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// Copyright 2014 The Cockroach 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. See the AUTHORS file
// for names of contributors.
//
// Author: Tyler Neely (t@jujit.su)
package loghisto
import (
"net"
"sync"
"time"
)
type requestable interface{}
type requestableArray interface {
ToRequest() []byte
}
// Submitter encapsulates the state of a metric submitter.
type Submitter struct {
// backlog works as an evicting queue
backlog [60][]byte
backlogHead uint
backlogTail uint
backlogMu sync.Mutex
serializer func(*ProcessedMetricSet) []byte
DestinationNetwork string
DestinationAddress string
metricSystem *MetricSystem
metricChan chan *ProcessedMetricSet
shutdownChan chan struct{}
}
// NewSubmitter creates a Submitter that receives metrics off of a
// specified metric channel, serializes them using the provided
// serialization function, and attempts to send them to the
// specified destination.
func NewSubmitter(metricSystem *MetricSystem,
serializer func(*ProcessedMetricSet) []byte, destinationNetwork string,
destinationAddress string) *Submitter {
metricChan := make(chan *ProcessedMetricSet, 60)
metricSystem.SubscribeToProcessedMetrics(metricChan)
return &Submitter{
backlog: [60][]byte{},
backlogHead: 0,
backlogTail: 0,
serializer: serializer,
DestinationNetwork: destinationNetwork,
DestinationAddress: destinationAddress,
metricSystem: metricSystem,
metricChan: metricChan,
shutdownChan: make(chan struct{}),
}
}
func (s *Submitter) retryBacklog() error {
var request []byte
for {
s.backlogMu.Lock()
head := s.backlogHead
tail := s.backlogTail
if head != tail {
request = s.backlog[head]
}
s.backlogMu.Unlock()
if head == tail {
return nil
}
err := s.submit(request)
if err != nil {
return err
}
s.backlogMu.Lock()
s.backlogHead = (s.backlogHead + 1) % 60
s.backlogMu.Unlock()
}
}
func (s *Submitter) appendToBacklog(request []byte) {
s.backlogMu.Lock()
s.backlog[s.backlogTail] = request
s.backlogTail = (s.backlogTail + 1) % 60
// if we've run into the head, evict it
if s.backlogHead == s.backlogTail {
s.backlogHead = (s.backlogHead + 1) % 60
}
s.backlogMu.Unlock()
}
func (s *Submitter) submit(request []byte) error {
conn, err := net.DialTimeout(s.DestinationNetwork, s.DestinationAddress,
5*time.Second)
if err != nil {
return err
}
conn.SetDeadline(time.Now().Add(5 * time.Second))
_, err = conn.Write(request)
conn.Close()
return err
}
// Start creates the goroutines that receive, serialize, and send metrics.
func (s *Submitter) Start() {
go func() {
for {
select {
case metrics, ok := <-s.metricChan:
if !ok {
// We can no longer make progress.
return
}
request := s.serializer(metrics)
s.appendToBacklog(request)
case <-s.shutdownChan:
return
}
}
}()
go func() {
for {
select {
case <-s.shutdownChan:
return
default:
s.retryBacklog()
tts := s.metricSystem.interval.Nanoseconds() -
(time.Now().UnixNano() % s.metricSystem.interval.Nanoseconds())
time.Sleep(time.Duration(tts))
}
}
}()
}
// Shutdown shuts down a submitter
func (s *Submitter) Shutdown() {
select {
case <-s.shutdownChan:
// already closed
default:
close(s.shutdownChan)
}
}
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