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d648712cf2
* Temporarily opt-out export.Labels from label encoding stuff * Stop passing label encoding stuff to export.Labels * Drop label encoding stuff from SDK * Dogstatd exporter does not need to implement label exporter anymore * more dogstatd exporter fixes * export labels get back to encoding stuff in a lame way, but improvements are coming in following commits * Get encoded labels through export.Labels * make SDK to provide its own implementation of export.Labels * drop dead code * add noop label exporter * make export simple labels immutable * Move the default label encoder to export package * Simplify the simple export labels a bit * Reserve some label exporter IDs * Document and shuffle the code a bit * Prepare for bring the iterator benchmark test back We can install a callback to the Batcher's process function - this is the place where we can access the labels, and thus test the label iterator. * Bring back the iterator benchmarks * Simplifications and docs * Fix copyright to be consistent with the rest * Fix typo * Put reserved label encoder IDs into constants We get fewer comments about magic numbers that way. * Fix the label encoder as label exporter thinko
96 lines
2.6 KiB
Go
96 lines
2.6 KiB
Go
// Copyright The OpenTelemetry Authors
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package metric
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import (
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"bytes"
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"sync"
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"go.opentelemetry.io/otel/api/core"
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)
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// escapeChar is used to ensure uniqueness of the label encoding where
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// keys or values contain either '=' or ','. Since there is no parser
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// needed for this encoding and its only requirement is to be unique,
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// this choice is arbitrary. Users will see these in some exporters
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// (e.g., stdout), so the backslash ('\') is used a conventional choice.
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const escapeChar = '\\'
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type defaultLabelEncoder struct {
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// pool is a pool of labelset builders. The buffers in this
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// pool grow to a size that most label encodings will not
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// allocate new memory.
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pool sync.Pool // *bytes.Buffer
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}
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var _ LabelEncoder = &defaultLabelEncoder{}
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// NewDefaultLabelEncoder returns a label encoder that encodes labels
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// in such a way that each escaped label's key is followed by an equal
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// sign and then by an escaped label's value. All key-value pairs are
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// separated by a comma.
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//
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// Escaping is done by prepending a backslash before either a
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// backslash, equal sign or a comma.
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func NewDefaultLabelEncoder() LabelEncoder {
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return &defaultLabelEncoder{
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pool: sync.Pool{
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New: func() interface{} {
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return &bytes.Buffer{}
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},
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},
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}
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}
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// Encode is a part of an implementation of the LabelEncoder
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// interface.
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func (d *defaultLabelEncoder) Encode(iter LabelIterator) string {
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buf := d.pool.Get().(*bytes.Buffer)
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defer d.pool.Put(buf)
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buf.Reset()
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for iter.Next() {
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i, kv := iter.IndexedLabel()
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if i > 0 {
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_, _ = buf.WriteRune(',')
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}
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copyAndEscape(buf, string(kv.Key))
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_, _ = buf.WriteRune('=')
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if kv.Value.Type() == core.STRING {
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copyAndEscape(buf, kv.Value.AsString())
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} else {
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_, _ = buf.WriteString(kv.Value.Emit())
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}
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}
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return buf.String()
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}
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// ID is a part of an implementation of the LabelEncoder interface.
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func (*defaultLabelEncoder) ID() int64 {
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return defaultLabelEncoderID
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}
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func copyAndEscape(buf *bytes.Buffer, val string) {
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for _, ch := range val {
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switch ch {
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case '=', ',', escapeChar:
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buf.WriteRune(escapeChar)
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}
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buf.WriteRune(ch)
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}
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}
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