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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"
- "github.com/golang/protobuf/proto"
- "github.com/matttproud/golang_protobuf_extensions/pbutil"
- "github.com/prometheus/common/internal/bitbucket.org/ww/goautoneg"
- 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 {
- for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
- ver := ac.Params["version"]
- if ac.Type+"/"+ac.SubType == ProtoType && ac.Params["proto"] == ProtoProtocol {
- switch ac.Params["encoding"] {
- case "delimited":
- return FmtProtoDelim
- case "text":
- return FmtProtoText
- case "compact-text":
- return FmtProtoCompact
- }
- }
- if ac.Type == "text" && ac.SubType == "plain" && (ver == TextVersion || ver == "") {
- return FmtText
- }
- }
- return FmtText
- }
- // 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 {
- for _, ac := range goautoneg.ParseAccept(h.Get(hdrAccept)) {
- ver := ac.Params["version"]
- if ac.Type+"/"+ac.SubType == ProtoType && ac.Params["proto"] == ProtoProtocol {
- switch ac.Params["encoding"] {
- case "delimited":
- return FmtProtoDelim
- case "text":
- return FmtProtoText
- case "compact-text":
- return FmtProtoCompact
- }
- }
- if ac.Type == "text" && ac.SubType == "plain" && (ver == TextVersion || ver == "") {
- return FmtText
- }
- if ac.Type+"/"+ac.SubType == OpenMetricsType && (ver == OpenMetricsVersion || ver == "") {
- return FmtOpenMetrics
- }
- }
- return FmtText
- }
- // 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.
- func NewEncoder(w io.Writer, format Format) Encoder {
- switch format {
- case FmtProtoDelim:
- return encoderCloser{
- encode: func(v *dto.MetricFamily) error {
- _, err := pbutil.WriteDelimited(w, v)
- return err
- },
- close: func() error { return nil },
- }
- case FmtProtoCompact:
- return encoderCloser{
- encode: func(v *dto.MetricFamily) error {
- _, err := fmt.Fprintln(w, v.String())
- return err
- },
- close: func() error { return nil },
- }
- case FmtProtoText:
- return encoderCloser{
- encode: func(v *dto.MetricFamily) error {
- _, err := fmt.Fprintln(w, proto.MarshalTextString(v))
- return err
- },
- close: func() error { return nil },
- }
- case FmtText:
- return encoderCloser{
- encode: func(v *dto.MetricFamily) error {
- _, err := MetricFamilyToText(w, v)
- return err
- },
- close: func() error { return nil },
- }
- case FmtOpenMetrics:
- return encoderCloser{
- encode: func(v *dto.MetricFamily) error {
- _, err := MetricFamilyToOpenMetrics(w, v)
- return err
- },
- close: func() error {
- _, err := FinalizeOpenMetrics(w)
- return err
- },
- }
- }
- panic(fmt.Errorf("expfmt.NewEncoder: unknown format %q", format))
- }
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