fermentord/vendor/github.com/prometheus/common/expfmt/encode.go

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// Copyright 2015 The Prometheus 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 expfmt
import (
"fmt"
"io"
"net/http"
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"google.golang.org/protobuf/encoding/protodelim"
"google.golang.org/protobuf/encoding/prototext"
"github.com/prometheus/common/internal/bitbucket.org/ww/goautoneg"
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"github.com/prometheus/common/model"
dto "github.com/prometheus/client_model/go"
)
// Encoder types encode metric families into an underlying wire protocol.
type Encoder interface {
Encode(*dto.MetricFamily) error
}
// Closer is implemented by Encoders that need to be closed to finalize
// encoding. (For example, OpenMetrics needs a final `# EOF` line.)
//
// Note that all Encoder implementations returned from this package implement
// Closer, too, even if the Close call is a no-op. This happens in preparation
// for adding a Close method to the Encoder interface directly in a (mildly
// breaking) release in the future.
type Closer interface {
Close() error
}
type encoderCloser struct {
encode func(*dto.MetricFamily) error
close func() error
}
func (ec encoderCloser) Encode(v *dto.MetricFamily) error {
return ec.encode(v)
}
func (ec encoderCloser) Close() error {
return ec.close()
}
// Negotiate returns the Content-Type based on the given Accept header. If no
// appropriate accepted type is found, FmtText is returned (which is the
// Prometheus text format). This function will never negotiate FmtOpenMetrics,
// as the support is still experimental. To include the option to negotiate
// FmtOpenMetrics, use NegotiateOpenMetrics.
func Negotiate(h http.Header) Format {
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escapingScheme := Format(fmt.Sprintf("; escaping=%s", Format(model.NameEscapingScheme.String())))
for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
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if escapeParam := ac.Params[model.EscapingKey]; escapeParam != "" {
switch Format(escapeParam) {
case model.AllowUTF8, model.EscapeUnderscores, model.EscapeDots, model.EscapeValues:
escapingScheme = Format(fmt.Sprintf("; escaping=%s", escapeParam))
default:
// If the escaping parameter is unknown, ignore it.
}
}
ver := ac.Params["version"]
if ac.Type+"/"+ac.SubType == ProtoType && ac.Params["proto"] == ProtoProtocol {
switch ac.Params["encoding"] {
case "delimited":
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return fmtProtoDelim + escapingScheme
case "text":
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return fmtProtoText + escapingScheme
case "compact-text":
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return fmtProtoCompact + escapingScheme
}
}
if ac.Type == "text" && ac.SubType == "plain" && (ver == TextVersion || ver == "") {
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return fmtText + escapingScheme
}
}
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return fmtText + escapingScheme
}
// NegotiateIncludingOpenMetrics works like Negotiate but includes
// FmtOpenMetrics as an option for the result. Note that this function is
// temporary and will disappear once FmtOpenMetrics is fully supported and as
// such may be negotiated by the normal Negotiate function.
func NegotiateIncludingOpenMetrics(h http.Header) Format {
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escapingScheme := Format(fmt.Sprintf("; escaping=%s", Format(model.NameEscapingScheme.String())))
for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
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if escapeParam := ac.Params[model.EscapingKey]; escapeParam != "" {
switch Format(escapeParam) {
case model.AllowUTF8, model.EscapeUnderscores, model.EscapeDots, model.EscapeValues:
escapingScheme = Format(fmt.Sprintf("; escaping=%s", escapeParam))
default:
// If the escaping parameter is unknown, ignore it.
}
}
ver := ac.Params["version"]
if ac.Type+"/"+ac.SubType == ProtoType && ac.Params["proto"] == ProtoProtocol {
switch ac.Params["encoding"] {
case "delimited":
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return fmtProtoDelim + escapingScheme
case "text":
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return fmtProtoText + escapingScheme
case "compact-text":
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return fmtProtoCompact + escapingScheme
}
}
if ac.Type == "text" && ac.SubType == "plain" && (ver == TextVersion || ver == "") {
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return fmtText + escapingScheme
}
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if ac.Type+"/"+ac.SubType == OpenMetricsType && (ver == OpenMetricsVersion_0_0_1 || ver == OpenMetricsVersion_1_0_0 || ver == "") {
switch ver {
case OpenMetricsVersion_1_0_0:
return fmtOpenMetrics_1_0_0 + escapingScheme
default:
return fmtOpenMetrics_0_0_1 + escapingScheme
}
}
}
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return fmtText + escapingScheme
}
// NewEncoder returns a new encoder based on content type negotiation. All
// Encoder implementations returned by NewEncoder also implement Closer, and
// callers should always call the Close method. It is currently only required
// for FmtOpenMetrics, but a future (breaking) release will add the Close method
// to the Encoder interface directly. The current version of the Encoder
// interface is kept for backwards compatibility.
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// In cases where the Format does not allow for UTF-8 names, the global
// NameEscapingScheme will be applied.
//
// NewEncoder can be called with additional options to customize the OpenMetrics text output.
// For example:
// NewEncoder(w, FmtOpenMetrics_1_0_0, WithCreatedLines())
//
// Extra options are ignored for all other formats.
func NewEncoder(w io.Writer, format Format, options ...EncoderOption) Encoder {
escapingScheme := format.ToEscapingScheme()
switch format.FormatType() {
case TypeProtoDelim:
return encoderCloser{
encode: func(v *dto.MetricFamily) error {
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_, err := protodelim.MarshalTo(w, v)
return err
},
close: func() error { return nil },
}
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case TypeProtoCompact:
return encoderCloser{
encode: func(v *dto.MetricFamily) error {
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_, err := fmt.Fprintln(w, model.EscapeMetricFamily(v, escapingScheme).String())
return err
},
close: func() error { return nil },
}
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case TypeProtoText:
return encoderCloser{
encode: func(v *dto.MetricFamily) error {
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_, err := fmt.Fprintln(w, prototext.Format(model.EscapeMetricFamily(v, escapingScheme)))
return err
},
close: func() error { return nil },
}
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case TypeTextPlain:
return encoderCloser{
encode: func(v *dto.MetricFamily) error {
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_, err := MetricFamilyToText(w, model.EscapeMetricFamily(v, escapingScheme))
return err
},
close: func() error { return nil },
}
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case TypeOpenMetrics:
return encoderCloser{
encode: func(v *dto.MetricFamily) error {
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_, err := MetricFamilyToOpenMetrics(w, model.EscapeMetricFamily(v, escapingScheme), options...)
return err
},
close: func() error {
_, err := FinalizeOpenMetrics(w)
return err
},
}
}
panic(fmt.Errorf("expfmt.NewEncoder: unknown format %q", format))
}