465 lines
11 KiB
Go
465 lines
11 KiB
Go
// Copyright 2014 The Prometheus Authors
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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 expfmt
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import (
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"bufio"
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"fmt"
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"io"
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"math"
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"strconv"
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"strings"
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"sync"
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"github.com/prometheus/common/model"
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dto "github.com/prometheus/client_model/go"
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)
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// enhancedWriter has all the enhanced write functions needed here. bufio.Writer
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// implements it.
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type enhancedWriter interface {
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io.Writer
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WriteRune(r rune) (n int, err error)
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WriteString(s string) (n int, err error)
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WriteByte(c byte) error
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}
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const (
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initialNumBufSize = 24
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)
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var (
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bufPool = sync.Pool{
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New: func() interface{} {
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return bufio.NewWriter(io.Discard)
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},
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}
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numBufPool = sync.Pool{
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New: func() interface{} {
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b := make([]byte, 0, initialNumBufSize)
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return &b
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},
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}
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)
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// MetricFamilyToText converts a MetricFamily proto message into text format and
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// writes the resulting lines to 'out'. It returns the number of bytes written
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// and any error encountered. The output will have the same order as the input,
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// no further sorting is performed. Furthermore, this function assumes the input
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// is already sanitized and does not perform any sanity checks. If the input
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// contains duplicate metrics or invalid metric or label names, the conversion
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// will result in invalid text format output.
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//
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// This method fulfills the type 'prometheus.encoder'.
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func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err error) {
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// Fail-fast checks.
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if len(in.Metric) == 0 {
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return 0, fmt.Errorf("MetricFamily has no metrics: %s", in)
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}
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name := in.GetName()
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if name == "" {
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return 0, fmt.Errorf("MetricFamily has no name: %s", in)
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}
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// Try the interface upgrade. If it doesn't work, we'll use a
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// bufio.Writer from the sync.Pool.
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w, ok := out.(enhancedWriter)
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if !ok {
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b := bufPool.Get().(*bufio.Writer)
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b.Reset(out)
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w = b
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defer func() {
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bErr := b.Flush()
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if err == nil {
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err = bErr
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}
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bufPool.Put(b)
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}()
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}
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var n int
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// Comments, first HELP, then TYPE.
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if in.Help != nil {
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n, err = w.WriteString("# HELP ")
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written += n
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if err != nil {
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return
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}
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n, err = w.WriteString(name)
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written += n
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if err != nil {
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return
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}
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err = w.WriteByte(' ')
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written++
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if err != nil {
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return
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}
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n, err = writeEscapedString(w, *in.Help, false)
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written += n
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if err != nil {
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return
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}
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err = w.WriteByte('\n')
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written++
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if err != nil {
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return
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}
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}
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n, err = w.WriteString("# TYPE ")
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written += n
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if err != nil {
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return
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}
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n, err = w.WriteString(name)
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written += n
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if err != nil {
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return
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}
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metricType := in.GetType()
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switch metricType {
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case dto.MetricType_COUNTER:
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n, err = w.WriteString(" counter\n")
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case dto.MetricType_GAUGE:
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n, err = w.WriteString(" gauge\n")
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case dto.MetricType_SUMMARY:
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n, err = w.WriteString(" summary\n")
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case dto.MetricType_UNTYPED:
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n, err = w.WriteString(" untyped\n")
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case dto.MetricType_HISTOGRAM:
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n, err = w.WriteString(" histogram\n")
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default:
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return written, fmt.Errorf("unknown metric type %s", metricType.String())
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}
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written += n
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if err != nil {
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return
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}
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// Finally the samples, one line for each.
