rename Log and Logf interface to AddEvent and AddEventf. (#22)

* rename Log and Logf interface to AddEvent and AddEventf.
- also remove log package.

* provide only AddEvent interface to Span
- Event can be created using Event specific interface.

* add var trick for Event interface.

api/event/event.go

@@ -0,0 +1,59 @@
+// Copyright 2019, 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 event
+
+import (
+	"fmt"
+
+	"github.com/open-telemetry/opentelemetry-go/api/core"
+)
+
+type (
+	event struct {
+		message    string
+		attributes []core.KeyValue
+	}
+
+	// Event interface provides methods to retrieve Event properties.
+	Event interface {
+
+		// Message interface retrieves message string of the Event.
+		Message() string
+
+		// Attributes interface returns a copy of attributes associated with the Event.
+		Attributes() []core.KeyValue
+	}
+)
+
+var _ Event = (*event)(nil)
+
+// WithAttr creates an Event with Attributes and a message.
+// Attributes are immutable.
+func WithAttr(msg string, attributes ...core.KeyValue) Event {
+	return event{message: msg, attributes: attributes}
+}
+
+// WithString creates an Event with formatted string.
+func WithString(f string, args ...interface{}) Event {
+	return event{message: fmt.Sprint(f, args), attributes: nil}
+}
+
+func (e event) Message() string {
+	return e.message
+}
+
+func (e event) Attributes() []core.KeyValue {
+	return append(e.attributes[:0:0], e.attributes...)
+}

api/log/log.go

@@ -1,66 +0,0 @@
-// Copyright 2019, 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 log
-
-import (
-	"context"
-
-	"github.com/open-telemetry/opentelemetry-go/api/core"
-	"github.com/open-telemetry/opentelemetry-go/api/scope"
-	"github.com/open-telemetry/opentelemetry-go/exporter/observer"
-)
-
-type (
-	Interface interface {
-		Log(ctx context.Context, msg string, fields ...core.KeyValue)
-		Logf(ctx context.Context, fmt string, args ...interface{})
-	}
-
-	Logger struct {
-		scope.Scope
-	}
-)
-
-func With(scope scope.Scope) Logger {
-	return Logger{scope}
-}
-
-func Log(ctx context.Context, msg string, fields ...core.KeyValue) {
-	With(scope.Active(ctx)).Log(ctx, msg, fields...)
-}
-
-func Logf(ctx context.Context, fmt string, args ...interface{}) {
-	With(scope.Active(ctx)).Logf(ctx, fmt, args...)
-}
-
-func (l Logger) Log(ctx context.Context, msg string, fields ...core.KeyValue) {
-	observer.Record(observer.Event{
-		Type:       observer.LOG_EVENT,
-		Scope:      l.ScopeID(),
-		String:     msg,
-		Attributes: fields,
-		Context:    ctx,
-	})
-}
-
-func (l Logger) Logf(ctx context.Context, fmt string, args ...interface{}) {
-	observer.Record(observer.Event{
-		Type:      observer.LOGF_EVENT,
-		Scope:     l.ScopeID(),
-		String:    fmt,
-		Arguments: args,
-		Context:   ctx,
-	})
-}

api/trace/api.go

@@ -21,7 +21,7 @@ import (
 	"google.golang.org/grpc/codes"
 
 	"github.com/open-telemetry/opentelemetry-go/api/core"
-	"github.com/open-telemetry/opentelemetry-go/api/log"
+	"github.com/open-telemetry/opentelemetry-go/api/event"
 	"github.com/open-telemetry/opentelemetry-go/api/scope"
 	"github.com/open-telemetry/opentelemetry-go/api/stats"
 	"github.com/open-telemetry/opentelemetry-go/api/tag"
@@ -51,8 +51,6 @@ type (
 	Span interface {
 		scope.Mutable
 
-		log.Interface
-
 		stats.Interface
 
 		SetError(bool)
@@ -61,6 +59,9 @@ type (
 
 		Finish()
 
+		// AddEvent adds an event to the span.
+		AddEvent(ctx context.Context, event event.Event)
+
 		// IsRecordingEvents returns true is the span is active and recording events is enabled.
 		IsRecordingEvents() bool
 

api/trace/span.go

@@ -20,7 +20,7 @@ import (
 	"google.golang.org/grpc/codes"
 
 	"github.com/open-telemetry/opentelemetry-go/api/core"
-	"github.com/open-telemetry/opentelemetry-go/api/log"
+	"github.com/open-telemetry/opentelemetry-go/api/event"
 	"github.com/open-telemetry/opentelemetry-go/api/stats"
 	"github.com/open-telemetry/opentelemetry-go/exporter/observer"
 )
@@ -167,12 +167,13 @@ func (sp *span) Tracer() Tracer {
 	return sp.tracer
 }
 
-func (sp *span) Log(ctx context.Context, msg string, args ...core.KeyValue) {
-	log.With(sp).Log(ctx, msg, args...)
-}
+func (sp *span) AddEvent(ctx context.Context, event event.Event) {
 
-func (sp *span) Logf(ctx context.Context, fmt string, args ...interface{}) {
-	log.With(sp).Logf(ctx, fmt, args...)
+	observer.Record(observer.Event{
+		Type:    observer.ADD_EVENT,
+		Event:   event,
+		Context: ctx,
+	})
 }
 
 func (sp *span) Record(ctx context.Context, m ...core.Measurement) {

api/trace/trace.go

@@ -23,7 +23,7 @@ import (
 	"google.golang.org/grpc/codes"
 
 	"github.com/open-telemetry/opentelemetry-go/api/core"
-	"github.com/open-telemetry/opentelemetry-go/api/log"
+	"github.com/open-telemetry/opentelemetry-go/api/event"
 	"github.com/open-telemetry/opentelemetry-go/api/scope"
 	"github.com/open-telemetry/opentelemetry-go/api/tag"
 	"github.com/open-telemetry/opentelemetry-go/exporter/observer"
@@ -90,7 +90,7 @@ func (t *tracer) WithSpan(ctx context.Context, name string, body func(context.Co
 
 	if err := body(ctx); err != nil {
 		span.SetAttribute(ErrorKey.Bool(true))
-		log.Log(ctx, "span error", MessageKey.String(err.Error()))
+		span.AddEvent(ctx, event.WithAttr("span error", MessageKey.String(err.Error())))
 		return err
 	}
 	return nil