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|
package binary
import (
"encoding/binary"
"io"
"math"
"reflect"
"unsafe"
)
func NewEncoder(w io.Writer) *Encoder {
return &Encoder{
output: w,
}
}
func NewEncoderWithCompress(w io.Writer) *Encoder {
return &Encoder{
output: w,
compressOutput: NewCompressWriter(w),
}
}
type Encoder struct {
compress bool
output io.Writer
compressOutput io.Writer
scratch [binary.MaxVarintLen64]byte
}
func (enc *Encoder) SelectCompress(compress bool) {
if enc.compressOutput == nil {
return
}
if enc.compress && !compress {
enc.Flush()
}
enc.compress = compress
}
func (enc *Encoder) Get() io.Writer {
if enc.compress && enc.compressOutput != nil {
return enc.compressOutput
}
return enc.output
}
func (enc *Encoder) Uvarint(v uint64) error {
ln := binary.PutUvarint(enc.scratch[:binary.MaxVarintLen64], v)
if _, err := enc.Get().Write(enc.scratch[0:ln]); err != nil {
return err
}
return nil
}
func (enc *Encoder) Bool(v bool) error {
if v {
return enc.UInt8(1)
}
return enc.UInt8(0)
}
func (enc *Encoder) Int8(v int8) error {
return enc.UInt8(uint8(v))
}
func (enc *Encoder) Int16(v int16) error {
return enc.UInt16(uint16(v))
}
func (enc *Encoder) Int32(v int32) error {
return enc.UInt32(uint32(v))
}
func (enc *Encoder) Int64(v int64) error {
return enc.UInt64(uint64(v))
}
func (enc *Encoder) UInt8(v uint8) error {
enc.scratch[0] = v
if _, err := enc.Get().Write(enc.scratch[:1]); err != nil {
return err
}
return nil
}
func (enc *Encoder) UInt16(v uint16) error {
enc.scratch[0] = byte(v)
enc.scratch[1] = byte(v >> 8)
if _, err := enc.Get().Write(enc.scratch[:2]); err != nil {
return err
}
return nil
}
func (enc *Encoder) UInt32(v uint32) error {
enc.scratch[0] = byte(v)
enc.scratch[1] = byte(v >> 8)
enc.scratch[2] = byte(v >> 16)
enc.scratch[3] = byte(v >> 24)
if _, err := enc.Get().Write(enc.scratch[:4]); err != nil {
return err
}
return nil
}
func (enc *Encoder) UInt64(v uint64) error {
enc.scratch[0] = byte(v)
enc.scratch[1] = byte(v >> 8)
enc.scratch[2] = byte(v >> 16)
enc.scratch[3] = byte(v >> 24)
enc.scratch[4] = byte(v >> 32)
enc.scratch[5] = byte(v >> 40)
enc.scratch[6] = byte(v >> 48)
enc.scratch[7] = byte(v >> 56)
if _, err := enc.Get().Write(enc.scratch[:8]); err != nil {
return err
}
return nil
}
func (enc *Encoder) Float32(v float32) error {
return enc.UInt32(math.Float32bits(v))
}
func (enc *Encoder) Float64(v float64) error {
return enc.UInt64(math.Float64bits(v))
}
func (enc *Encoder) String(v string) error {
str := Str2Bytes(v)
if err := enc.Uvarint(uint64(len(str))); err != nil {
return err
}
if _, err := enc.Get().Write(str); err != nil {
return err
}
return nil
}
func (enc *Encoder) RawString(str []byte) error {
if err := enc.Uvarint(uint64(len(str))); err != nil {
return err
}
if _, err := enc.Get().Write(str); err != nil {
return err
}
return nil
}
func (enc *Encoder) Decimal128(bytes []byte) error {
_, err := enc.Get().Write(bytes)
return err
}
func (enc *Encoder) Write(b []byte) (int, error) {
return enc.Get().Write(b)
}
func (enc *Encoder) Flush() error {
if w, ok := enc.Get().(WriteFlusher); ok {
return w.Flush()
}
return nil
}
type WriteFlusher interface {
Flush() error
}
func Str2Bytes(str string) []byte {
// Copied from https://github.com/m3db/m3/blob/master/src/x/unsafe/string.go#L62
if len(str) == 0 {
return nil
}
// We need to declare a real byte slice so internally the compiler
// knows to use an unsafe.Pointer to keep track of the underlying memory so that
// once the slice's array pointer is updated with the pointer to the string's
// underlying bytes, the compiler won't prematurely GC the memory when the string
// goes out of scope.
var b []byte
byteHeader := (*reflect.SliceHeader)(unsafe.Pointer(&b))
// This makes sure that even if GC relocates the string's underlying
// memory after this assignment, the corresponding unsafe.Pointer in the internal
// slice struct will be updated accordingly to reflect the memory relocation.
byteHeader.Data = (*reflect.StringHeader)(unsafe.Pointer(&str)).Data
// It is important that we access str after we assign the Data
// pointer of the string header to the Data pointer of the slice header to
// make sure the string (and the underlying bytes backing the string) don't get
// GC'ed before the assignment happens.
l := len(str)
byteHeader.Len = l
byteHeader.Cap = l
return b
}
|
