108 lines
3.8 KiB
Go
108 lines
3.8 KiB
Go
// Copyright 2024 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 remote
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import (
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"errors"
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"net/http"
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"strconv"
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)
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const (
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rw20WrittenSamplesHeader = "X-Prometheus-Remote-Write-Samples-Written"
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rw20WrittenHistogramsHeader = "X-Prometheus-Remote-Write-Histograms-Written"
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rw20WrittenExemplarsHeader = "X-Prometheus-Remote-Write-Exemplars-Written"
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)
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// WriteResponseStats represents the response write statistics specified in https://github.com/prometheus/docs/pull/2486
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type WriteResponseStats struct {
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// Samples represents X-Prometheus-Remote-Write-Written-Samples
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Samples int
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// Histograms represents X-Prometheus-Remote-Write-Written-Histograms
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Histograms int
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// Exemplars represents X-Prometheus-Remote-Write-Written-Exemplars
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Exemplars int
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// Confirmed means we can trust those statistics from the point of view
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// of the PRW 2.0 spec. When parsed from headers, it means we got at least one
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// response header from the Receiver to confirm those numbers, meaning it must
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// be a at least 2.0 Receiver. See ParseWriteResponseStats for details.
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Confirmed bool
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}
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// NoDataWritten returns true if statistics indicate no data was written.
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func (s WriteResponseStats) NoDataWritten() bool {
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return (s.Samples + s.Histograms + s.Exemplars) == 0
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}
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// AllSamples returns both float and histogram sample numbers.
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func (s WriteResponseStats) AllSamples() int {
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return s.Samples + s.Histograms
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}
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// Add returns the sum of this WriteResponseStats plus the given WriteResponseStats.
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func (s WriteResponseStats) Add(rs WriteResponseStats) WriteResponseStats {
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s.Confirmed = rs.Confirmed
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s.Samples += rs.Samples
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s.Histograms += rs.Histograms
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s.Exemplars += rs.Exemplars
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return s
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}
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// SetHeaders sets response headers in a given response writer.
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// Make sure to use it before http.ResponseWriter.WriteHeader and .Write.
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func (s WriteResponseStats) SetHeaders(w http.ResponseWriter) {
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h := w.Header()
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h.Set(rw20WrittenSamplesHeader, strconv.Itoa(s.Samples))
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h.Set(rw20WrittenHistogramsHeader, strconv.Itoa(s.Histograms))
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h.Set(rw20WrittenExemplarsHeader, strconv.Itoa(s.Exemplars))
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}
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// ParseWriteResponseStats returns WriteResponseStats parsed from the response headers.
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//
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// As per 2.0 spec, missing header means 0. However, abrupt HTTP errors, 1.0 Receivers
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// or buggy 2.0 Receivers might result in no response headers specified and that
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// might NOT necessarily mean nothing was written. To represent that we set
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// s.Confirmed = true only when see at least on response header.
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//
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// Error is returned when any of the header fails to parse as int64.
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func ParseWriteResponseStats(r *http.Response) (s WriteResponseStats, err error) {
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var (
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errs []error
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h = r.Header
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)
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if v := h.Get(rw20WrittenSamplesHeader); v != "" { // Empty means zero.
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s.Confirmed = true
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if s.Samples, err = strconv.Atoi(v); err != nil {
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s.Samples = 0
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errs = append(errs, err)
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}
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}
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if v := h.Get(rw20WrittenHistogramsHeader); v != "" { // Empty means zero.
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s.Confirmed = true
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if s.Histograms, err = strconv.Atoi(v); err != nil {
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s.Histograms = 0
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errs = append(errs, err)
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}
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}
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if v := h.Get(rw20WrittenExemplarsHeader); v != "" { // Empty means zero.
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s.Confirmed = true
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if s.Exemplars, err = strconv.Atoi(v); err != nil {
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s.Exemplars = 0
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errs = append(errs, err)
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}
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}
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return s, errors.Join(errs...)
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}
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