/
opencensus.go
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/
opencensus.go
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// Copyright The OpenTelemetry 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 opencensusexporter
import (
"context"
"errors"
"fmt"
commonpb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/common/v1"
agentmetricspb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/metrics/v1"
agenttracepb "github.com/census-instrumentation/opencensus-proto/gen-go/agent/trace/v1"
resourcepb "github.com/census-instrumentation/opencensus-proto/gen-go/resource/v1"
"google.golang.org/grpc"
"google.golang.org/grpc/metadata"
"go.opentelemetry.io/collector/component"
"go.opentelemetry.io/collector/model/pdata"
"go.opentelemetry.io/collector/translator/internaldata"
)
// See https://godoc.org/google.golang.org/grpc#ClientConn.NewStream
// why we need to keep the cancel func to cancel the stream
type tracesClientWithCancel struct {
cancel context.CancelFunc
tsec agenttracepb.TraceService_ExportClient
}
// See https://godoc.org/google.golang.org/grpc#ClientConn.NewStream
// why we need to keep the cancel func to cancel the stream
type metricsClientWithCancel struct {
cancel context.CancelFunc
msec agentmetricspb.MetricsService_ExportClient
}
type ocExporter struct {
cfg *Config
// gRPC clients and connection.
traceSvcClient agenttracepb.TraceServiceClient
metricsSvcClient agentmetricspb.MetricsServiceClient
// In any of the channels we keep always NumWorkers object (sometimes nil),
// to make sure we don't open more than NumWorkers RPCs at any moment.
tracesClients chan *tracesClientWithCancel
metricsClients chan *metricsClientWithCancel
grpcClientConn *grpc.ClientConn
metadata metadata.MD
}
func newOcExporter(_ context.Context, cfg *Config) (*ocExporter, error) {
if cfg.Endpoint == "" {
return nil, errors.New("OpenCensus exporter cfg requires an Endpoint")
}
if cfg.NumWorkers <= 0 {
return nil, errors.New("OpenCensus exporter cfg requires at least one worker")
}
oce := &ocExporter{
cfg: cfg,
metadata: metadata.New(cfg.GRPCClientSettings.Headers),
}
return oce, nil
}
// start creates the gRPC client Connection
func (oce *ocExporter) start(ctx context.Context, host component.Host) error {
dialOpts, err := oce.cfg.GRPCClientSettings.ToDialOptions(host.GetExtensions())
if err != nil {
return err
}
var clientConn *grpc.ClientConn
if clientConn, err = grpc.DialContext(ctx, oce.cfg.GRPCClientSettings.Endpoint, dialOpts...); err != nil {
return err
}
oce.grpcClientConn = clientConn
if oce.tracesClients != nil {
oce.traceSvcClient = agenttracepb.NewTraceServiceClient(oce.grpcClientConn)
// Try to create rpc clients now.
for i := 0; i < oce.cfg.NumWorkers; i++ {
// Populate the channel with NumWorkers nil RPCs to keep the number of workers
// constant in the channel.
oce.tracesClients <- nil
}
}
if oce.metricsClients != nil {
oce.metricsSvcClient = agentmetricspb.NewMetricsServiceClient(oce.grpcClientConn)
// Try to create rpc clients now.
for i := 0; i < oce.cfg.NumWorkers; i++ {
// Populate the channel with NumWorkers nil RPCs to keep the number of workers
// constant in the channel.
oce.metricsClients <- nil
}
}
return nil
}
func (oce *ocExporter) shutdown(context.Context) error {
if oce.tracesClients != nil {
// First remove all the clients from the channel.
for i := 0; i < oce.cfg.NumWorkers; i++ {
<-oce.tracesClients
}
// Now close the channel
close(oce.tracesClients)
}
if oce.metricsClients != nil {
// First remove all the clients from the channel.
for i := 0; i < oce.cfg.NumWorkers; i++ {
<-oce.metricsClients
}
// Now close the channel
close(oce.metricsClients)
}
return oce.grpcClientConn.Close()
}
func newTracesExporter(ctx context.Context, cfg *Config) (*ocExporter, error) {
oce, err := newOcExporter(ctx, cfg)
if err != nil {
return nil, err
}
oce.tracesClients = make(chan *tracesClientWithCancel, oce.cfg.NumWorkers)
return oce, nil
}
func newMetricsExporter(ctx context.Context, cfg *Config) (*ocExporter, error) {
oce, err := newOcExporter(ctx, cfg)
if err != nil {
return nil, err
}
oce.metricsClients = make(chan *metricsClientWithCancel, oce.cfg.NumWorkers)
return oce, nil
}
func (oce *ocExporter) pushTraces(_ context.Context, td pdata.Traces) error {
// Get first available trace Client.
tClient, ok := <-oce.tracesClients
if !ok {
err := errors.New("failed to push traces, OpenCensus exporter was already stopped")
return err
}
// In any of the metricsClients channel we keep always NumWorkers object (sometimes nil),
// to make sure we don't open more than NumWorkers RPCs at any moment.
