fix race conditions in scope manager when uninitialized (#21)

scope/scope.go

@@ -134,7 +134,9 @@ func (s *scope) With(keyValuePairs ...interface{}) telemetry.Logger {
 			sc.kvs = append(sc.kvs, k, keyValuePairs[i+1])
 		}
 	}
+	lock.Lock()
 	uninitialized[s.name] = append(uninitialized[s.name], sc)
+	lock.Unlock()
 
 	return sc
 }
@@ -147,7 +149,9 @@ func (s *scope) Context(ctx context.Context) telemetry.Logger {
 
 	sc := s.Clone()
 	sc.(*scope).ctx = ctx
+	lock.Lock()
 	uninitialized[s.name] = append(uninitialized[s.name], sc.(*scope))
+	lock.Unlock()
 	return sc
 }
 
@@ -159,7 +163,9 @@ func (s *scope) Metric(m telemetry.Metric) telemetry.Logger {
 
 	sc := s.Clone()
 	sc.(*scope).metric = m
+	lock.Lock()
 	uninitialized[s.name] = append(uninitialized[s.name], sc.(*scope))
+	lock.Unlock()
 	return sc
 }
 
@@ -226,7 +232,7 @@ func Register(name, description string) Scope {
 	name = strings.ToLower(strings.Trim(name, "\r\n\t "))
 	sc, ok := scopes[name]
 	if !ok {
-		level := int32(DefaultLevel())
+		level := int32(defaultLevel())
 		sc = &scope{
 			name:        name,
 			description: description,
@@ -249,11 +255,10 @@ func Register(name, description string) Scope {
 
 // Find a scoped logger by its name.
 func Find(name string) (Scope, bool) {
-	lock.Lock()
-	defer lock.Unlock()
-
 	name = strings.ToLower(strings.Trim(name, "\r\n\t "))
+	lock.Lock()
 	s, ok := scopes[name]
+	lock.Unlock()
 	return s, ok
 }
 
@@ -303,7 +308,7 @@ func PrintRegistered() {
 	fmt.Printf("- %-*s [%-5s]  %s\n",
 		pad,
 		"default",
-		DefaultLevel().String(),
+		defaultLevel().String(),
 		"",
 	)
 	for _, n := range names {
@@ -343,6 +348,13 @@ func SetDefaultLevel(lvl telemetry.Level) {
 
 // DefaultLevel returns the logging level used for new scopes.
 func DefaultLevel() telemetry.Level {
+	lock.Lock()
+	defer lock.Unlock()
+
+	return defaultLevel()
+}
+
+func defaultLevel() telemetry.Level {
 	if defaultLogger != nil {
 		return defaultLogger.Level()
 	}

scope/scope_test.go

@@ -20,12 +20,46 @@ import (
 	"errors"
 	"fmt"
 	"io"
+	"strconv"
+	"sync"
 	"testing"
 
 	"github.com/tetratelabs/telemetry"
 	"github.com/tetratelabs/telemetry/function"
 )
 
+func TestParallel(t *testing.T) {
+	logger := Register("root", "root scope")
+	ctx := context.Background()
+	wg := sync.WaitGroup{}
+	routines := 100
+	wg.Add(4 * routines)
+	m := &mockMetric{}
+	for i := 0; i < routines; i++ {
+		scopeName := strconv.Itoa(i - i%2)
+		go func() {
+			l := logger.Context(ctx).Metric(m).With("key", "value")
+			l.Debug("test log line")
+			wg.Done()
+		}()
+		go func() {
+			Register(scopeName, "test scope")
+			wg.Done()
+		}()
+		go func() {
+			lvl := DefaultLevel()
+			logger.Debug(strconv.Itoa(int(lvl)))
+			wg.Done()
+		}()
+		go func() {
+			SetDefaultLevel(telemetry.LevelInfo)
+			wg.Done()
+		}()
+	}
+	wg.Wait()
+	cleanup()
+}
+
 func TestLogger(t *testing.T) {
 	emitter := func(w io.Writer) function.Emit {
 		return func(level telemetry.Level, msg string, err error, values function.Values) {