxEncodedLen(len(src)); n < 0 {
panic(ErrTooLarge)
} else if len(dst) < n {
} else if cap(dst) < n {
dst = make([]byte, n)
} else {
dst = dst[:n]
}

// The block starts with the varint-encoded length of the decompressed bytes.
Expand Down Expand Up @@ -159,8 +161,10 @@ func EncodeBetter(dst, src []byte) []byte {
func EncodeBest(dst, src []byte) []byte {
if n := MaxEncodedLen(len(src)); n < 0 {
panic(ErrTooLarge)
} else if len(dst) < n {
} else if cap(dst) < n {
dst = make([]byte, n)
} else {
dst = dst[:n]
}

// The block starts with the varint-encoded length of the decompressed bytes.
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60 changes: 40 additions & 20 deletions s2/s2_test.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1388,11 +1388,13 @@ func testSnappyDecode(t *testing.T, src []byte) {
func benchDecode(b *testing.B, src []byte) {
b.Run("default", func(b *testing.B) {
encoded := Encode(nil, src)
buf := make([]byte, 0, len(src))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
var err error
for i := 0; i < b.N; i++ {
_, err := Decode(src[:0], encoded)
buf, err = Decode(buf[:0], encoded)
if err != nil {
b.Fatal(err)
}
Expand All @@ -1401,11 +1403,13 @@ func benchDecode(b *testing.B, src []byte) {
})
b.Run("better", func(b *testing.B) {
encoded := EncodeBetter(nil, src)
buf := make([]byte, 0, len(src))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
var err error
for i := 0; i < b.N; i++ {
_, err := Decode(src[:0], encoded)
buf, err = Decode(buf[:0], encoded)
if err != nil {
b.Fatal(err)
}
Expand All @@ -1414,11 +1418,13 @@ func benchDecode(b *testing.B, src []byte) {
})
b.Run("best", func(b *testing.B) {
encoded := EncodeBest(nil, src)
buf := make([]byte, 0, len(src))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
var err error
for i := 0; i < b.N; i++ {
_, err := Decode(src[:0], encoded)
buf, err = Decode(buf[:0], encoded)
if err != nil {
b.Fatal(err)
}
Expand All @@ -1427,11 +1433,13 @@ func benchDecode(b *testing.B, src []byte) {
})
b.Run("snappy-input", func(b *testing.B) {
encoded := snapref.Encode(nil, src)
buf := make([]byte, 0, len(src))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
var err error
for i := 0; i < b.N; i++ {
_, err := Decode(src[:0], encoded)
buf, err = Decode(buf[:0], encoded)
if err != nil {
b.Fatal(err)
}
Expand All @@ -1442,63 +1450,75 @@ func benchDecode(b *testing.B, src []byte) {

func benchEncode(b *testing.B, src []byte) {
// Bandwidth is in amount of uncompressed data.
dst := make([]byte, snapref.MaxEncodedLen(len(src)))
b.ResetTimer()
b.Run("default", func(b *testing.B) {
dst := make([]byte, MaxEncodedLen(len(src)))
b.ResetTimer()
b.SetBytes(int64(len(src)))
b.ReportAllocs()
for i := 0; i < b.N; i++ {
Encode(dst, src)
dst = Encode(dst[:0], src)
}
b.ReportMetric(100*float64(len(Encode(dst, src)))/float64(len(src)), "pct")
b.ReportMetric(100*float64(len(dst))/float64(len(src)), "pct")
})
b.Run("better", func(b *testing.B) {
dst := make([]byte, MaxEncodedLen(len(src)))
b.ResetTimer()
b.SetBytes(int64(len(src)))
b.ReportAllocs()
for i := 0; i < b.N; i++ {
EncodeBetter(dst, src)
dst = EncodeBetter(dst[:0], src)
}
b.ReportMetric(100*float64(len(EncodeBetter(dst, src)))/float64(len(src)), "pct")
b.ReportMetric(100*float64(len(dst))/float64(len(src)), "pct")
})
b.Run("best", func(b *testing.B) {
dst := make([]byte, MaxEncodedLen(len(src)))
b.ResetTimer()
b.SetBytes(int64(len(src)))
b.ReportAllocs()
for i := 0; i < b.N; i++ {
EncodeBest(dst, src)
dst = EncodeBest(dst[:0], src)
}
b.ReportMetric(100*float64(len(EncodeBest(dst, src)))/float64(len(src)), "pct")
b.ReportMetric(100*float64(len(dst))/float64(len(src)), "pct")
})
b.Run("snappy-default", func(b *testing.B) {
dst := make([]byte, MaxEncodedLen(len(src)))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
EncodeSnappy(dst, src)
dst = EncodeSnappy(dst[:0], src)
}
b.ReportMetric(100*float64(len(EncodeSnappy(dst, src)))/float64(len(src)), "pct")
b.ReportMetric(100*float64(len(dst))/float64(len(src)), "pct")
})
b.Run("snappy-better", func(b *testing.B) {
dst := make([]byte, MaxEncodedLen(len(src)))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
EncodeSnappyBetter(dst, src)
dst = EncodeSnappyBetter(dst[:0], src)
}
b.ReportMetric(100*float64(len(EncodeSnappyBetter(dst, src)))/float64(len(src)), "pct")
b.ReportMetric(100*float64(len(dst))/float64(len(src)), "pct")
})
b.Run("snappy-best", func(b *testing.B) {
dst := make([]byte, MaxEncodedLen(len(src)))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
EncodeSnappyBest(dst, src)
dst = EncodeSnappyBest(dst[:0], src)
}
b.ReportMetric(100*float64(len(EncodeSnappyBest(dst, src)))/float64(len(src)), "pct")
b.ReportMetric(100*float64(len(dst))/float64(len(src)), "pct")
})
b.Run("snappy-ref-noasm", func(b *testing.B) {
dst := make([]byte, snapref.MaxEncodedLen(len(src)))
b.SetBytes(int64(len(src)))
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
snapref.Encode(dst, src)
dst = snapref.Encode(dst[:0], src)
}
b.ReportMetric(100*float64(len(snapref.Encode(dst, src)))/float64(len(src)), "pct")
b.ReportMetric(100*float64(len(dst))/float64(len(src)), "pct")
})
}

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