forked from jaegertracing/jaeger
/
agent.go
86 lines (74 loc) · 2.42 KB
/
agent.go
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// Copyright (c) 2017 Uber Technologies, Inc.
//
// 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 services
import (
"encoding/json"
"errors"
"fmt"
"io/ioutil"
"net/http"
"go.uber.org/zap"
"github.com/jaegertracing/jaeger/thrift-gen/sampling"
)
var (
errSamplingRateMissing = errors.New("sampling rate is missing")
)
// AgentService is the service used to report traces to the collector.
type AgentService interface {
GetSamplingRate(service, operation string) (float64, error)
}
type agentService struct {
url string
logger *zap.Logger
}
// NewAgentService returns an instance of AgentService.
func NewAgentService(url string, logger *zap.Logger) AgentService {
return &agentService{
url: url,
logger: logger,
}
}
func getSamplingURL(url string) string {
return url + "/sampling?service=%s"
}
// GetSamplingRate returns the sampling rate for the service-operation from the agent service.
func (s *agentService) GetSamplingRate(service, operation string) (float64, error) {
url := fmt.Sprintf(getSamplingURL(s.url), getTracerServiceName(service))
resp, err := http.Get(url)
if err != nil {
return 0, err
}
defer resp.Body.Close()
body, _ := ioutil.ReadAll(resp.Body)
s.logger.Info("Retrieved sampling rates from agent", zap.String("body", string(body)))
var response sampling.SamplingStrategyResponse
if err = json.Unmarshal(body, &response); err != nil {
return 0, err
}
return getSamplingRate(operation, &response)
}
func getSamplingRate(operation string, response *sampling.SamplingStrategyResponse) (float64, error) {
if response.OperationSampling == nil {
return 0, errSamplingRateMissing
}
if len(response.OperationSampling.PerOperationStrategies) == 0 {
return 0, errSamplingRateMissing
}
for _, strategy := range response.OperationSampling.PerOperationStrategies {
if strategy.Operation == operation {
return strategy.ProbabilisticSampling.SamplingRate, nil
}
}
return 0, errSamplingRateMissing
}