/
writer.go
354 lines (297 loc) · 7.41 KB
/
writer.go
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package cereal
import (
"bytes"
"encoding/binary"
"fmt"
"hash/crc32"
"io"
"os"
"sort"
"reflect"
"github.com/pierrec/lz4"
)
var (
// LZ4 properties
hashTable [64 << 10]int
lz4BlockSize = 64 << 10
)
type Writer struct {
w *HashWriter
checksum uint32
file *os.File
reusableBuf []byte
excludeWriteType bool
}
// NewWriter will return a new writer.
func NewWriter(f *os.File) *Writer {
return &Writer{
w: NewHashWriter(f),
file: f,
}
}
// NewBufferFromBuffer will return a new writer from a specified byte buffer.
func NewWriterFromBuffer(buf *bytes.Buffer) *Writer {
return &Writer{
w: NewHashWriter(buf),
}
}
// Offset returns the current writer offset.
func (w *Writer) Offset() uint64 {
return w.w.Count()
}
// SetExcludeWriteType will toggle whether data type enums are written to the buffer.
func (w *Writer) SetExcludeWriteType(b bool) {
w.excludeWriteType = b
}
func (w *Writer) SeekOffset(offset uint64) error {
if w.file != nil {
_, err := w.file.Seek(int64(offset), io.SeekStart)
return err
}
return nil
}
func (w *Writer) Write(data interface{}) (offset uint64, length int, err error) {
offset = w.w.Count()
switch vv := data.(type) {
case uint, uint8, uint16, uint32, uint64:
offset, err = w.writeUint(uint64Value(vv))
case int, int8, int16, int32, int64:
offset, err = w.writeInt(int64Value(vv))
case float32, float64:
offset, err = w.writeFloat(floatValue(vv))
case []byte:
offset, err = w.writeBytes(vv)
case string:
offset, err = w.writeString(vv)
case []string:
offset, err = w.writeStringSlice(vv)
case bool:
offset, err = w.writeBoolean(vv)
case map[string]interface{}:
offset, err = w.writeKeyValueMap(vv)
default:
panic(fmt.Errorf("cannot write value, unknown data type for value: '%v' (type: %s)", vv, reflect.TypeOf(vv).String()))
}
if err != nil {
return 0, 0, err
}
length = int(w.w.Count() - offset)
return offset, length, err
}
// WriteRaw will write the raw bytes into the writer.
func (w *Writer) WriteRaw(buf []byte) (offset uint64, err error) {
offset = w.w.Count()
_, err = w.w.Write(buf)
return offset, err
}
// WriteRawToCompress will write raw bytes to compress into LZ4, then to the writer.
func (w *Writer) WriteRawToLZ4Compress(buf []byte) (offset uint64, length int, err error) {
currentOffset := w.w.Count()
zbuf := make([]byte, lz4BlockSize)
chunkData := make([]byte, lz4BlockSize)
r := bytes.NewReader(buf)
for {
// Read chunk
n, err := r.Read(chunkData)
if err != nil && err != io.EOF {
return 0, 0, err
}
if n == 0 {
break
}
compSize, err := lz4.CompressBlock(chunkData, zbuf, hashTable[:])
if _, err = w.WriteRaw(zbuf[0:compSize]); err != nil {
return 0, 0, err
}
}
return currentOffset, int(w.w.Count() - currentOffset), nil
}
// WriteRawByte will write a single byte into the writer.
