[target-allocator] marshal with jsoniter (#1323)

* benchmarking jsoniter

* fix imports

* fix lint issues

* add chlog file

* remove duplicate funcs used for benchmarking

* fix imports

.chloggen/use-json-iterator.yaml

@@ -0,0 +1,17 @@
+# One of 'breaking', 'deprecation', 'new_component', 'enhancement', 'bug_fix'
+change_type: enhancement
+
+# The name of the component, or a single word describing the area of concern, (e.g. operator, target allocator, github action)
+component: Target Allocator
+
+# A brief description of the change. Surround your text with quotes ("") if it needs to start with a backtick (`).
+note: Use json-iter to marshal json
+
+# One or more tracking issues related to the change
+issues:
+  - 1336
+
+# (Optional) One or more lines of additional information to render under the primary note.
+# These lines will be padded with 2 spaces and then inserted directly into the document.
+# Use pipe (|) for multiline entries.
+subtext:

cmd/otel-allocator/go.mod

@@ -10,6 +10,7 @@ require (
 	github.com/go-kit/log v0.2.1
 	github.com/go-logr/logr v1.2.3
 	github.com/gorilla/mux v1.8.0
+	github.com/json-iterator/go v1.1.12
 	github.com/mitchellh/hashstructure v1.1.0
 	github.com/oklog/run v1.1.0
 	github.com/prometheus-operator/prometheus-operator v0.53.1
@@ -111,7 +112,6 @@ require (
 	github.com/jmespath/go-jmespath v0.4.0 // indirect
 	github.com/josharian/intern v1.0.0 // indirect
 	github.com/jpillora/backoff v1.0.0 // indirect
-	github.com/json-iterator/go v1.1.12 // indirect
 	github.com/kolo/xmlrpc v0.0.0-20201022064351-38db28db192b // indirect
 	github.com/linode/linodego v1.8.0 // indirect
 	github.com/mailru/easyjson v0.7.7 // indirect

cmd/otel-allocator/server/server.go

@@ -16,20 +16,19 @@ package server
 
 import (
 	"context"
-	"encoding/json"
 	"fmt"
 	"net/http"
 	"net/url"
 	"time"
 
-	yaml2 "github.com/ghodss/yaml"
 	"github.com/go-logr/logr"
 	"github.com/gorilla/mux"
+	jsoniter "github.com/json-iterator/go"
 	"github.com/mitchellh/hashstructure"
 	"github.com/prometheus/client_golang/prometheus"
 	"github.com/prometheus/client_golang/prometheus/promauto"
 	"github.com/prometheus/client_golang/prometheus/promhttp"
-	"gopkg.in/yaml.v2"
+	promconfig "github.com/prometheus/prometheus/config"
 
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/allocation"
 	"github.com/open-telemetry/opentelemetry-operator/cmd/otel-allocator/target"
@@ -42,27 +41,49 @@ var (
 	}, []string{"path"})
 )
 
+var (
+	yamlConfig = jsoniter.Config{
+		EscapeHTML:                    false,
+		MarshalFloatWith6Digits:       true,
+		ObjectFieldMustBeSimpleString: true,
+		TagKey:                        "yaml",
+	}.Froze()
+	jsonConfig = jsoniter.Config{
+		EscapeHTML:                    false,
+		MarshalFloatWith6Digits:       true,
+		ObjectFieldMustBeSimpleString: true,
+	}.Froze()
+)
+
 type collectorJSON struct {
 	Link string         `json:"_link"`
 	Jobs []*target.Item `json:"targets"`
 }
 
+type DiscoveryManager interface {
+	GetScrapeConfigs() map[string]*promconfig.ScrapeConfig
+}
+
 type Server struct {
 	logger           logr.Logger
 	allocator        allocation.Allocator
-	discoveryManager *target.Discoverer
+	discoveryManager DiscoveryManager
 	server           *http.Server
+	yamlMarshaller   jsoniter.API // TODO: for testing, it would make a lot of sense to have a simpler interface
+	jsonMarshaller   jsoniter.API // TODO: for testing, it would make a lot of sense to have a simpler interface
 
 	compareHash          uint64
 	scrapeConfigResponse []byte
 }
 
-func NewServer(log logr.Logger, allocator allocation.Allocator, discoveryManager *target.Discoverer, listenAddr *string) *Server {
+func NewServer(log logr.Logger, allocator allocation.Allocator, discoveryManager DiscoveryManager, listenAddr *string) *Server {
 	s := &Server{
 		logger:           log,
 		allocator:        allocator,
 		discoveryManager: discoveryManager,
 		compareHash:      uint64(0),
+		yamlMarshaller:   yamlConfig,
+		jsonMarshaller:   jsonConfig,
 	}
 	router := mux.NewRouter().UseEncodedPath()
 	router.Use(s.PrometheusMiddleware)
@@ -87,7 +108,7 @@ func (s *Server) Shutdown(ctx context.Context) error {
 // ScrapeConfigsHandler returns the available scrape configuration discovered by the target allocator.
 // The target allocator first marshals these configurations such that the underlying prometheus marshaling is used.
 // After that, the YAML is converted in to a JSON format for consumers to use.
-func (s *Server) ScrapeConfigsHandler(w http.ResponseWriter, r *http.Request) {
+func (s *Server) ScrapeConfigsHandler(w http.ResponseWriter, _ *http.Request) {
 	configs := s.discoveryManager.GetScrapeConfigs()
 
 	hash, err := hashstructure.Hash(configs, nil)
@@ -98,19 +119,13 @@ func (s *Server) ScrapeConfigsHandler(w http.ResponseWriter, r *http.Request) {
 	}
 	// if the hashes are different, we need to recompute the scrape config
 	if hash != s.compareHash {
-		var configBytes []byte
-		configBytes, err = yaml.Marshal(configs)
-		if err != nil {
-			s.errorHandler(w, err)
-			return
-		}
-		var jsonConfig []byte
-		jsonConfig, err = yaml2.YAMLToJSON(configBytes)
-		if err != nil {
-			s.errorHandler(w, err)
+		configBytes, mErr := s.yamlMarshaller.Marshal(configs)
+		if mErr != nil {
+			s.errorHandler(w, mErr)
 			return
 		}
-		s.scrapeConfigResponse = jsonConfig
+		// Update the response and the hash
+		s.scrapeConfigResponse = configBytes
 		s.compareHash = hash
 	}
 	// We don't use the jsonHandler method because we don't want our bytes to be re-encoded
@@ -121,7 +136,7 @@ func (s *Server) ScrapeConfigsHandler(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
-func (s *Server) JobHandler(w http.ResponseWriter, r *http.Request) {
+func (s *Server) JobHandler(w http.ResponseWriter, _ *http.Request) {
 	displayData := make(map[string]target.LinkJSON)
 	for _, v := range s.allocator.TargetItems() {
 		displayData[v.JobName] = target.LinkJSON{Link: v.Link.Link}
@@ -172,7 +187,7 @@ func (s *Server) errorHandler(w http.ResponseWriter, err error) {
 
 func (s *Server) jsonHandler(w http.ResponseWriter, data interface{}) {
 	w.Header().Set("Content-Type", "application/json")
-	err := json.NewEncoder(w).Encode(data)
+	err := s.jsonMarshaller.NewEncoder(w).Encode(data)
 	if err != nil {
 		s.logger.Error(err, "failed to encode data for http response")
 	}