Add ocagent exporter
ocagent allows users to send traces out of VK to a "standard" external forwarder (standard as in this is a format/protocol defined in the opencensus project). This allows uers to implement metrics for whatever backend they want without having to add it into VK directly.
This commit is contained in:
Brian Goff
320
vendor/contrib.go.opencensus.io/exporter/ocagent/ocagent.go
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320
vendor/contrib.go.opencensus.io/exporter/ocagent/ocagent.go
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// 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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"context"
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"errors"
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"fmt"
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"sync"
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"time"
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"google.golang.org/api/support/bundler"
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"google.golang.org/grpc"
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"go.opencensus.io/trace"
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agentcommonpb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/common/v1"
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agenttracepb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/trace/v1"
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tracepb "github.com/census-instrumentation/opencensus-proto/gen-go/trace/v1"
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)
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var startupMu sync.Mutex
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var startTime time.Time
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func init() {
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startupMu.Lock()
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startTime = time.Now()
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startupMu.Unlock()
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}
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var _ trace.Exporter = (*Exporter)(nil)
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type Exporter struct {
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connectionState int32
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// mu protects the non-atomic and non-channel variables
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mu sync.RWMutex
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started bool
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stopped bool
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agentAddress string
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serviceName string
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canDialInsecure bool
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traceSvcClient agenttracepb.TraceServiceClient
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traceExporter agenttracepb.TraceService_ExportClient
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nodeInfo *agentcommonpb.Node
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grpcClientConn *grpc.ClientConn
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reconnectionPeriod time.Duration
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startOnce sync.Once
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stopCh chan bool
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disconnectedCh chan bool
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backgroundConnectionDoneCh chan bool
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traceBundler *bundler.Bundler
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}
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func NewExporter(opts ...ExporterOption) (*Exporter, error) {
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exp, err := NewUnstartedExporter(opts...)
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if err != nil {
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return nil, err
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}
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if err := exp.Start(); err != nil {
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return nil, err
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}
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return exp, nil
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}
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const spanDataBufferSize = 300
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func NewUnstartedExporter(opts ...ExporterOption) (*Exporter, error) {
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e := new(Exporter)
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for _, opt := range opts {
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opt.withExporter(e)
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}
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traceBundler := bundler.NewBundler((*trace.SpanData)(nil), func(bundle interface{}) {
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e.uploadTraces(bundle.([]*trace.SpanData))
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})
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traceBundler.DelayThreshold = 2 * time.Second
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traceBundler.BundleCountThreshold = spanDataBufferSize
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e.traceBundler = traceBundler
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e.nodeInfo = createNodeInfo(e.serviceName)
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return e, nil
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}
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const (
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maxInitialConfigRetries = 10
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maxInitialTracesRetries = 10
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)
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var (
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errAlreadyStarted = errors.New("already started")
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errStopped = errors.New("stopped")
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)
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// Start dials to the agent, establishing a connection to it. It also
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// initiates the Config and Trace services by sending over the initial
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// messages that consist of the node identifier. Start invokes a background
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// connector that will reattempt connections to the agent periodically
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// if the connection dies.
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func (ae *Exporter) Start() error {
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var err = errAlreadyStarted
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ae.startOnce.Do(func() {
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ae.mu.Lock()
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defer ae.mu.Unlock()
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ae.started = true
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ae.disconnectedCh = make(chan bool, 1)
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ae.stopCh = make(chan bool)
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ae.backgroundConnectionDoneCh = make(chan bool)
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ae.setStateDisconnected()
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go ae.indefiniteBackgroundConnection()
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err = nil
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})
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return err
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}
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func (ae *Exporter) prepareAgentAddress() string {
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if ae.agentAddress != "" {
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return ae.agentAddress
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}
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return fmt.Sprintf("%s:%d", DefaultAgentHost, DefaultAgentPort)
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}
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func (ae *Exporter) enableConnectionStreams(cc *grpc.ClientConn) error {
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ae.mu.RLock()
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started := ae.started
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nodeInfo := ae.nodeInfo
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ae.mu.RUnlock()
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if !started {
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return errNotStarted
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}
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ae.mu.Lock()
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// If the previous clientConn was non-nil, close it
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if ae.grpcClientConn != nil {
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_ = ae.grpcClientConn.Close()
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}
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ae.grpcClientConn = cc
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ae.mu.Unlock()
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// Initiate the trace service by sending over node identifier info.
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traceSvcClient := agenttracepb.NewTraceServiceClient(cc)
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traceExporter, err := traceSvcClient.Export(context.Background())
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if err != nil {
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return fmt.Errorf("Exporter.Start:: TraceServiceClient: %v", err)
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}
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firstTraceMessage := &agenttracepb.ExportTraceServiceRequest{Node: nodeInfo}
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if err := traceExporter.Send(firstTraceMessage); err != nil {
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return fmt.Errorf("Exporter.Start:: Failed to initiate the Config service: %v", err)
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}
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ae.traceExporter = traceExporter
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// Initiate the config service by sending over node identifier info.
