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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 tagencoding contains the tag encoding
- // used interally by the stats collector.
- package tagencoding // import "go.opencensus.io/internal/tagencoding"
-
- // Values represent the encoded buffer for the values.
- type Values struct {
- Buffer []byte
- WriteIndex int
- ReadIndex int
- }
-
- func (vb *Values) growIfRequired(expected int) {
- if len(vb.Buffer)-vb.WriteIndex < expected {
- tmp := make([]byte, 2*(len(vb.Buffer)+1)+expected)
- copy(tmp, vb.Buffer)
- vb.Buffer = tmp
- }
- }
-
- // WriteValue is the helper method to encode Values from map[Key][]byte.
- func (vb *Values) WriteValue(v []byte) {
- length := len(v) & 0xff
- vb.growIfRequired(1 + length)
-
- // writing length of v
- vb.Buffer[vb.WriteIndex] = byte(length)
- vb.WriteIndex++
-
- if length == 0 {
- // No value was encoded for this key
- return
- }
-
- // writing v
- copy(vb.Buffer[vb.WriteIndex:], v[:length])
- vb.WriteIndex += length
- }
-
- // ReadValue is the helper method to decode Values to a map[Key][]byte.
- func (vb *Values) ReadValue() []byte {
- // read length of v
- length := int(vb.Buffer[vb.ReadIndex])
- vb.ReadIndex++
- if length == 0 {
- // No value was encoded for this key
- return nil
- }
-
- // read value of v
- v := make([]byte, length)
- endIdx := vb.ReadIndex + length
- copy(v, vb.Buffer[vb.ReadIndex:endIdx])
- vb.ReadIndex = endIdx
- return v
- }
-
- // Bytes returns a reference to already written bytes in the Buffer.
- func (vb *Values) Bytes() []byte {
- return vb.Buffer[:vb.WriteIndex]
- }
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