Merge pull request #778 from MrAlias/oterror

Add oterror package and implementation in api/global

api/global/handler.go

@@ -0,0 +1,92 @@
+// 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 global
+
+import (
+	"log"
+	"os"
+	"sync"
+	"sync/atomic"
+
+	"go.opentelemetry.io/otel/api/oterror"
+)
+
+var (
+	// globalHandler provides an oterror.Handler that can be used throughout
+	// an OpenTelemetry instrumented project. When a user specified Handler
+	// is registered (`SetHandler`) all calls to `Handle` will be delegated
+	// to the registered Handler.
+	globalHandler = &handler{
+		l: log.New(os.Stderr, "", log.LstdFlags),
+	}
+
+	// delegateHanderOnce ensures that a user provided Handler is only ever
+	// registered once.
+	delegateHanderOnce sync.Once
+
+	// Ensure the handler implements oterror.Handle at build time.
+	_ oterror.Handler = (*handler)(nil)
+)
+
+// handler logs all errors to STDERR.
+type handler struct {
+	delegate atomic.Value
+
+	l *log.Logger
+}
+
+// setDelegate sets the handler delegate if one is not already set.
+func (h *handler) setDelegate(d oterror.Handler) {
+	if h.delegate.Load() != nil {
+		// Delegate already registered
+		return
+	}
+	h.delegate.Store(d)
+}
+
+// Handle implements oterror.Handler.
+func (h *handler) Handle(err error) {
+	if d := h.delegate.Load(); d != nil {
+		d.(oterror.Handler).Handle(err)
+		return
+	}
+	h.l.Print(err)
+}
+
+// Handler returns the global Handler instance. If no Handler instance has
+// be explicitly set yet, a default Handler is returned that logs to STDERR
+// until an Handler is set (all functionality is delegated to the set
+// Handler once it is set).
+func Handler() oterror.Handler {
+	return globalHandler
+}
+
+// SetHandler sets the global Handler to be h.
+func SetHandler(h oterror.Handler) {
+	delegateHanderOnce.Do(func() {
+		current := Handler()
+		if current == h {
+			return
+		}
+		if internalHandler, ok := current.(*handler); ok {
+			internalHandler.setDelegate(h)
+		}
+	})
+}
+
+// Handle is a convience function for Handler().Handle(err)
+func Handle(err error) {
+	globalHandler.Handle(err)
+}

api/global/handler_test.go

@@ -0,0 +1,137 @@
+// 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 global
+
+import (
+	"bytes"
+	"errors"
+	"log"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/suite"
+)
+
+type errLogger []string
+
+func (l *errLogger) Write(p []byte) (int, error) {
+	msg := bytes.TrimRight(p, "\n")
+	(*l) = append(*l, string(msg))
+	return len(msg), nil
+}
+
+func (l *errLogger) Reset() {
+	*l = errLogger([]string{})
+}
+
+func (l *errLogger) Got() []string {
+	return []string(*l)
+}
+
+type HandlerTestSuite struct {
+	suite.Suite
+
+	origHandler *handler
+	errLogger   *errLogger
+}
+
+func (s *HandlerTestSuite) SetupSuite() {
+	s.errLogger = new(errLogger)
+	s.origHandler = globalHandler
+	globalHandler = &handler{
+		l: log.New(s.errLogger, "", 0),
+	}
+}
+
+func (s *HandlerTestSuite) TearDownSuite() {
+	globalHandler = s.origHandler
+}
+
+func (s *HandlerTestSuite) SetupTest() {
+	s.errLogger.Reset()
+}
+
+func (s *HandlerTestSuite) TestGlobalHandler() {
+	errs := []string{"one", "two"}
+	Handler().Handle(errors.New(errs[0]))
+	Handle(errors.New(errs[1]))
+	s.Assert().Equal(errs, s.errLogger.Got())
+}
+
+func (s *HandlerTestSuite) TestNoDropsOnDelegate() {
+	var sent int
+	err := errors.New("")
+	stop := make(chan struct{})
+	beat := make(chan struct{})
+	done := make(chan struct{})
+
+	go func() {
+		for {
+			select {
+			case <-stop:
+				done <- struct{}{}
+				return
+			default:
+				sent++
+				Handle(err)
+			}
+
+			select {
+			case beat <- struct{}{}:
+			default:
+			}
+		}
+	}()
+
+	// Wait for the spice to flow
+	select {
+	case <-time.Tick(2 * time.Millisecond):
+		s.T().Fatal("no errors were sent in 2ms")
+	case <-beat:
+	}
+
+	// Change to another Handler. We are testing this is loss-less.
+	newErrLogger := new(errLogger)
+	secondary := &handler{
+		l: log.New(newErrLogger, "", 0),
+	}
+	SetHandler(secondary)
+
+	select {
+	case <-time.Tick(2 * time.Millisecond):
+		s.T().Fatal("no errors were sent within 2ms after SetHandler")
+	case <-beat:
+	}
+
+	// Now beat is clear, wait for a fresh send.
+	select {
+	case <-time.Tick(2 * time.Millisecond):
+		s.T().Fatal("no fresh errors were sent within 2ms after SetHandler")
+	case <-beat:
+	}
+
+	// Stop sending errors.
+	stop <- struct{}{}
+	// Ensure we do not lose any straglers.
+	<-done
+
+	got := append(s.errLogger.Got(), newErrLogger.Got()...)
+	s.Assert().Greater(len(got), 1, "at least 2 errors should have been sent")
+	s.Assert().Len(got, sent)
+}
+
+func TestHandlerTestSuite(t *testing.T) {
+	suite.Run(t, new(HandlerTestSuite))
+}

