manager.go

// Copyright 2015 Google Inc. All Rights Reserved.
//
// 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 sinks

import (
	"sync"
	"time"

	"github.com/golang/glog"
	"github.com/prometheus/client_golang/prometheus"
	"k8s.io/heapster/metrics/core"
)

const (
	DefaultSinkStopTimeout = 60 * time.Second
)

var (
	// Last time Heapster exported data since unix epoch in seconds.
	lastExportTimestamp = prometheus.NewGaugeVec(
		prometheus.GaugeOpts{
			Namespace: "heapster",
			Subsystem: "exporter",
			Name:      "last_time_seconds",
			Help:      "Last time Heapster exported data since unix epoch in seconds.",
		},
		[]string{"exporter"},
	)

	// Time spent exporting data to sink in milliseconds.
	exporterDuration = prometheus.NewSummaryVec(
		prometheus.SummaryOpts{
			Namespace: "heapster",
			Subsystem: "exporter",
			Name:      "duration_milliseconds",
			Help:      "Time spent exporting data to sink in milliseconds.",
		},
		[]string{"exporter"},
	)
)

func init() {
	prometheus.MustRegister(lastExportTimestamp)
	prometheus.MustRegister(exporterDuration)
}

type sinkHolder struct {
	sink             core.DataSink
	dataBatchChannel chan *core.DataBatch
	stopChannel      chan bool
}

// Sink Manager - a special sink that distributes data to other sinks. It pushes data
// only to these sinks that completed their previous exports. Data that could not be
// pushed in the defined time is dropped and not retried.
type sinkManager struct {
	sinkHolders       []sinkHolder
	exportDataTimeout time.Duration
	stopTimeout       time.Duration
}

func NewDataSinkManager(sinks []core.DataSink, exportDataTimeout, stopTimeout time.Duration) (core.DataSink, error) {
	sinkHolders := []sinkHolder{}
	for _, sink := range sinks {
		sh := sinkHolder{
			sink:             sink,
			dataBatchChannel: make(chan *core.DataBatch),
			stopChannel:      make(chan bool),
		}
		sinkHolders = append(sinkHolders, sh)
		go func(sh sinkHolder) {
			for {
				select {
				case data := <-sh.dataBatchChannel:
					export(sh.sink, data)
				case isStop := <-sh.stopChannel:
					glog.V(2).Infof("Stop received: %s", sh.sink.Name())
					if isStop {
						sh.sink.Stop()
						return
					}
				}
			}
		}(sh)
	}
	return &sinkManager{
		sinkHolders:       sinkHolders,
		exportDataTimeout: exportDataTimeout,
		stopTimeout:       stopTimeout,
	}, nil
}

// Guarantees that the export will complete in sinkExportDataTimeout.
func (this *sinkManager) ExportData(data *core.DataBatch) {
	var wg sync.WaitGroup
	for _, sh := range this.sinkHolders {
		wg.Add(1)
		go func(sh sinkHolder, wg *sync.WaitGroup) {
			defer wg.Done()
			glog.V(2).Infof("Pushing data to: %s", sh.sink.Name())
			select {
			case sh.dataBatchChannel <- data:
				glog.V(2).Infof("Data push completed: %s", sh.sink.Name())
				// everything ok
			case <-time.After(this.exportDataTimeout):
				glog.Warningf("Failed to push data to sink: %s", sh.sink.Name())
			}
		}(sh, &wg)
	}
	// Wait for all pushes to complete or timeout.
	wg.Wait()
}

func (this *sinkManager) Name() string {
	return "Manager"
}

func (this *sinkManager) Stop() {
	for _, sh := range this.sinkHolders {
		glog.V(2).Infof("Running stop for: %s", sh.sink.Name())

		go func(sh sinkHolder) {
			select {
			case sh.stopChannel <- true:
				// everything ok
				glog.V(2).Infof("Stop sent to sink: %s", sh.sink.Name())

			case <-time.After(this.stopTimeout):
				glog.Warningf("Failed to stop sink: %s", sh.sink.Name())
			}
			return
		}(sh)
	}
}

func export(s core.DataSink, data *core.DataBatch) {
	startTime := time.Now()

	defer func() {
		lastExportTimestamp.
			WithLabelValues(s.Name()).
			Set(float64(time.Now().Unix()))
	}()
	defer func() {
		exporterDuration.
			WithLabelValues(s.Name()).
			Observe(float64(time.Since(startTime)) / float64(time.Millisecond))
	}()

	s.ExportData(data)
}