prometheus/vendor/contrib.go.opencensus.io/exporter/ocagent/connection.go

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// Copyright 2018, OpenCensus 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 ocagent
import (
"math/rand"
"sync/atomic"
"time"
)
const (
sDisconnected int32 = 5 + iota
sConnected
)
func (ae *Exporter) setStateDisconnected() {
atomic.StoreInt32(&ae.connectionState, sDisconnected)
ae.disconnectedCh <- true
}
func (ae *Exporter) setStateConnected() {
atomic.StoreInt32(&ae.connectionState, sConnected)
}
func (ae *Exporter) connected() bool {
return atomic.LoadInt32(&ae.connectionState) == sConnected
}
const defaultConnReattemptPeriod = 10 * time.Second
func (ae *Exporter) indefiniteBackgroundConnection() error {
defer func() {
ae.backgroundConnectionDoneCh <- true
}()
connReattemptPeriod := ae.reconnectionPeriod
if connReattemptPeriod <= 0 {
connReattemptPeriod = defaultConnReattemptPeriod
}
// No strong seeding required, nano time can
// already help with pseudo uniqueness.
rng := rand.New(rand.NewSource(time.Now().UnixNano() + rand.Int63n(1024)))
// maxJitter: 1 + (70% of the connectionReattemptPeriod)
maxJitter := int64(1 + 0.7*float64(connReattemptPeriod))
for {
// Otherwise these will be the normal scenarios to enable
// reconnections if we trip out.
// 1. If we've stopped, return entirely
// 2. Otherwise block until we are disconnected, and
// then retry connecting
select {
case <-ae.stopCh:
return errStopped
case <-ae.disconnectedCh:
// Normal scenario that we'll wait for
}
if err := ae.connect(); err == nil {
ae.setStateConnected()
} else {
ae.setStateDisconnected()
}
// Apply some jitter to avoid lockstep retrials of other
// agent-exporters. Lockstep retrials could result in an
// innocent DDOS, by clogging the machine's resources and network.
jitter := time.Duration(rng.Int63n(maxJitter))
<-time.After(connReattemptPeriod + jitter)
}
}
func (ae *Exporter) connect() error {
cc, err := ae.dialToAgent()
if err != nil {
return err
}
return ae.enableConnectionStreams(cc)
}