prometheus/storage/remote/queue_manager.go

217 lines
6.2 KiB
Go

// Copyright 2013 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 (
"time"
"github.com/golang/glog"
clientmodel "github.com/prometheus/client_golang/model"
"github.com/prometheus/client_golang/prometheus"
)
const (
// The maximum number of concurrent send requests to the TSDB.
maxConcurrentSends = 10
// The maximum number of samples to fit into a single request to the TSDB.
maxSamplesPerSend = 100
// The deadline after which to send queued samples even if the maximum batch
// size has not been reached.
batchSendDeadline = 5 * time.Second
)
// String constants for instrumentation.
const (
namespace = "prometheus"
subsystem = "remote_storage"
result = "result"
success = "success"
failure = "failure"
dropped = "dropped"
)
// TSDBClient defines an interface for sending a batch of samples to an
// external timeseries database (TSDB).
type TSDBClient interface {
Store(clientmodel.Samples) error
}
// TSDBQueueManager manages a queue of samples to be sent to the TSDB indicated
// by the provided TSDBClient.
type TSDBQueueManager struct {
tsdb TSDBClient
queue chan clientmodel.Samples
pendingSamples clientmodel.Samples
sendSemaphore chan bool
drained chan bool
samplesCount *prometheus.CounterVec
sendLatency prometheus.Summary
sendErrors prometheus.Counter
queueLength prometheus.Gauge
queueCapacity prometheus.Metric
}
// NewTSDBQueueManager builds a new TSDBQueueManager.
func NewTSDBQueueManager(tsdb TSDBClient, queueCapacity int) *TSDBQueueManager {
return &TSDBQueueManager{
tsdb: tsdb,
queue: make(chan clientmodel.Samples, queueCapacity),
sendSemaphore: make(chan bool, maxConcurrentSends),
drained: make(chan bool),
samplesCount: prometheus.NewCounterVec(
prometheus.CounterOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "sent_samples_total",
Help: "Total number of processed samples to be sent to remote TSDB.",
},
[]string{result},
),
sendLatency: prometheus.NewSummary(prometheus.SummaryOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "sent_latency_milliseconds",
Help: "Latency quantiles for sending sample batches to the remote TSDB.",
}),
sendErrors: prometheus.NewCounter(prometheus.CounterOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "sent_errors_total",
Help: "Total number of errors sending sample batches to the remote TSDB.",
}),
queueLength: prometheus.NewGauge(prometheus.GaugeOpts{
Namespace: namespace,
Subsystem: subsystem,
Name: "queue_length",
Help: "The number of processed samples queued to be sent to the remote TSDB.",
}),
queueCapacity: prometheus.MustNewConstMetric(
prometheus.NewDesc(
prometheus.BuildFQName(namespace, subsystem, "queue_capacity"),
"The capacity of the queue of samples to be sent to the remote TSDB.",
nil, nil,
),
prometheus.GaugeValue,
float64(queueCapacity),
),
}
}
// Queue queues a sample batch to be sent to the TSDB. It drops the most
// recently queued samples on the floor if the queue is full.
func (t *TSDBQueueManager) Queue(s clientmodel.Samples) {
if len(s) == 0 {
return
}
select {
case t.queue <- s:
default:
t.samplesCount.WithLabelValues(dropped).Add(float64(len(s)))
glog.Warningf("TSDB queue full, discarding %d samples", len(s))
}
}
// Stop stops sending samples to the TSDB and waits for pending sends to
// complete.
func (t *TSDBQueueManager) Stop() {
glog.Infof("Stopping remote storage...")
close(t.queue)
<-t.drained
for i := 0; i < maxConcurrentSends; i++ {
t.sendSemaphore <- true
}
glog.Info("Remote storage stopped.")
}
// Describe implements prometheus.Collector.
func (t *TSDBQueueManager) Describe(ch chan<- *prometheus.Desc) {
t.samplesCount.Describe(ch)
t.sendLatency.Describe(ch)
ch <- t.queueLength.Desc()
ch <- t.queueCapacity.Desc()
}
// Collect implements prometheus.Collector.
func (t *TSDBQueueManager) Collect(ch chan<- prometheus.Metric) {
t.samplesCount.Collect(ch)
t.sendLatency.Collect(ch)
t.queueLength.Set(float64(len(t.queue)))
ch <- t.queueLength
ch <- t.queueCapacity
}
func (t *TSDBQueueManager) sendSamples(s clientmodel.Samples) {
t.sendSemaphore <- true
defer func() {
<-t.sendSemaphore
}()
// Samples are sent to the TSDB on a best-effort basis. If a sample isn't
// sent correctly the first time, it's simply dropped on the floor.
begin := time.Now()
err := t.tsdb.Store(s)
duration := time.Since(begin) / time.Millisecond
labelValue := success
if err != nil {
glog.Warningf("error sending %d samples to TSDB: %s", len(s), err)
labelValue = failure
t.sendErrors.Inc()
}
t.samplesCount.WithLabelValues(labelValue).Add(float64(len(s)))
t.sendLatency.Observe(float64(duration))
}
// Run continuously sends samples to the TSDB.
func (t *TSDBQueueManager) Run() {
defer func() {
close(t.drained)
}()
// Send batches of at most maxSamplesPerSend samples to the TSDB. If we
// have fewer samples than that, flush them out after a deadline anyways.
for {
select {
case s, ok := <-t.queue:
if !ok {
glog.Infof("Flushing %d samples to OpenTSDB...", len(t.pendingSamples))
t.flush()
glog.Infof("Done flushing.")
return
}
t.pendingSamples = append(t.pendingSamples, s...)
for len(t.pendingSamples) >= maxSamplesPerSend {
go t.sendSamples(t.pendingSamples[:maxSamplesPerSend])
t.pendingSamples = t.pendingSamples[maxSamplesPerSend:]
}
case <-time.After(batchSendDeadline):
t.flush()
}
}
}
// Flush flushes remaining queued samples.
func (t *TSDBQueueManager) flush() {
if len(t.pendingSamples) > 0 {
go t.sendSamples(t.pendingSamples)
}
t.pendingSamples = t.pendingSamples[:0]
}