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for _, metric := range in.Metric {
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switch metricType {
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case dto.MetricType_COUNTER:
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if metric.Counter == nil {
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return written, fmt.Errorf(
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"expected counter in metric %s %s", name, metric,
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)
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}
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n, err = writeSample(
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w, name, "", metric, "", 0,
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metric.Counter.GetValue(),
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)
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case dto.MetricType_GAUGE:
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if metric.Gauge == nil {
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return written, fmt.Errorf(
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"expected gauge in metric %s %s", name, metric,
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)
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}
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n, err = writeSample(
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w, name, "", metric, "", 0,
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metric.Gauge.GetValue(),
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)
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case dto.MetricType_UNTYPED:
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if metric.Untyped == nil {
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return written, fmt.Errorf(
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"expected untyped in metric %s %s", name, metric,
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)
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}
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n, err = writeSample(
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w, name, "", metric, "", 0,
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metric.Untyped.GetValue(),
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)
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case dto.MetricType_SUMMARY:
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if metric.Summary == nil {
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return written, fmt.Errorf(
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"expected summary in metric %s %s", name, metric,
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)
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}
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for _, q := range metric.Summary.Quantile {
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n, err = writeSample(
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w, name, "", metric,
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model.QuantileLabel, q.GetQuantile(),
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q.GetValue(),
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)
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written += n
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if err != nil {
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return
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}
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}
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n, err = writeSample(
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w, name, "_sum", metric, "", 0,
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metric.Summary.GetSampleSum(),
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)
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written += n
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if err != nil {
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return
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}
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n, err = writeSample(
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w, name, "_count", metric, "", 0,
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float64(metric.Summary.GetSampleCount()),
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)
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case dto.MetricType_HISTOGRAM:
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if metric.Histogram == nil {
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return written, fmt.Errorf(
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"expected histogram in metric %s %s", name, metric,
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)
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}
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infSeen := false
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for _, b := range metric.Histogram.Bucket {
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n, err = writeSample(
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w, name, "_bucket", metric,
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model.BucketLabel, b.GetUpperBound(),
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float64(b.GetCumulativeCount()),
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)
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written += n
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if err != nil {
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return
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}
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if math.IsInf(b.GetUpperBound(), +1) {
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infSeen = true
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}
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}
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if !infSeen {
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n, err = writeSample(
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w, name, "_bucket", metric,
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model.BucketLabel, math.Inf(+1),
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float64(metric.Histogram.GetSampleCount()),
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)
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written += n
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if err != nil {
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return
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}
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}
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n, err = writeSample(
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w, name, "_sum", metric, "", 0,
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metric.Histogram.GetSampleSum(),
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)
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written += n
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if err != nil {
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return
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}
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n, err = writeSample(
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w, name, "_count", metric, "", 0,
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float64(metric.Histogram.GetSampleCount()),
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)
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default:
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return written, fmt.Errorf(
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"unexpected type in metric %s %s", name, metric,
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)
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}
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written += n
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if err != nil {
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return
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}
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}
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return
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}
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// writeSample writes a single sample in text format to w, given the metric
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// name, the metric proto message itself, optionally an additional label name
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// with a float64 value (use empty string as label name if not required), and
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// the value. The function returns the number of bytes written and any error
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// encountered.
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func writeSample(
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w enhancedWriter,
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name, suffix string,
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metric *dto.Metric,
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additionalLabelName string, additionalLabelValue float64,
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value float64,
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) (int, error) {
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var written int
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n, err := w.WriteString(name)
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written += n
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if err != nil {
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return written, err
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}
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if suffix != "" {
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n, err = w.WriteString(suffix)
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written += n
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if err != nil {
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return written, err
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}
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}
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n, err = writeLabelPairs(
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w, metric.Label, additionalLabelName, additionalLabelValue,
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)
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written += n
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if err != nil {
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return written, err
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}
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err = w.WriteByte(' ')
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written++
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if err != nil {
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return written, err
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}
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n, err = writeFloat(w, value)
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written += n
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if err != nil {
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return written, err
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}
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if metric.TimestampMs != nil {
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err = w.WriteByte(' ')
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written++
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if err != nil {
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return written, err
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}
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n, err = writeInt(w, *metric.TimestampMs)
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written += n
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if err != nil {
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return written, err
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}
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}
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err = w.WriteByte('\n')
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written++
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if err != nil {
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return written, err
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}
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return written, nil
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}
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// writeLabelPairs converts a slice of LabelPair proto messages plus the
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// explicitly given additional label pair into text formatted as required by the
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// text format and writes it to 'w'. An empty slice in combination with an empty
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// string 'additionalLabelName' results in nothing being written. Otherwise, the
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// label pairs are written, escaped as required by the text format, and enclosed
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// in '{...}'. The function returns the number of bytes written and any error
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// encountered.
