// PeekValueLength returns the length of the encoded value at the start of b.
// Note: If this function succeeds, it's not a guarantee that decoding the value
// will succeed.
func PeekValueLength(b []byte) (int, error) {
if len(b) == 0 {
return 0, util.Errorf("empty slice")
}
tag := ValueType(b[0])
switch tag {
case ValueType_NULL:
return 1, nil
case ValueType_INT:
_, n, _, err := encoding.DecodeNonsortingVarint(b[1:])
return 1 + n, err
case ValueType_FLOAT:
return 9, nil
case ValueType_DELIMITED_BYTES, ValueType_DELIMITED_DECIMAL:
_, n, i, err := encoding.DecodeNonsortingVarint(b[1:])
return 1 + n + int(i), err
case ValueType_TIME:
n, err := encoding.GetMultiVarintLen(b[1:], 2)
return 1 + n, err
case ValueType_DURATION:
n, err := encoding.GetMultiVarintLen(b[1:], 3)
return 1 + n, err
case ValueType_BYTES, ValueType_DECIMAL:
return 0, util.Errorf("not a self-delimiting tag: %q", tag)
}
return 0, util.Errorf("unknown tag %q", tag)
}
// DecodeIntValue decodes a value encoded by EncodeIntValue.
func DecodeIntValue(b []byte) ([]byte, int64, error) {
if len(b) == 0 {
return nil, 0, fmt.Errorf("array is empty")
}
if tag := ValueType(b[0]); tag != ValueType_INT {
return nil, 0, fmt.Errorf("value type is not %s: %s", ValueType_INT, tag)
}
var i int64
var err error
b, _, i, err = encoding.DecodeNonsortingVarint(b[1:])
return b, i, err
}
// DecodeBytesValue decodes a value encoded by EncodeBytesValue.
func DecodeBytesValue(b []byte) ([]byte, []byte, error) {
if len(b) == 0 {
return nil, nil, fmt.Errorf("array is empty")
}
tag := ValueType(b[0])
b = b[1:]
switch tag {
case ValueType_BYTES:
return nil, b, nil
case ValueType_DELIMITED_BYTES:
var i int64
var err error
b, _, i, err = encoding.DecodeNonsortingVarint(b)
if err != nil {
return nil, nil, err
}
return b[int(i):], b[:int(i)], nil
}
return nil, nil, fmt.Errorf(
"value type is not %s or %s: %s", ValueType_BYTES, ValueType_DELIMITED_BYTES, tag)
}
// DecodeDecimalValue decodes a value encoded by EncodeDecimalValue.
func DecodeDecimalValue(b []byte) ([]byte, *inf.Dec, error) {
if len(b) == 0 {
return nil, nil, fmt.Errorf("array is empty")
}
tag := ValueType(b[0])
b = b[1:]
switch tag {
case ValueType_DECIMAL:
d, err := encoding.DecodeNonsortingDecimal(b, nil)
return nil, d, err
case ValueType_DELIMITED_DECIMAL:
var i int64
var err error
b, _, i, err = encoding.DecodeNonsortingVarint(b)
if err != nil {
return nil, nil, err
}
d, err := encoding.DecodeNonsortingDecimal(b[:int(i)], nil)
return b[int(i):], d, err
}
return nil, nil, fmt.Errorf("value type is not %s or %s: %s", ValueType_DECIMAL, ValueType_DELIMITED_DECIMAL, tag)
}
// processValueTuple processes the given values (of columns family.ColumnIDs),
// setting values in the rf.row accordingly. The key is only used for logging.
func (rf *RowFetcher) processValueTuple(
family *ColumnFamilyDescriptor, kv client.KeyValue, debugStrings bool, prettyKeyPrefix string,
) (prettyKey string, prettyValue string, err error) {
prettyKey = prettyKeyPrefix
if debugStrings {
rf.prettyValueBuf.Reset()
}
tupleBytes, err := kv.Value.GetTuple()
if err != nil {
return "", "", err
}
var colIDRaw int64
var value parser.Datum
for len(tupleBytes) > 0 {
tupleBytes, _, colIDRaw, err = encoding.DecodeNonsortingVarint(tupleBytes)
if err != nil {
return "", "", err
}
if colIDRaw < 0 || colIDRaw > math.MaxUint32 {
return "", "", util.Errorf("invalid column-id: %d", colIDRaw)
}
idx, ok := rf.colIdxMap[ColumnID(colIDRaw)]
// TODO(dan): Ideally rowFetcher would generate EncDatums instead of Datums
// and that would make the logic simpler. We won't need valNeededForCol at
// all, it would be up to the user of the class to decide if they want to
// decode them or not.
if !ok || !rf.valNeededForCol[idx] {
// This column wasn't requested, so read its length and skip it.
i, err := roachpb.PeekValueLength(tupleBytes)
if err != nil {
return "", "", err
}
tupleBytes = tupleBytes[i:]
if log.V(3) {
log.Infof("Scan %s -> [%d] (skipped)", kv.Key, colIDRaw)
}
continue
}
if debugStrings {
prettyKey = fmt.Sprintf("%s/%s", prettyKey, rf.desc.Columns[idx].Name)
}
kind := rf.cols[idx].Type.Kind.ToDatumType()
value, tupleBytes, err = DecodeTableValue(&rf.alloc, kind, tupleBytes)
if err != nil {
return "", "", err
}
if debugStrings {
fmt.Fprintf(&rf.prettyValueBuf, "/%v", value)
}
if rf.row[idx] != nil {
panic(fmt.Sprintf("duplicate value for column %d", idx))
}
rf.row[idx] = value
if log.V(3) {
log.Infof("Scan %d -> %v", idx, value)
}
}
if debugStrings {
prettyValue = rf.prettyValueBuf.String()
}
return prettyKey, prettyValue, nil
}