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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"
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
}
}
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 read the values when decoding valuesBytes 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
}
func (vb *Values) Bytes() []byte {
return vb.Buffer[:vb.WriteIndex]
}
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