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Update uintsize implementation #2590

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Merged
merged 2 commits into from
Jan 7, 2024
Merged

Update uintsize implementation #2590

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bb085b3
update uintsize implementation
Jan 5, 2024
f579992
appease linter
Jan 5, 2024
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13 changes: 5 additions & 8 deletions x/merkledb/codec.go
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Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,7 @@ import (
"errors"
"io"
"math"
"math/bits"
"sync"

"golang.org/x/exp/maps"
Expand Down Expand Up @@ -101,14 +102,10 @@ func (c *codecImpl) childSize(index byte, childEntry *child) int {

// based on the current implementation of codecImpl.encodeUint which uses binary.PutUvarint
func (*codecImpl) uintSize(value uint64) int {
// binary.PutUvarint repeatedly divides by 128 until the value is under 128,
// so count the number of times that will occur
i := 0
for value >= 0x80 {
value >>= 7
i++
}
return i + 1
if value == 0 {
return 1
}
return (bits.Len64(value) + 6) / 7
}

func (c *codecImpl) keySize(p Key) int {
Expand Down
21 changes: 17 additions & 4 deletions x/merkledb/codec_test.go
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Expand Up @@ -247,9 +247,22 @@ func TestCodecDecodeKeyLengthOverflowRegression(t *testing.T) {

func TestUintSize(t *testing.T) {
c := codec.(*codecImpl)
for i := uint64(0); i < math.MaxInt16; i++ {
expectedSize := c.uintSize(i)
actualSize := binary.PutUvarint(make([]byte, binary.MaxVarintLen64), i)
require.Equal(t, expectedSize, actualSize, i)

// Test lower bound
expectedSize := c.uintSize(0)
actualSize := binary.PutUvarint(make([]byte, binary.MaxVarintLen64), 0)
require.Equal(t, expectedSize, actualSize)

// Test upper bound
expectedSize = c.uintSize(math.MaxUint64)
actualSize = binary.PutUvarint(make([]byte, binary.MaxVarintLen64), math.MaxUint64)
require.Equal(t, expectedSize, actualSize)

// Test powers of 2
for power := 0; power < 64; power++ {
n := uint64(1) << uint(power)
expectedSize := c.uintSize(n)
actualSize := binary.PutUvarint(make([]byte, binary.MaxVarintLen64), n)
require.Equal(t, expectedSize, actualSize, power)
}
}