api/global/global.go → api/global/metric.go

@@ -17,34 +17,8 @@ package global
 import (
 	"go.opentelemetry.io/otel/api/global/internal"
 	"go.opentelemetry.io/otel/api/metric"
-	"go.opentelemetry.io/otel/api/propagation"
-	"go.opentelemetry.io/otel/api/trace"
 )
 
-// Tracer creates a named tracer that implements Tracer interface.
-// If the name is an empty string then provider uses default name.
-//
-// This is short for TraceProvider().Tracer(name)
-func Tracer(name string) trace.Tracer {
-	return TraceProvider().Tracer(name)
-}
-
-// TraceProvider returns the registered global trace provider.
-// If none is registered then an instance of trace.NoopProvider is returned.
-//
-// Use the trace provider to create a named tracer. E.g.
-//     tracer := global.TraceProvider().Tracer("example.com/foo")
-// or
-//     tracer := global.Tracer("example.com/foo")
-func TraceProvider() trace.Provider {
-	return internal.TraceProvider()
-}
-
-// SetTraceProvider registers `tp` as the global trace provider.
-func SetTraceProvider(tp trace.Provider) {
-	internal.SetTraceProvider(tp)
-}
-
 // Meter gets a named Meter interface.  If the name is an
 // empty string, the provider uses a default name.
 //
@@ -69,15 +43,3 @@ func MeterProvider() metric.Provider {
 func SetMeterProvider(mp metric.Provider) {
 	internal.SetMeterProvider(mp)
 }
-
-// Propagators returns the registered global propagators instance.  If
-// none is registered then an instance of propagators.NoopPropagators
-// is returned.
-func Propagators() propagation.Propagators {
-	return internal.Propagators()
-}
-
-// SetPropagators registers `p` as the global propagators instance.
-func SetPropagators(p propagation.Propagators) {
-	internal.SetPropagators(p)
-}

api/global/metric_test.go

@@ -0,0 +1,43 @@
+// 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 global_test
+
+import (
+	"testing"
+
+	"go.opentelemetry.io/otel/api/global"
+	"go.opentelemetry.io/otel/api/metric"
+)
+
+type testMeterProvider struct{}
+
+var _ metric.Provider = &testMeterProvider{}
+
+func (*testMeterProvider) Meter(_ string) metric.Meter {
+	return metric.Meter{}
+}
+
+func TestMultipleGlobalMeterProvider(t *testing.T) {
+	p1 := testMeterProvider{}
+	p2 := metric.NoopProvider{}
+	global.SetMeterProvider(&p1)
+	global.SetMeterProvider(&p2)
+
+	got := global.MeterProvider()
+	want := &p2
+	if got != want {
+		t.Fatalf("Provider: got %p, want %p\n", got, want)
+	}
+}

api/global/propagation.go

@@ -0,0 +1,32 @@
+// 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 global
+
+import (
+	"go.opentelemetry.io/otel/api/global/internal"
+	"go.opentelemetry.io/otel/api/propagation"
+)
+
+// Propagators returns the registered global propagators instance.  If
+// none is registered then an instance of propagators.NoopPropagators
+// is returned.
+func Propagators() propagation.Propagators {
+	return internal.Propagators()
+}
+
+// SetPropagators registers `p` as the global propagators instance.
+func SetPropagators(p propagation.Propagators) {
+	internal.SetPropagators(p)
+}