/
hedged_requests.go
69 lines (62 loc) · 2.03 KB
/
hedged_requests.go
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/*
* Copyright (C) 2023 Intergral GmbH
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, either version 3 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
package frontend
import (
"net/http"
"time"
"github.com/cristalhq/hedgedhttp"
"github.com/prometheus/client_golang/prometheus"
"github.com/prometheus/client_golang/prometheus/promauto"
)
const (
hedgedMetricsPublishDuration = 10 * time.Second
)
var hedgedRequestsMetrics = promauto.NewGauge(
prometheus.GaugeOpts{
Namespace: "deep",
Subsystem: "query_frontend",
Name: "hedged_roundtrips_total",
Help: "Total number of hedged snapshot by ID requests. Registered as a gauge for code sanity. This is a counter.",
},
)
func newHedgedRequestWare(cfg HedgingConfig) Middleware {
return MiddlewareFunc(func(next http.RoundTripper) http.RoundTripper {
if cfg.HedgeRequestsAt == 0 {
return next
}
ret, stats, err := hedgedhttp.NewRoundTripperAndStats(cfg.HedgeRequestsAt, cfg.HedgeRequestsUpTo, next)
if err != nil {
panic(err)
}
publishHedgedMetrics(stats)
return ret
})
}
// PublishHedgedMetrics flushes metrics from hedged requests every 10 seconds
func publishHedgedMetrics(s *hedgedhttp.Stats) {
ticker := time.NewTicker(hedgedMetricsPublishDuration)
go func() {
for range ticker.C {
snap := s.Snapshot()
hedgedRequests := int64(snap.ActualRoundTrips) - int64(snap.RequestedRoundTrips)
if hedgedRequests < 0 {
hedgedRequests = 0
}
hedgedRequestsMetrics.Set(float64(hedgedRequests))
}
}()
}