tracer
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README¶
🧶 tracer
Simple, lightweight tracing.
💡 Idea
The tracer provides API to trace execution flow.
func Do(ctx context.Context) {defer tracer.Fetch(ctx).Start().Stop()// do some heavy job}Full description of the idea is availablehere.
🏆 Motivation
AtAvito, we use theJaeger - a distributed tracing platform.It is handy in most cases, but at production, we also use sampling. So, what is a problem, you say?
I had 0.02% requests with awrite: broken pipe error and it was difficult to find the appropriate one intheSentry which also has trace related to it in theJaeger.
For that reason, I wrote the simple solution to handle this specific case and found the bottleneck in our code quickly.
🤼♂️ How to
import ("context""io""net/http""time""github.com/kamilsk/tracer")func InjectTracer(handler http.Handler) http.Handler {return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {req = req.WithContext(tracer.Inject(req.Context(), make([]*tracer.Call, 0, 10)))handler.ServeHTTP(rw, req)})}func Handle(rw http.ResponseWriter, req *http.Request) {ctx, cancel := context.WithTimeout(req.Context(), time.Second)defer cancel()call := tracer.Fetch(req.Context()).Start(req.Header.Get("X-Request-Id"))defer call.Stop()...call.Checkpoint("serialize")data, err := FetchData(ctx, req.Body)if err != nil {http.Error(rw, err.Error(), http.StatusInternalServerError)return}call.Checkpoint("store")if err := StoreIntoDatabase(ctx, data); err != nil {http.Error(rw,http.StatusText(http.StatusInternalServerError),http.StatusInternalServerError)return}rw.WriteHeader(http.StatusOK)}func FetchData(ctx context.Context, r io.Reader) (Data, error) {defer tracer.Fetch(ctx).Start().Stop()// fetch a data into a struct}func StoreIntoDatabase(ctx context.Context, data Data) error {defer tracer.Fetch(ctx).Start().Stop()// store the data into a database}Output:
allocates at call stack: 0, detailed call stack:call Handle [ca7a87c4-58d0-4fdf-857c-ef49fc3bf271]: 14.038083ms, allocates: 2checkpoint [serialize]: 1.163587mscheckpoint [store]: 2.436265mscall FetchData: 1.192829ms, allocates: 0call StoreIntoDatabase: 10.428663ms, allocates: 0🧩 Integration
The library usesSemVer for versioning, and it is notBC-safe through major releases.You can usego modules ordep to manage its version.
$ go get -u github.com/kamilsk/tracer$ dep ensure -add github.com/kamilsk/tracermade with ❤️ for everyone
Documentation¶
Overview¶
Example¶
package mainimport ("bytes""context""encoding/gob""encoding/json""io""net/http""net/http/httptest""os""regexp""strings""time""github.com/kamilsk/tracer")type Data struct {Title string `json:"title"`Subtitle string `json:"subtitle"`}func main() {rec := httptest.NewRecorder()req := httptest.NewRequest(http.MethodPost, "/message",strings.NewReader(`{"title": "tracer", "subtitle": "🧶 Simple, lightweight tracing mechanism."}`))req.Header.Set("X-Request-Id", "ca7a87c4-58d0-4fdf-857c-ef49fc3bf271")handler := InjectTracer(FlushTracer(http.HandlerFunc(Handle)))handler.ServeHTTP(rec, req)_, _ = io.Copy(os.Stdout, strings.NewReader(stabilize(rec.Body.String())))}func FlushTracer(handler http.Handler) http.Handler {return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {handler.ServeHTTP(rw, req)_, _ = rw.Write([]byte(tracer.Fetch(req.Context()).String()))})}func InjectTracer(handler http.Handler) http.Handler {return http.HandlerFunc(func(rw