435c0d9fc8
This PR switches the Nomad repository from using govendor to Go modules for managing dependencies. Aspects of the Nomad workflow remain pretty much the same. The usual Makefile targets should continue to work as they always did. The API submodule simply defers to the parent Nomad version on the repository, keeping the semantics of API versioning that currently exists.
98 lines
2.5 KiB
Go
98 lines
2.5 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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)
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const (
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sDisconnected int32 = 5 + iota
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sConnected
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)
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func (ae *Exporter) setStateDisconnected() {
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atomic.StoreInt32(&ae.connectionState, sDisconnected)
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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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atomic.StoreInt32(&ae.connectionState, sConnected)
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}
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func (ae *Exporter) connected() bool {
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return atomic.LoadInt32(&ae.connectionState) == sConnected
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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()
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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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<-time.After(connReattemptPeriod + jitter)
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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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