// Here check if the client is nil and create a new one if that is the case. A nil
// object means that an error happened: could not connect, service went down, etc.
if tClient == nil {
var err error
tClient, err = oce.createTraceServiceRPC()
if err != nil {
// Cannot create an RPC, put back nil to keep the number of workers constant.
oce.tracesClients <- nil
return err
}
}
rss := td.ResourceSpans()
for i := 0; i < rss.Len(); i++ {
node, resource, spans := internaldata.ResourceSpansToOC(rss.At(i))
// This is a hack because OC protocol expects a Node for the initial message.
if node == nil {
node = &commonpb.Node{}
}
if resource == nil {
resource = &resourcepb.Resource{}
}
req := &agenttracepb.ExportTraceServiceRequest{
Spans: spans,
Resource: resource,
Node: node,
}
if err := tClient.tsec.Send(req); err != nil {
// Error received, cancel the context used to create the RPC to free all resources,
// put back nil to keep the number of workers constant.
tClient.cancel()
oce.tracesClients <- nil
return err
}
}
oce.tracesClients <- tClient
return nil
}
func (oce *ocExporter) pushMetrics(_ context.Context, md pdata.Metrics) error {
// Get first available mClient.
mClient, ok := <-oce.metricsClients
if !ok {
err := errors.New("failed to push metrics, OpenCensus exporter was already stopped")
return err
}
// In any of the metricsClients channel we keep always NumWorkers object (sometimes nil),
// to make sure we don't open more than NumWorkers RPCs at any moment.
// Here check if the client is nil and create a new one if that is the case. A nil
// object means that an error happened: could not connect, service went down, etc.
if mClient == nil {
var err error
mClient, err = oce.createMetricsServiceRPC()
if err != nil {
// Cannot create an RPC, put back nil to keep the number of workers constant.
oce.metricsClients <- nil
return err
}
}
rms := md.ResourceMetrics()
for i := 0; i < rms.Len(); i++ {
ocReq := agentmetricspb.ExportMetricsServiceRequest{}
ocReq.Node, ocReq.Resource, ocReq.Metrics = internaldata.ResourceMetricsToOC(rms.At(i))
// This is a hack because OC protocol expects a Node for the initial message.
if ocReq.Node == nil {
ocReq.Node = &commonpb.Node{}
}
if ocReq.Resource == nil {
ocReq.Resource = &resourcepb.Resource{}
}
if err := mClient.msec.Send(&ocReq); err != nil {
// Error received, cancel the context used to create the RPC to free all resources,
// put back nil to keep the number of workers constant.
mClient.cancel()
oce.metricsClients <- nil
return err
}
}
oce.metricsClients <- mClient
return nil
}
func (oce *ocExporter) createTraceServiceRPC() (*tracesClientWithCancel, error) {
// Initiate the trace service by sending over node identifier info.
ctx, cancel := context.WithCancel(context.Background())
if len(oce.cfg.Headers) > 0 {
ctx = metadata.NewOutgoingContext(ctx, metadata.New(oce.cfg.Headers))
}
// Cannot use grpc.WaitForReady(cfg.WaitForReady) because will block forever.
traceClient, err := oce.traceSvcClient.Export(ctx)
if err != nil {
cancel()
return nil, fmt.Errorf("TraceServiceClient: %w", err)
}
return &tracesClientWithCancel{cancel: cancel, tsec: traceClient}, nil
}
func (oce *ocExporter) createMetricsServiceRPC() (*metricsClientWithCancel, error) {
// Initiate the trace service by sending over node identifier info.
ctx, cancel := context.WithCancel(context.Background())
if len(oce.cfg.Headers) > 0 {
ctx = metadata.NewOutgoingContext(ctx, metadata.New(oce.cfg.Headers))
}
// Cannot use grpc.WaitForReady(cfg.WaitForReady) because will block forever.
metricsClient, err := oce.metricsSvcClient.Export(ctx)
if err != nil {
cancel()
return nil, fmt.Errorf("MetricsServiceClient: %w", err)
}
return &metricsClientWithCancel{cancel: cancel, msec: metricsClient}, nil
}