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89 lines
2.5 KiB
89 lines
2.5 KiB
6 years ago
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// Copyright 2015 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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"fmt"
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"io"
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"net/http"
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"github.com/golang/protobuf/proto"
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"github.com/matttproud/golang_protobuf_extensions/pbutil"
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"github.com/prometheus/common/internal/bitbucket.org/ww/goautoneg"
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dto "github.com/prometheus/client_model/go"
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)
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// Encoder types encode metric families into an underlying wire protocol.
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type Encoder interface {
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Encode(*dto.MetricFamily) error
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}
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type encoder func(*dto.MetricFamily) error
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func (e encoder) Encode(v *dto.MetricFamily) error {
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return e(v)
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}
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// Negotiate returns the Content-Type based on the given Accept header.
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// If no appropriate accepted type is found, FmtText is returned.
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func Negotiate(h http.Header) Format {
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for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
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// Check for protocol buffer
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if ac.Type+"/"+ac.SubType == ProtoType && ac.Params["proto"] == ProtoProtocol {
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switch ac.Params["encoding"] {
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case "delimited":
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return FmtProtoDelim
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case "text":
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return FmtProtoText
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case "compact-text":
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return FmtProtoCompact
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}
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}
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// Check for text format.
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ver := ac.Params["version"]
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if ac.Type == "text" && ac.SubType == "plain" && (ver == TextVersion || ver == "") {
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return FmtText
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}
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}
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return FmtText
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}
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// NewEncoder returns a new encoder based on content type negotiation.
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func NewEncoder(w io.Writer, format Format) Encoder {
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switch format {
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case FmtProtoDelim:
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return encoder(func(v *dto.MetricFamily) error {
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_, err := pbutil.WriteDelimited(w, v)
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return err
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})
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case FmtProtoCompact:
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return encoder(func(v *dto.MetricFamily) error {
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_, err := fmt.Fprintln(w, v.String())
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return err
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})
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case FmtProtoText:
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return encoder(func(v *dto.MetricFamily) error {
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_, err := fmt.Fprintln(w, proto.MarshalTextString(v))
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return err
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})
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case FmtText:
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return encoder(func(v *dto.MetricFamily) error {
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_, err := MetricFamilyToText(w, v)
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return err
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})
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}
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panic("expfmt.NewEncoder: unknown format")
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}
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