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Introduce KeyFormat that uses a full 8 bytes for int64 values and avoids
string manipulatio/scanning Signed-off-by: Silas Davis <[email protected]>
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Silas Davis
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Aug 30, 2018
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,127 @@ | ||
| package iavl | ||
|
|
||
| import ( | ||
| "encoding/binary" | ||
| "fmt" | ||
| ) | ||
|
|
||
| // Provides a fixed-width lexicographically sortable []byte key format | ||
| type KeyFormat struct { | ||
| prefix byte | ||
| layout []int | ||
| length int | ||
| } | ||
|
|
||
| // Create a []byte key format based on a single byte prefix and fixed width key segments each of whose length is | ||
| // specified by by the corresponding element of layout | ||
| func NewKeyFormat(prefix byte, layout ...int) *KeyFormat { | ||
| // For prefix | ||
| length := 1 | ||
| for _, l := range layout { | ||
| length += int(l) | ||
| } | ||
| return &KeyFormat{ | ||
| prefix: prefix, | ||
| layout: layout, | ||
| length: length, | ||
| } | ||
| } | ||
|
|
||
| // Format the byte segments into the key format - will panic if the segment lengths to do match the layout. | ||
| func (kf *KeyFormat) KeyBytes(segments ...[]byte) []byte { | ||
| key := make([]byte, kf.length) | ||
| key[0] = kf.prefix | ||
| n := 1 | ||
| for i, s := range segments { | ||
| l := kf.layout[i] | ||
| if len(s) > l { | ||
| panic(fmt.Errorf("length of segment %X provided to KeyFormat.Key() is longer than the %d bytes "+ | ||
| "required by layout for segment %d", s, l, i)) | ||
| } | ||
| copy(key[n+(l-len(s)):n+l], s) | ||
| n += l | ||
| } | ||
| return key[:n] | ||
| } | ||
|
|
||
| // Format the args passed into the key format - will panic if the arguments passed to not match the length | ||
| // of the segment to which they correspond. When called with no arguments returns the raw prefix (useful as a start | ||
| // element of the entire keys space when sorted lexicographically) | ||
| func (kf *KeyFormat) Key(args ...interface{}) []byte { | ||
| if len(args) > len(kf.layout) { | ||
| panic(fmt.Errorf("KeyFormat.Key() is provided with %d args but format only has %d segments", | ||
| len(args), len(kf.layout))) | ||
| } | ||
| segments := make([][]byte, len(args)) | ||
| for i, a := range args { | ||
| segments[i] = format(a) | ||
| } | ||
| return kf.KeyBytes(segments...) | ||
| } | ||
|
|
||
| // Reads out the bytes associated with each segment of the key format from key | ||
| func (kf *KeyFormat) ScanBytes(key []byte) [][]byte { | ||
| segments := make([][]byte, len(kf.layout)) | ||
| n := 1 | ||
| for i, l := range kf.layout { | ||
| end := n + l | ||
| if end > len(key) { | ||
| return segments[:i] | ||
| } | ||
| segments[i] = key[n:end] | ||
| n = end | ||
| } | ||
| return segments | ||
| } | ||
|
|
||
| // Extracts the segments into the values pointed to by each of args. Each arg must be a pointer to int64, uint64, or | ||
| // []byte, and the width of the args must match layout. | ||
| func (kf *KeyFormat) Scan(key []byte, args ...interface{}) { | ||
| segments := kf.ScanBytes(key) | ||
