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// Copyright 2017, OpenCensus Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
//
package tag
import (
"encoding/binary"
"fmt"
)
// KeyType defines the types of keys allowed. Currently only keyTypeString is
// supported.
type keyType byte
const (
keyTypeString keyType = iota
keyTypeInt64
keyTypeTrue
keyTypeFalse
tagsVersionID = byte(0)
)
type encoderGRPC struct {
buf []byte
writeIdx, readIdx int
}
// writeKeyString writes the fieldID '0' followed by the key string and value
// string.
func (eg *encoderGRPC) writeTagString(k, v string) {
eg.writeByte(byte(keyTypeString))
eg.writeStringWithVarintLen(k)
eg.writeStringWithVarintLen(v)
}
func (eg *encoderGRPC) writeTagUint64(k string, i uint64) {
eg.writeByte(byte(keyTypeInt64))
eg.writeStringWithVarintLen(k)
eg.writeUint64(i)
}
func (eg *encoderGRPC) writeTagTrue(k string) {
eg.writeByte(byte(keyTypeTrue))
eg.writeStringWithVarintLen(k)
}
func (eg *encoderGRPC) writeTagFalse(k string) {
eg.writeByte(byte(keyTypeFalse))
eg.writeStringWithVarintLen(k)
}
func (eg *encoderGRPC) writeBytesWithVarintLen(bytes []byte) {
length := len(bytes)
eg.growIfRequired(binary.MaxVarintLen64 + length)
eg.writeIdx += binary.PutUvarint(eg.buf[eg.writeIdx:], uint64(length))
copy(eg.buf[eg.writeIdx:], bytes)
eg.writeIdx += length
}
func (eg *encoderGRPC) writeStringWithVarintLen(s string) {
length := len(s)
eg.growIfRequired(binary.MaxVarintLen64 + length)
eg.writeIdx += binary.PutUvarint(eg.buf[eg.writeIdx:], uint64(length))
copy(eg.buf[eg.writeIdx:], s)
eg.writeIdx += length
}
func (eg *encoderGRPC) writeByte(v byte) {
eg.growIfRequired(1)
eg.buf[eg.writeIdx] = v
eg.writeIdx++
}
func (eg *encoderGRPC) writeUint32(i uint32) {
eg.growIfRequired(4)
binary.LittleEndian.PutUint32(eg.buf[eg.writeIdx:], i)
eg.writeIdx += 4
}
func (eg *encoderGRPC) writeUint64(i uint64) {
eg.growIfRequired(8)
binary.LittleEndian.PutUint64(eg.buf[eg.writeIdx:], i)
eg.writeIdx += 8
}
func (eg *encoderGRPC) readByte() byte {
b := eg.buf[eg.readIdx]
eg.readIdx++
return b
}
func (eg *encoderGRPC) readUint32() uint32 {
i := binary.LittleEndian.Uint32(eg.buf[eg.readIdx:])
eg.readIdx += 4
return i
}
func (eg *encoderGRPC) readUint64() uint64 {
i := binary.LittleEndian.Uint64(eg.buf[eg.readIdx:])
eg.readIdx += 8
return i
}
func (eg *encoderGRPC) readBytesWithVarintLen() ([]byte, error) {
if eg.readEnded() {
return nil, fmt.Errorf("unexpected end while readBytesWithVarintLen '%x' starting at idx '%v'", eg.buf, eg.readIdx)
}
length, valueStart := binary.Uvarint(eg.buf[eg.readIdx:])
if valueStart <= 0 {
return nil, fmt.Errorf("unexpected end while readBytesWithVarintLen '%x' starting at idx '%v'", eg.buf, eg.readIdx)
}
valueStart += eg.readIdx
valueEnd := valueStart + int(length)
if valueEnd > len(eg.buf) {
return nil, fmt.Errorf("malformed encoding: length:%v, upper:%v, maxLength:%v", length, valueEnd, len(eg.buf))
}
eg.readIdx = valueEnd
return eg.buf[valueStart:valueEnd], nil
}
func (eg *encoderGRPC) readStringWithVarintLen() (string, error) {
bytes, err := eg.readBytesWithVarintLen()
if err != nil {
return "", err
}
return string(bytes), nil
}
func (eg *encoderGRPC) growIfRequired(expected int) {
if len(eg.buf)-eg.writeIdx < expected {
tmp := make([]byte, 2*(len(eg.buf)+1)+expected)
copy(tmp, eg.buf)
eg.buf = tmp
}
}
func (eg *encoderGRPC) readEnded() bool {
return eg.readIdx >= len(eg.buf)
}
func (eg *encoderGRPC) bytes() []byte {
return eg.buf[:eg.writeIdx]
}
// Encode encodes the tag map into a []byte. It is useful to propagate
// the tag maps on wire in binary format.
func Encode(m *Map) []byte {
if m == nil {
return nil
}
eg := &encoderGRPC{
buf: make([]byte, len(m.m)),
}
eg.writeByte(byte(tagsVersionID))
for k, v := range m.m {
eg.writeByte(byte(keyTypeString))
eg.writeStringWithVarintLen(k.name)
eg.writeBytesWithVarintLen([]byte(v))
}
return eg.bytes()
}
// Decode decodes the given []byte into a tag map.
func Decode(bytes []byte) (*Map, error) {
ts := newMap()
err := DecodeEach(bytes, ts.upsert)
if err != nil {
// no partial failures
return nil, err
}
return ts, nil
}
// DecodeEach decodes the given serialized tag map, calling handler for each
// tag key and value decoded.
func DecodeEach(bytes []byte, fn func(key Key, val string)) error {
eg := &encoderGRPC{
buf: bytes,
}
if len(eg.buf) == 0 {
return nil
}
version := eg.readByte()
if version > tagsVersionID {
return fmt.Errorf("cannot decode: unsupported version: %q; supports only up to: %q", version, tagsVersionID)
}
for !eg.readEnded() {
typ := keyType(eg.readByte())
if typ != keyTypeString {
return fmt.Errorf("cannot decode: invalid key type: %q", typ)
}
k, err := eg.readBytesWithVarintLen()
if err != nil {
return err
}
v, err := eg.readBytesWithVarintLen()
if err != nil {
return err
}
key, err := NewKey(string(k))
if err != nil {
return err
}
val := string(v)
if !checkValue(val) {
return errInvalidValue
}
fn(key, val)
if err != nil {
return err
}
}
return nil
}