func (w *Writer) WriteRawByte(b byte) (offset uint64, err error) {
currentOffset := w.w.Count()
err = w.w.WriteByte(b)
w.checksum = crc32.Update(w.checksum, crc32.IEEETable, []byte{b})
return currentOffset, err
}
func (w *Writer) writeUint(v uint64) (offset uint64, err error) {
if len(w.reusableBuf) < binary.MaxVarintLen64 {
w.reusableBuf = make([]byte, binary.MaxVarintLen64)
}
size := binary.PutUvarint(w.reusableBuf, v)
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(UnsignedInteger)); err != nil {
return 0, err
}
}
// Write value
if _, err = w.w.Write(w.reusableBuf[0:size]); err != nil {
return 0, err
}
return offset, nil
}
func (w *Writer) writeInt(v int64) (offset uint64, err error) {
if len(w.reusableBuf) < binary.MaxVarintLen64 {
w.reusableBuf = make([]byte, binary.MaxVarintLen64)
}
size := binary.PutVarint(w.reusableBuf, v)
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(Integer)); err != nil {
return 0, err
}
}
// Write value
if _, err = w.w.Write(w.reusableBuf[0:size]); err != nil {
return 0, err
}
return offset, nil
}
func (w *Writer) writeFloat(v interface{}) (offset uint64, err error) {
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(Float)); err != nil {
return 0, err
}
}
// Write value
if err = binary.Write(w.w, binary.BigEndian, v); err != nil {
return 0, err
}
return offset, nil
}
func (w *Writer) appendBytes(b []byte) (err error) {
if len(w.reusableBuf) < binary.MaxVarintLen64 {
w.reusableBuf = make([]byte, binary.MaxVarintLen64)
}
// Write length
size := binary.PutUvarint(w.reusableBuf, uint64(len(b)))
if _, err = w.w.Write(w.reusableBuf[0:size]); err != nil {
return err
}
// Write bytes
if _, err := w.w.Write(b); err != nil {
return err
}
return nil
}
func (w *Writer) writeString(s string) (offset uint64, err error) {
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(String)); err != nil {
return 0, err
}
}
// Write string
if err := w.appendBytes([]byte(s)); err != nil {
return 0, err
}
return offset, nil
}
func (w *Writer) writeStringSlice(s []string) (offset uint64, err error) {
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(StringSlice)); err != nil {
return 0, err
}
}
// Write length of strings
if len(w.reusableBuf) < binary.MaxVarintLen64 {
w.reusableBuf = make([]byte, binary.MaxVarintLen64)
}
size := binary.PutUvarint(w.reusableBuf, uint64(len(s)))
if _, err = w.w.Write(w.reusableBuf[0:size]); err != nil {
return 0, err
}
// Write strings
for _, ss := range s {
if err := w.appendBytes([]byte(ss)); err != nil {
return 0, err
}
}
return offset, nil
}
func (w *Writer) writeKeyValueMap(m map[string]interface{}) (offset uint64, err error) {
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(KeyValueMap)); err != nil {
return 0, err
}
}
// Save current setting of excludeWriteType
tmpExcludeWriteType := w.excludeWriteType
defer func() { w.excludeWriteType = tmpExcludeWriteType }()
// Write length
w.excludeWriteType = true
if _, err = w.writeUint(uint64(len(m))); err != nil {
return 0, err
}
// Sort the fields alphabetically before writing
keys := make([]string, len(m))
i := 0
for k := range m {
keys[i] = k
i++
}
sort.Strings(keys)
// Write key-values
for _, k := range keys {
w.excludeWriteType = true
if _, err = w.writeString(k); err != nil {
return 0, err
}
// Value type is unknown so requires type to be written
w.excludeWriteType = false
if _, _, err = w.Write(m[k]); err != nil {
return 0, err
}
}
return offset, nil
}
func (w *Writer) writeBoolean(b bool) (offset uint64, err error) {
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(Boolean)); err != nil {
return 0, err
}
}
// Write value
if b {
if err = w.w.WriteByte(1); err != nil {
return 0, err
}
} else {
if err = w.w.WriteByte(0); err != nil {
return 0, err
}
}
return offset, nil
}
func (w *Writer) writeBytes(b []byte) (offset uint64, err error) {
offset = w.w.Count()
// Write type
if !w.excludeWriteType {
if err = w.w.WriteByte(byte(Bytes)); err != nil {
return 0, err
}
}
// Write bytes
if err := w.appendBytes(b); err != nil {
return 0, err
}
return offset, nil
}
// Close will close the writer.
func (w *Writer) Close() error {
if w.file != nil {
return w.file.Close()
}
return nil
}