http.ResponseWriter, req *http.Request) {req = req.WithContext(tracer.Inject(req.Context(), make([]*tracer.Call, 0, 10)))handler.ServeHTTP(rw, req)})}func Handle(rw http.ResponseWriter, req *http.Request) {ctx, cancel := context.WithTimeout(req.Context(), time.Second)defer cancel()call := tracer.Fetch(req.Context()).Start(req.Header.Get("X-Request-Id"))defer call.Stop()time.Sleep(time.Millisecond)call.Checkpoint("serialize")data, err := FetchData(ctx, req.Body)if err != nil {http.Error(rw, err.Error(), http.StatusInternalServerError)return}time.Sleep(time.Millisecond)call.Checkpoint("store")if err := StoreIntoDatabase(ctx, data); err != nil {http.Error(rw, err.Error(), http.StatusInternalServerError)return}rw.WriteHeader(http.StatusOK)}func FetchData(ctx context.Context, r io.Reader) (Data, error) {defer tracer.Fetch(ctx).Start().Stop()time.Sleep(time.Millisecond)var data Dataerr := json.NewDecoder(r).Decode(&data)return data, err}func StoreIntoDatabase(ctx context.Context, data Data) error {defer tracer.Fetch(ctx).Start().Stop()time.Sleep(10 * time.Millisecond)return gob.NewEncoder(bytes.NewBuffer(nil)).Encode(data)}func stabilize(raw string) string {raw = strings.Replace(raw, "tracer_test.", "", -1)raw = regexp.MustCompile(`Handle (.+): (\d{2}\.\d+ms)`).ReplaceAllString(raw, "Handle $1: 12.345678ms")raw = regexp.MustCompile(`\[serialize]: (\d\.\d+ms)`).ReplaceAllString(raw, "[serialize]: 1.234567ms")raw = regexp.MustCompile(`\[store]: (\d\.\d+ms)`).ReplaceAllString(raw, "[store]: 1.234567ms")raw = regexp.MustCompile(`FetchData: (\d\.\d+ms)`).ReplaceAllString(raw, "FetchData: 1.234567ms")raw = regexp.MustCompile(`StoreIntoDatabase: (\d{2}\.\d+ms)`).ReplaceAllString(raw, "StoreIntoDatabase: 12.345678ms")return raw}Output:allocates at call stack: 0, detailed call stack:call Handle [ca7a87c4-58d0-4fdf-857c-ef49fc3bf271]: 12.345678ms, allocates: 2checkpoint [serialize]: 1.234567mscheckpoint [store]: 1.234567mscall FetchData: 1.234567ms, allocates: 0call StoreIntoDatabase: 12.345678ms, allocates: 0
Index¶
Examples¶
Constants¶
This section is empty.
Variables¶
This section is empty.
Functions¶
Types¶
typeCall¶
type Call struct {// contains filtered or unexported fields}Call holds information about a current function call.
func (*Call)Checkpoint¶
Checkpoint stores timestamp of a current execution position of the current call.
func Do(ctx context.Context) {call := tracer.Fetch(ctx).Start()defer call.Stop()...call.Checkpoint()...call.Checkpoint("id", "labelX", "labelY")...}typeCallerInfo¶
type CallerInfo struct {Entryuintptr// the entry address of the functionNamestring// the name of the functionFilestring// the file name andLineint// line number of the source code of the function}CallerInfo holds information about a caller.
funcCaller¶
func Caller(skipint)CallerInfo
Caller returns information about a caller at position after the skip steps.
func StoreToDatabase(data Payload) error {defer stats.NewTiming().Send(Caller(2).Name)// do something heavy}typeCheckpoint¶
type Checkpoint struct {// contains filtered or unexported fields}Checkpoint holds information about a current execution position of a current call.
typeTrace¶
type Trace struct {// contains filtered or unexported fields}Trace holds information about a current execution flow.
funcFetch¶
Fetch tries to get the tracer from a context or returns safe nil.
tracer.Fetch(context.Background()).Start().Stop() // won't panic
Source Files