vendor/go.opencensus.io/tag/map_codec.go

   1 // Copyright 2017, OpenCensus Authors
   2 //
   3 // Licensed under the Apache License, Version 2.0 (the "License");
   4 // you may not use this file except in compliance with the License.
   5 // You may obtain a copy of the License at
   6 //
   7 //     http://www.apache.org/licenses/LICENSE-2.0
   8 //
   9 // Unless required by applicable law or agreed to in writing, software
  10 // distributed under the License is distributed on an "AS IS" BASIS,
  11 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  12 // See the License for the specific language governing permissions and
  13 // limitations under the License.
  14 //
  15
  16 package tag
  17
  18 import (
  19         "encoding/binary"
  20         "fmt"
  21 )
  22
  23 // KeyType defines the types of keys allowed. Currently only keyTypeString is
  24 // supported.
  25 type keyType byte
  26
  27 const (
  28         keyTypeString keyType = iota
  29         keyTypeInt64
  30         keyTypeTrue
  31         keyTypeFalse
  32
  33         tagsVersionID = byte(0)
  34 )
  35
  36 type encoderGRPC struct {
  37         buf               []byte
  38         writeIdx, readIdx int
  39 }
  40
  41 // writeKeyString writes the fieldID '0' followed by the key string and value
  42 // string.
  43 func (eg *encoderGRPC) writeTagString(k, v string) {
  44         eg.writeByte(byte(keyTypeString))
  45         eg.writeStringWithVarintLen(k)
  46         eg.writeStringWithVarintLen(v)
  47 }
  48
  49 func (eg *encoderGRPC) writeTagUint64(k string, i uint64) {
  50         eg.writeByte(byte(keyTypeInt64))
  51         eg.writeStringWithVarintLen(k)
  52         eg.writeUint64(i)
  53 }
  54
  55 func (eg *encoderGRPC) writeTagTrue(k string) {
  56         eg.writeByte(byte(keyTypeTrue))
  57         eg.writeStringWithVarintLen(k)
  58 }
  59
  60 func (eg *encoderGRPC) writeTagFalse(k string) {
  61         eg.writeByte(byte(keyTypeFalse))
  62         eg.writeStringWithVarintLen(k)
  63 }
  64
  65 func (eg *encoderGRPC) writeBytesWithVarintLen(bytes []byte) {
  66         length := len(bytes)
  67
  68         eg.growIfRequired(binary.MaxVarintLen64 + length)
  69         eg.writeIdx += binary.PutUvarint(eg.buf[eg.writeIdx:], uint64(length))
  70         copy(eg.buf[eg.writeIdx:], bytes)
  71         eg.writeIdx += length
  72 }
  73
  74 func (eg *encoderGRPC) writeStringWithVarintLen(s string) {
  75         length := len(s)
  76
  77         eg.growIfRequired(binary.MaxVarintLen64 + length)
  78         eg.writeIdx += binary.PutUvarint(eg.buf[eg.writeIdx:], uint64(length))
  79         copy(eg.buf[eg.writeIdx:], s)
  80         eg.writeIdx += length
  81 }
  82
  83 func (eg *encoderGRPC) writeByte(v byte) {
  84         eg.growIfRequired(1)
  85         eg.buf[eg.writeIdx] = v
  86         eg.writeIdx++
  87 }
  88
  89 func (eg *encoderGRPC) writeUint32(i uint32) {
  90         eg.growIfRequired(4)
  91         binary.LittleEndian.PutUint32(eg.buf[eg.writeIdx:], i)
  92         eg.writeIdx += 4
  93 }
  94
  95 func (eg *encoderGRPC) writeUint64(i uint64) {
  96         eg.growIfRequired(8)
  97         binary.LittleEndian.PutUint64(eg.buf[eg.writeIdx:], i)
  98         eg.writeIdx += 8
  99 }
 100
 101 func (eg *encoderGRPC) readByte() byte {
 102         b := eg.buf[eg.readIdx]
 103         eg.readIdx++
 104         return b
 105 }
 106
 107 func (eg *encoderGRPC) readUint32() uint32 {
 108         i := binary.LittleEndian.Uint32(eg.buf[eg.readIdx:])
 109         eg.readIdx += 4
 110         return i
 111 }
 112
 113 func (eg *encoderGRPC) readUint64() uint64 {
 114         i := binary.LittleEndian.Uint64(eg.buf[eg.readIdx:])
 115         eg.readIdx += 8
 116         return i
 117 }
 118
 119 func (eg *encoderGRPC) readBytesWithVarintLen() ([]byte, error) {
 120         if eg.readEnded() {
 121                 return nil, fmt.Errorf("unexpected end while readBytesWithVarintLen '%x' starting at idx '%v'", eg.buf, eg.readIdx)