| if len(args) > len(segments) { | ||
| panic(fmt.Errorf("KeyFormat.Scan() is provided with %d args but format only has %d segments", | ||
| len(args), len(segments))) | ||
| } | ||
| for i, a := range args { | ||
| scan(a, segments[i]) | ||
| } | ||
| } | ||
|
|
||
| // Return the prefix as a string | ||
| func (kf *KeyFormat) Prefix() string { | ||
| return string([]byte{kf.prefix}) | ||
| } | ||
|
|
||
| func scan(a interface{}, value []byte) { | ||
| switch v := a.(type) { | ||
| case *int64: | ||
| *v = int64(binary.BigEndian.Uint64(value)) | ||
| case *uint64: | ||
| *v = binary.BigEndian.Uint64(value) | ||
| case *[]byte: | ||
| *v = value | ||
| default: | ||
| panic(fmt.Errorf("KeyFormat.scan() does not support scanning value of type %T: %v", a, a)) | ||
| } | ||
| } | ||
|
|
||
| func format(a interface{}) []byte { | ||
| switch v := a.(type) { | ||
| case uint64: | ||
| bs := make([]byte, 8) | ||
| binary.BigEndian.PutUint64(bs, v) | ||
| return bs | ||
| case uint: | ||
| return format(uint64(v)) | ||
| case int64: | ||
| bs := make([]byte, 8) | ||
| binary.BigEndian.PutUint64(bs, uint64(v)) | ||
| return bs | ||
| case int: | ||
| return format(int64(v)) | ||
| case []byte: | ||
| return v | ||
| default: | ||
| panic(fmt.Errorf("KeyFormat.format() does not support formatting value of type %T: %v", a, a)) | ||
| } | ||
| } |
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,37 @@ | ||
| package iavl | ||
|
|
||
| import ( | ||
| "testing" | ||
|
|
||
| "github.com/stretchr/testify/assert" | ||
| ) | ||
|
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| func TestKeyFormatBytes(t *testing.T) { | ||
| kf := NewKeyFormat(byte('e'), 8, 8, 8) | ||
| assert.Equal(t, []byte{'e', 0, 0, 0, 0, 0, 1, 2, 3}, kf.KeyBytes([]byte{1, 2, 3})) | ||
| assert.Equal(t, []byte{'e', 1, 2, 3, 4, 5, 6, 7, 8}, kf.KeyBytes([]byte{1, 2, 3, 4, 5, 6, 7, 8})) | ||
| assert.Equal(t, []byte{'e', 1, 2, 3, 4, 5, 6, 7, 8, 1, 2, 3, 4, 5, 6, 7, 8, 0, 0, 1, 1, 2, 2, 3, 3}, | ||
| kf.KeyBytes([]byte{1, 2, 3, 4, 5, 6, 7, 8}, []byte{1, 2, 3, 4, 5, 6, 7, 8}, []byte{1, 1, 2, 2, 3, 3})) | ||
| assert.Equal(t, []byte{'e'}, kf.KeyBytes()) | ||
| } | ||
|
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| func TestKeyFormat(t *testing.T) { | ||
| kf := NewKeyFormat(byte('e'), 8, 8, 8) | ||
| key := []byte{'e', 0, 0, 0, 0, 0, 0, 0, 100, 0, 0, 0, 0, 0, 0, 0, 200, 0, 0, 0, 0, 0, 0, 1, 144} | ||
| var a, b, c int64 = 100, 200, 400 | ||
| assert.Equal(t, key, kf.Key(a, b, c)) | ||
|
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| var ao, bo, co = new(int64), new(int64), new(int64) | ||
| kf.Scan(key, ao, bo, co) | ||
| assert.Equal(t, a, *ao) | ||
| assert.Equal(t, b, *bo) | ||
| assert.Equal(t, c, *co) | ||
|
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| bs := new([]byte) | ||
| kf.Scan(key, ao, bo, bs) | ||
| assert.Equal(t, a, *ao) | ||
| assert.Equal(t, b, *bo) | ||
| assert.Equal(t, []byte{0, 0, 0, 0, 0, 0, 1, 144}, *bs) | ||
|
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| assert.Equal(t, []byte{'e', 0, 0, 0, 0, 0, 0, 0, 100, 0, 0, 0, 0, 0, 0, 0, 200}, kf.Key(a, b)) | ||
| } |
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