| // 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) |
| } |