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Refactor to reuse functions and improve code coverage #531

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merged 2 commits into from
May 5, 2024
Merged

Refactor to reuse functions and improve code coverage #531

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d3153aa
Refactor to remove encodeFixedLengthStruct()
fxamacker May 5, 2024
f83a7d0
Refactor to combine encodeHead() & encodedHeadLen()
fxamacker May 5, 2024
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22 changes: 2 additions & 20 deletions cache.go
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Original file line number Diff line number Diff line change
Expand Up @@ -170,8 +170,6 @@ type encodingStructType struct {
omitEmptyFieldsIdx []int
err error
toArray bool
fixedLength bool // Struct type doesn't have any omitempty or anonymous fields.
maxHeadLen int
}

func (st *encodingStructType) getFields(em *encMode) fields {
Expand Down Expand Up @@ -232,13 +230,10 @@ func getEncodingStructType(t reflect.Type) (*encodingStructType, error) {
return getEncodingStructToArrayType(t, flds)
}

nOptional := 0

var err error
var hasKeyAsInt bool
var hasKeyAsStr bool
var omitEmptyIdx []int
fixedLength := true
e := getEncoderBuffer()
for i := 0; i < len(flds); i++ {
// Get field's encodeFunc
Expand Down Expand Up @@ -286,20 +281,10 @@ func getEncodingStructType(t reflect.Type) (*encodingStructType, error) {
hasKeyAsStr = true
}

// Check if field is from embedded struct
if len(flds[i].idx) > 1 {
fixedLength = false
}

// Check if field can be omitted when empty
if flds[i].omitEmpty {
fixedLength = false
omitEmptyIdx = append(omitEmptyIdx, i)
}

if len(flds[i].idx) > 1 || flds[i].omitEmpty {
nOptional++
}
}
putEncoderBuffer(e)

Expand All @@ -326,8 +311,6 @@ func getEncodingStructType(t reflect.Type) (*encodingStructType, error) {
bytewiseFields: bytewiseFields,
lengthFirstFields: lengthFirstFields,
omitEmptyFieldsIdx: omitEmptyIdx,
fixedLength: fixedLength,
maxHeadLen: encodedHeadLen(uint64(len(flds))),
}

encodingStructTypeCache.Store(t, structType)
Expand All @@ -346,9 +329,8 @@ func getEncodingStructToArrayType(t reflect.Type, flds fields) (*encodingStructT
}

structType := &encodingStructType{
fields: flds,
toArray: true,
fixedLength: true,
fields: flds,
toArray: true,
}
encodingStructTypeCache.Store(t, structType)
return structType, structType.err
Expand Down
80 changes: 19 additions & 61 deletions encode.go
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Original file line number Diff line number Diff line change
Expand Up @@ -1250,36 +1250,6 @@ func encodeStructToArray(e *encoderBuffer, em *encMode, v reflect.Value) (err er
return nil
}

func encodeFixedLengthStruct(e *encoderBuffer, em *encMode, v reflect.Value, flds fields) error {
if b := em.encTagBytes(v.Type()); b != nil {
e.Write(b)
}

encodeHead(e, byte(cborTypeMap), uint64(len(flds)))

start := 0
if em.sort == SortFastShuffle {
start = rand.Intn(len(flds)) //nolint:gosec // Don't need a CSPRNG for deck cutting.
}

for offset := 0; offset < len(flds); offset++ {
i := (start + offset) % len(flds)
f := flds[i]
if !f.keyAsInt && em.fieldName == FieldNameToByteString {
e.Write(f.cborNameByteString)
} else { // int or text string
e.Write(f.cborName)
}

fv := v.Field(f.idx[0])
if err := f.ef(e, em, fv); err != nil {
return err
}
}

return nil
}

func encodeStruct(e *encoderBuffer, em *encMode, v reflect.Value) (err error) {
structType, err := getEncodingStructType(v.Type())
if err != nil {
Expand All @@ -1288,10 +1258,6 @@ func encodeStruct(e *encoderBuffer, em *encMode, v reflect.Value) (err error) {

flds := structType.getFields(em)

if structType.fixedLength {
return encodeFixedLengthStruct(e, em, v, flds)
}

start := 0
if em.sort == SortFastShuffle {
start = rand.Intn(len(flds)) //nolint:gosec // Don't need a CSPRNG for deck cutting.
Expand All @@ -1301,8 +1267,9 @@ func encodeStruct(e *encoderBuffer, em *encMode, v reflect.Value) (err error) {
e.Write(b)
}