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func writeLabelPairs(
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w enhancedWriter,
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in []*dto.LabelPair,
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additionalLabelName string, additionalLabelValue float64,
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) (int, error) {
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if len(in) == 0 && additionalLabelName == "" {
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return 0, nil
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}
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var (
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written int
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separator byte = '{'
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)
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for _, lp := range in {
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err := w.WriteByte(separator)
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written++
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if err != nil {
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return written, err
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}
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n, err := w.WriteString(lp.GetName())
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written += n
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if err != nil {
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return written, err
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}
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n, err = w.WriteString(`="`)
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written += n
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if err != nil {
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return written, err
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}
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n, err = writeEscapedString(w, lp.GetValue(), true)
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written += n
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if err != nil {
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return written, err
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}
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err = w.WriteByte('"')
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written++
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if err != nil {
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return written, err
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}
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separator = ','
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}
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if additionalLabelName != "" {
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err := w.WriteByte(separator)
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written++
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if err != nil {
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return written, err
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}
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n, err := w.WriteString(additionalLabelName)
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written += n
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if err != nil {
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return written, err
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}
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n, err = w.WriteString(`="`)
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written += n
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if err != nil {
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return written, err
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}
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n, err = writeFloat(w, additionalLabelValue)
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written += n
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if err != nil {
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return written, err
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}
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err = w.WriteByte('"')
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written++
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if err != nil {
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return written, err
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}
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}
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err := w.WriteByte('}')
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written++
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if err != nil {
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return written, err
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}
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return written, nil
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}
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// writeEscapedString replaces '\' by '\\', new line character by '\n', and - if
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// includeDoubleQuote is true - '"' by '\"'.
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var (
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escaper = strings.NewReplacer("\\", `\\`, "\n", `\n`)
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quotedEscaper = strings.NewReplacer("\\", `\\`, "\n", `\n`, "\"", `\"`)
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)
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func writeEscapedString(w enhancedWriter, v string, includeDoubleQuote bool) (int, error) {
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if includeDoubleQuote {
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return quotedEscaper.WriteString(w, v)
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}
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return escaper.WriteString(w, v)
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}
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// writeFloat is equivalent to fmt.Fprint with a float64 argument but hardcodes
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// a few common cases for increased efficiency. For non-hardcoded cases, it uses
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// strconv.AppendFloat to avoid allocations, similar to writeInt.
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func writeFloat(w enhancedWriter, f float64) (int, error) {
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switch {
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case f == 1:
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return 1, w.WriteByte('1')
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case f == 0:
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return 1, w.WriteByte('0')
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case f == -1:
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return w.WriteString("-1")
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case math.IsNaN(f):
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return w.WriteString("NaN")
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case math.IsInf(f, +1):
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return w.WriteString("+Inf")
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case math.IsInf(f, -1):
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return w.WriteString("-Inf")
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default:
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bp := numBufPool.Get().(*[]byte)
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*bp = strconv.AppendFloat((*bp)[:0], f, 'g', -1, 64)
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written, err := w.Write(*bp)
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numBufPool.Put(bp)
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return written, err
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}
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}
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// writeInt is equivalent to fmt.Fprint with an int64 argument but uses
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// strconv.AppendInt with a byte slice taken from a sync.Pool to avoid
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// allocations.
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func writeInt(w enhancedWriter, i int64) (int, error) {
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bp := numBufPool.Get().(*[]byte)
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*bp = strconv.AppendInt((*bp)[:0], i, 10)
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written, err := w.Write(*bp)
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numBufPool.Put(bp)
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return written, err
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}
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