mirror of
https://github.com/prometheus/prometheus.git
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259 lines
7.3 KiB
Go
259 lines
7.3 KiB
Go
// Copyright 2013 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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"sync"
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"time"
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"github.com/prometheus/client_golang/prometheus"
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"github.com/prometheus/common/log"
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"github.com/prometheus/common/model"
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)
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// String constants for instrumentation.
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const (
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namespace = "prometheus"
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subsystem = "remote_storage"
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result = "result"
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success = "success"
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failure = "failure"
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dropped = "dropped"
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)
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// StorageClient defines an interface for sending a batch of samples to an
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// external timeseries database.
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type StorageClient interface {
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// Store stores the given samples in the remote storage.
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Store(model.Samples) error
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// Name identifies the remote storage implementation.
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Name() string
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}
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type StorageQueueManagerConfig struct {
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QueueCapacity int // Number of samples to buffer per shard before we start dropping them.
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Shards int // Number of shards, i.e. amount of concurrency.
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MaxSamplesPerSend int // Maximum number of samples per send.
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BatchSendDeadline time.Duration // Maximum time sample will wait in buffer.
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}
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var defaultConfig = StorageQueueManagerConfig{
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QueueCapacity: 100 * 1024 / 10,
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Shards: 10,
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MaxSamplesPerSend: 100,
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BatchSendDeadline: 5 * time.Second,
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}
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// StorageQueueManager manages a queue of samples to be sent to the Storage
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// indicated by the provided StorageClient.
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type StorageQueueManager struct {
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cfg StorageQueueManagerConfig
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tsdb StorageClient
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shards []chan *model.Sample
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wg sync.WaitGroup
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done chan struct{}
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sentSamplesTotal *prometheus.CounterVec
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sentBatchDuration *prometheus.HistogramVec
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queueLength prometheus.Gauge
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queueCapacity prometheus.Metric
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}
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// NewStorageQueueManager builds a new StorageQueueManager.
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func NewStorageQueueManager(tsdb StorageClient, cfg *StorageQueueManagerConfig) *StorageQueueManager {
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constLabels := prometheus.Labels{
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"type": tsdb.Name(),
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}
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if cfg == nil {
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cfg = &defaultConfig
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}
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shards := make([]chan *model.Sample, cfg.Shards)
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for i := 0; i < cfg.Shards; i++ {
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shards[i] = make(chan *model.Sample, cfg.QueueCapacity)
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}
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t := &StorageQueueManager{
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cfg: *cfg,
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tsdb: tsdb,
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shards: shards,
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done: make(chan struct{}),
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sentSamplesTotal: prometheus.NewCounterVec(
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prometheus.CounterOpts{
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Namespace: namespace,
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Subsystem: subsystem,
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Name: "sent_samples_total",
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Help: "Total number of processed samples sent to remote storage.",
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ConstLabels: constLabels,
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},
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[]string{result},
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),
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sentBatchDuration: prometheus.NewHistogramVec(
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prometheus.HistogramOpts{
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Namespace: namespace,
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Subsystem: subsystem,
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Name: "sent_batch_duration_seconds",
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Help: "Duration of sample batch send calls to the remote storage.",
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ConstLabels: constLabels,
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Buckets: prometheus.DefBuckets,
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},
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[]string{result},
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),
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queueLength: prometheus.NewGauge(prometheus.GaugeOpts{
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Namespace: namespace,
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Subsystem: subsystem,
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Name: "queue_length",
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Help: "The number of processed samples queued to be sent to the remote storage.",
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ConstLabels: constLabels,
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}),
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queueCapacity: prometheus.MustNewConstMetric(
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prometheus.NewDesc(
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prometheus.BuildFQName(namespace, subsystem, "queue_capacity"),
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"The capacity of the queue of samples to be sent to the remote storage.",
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nil,
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constLabels,
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),
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prometheus.GaugeValue,
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float64(cfg.QueueCapacity*cfg.Shards),
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),
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}
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t.wg.Add(cfg.Shards)
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return t
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}
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// Append queues a sample to be sent to the remote storage. It drops the
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// sample on the floor if the queue is full.
