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prometheus/storage/remote/stats.go

108 lines
3.8 KiB

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