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configStream, err := traceSvcClient.Config(context.Background())
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if err != nil {
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return fmt.Errorf("Exporter.Start:: ConfigStream: %v", err)
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}
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firstCfgMessage := &agenttracepb.CurrentLibraryConfig{Node: nodeInfo}
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if err := configStream.Send(firstCfgMessage); err != nil {
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return fmt.Errorf("Exporter.Start:: Failed to initiate the Config service: %v", err)
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}
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// In the background, handle trace configurations that are beamed down
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// by the agent, but also reply to it with the applied configuration.
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go ae.handleConfigStreaming(configStream)
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return nil
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}
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func (ae *Exporter) dialToAgent() (*grpc.ClientConn, error) {
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addr := ae.prepareAgentAddress()
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var dialOpts []grpc.DialOption
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if ae.canDialInsecure {
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dialOpts = append(dialOpts, grpc.WithInsecure())
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}
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return grpc.Dial(addr, dialOpts...)
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}
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func (ae *Exporter) handleConfigStreaming(configStream agenttracepb.TraceService_ConfigClient) error {
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// Note: We haven't yet implemented configuration sending so we
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// should NOT be changing connection states within this function for now.
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for {
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recv, err := configStream.Recv()
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if err != nil {
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// TODO: Check if this is a transient error or exponential backoff-able.
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return err
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}
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cfg := recv.Config
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if cfg == nil {
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continue
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}
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// Otherwise now apply the trace configuration sent down from the agent
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if psamp := cfg.GetProbabilitySampler(); psamp != nil {
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trace.ApplyConfig(trace.Config{DefaultSampler: trace.ProbabilitySampler(psamp.SamplingProbability)})
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} else if csamp := cfg.GetConstantSampler(); csamp != nil {
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alwaysSample := csamp.Decision == true
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if alwaysSample {
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trace.ApplyConfig(trace.Config{DefaultSampler: trace.AlwaysSample()})
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} else {
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trace.ApplyConfig(trace.Config{DefaultSampler: trace.NeverSample()})
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}
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} else { // TODO: Add the rate limiting sampler here
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}
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// Then finally send back to upstream the newly applied configuration
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err = configStream.Send(&agenttracepb.CurrentLibraryConfig{Config: &tracepb.TraceConfig{Sampler: cfg.Sampler}})
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if err != nil {
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return err
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}
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}
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}
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var (
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errNotStarted = errors.New("not started")
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)
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// Stop shuts down all the connections and resources
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// related to the exporter.
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func (ae *Exporter) Stop() error {
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ae.mu.RLock()
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cc := ae.grpcClientConn
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started := ae.started
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stopped := ae.stopped
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ae.mu.RUnlock()
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if !started {
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return errNotStarted
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}
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if stopped {
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// TODO: tell the user that we've already stopped, so perhaps a sentinel error?
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return nil
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}
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ae.Flush()
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// Now close the underlying gRPC connection.
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var err error
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if cc != nil {
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err = cc.Close()
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}
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// At this point we can change the state variables: started and stopped
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ae.mu.Lock()
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ae.started = false
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ae.stopped = true
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ae.mu.Unlock()
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close(ae.stopCh)
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// Ensure that the backgroundConnector returns
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<-ae.backgroundConnectionDoneCh
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return err
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}
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func (ae *Exporter) ExportSpan(sd *trace.SpanData) {
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if sd == nil {
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return
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}
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_ = ae.traceBundler.Add(sd, 1)
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}
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func ocSpanDataToPbSpans(sdl []*trace.SpanData) []*tracepb.Span {
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if len(sdl) == 0 {
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return nil
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}
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protoSpans := make([]*tracepb.Span, 0, len(sdl))
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for _, sd := range sdl {
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if sd != nil {
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protoSpans = append(protoSpans, ocSpanToProtoSpan(sd))
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}
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}
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return protoSpans
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}
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func (ae *Exporter) uploadTraces(sdl []*trace.SpanData) {
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select {
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case <-ae.stopCh:
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return
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default:
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if !ae.connected() {
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return
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}
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protoSpans := ocSpanDataToPbSpans(sdl)
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if len(protoSpans) == 0 {
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return
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}
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err := ae.traceExporter.Send(&agenttracepb.ExportTraceServiceRequest{
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Spans: protoSpans,
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})
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if err != nil {
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ae.setStateDisconnected()
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}
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}
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}
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func (ae *Exporter) Flush() {
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ae.traceBundler.Flush()
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}
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