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// Always returns nil.
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func (t *StorageQueueManager) Append(s *model.Sample) error {
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fp := s.Metric.FastFingerprint()
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shard := uint64(fp) % uint64(t.cfg.Shards)
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select {
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case t.shards[shard] <- s:
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default:
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t.sentSamplesTotal.WithLabelValues(dropped).Inc()
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log.Warn("Remote storage queue full, discarding sample.")
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}
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return nil
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}
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// NeedsThrottling implements storage.SampleAppender. It will always return
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// false as a remote storage drops samples on the floor if backlogging instead
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// of asking for throttling.
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func (*StorageQueueManager) NeedsThrottling() bool {
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return false
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}
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// Describe implements prometheus.Collector.
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func (t *StorageQueueManager) Describe(ch chan<- *prometheus.Desc) {
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t.sentSamplesTotal.Describe(ch)
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t.sentBatchDuration.Describe(ch)
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ch <- t.queueLength.Desc()
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ch <- t.queueCapacity.Desc()
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}
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// QueueLength returns the number of outstanding samples in the queue.
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func (t *StorageQueueManager) queueLen() int {
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queueLength := 0
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for _, shard := range t.shards {
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queueLength += len(shard)
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}
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return queueLength
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}
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// Collect implements prometheus.Collector.
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func (t *StorageQueueManager) Collect(ch chan<- prometheus.Metric) {
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t.sentSamplesTotal.Collect(ch)
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t.sentBatchDuration.Collect(ch)
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t.queueLength.Set(float64(t.queueLen()))
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ch <- t.queueLength
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ch <- t.queueCapacity
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}
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// Run continuously sends samples to the remote storage.
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func (t *StorageQueueManager) Run() {
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for i := 0; i < t.cfg.Shards; i++ {
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go t.runShard(i)
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}
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t.wg.Wait()
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}
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// Stop stops sending samples to the remote storage and waits for pending
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// sends to complete.
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func (t *StorageQueueManager) Stop() {
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log.Infof("Stopping remote storage...")
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for _, shard := range t.shards {
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close(shard)
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}
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t.wg.Wait()
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log.Info("Remote storage stopped.")
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}
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func (t *StorageQueueManager) runShard(i int) {
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defer t.wg.Done()
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shard := t.shards[i]
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// Send batches of at most MaxSamplesPerSend samples to the remote storage.
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// If we have fewer samples than that, flush them out after a deadline
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// anyways.
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pendingSamples := model.Samples{}
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for {
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select {
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case s, ok := <-shard:
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if !ok {
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if len(pendingSamples) > 0 {
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log.Infof("Flushing %d samples to remote storage...", len(pendingSamples))
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t.sendSamples(pendingSamples)
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log.Infof("Done flushing.")
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}
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return
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}
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pendingSamples = append(pendingSamples, s)
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for len(pendingSamples) >= t.cfg.MaxSamplesPerSend {
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t.sendSamples(pendingSamples[:t.cfg.MaxSamplesPerSend])
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pendingSamples = pendingSamples[t.cfg.MaxSamplesPerSend:]
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}
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case <-time.After(t.cfg.BatchSendDeadline):
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if len(pendingSamples) > 0 {
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t.sendSamples(pendingSamples)
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pendingSamples = pendingSamples[:0]
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}
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}
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}
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}
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func (t *StorageQueueManager) sendSamples(s model.Samples) {
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// Samples are sent to the remote storage on a best-effort basis. If a
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// sample isn't sent correctly the first time, it's simply dropped on the
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// floor.
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begin := time.Now()
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err := t.tsdb.Store(s)
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duration := time.Since(begin).Seconds()
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labelValue := success
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if err != nil {
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log.Warnf("error sending %d samples to remote storage: %s", len(s), err)
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labelValue = failure
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}
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t.sentSamplesTotal.WithLabelValues(labelValue).Add(float64(len(s)))
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t.sentBatchDuration.WithLabelValues(labelValue).Observe(duration)
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}
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