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