Remove license headers and add notes about origins of code

propagation/b3.go

@@ -6,6 +6,11 @@ import (
 	"strings"
 )
 
+// this file contains functions and types used for parsing and generating B3 headers.
+// it mostly contains code based on the implementation found here:
+// https://github.com/open-telemetry/opentelemetry-go-contrib/blob/05ef436536dc499361b6c9d3546662a99c2f918f/propagators/b3/b3_propagator.go
+// the only exported functions are MarshalB3TraceContext and UnmarshalB3TraceContext
+
 const (
 	// Default B3 Header names.
 	b3ContextHeader      = "b3"
@@ -43,15 +48,15 @@ var (
 	errInvalidParentSpanIDValue  = errors.New("invalid B3 ParentSpanID value found")
 )
 
-// extractMultiple reconstructs a SpanContext from header values based on B3
+// extractMultiple reconstructs a PropagationContext from header values based on B3
 // Multiple header. It is based on the implementation found here:
 // https://github.com/openzipkin/zipkin-go/blob/v0.2.2/propagation/b3/spancontext.go
-// and adapted to support a SpanContext.
+// and adapted to support a PropagationContext.
 func extractMultiple(ctx context.Context, traceID, spanID, parentSpanID, sampled, flags string) (context.Context, PropagationContext, error) {
 	var (
 		err           error
 		requiredCount int
-		scc           = PropagationContext{}
+		prop          = PropagationContext{}
 	)
 
 	// correct values for an existing sampled header are "0" and "1".
@@ -61,7 +66,7 @@ func extractMultiple(ctx context.Context, traceID, spanID, parentSpanID, sampled
 	case "0", "false":
 		// Zero value for TraceFlags sample bit is unset.
 	case "1", "true":
-		scc.TraceFlags = FlagsSampled
+		prop.TraceFlags = FlagsSampled
 	case "":
 		ctx = withDeferred(ctx, true)
 	default:
@@ -76,7 +81,7 @@ func extractMultiple(ctx context.Context, traceID, spanID, parentSpanID, sampled
 	if flags == "1" {
 		ctx = withDeferred(ctx, false)
 		ctx = withDebug(ctx, true)
-		scc.TraceFlags |= FlagsSampled
+		prop.TraceFlags |= FlagsSampled
 	}
 
 	if traceID != "" {
@@ -90,7 +95,7 @@ func extractMultiple(ctx context.Context, traceID, spanID, parentSpanID, sampled
 		if err != nil {
 			return ctx, empty, errInvalidTraceIDHeader
 		}
-		scc.TraceID = tID.String()
+		prop.TraceID = tID.String()
 	}
 
 	if spanID != "" {
@@ -99,7 +104,7 @@ func extractMultiple(ctx context.Context, traceID, spanID, parentSpanID, sampled
 		if err != nil {
 			return ctx, empty, errInvalidSpanIDHeader
 		}
-		scc.ParentID = sID.String()
+		prop.ParentID = sID.String()
 	}
 
 	if requiredCount != 0 && requiredCount != 2 {
@@ -116,7 +121,7 @@ func extractMultiple(ctx context.Context, traceID, spanID, parentSpanID, sampled
 		}
 	}
 
-	return ctx, scc, nil
+	return ctx, prop, nil
 }
 
 // extractSingle reconstructs a SpanContext from contextHeader based on a B3
@@ -129,7 +134,7 @@ func extractSingle(ctx context.Context, contextHeader string) (context.Context,
 	}
 
 	var (
-		scc      = PropagationContext{}
+		prop     = PropagationContext{}
 		sampling string
 	)
 
@@ -159,15 +164,15 @@ func extractSingle(ctx context.Context, contextHeader string) (context.Context,
 		if err != nil {
 			return ctx, empty, errInvalidTraceIDValue
 		}
-		scc.TraceID = tID.String()
+		prop.TraceID = tID.String()
 
 		pos += separatorWidth // {traceID}-
 
 		spanID, err := spanIDFromHex(contextHeader[pos : pos+spanIDWidth])
 		if err != nil {
 			return ctx, empty, errInvalidSpanIDValue
 		}
-		scc.ParentID = spanID.String()
+		prop.ParentID = spanID.String()
 		pos += spanIDWidth // {traceID}-{spanID}
 
 		if headerLen > pos {
@@ -204,16 +209,16 @@ func extractSingle(ctx context.Context, contextHeader string) (context.Context,
 		ctx = withDeferred(ctx, true)
 	case "d":
 		ctx = withDebug(ctx, true)
-		scc.TraceFlags = FlagsSampled
+		prop.TraceFlags = FlagsSampled
 	case "1":
-		scc.TraceFlags = FlagsSampled
+		prop.TraceFlags = FlagsSampled
 	case "0":
 		// Zero value for TraceFlags sample bit is unset.
 	default:
 		return ctx, empty, errInvalidSampledByte
 	}
 
-	return ctx, scc, nil
+	return ctx, prop, nil
 }
 
 type b3KeyType int

propagation/trace.go

@@ -1,25 +1,16 @@
-// 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 propagation // import "go.opentelemetry.io/otel/trace"
+package propagation
 
 import (
 	"bytes"
 	"encoding/hex"
 	"encoding/json"
 )
 
+// this file contains definitions of types used in propagation between OpenTelemetry and
+// beeline instrumented applications. Many of the types have been lifted from the
+// opentelemetry-go sdk found here:
+// https://github.com/open-telemetry/opentelemetry-go/blob/c912b179fd595cc7c6eec0b22e6c1371e31241d7/trace/trace.go
+
 const (
 	// FlagsSampled is a bitmask with the sampled bit set. A SpanContext
 	// with the sampling bit set means the span is sampled.
@@ -41,7 +32,6 @@ func (e errorConst) Error() string {
 }
 
 // TraceID is a unique identity of a trace.
-// nolint:revive // revive complains about stutter of `trace.TraceID`.
 type TraceID [16]byte
 
 var nilTraceID TraceID

propagation/tracestate.go

@@ -1,17 +1,3 @@
-// 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 propagation
 
 import (
@@ -21,6 +7,11 @@ import (
 	"strings"
 )
 
+// tracestate contains types and methods for constructing and parsing trace state
+// which is included in W3C trace context headers. Most of this code has been lifted
+// almost verbatim from:
+// https://github.com/open-telemetry/opentelemetry-go/blob/c912b179fd595cc7c6eec0b22e6c1371e31241d7/trace/tracestate.go
+
 var (
 	maxListMembers = 32