 122         }
 123         length, valueStart := binary.Uvarint(eg.buf[eg.readIdx:])
 124         if valueStart <= 0 {
 125                 return nil, fmt.Errorf("unexpected end while readBytesWithVarintLen '%x' starting at idx '%v'", eg.buf, eg.readIdx)
 126         }
 127
 128         valueStart += eg.readIdx
 129         valueEnd := valueStart + int(length)
 130         if valueEnd > len(eg.buf) {
 131                 return nil, fmt.Errorf("malformed encoding: length:%v, upper:%v, maxLength:%v", length, valueEnd, len(eg.buf))
 132         }
 133
 134         eg.readIdx = valueEnd
 135         return eg.buf[valueStart:valueEnd], nil
 136 }
 137
 138 func (eg *encoderGRPC) readStringWithVarintLen() (string, error) {
 139         bytes, err := eg.readBytesWithVarintLen()
 140         if err != nil {
 141                 return "", err
 142         }
 143         return string(bytes), nil
 144 }
 145
 146 func (eg *encoderGRPC) growIfRequired(expected int) {
 147         if len(eg.buf)-eg.writeIdx < expected {
 148                 tmp := make([]byte, 2*(len(eg.buf)+1)+expected)
 149                 copy(tmp, eg.buf)
 150                 eg.buf = tmp
 151         }
 152 }
 153
 154 func (eg *encoderGRPC) readEnded() bool {
 155         return eg.readIdx >= len(eg.buf)
 156 }
 157
 158 func (eg *encoderGRPC) bytes() []byte {
 159         return eg.buf[:eg.writeIdx]
 160 }
 161
 162 // Encode encodes the tag map into a []byte. It is useful to propagate
 163 // the tag maps on wire in binary format.
 164 func Encode(m *Map) []byte {
 165         eg := &encoderGRPC{
 166                 buf: make([]byte, len(m.m)),
 167         }
 168         eg.writeByte(byte(tagsVersionID))
 169         for k, v := range m.m {
 170                 eg.writeByte(byte(keyTypeString))
 171                 eg.writeStringWithVarintLen(k.name)
 172                 eg.writeBytesWithVarintLen([]byte(v))
 173         }
 174         return eg.bytes()
 175 }
 176
 177 // Decode decodes the given []byte into a tag map.
 178 func Decode(bytes []byte) (*Map, error) {
 179         ts := newMap()
 180         err := DecodeEach(bytes, ts.upsert)
 181         if err != nil {
 182                 // no partial failures
 183                 return nil, err
 184         }
 185         return ts, nil
 186 }
 187
 188 // DecodeEach decodes the given serialized tag map, calling handler for each
 189 // tag key and value decoded.
 190 func DecodeEach(bytes []byte, fn func(key Key, val string)) error {
 191         eg := &encoderGRPC{
 192                 buf: bytes,
 193         }
 194         if len(eg.buf) == 0 {
 195                 return nil
 196         }
 197
 198         version := eg.readByte()
 199         if version > tagsVersionID {
 200                 return fmt.Errorf("cannot decode: unsupported version: %q; supports only up to: %q", version, tagsVersionID)
 201         }
 202
 203         for !eg.readEnded() {
 204                 typ := keyType(eg.readByte())
 205
 206                 if typ != keyTypeString {
 207                         return fmt.Errorf("cannot decode: invalid key type: %q", typ)
 208                 }
 209
 210                 k, err := eg.readBytesWithVarintLen()
 211                 if err != nil {
 212                         return err
 213                 }
 214
 215                 v, err := eg.readBytesWithVarintLen()
 216                 if err != nil {
 217                         return err
 218                 }
 219
 220                 key, err := NewKey(string(k))
 221                 if err != nil {
 222                         return err
 223                 }
 224                 val := string(v)
 225                 if !checkValue(val) {
 226                         return errInvalidValue
 227                 }
 228                 fn(key, val)
 229                 if err != nil {
 230                         return err
 231                 }
 232         }
 233         return nil
 234 }