// Reserve space in the output buffer for the head if its encoded size is fixed.
encodeHead(e, byte(cborTypeMap), uint64(len(flds)))
// Encode head with struct field count.
// Head is rewritten later if actual encoded field count is different from struct field count.
encodedHeadLen := encodeHead(e, byte(cborTypeMap), uint64(len(flds)))

kvbegin := e.Len()
kvcount := 0
Expand Down Expand Up @@ -1345,14 +1312,19 @@ func encodeStruct(e *encoderBuffer, em *encMode, v reflect.Value) (err error) {
kvcount++
}

if len(flds) == kvcount {
// Encoded element count in head is the same as actual element count.
return nil
}

// Overwrite the bytes that were reserved for the head before encoding the map entries.
var actualHeadLen int
{
headbuf := encoderBuffer{Buffer: *bytes.NewBuffer(e.Bytes()[kvbegin-structType.maxHeadLen : kvbegin-structType.maxHeadLen : kvbegin])}
encodeHead(&headbuf, byte(cborTypeMap), uint64(kvcount))
headbuf := encoderBuffer{Buffer: *bytes.NewBuffer(e.Bytes()[kvbegin-encodedHeadLen : kvbegin-encodedHeadLen : kvbegin])}
actualHeadLen = encodeHead(&headbuf, byte(cborTypeMap), uint64(kvcount))
}

actualHeadLen := encodedHeadLen(uint64(kvcount))
if actualHeadLen == structType.maxHeadLen {
if actualHeadLen == encodedHeadLen {
// The bytes reserved for the encoded head were exactly the right size, so the
// encoded entries are already in their final positions.
return nil
Expand All @@ -1361,7 +1333,7 @@ func encodeStruct(e *encoderBuffer, em *encMode, v reflect.Value) (err error) {
// We reserved more bytes than needed for the encoded head, based on the number of fields
// encoded. The encoded entries are offset to the right by the number of excess reserved
// bytes. Shift the entries left to remove the gap.
excessReservedBytes := structType.maxHeadLen - actualHeadLen
excessReservedBytes := encodedHeadLen - actualHeadLen
dst := e.Bytes()[kvbegin-excessReservedBytes : e.Len()-excessReservedBytes]
src := e.Bytes()[kvbegin:e.Len()]
copy(dst, src)
Expand Down Expand Up @@ -1519,47 +1491,33 @@ func encodeTag(e *encoderBuffer, em *encMode, v reflect.Value) error {
return encode(e, em, reflect.ValueOf(t.Content))
}

func encodeHead(e *encoderBuffer, t byte, n uint64) {
// encodeHead writes CBOR head of specified type t and returns number of bytes written.
func encodeHead(e *encoderBuffer, t byte, n uint64) int {
if n <= 23 {
e.WriteByte(t | byte(n))
return
return 1
}
if n <= math.MaxUint8 {
e.scratch[0] = t | byte(24)
e.scratch[1] = byte(n)
e.Write(e.scratch[:2])
return
return 2
}
if n <= math.MaxUint16 {
e.scratch[0] = t | byte(25)
binary.BigEndian.PutUint16(e.scratch[1:], uint16(n))
e.Write(e.scratch[:3])
return
return 3
}
if n <= math.MaxUint32 {
e.scratch[0] = t | byte(26)
binary.BigEndian.PutUint32(e.scratch[1:], uint32(n))
e.Write(e.scratch[:5])
return
return 5
}
e.scratch[0] = t | byte(27)
binary.BigEndian.PutUint64(e.scratch[1:], n)
e.Write(e.scratch[:9])
}

// encodedHeadLen returns the number of bytes that will be written by a call to encodeHead with the
// given argument. This must be kept in sync with encodeHead.
func encodedHeadLen(arg uint64) int {
switch {
case arg <= 23:
return 1
case arg <= math.MaxUint8:
return 2
case arg <= math.MaxUint16:
return 3
case arg <= math.MaxUint32:
return 5
}
return 9
}

Expand Down
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