add the option to clobber to clients or not

chttp/chttp.go

@@ -21,9 +21,10 @@ func NewInheritorHTTPMiddleware(
 	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		rctx := r.Context()
 
-		rctx = clues.Inherit(ctx, rctx)
-		rctx = clog.Inherit(ctx, rctx)
-		rctx = ctats.Inherit(ctx, rctx)
+		// always assume the request context needs to be clobbered.
+		rctx = clues.Inherit(ctx, rctx, true)
+		rctx = clog.Inherit(ctx, rctx, true)
+		rctx = ctats.Inherit(ctx, rctx, true)
 
 		r = r.WithContext(rctx)
 

clog/logger.go

@@ -266,7 +266,11 @@ func Flush(ctx context.Context) {
 // is available for request-bound conetxts, such as in a http server pattern.
 //
 // If the 'to' context already contains an initialized logger, no change is made.
-func Inherit(from, to context.Context) context.Context {
+// Callers can force a 'from' logger to override a 'to' logger by setting clobber=true.
+func Inherit(
+	from, to context.Context,
+	clobber bool,
+) context.Context {
 	fromClogger, foundFrom := fromCtx(from)
 	_, foundTo := fromCtx(to)
 
@@ -275,7 +279,7 @@ func Inherit(from, to context.Context) context.Context {
 	}
 
 	// return the 'to' context unmodified if we won't update the context.
-	if !foundFrom || foundTo {
+	if !foundFrom || (foundTo && !clobber) {
 		return to
 	}
 

clog/logger_internal_test.go

@@ -17,10 +17,11 @@ func TestInherit(t *testing.T) {
 	stubClogger2 := &clogger{}
 
 	table := []struct {
-		name   string
-		from   func() context.Context
-		to     func() context.Context
-		assert func(t *testing.T, ctx context.Context)
+		name    string
+		from    func() context.Context
+		to      func() context.Context
+		clobber bool
+		assert  func(t *testing.T, ctx context.Context)
 	}{
 		{
 			name: "from: nil, to: nil",
@@ -129,10 +130,26 @@ func TestInherit(t *testing.T) {
 				assert.Equal(t, stubClogger2, logger)
 			},
 		},
+		{
+			name: "from: populated, to: populated, clobbered",
+			from: func() context.Context {
+				return plantLoggerInCtx(context.Background(), stubClogger1)
+			},
+			to: func() context.Context {
+				return plantLoggerInCtx(context.Background(), stubClogger2)
+			},
+			clobber: true,
+			assert: func(t *testing.T, ctx context.Context) {
+				logger, found := fromCtx(ctx)
+				require.NotNil(t, logger)
+				assert.True(t, found)
+				assert.Equal(t, stubClogger1, logger)
+			},
+		},
 	}
 	for _, test := range table {
 		t.Run(test.name, func(t *testing.T) {
-			result := Inherit(test.from(), test.to())
+			result := Inherit(test.from(), test.to(), test.clobber)
 			require.NotNil(t, result)
 			test.assert(t, result)
 		})

clues.go

@@ -54,22 +54,31 @@ func Close(ctx context.Context) error {
 // are available for request-bound conetxts, such as in a http server pattern.
 //
 // If the 'to' context already contains an initialized client, no change is made.
-func Inherit(from, to context.Context) context.Context {
+// Callers can force a 'from' client to override a 'to' client by setting clobber=true.
+func Inherit(
+	from, to context.Context,
+	clobber bool,
+) context.Context {
 	fromNode := node.FromCtx(from)
 	toNode := node.FromCtx(to)
 
-	if toNode.OTEL == nil && fromNode.OTEL != nil {
-		toNode.OTEL = fromNode.OTEL
-		// A span may already exist in the 'to' context thanks to otel packar integration.
+	if to == nil {
+		to = context.Background()
+	} else if toNode.Span == nil {
+		// A span may already exist in the 'to' context thanks to otel package integration.
 		// Likewise, the 'from' ctx is not expected to contain a span, so we only want to
 		// maintain the span information that's currently live.
 		toNode.Span = trace.SpanFromContext(to)
 	}
 
-	if to == nil {
-		to = context.Background()
+	// if we have no fromNode OTEL, or are not clobbering, return the toNode.
+	if fromNode.OTEL == nil || (toNode.OTEL != nil && !clobber) {
+		return node.EmbedInCtx(to, toNode)
 	}
 
+	// otherwise pass along the fromNode OTEL client.
+	toNode.OTEL = fromNode.OTEL
+
 	return node.EmbedInCtx(to, toNode)
 }
 

clues_internal_test.go

@@ -12,10 +12,11 @@ import (
 
 func TestInherit(t *testing.T) {
 	table := []struct {
-		name   string
-		from   func() context.Context
-		to     func() context.Context
-		assert func(t *testing.T, ctx context.Context)
+		name    string
+		from    func() context.Context
+		to      func() context.Context
+		clobber bool
+		assert  func(t *testing.T, ctx context.Context)
 	}{
 		{
 			name: "from: nil, to: nil",
@@ -145,10 +146,35 @@ func TestInherit(t *testing.T) {
 				assert.Equal(t, "to", n.OTEL.ServiceName)
 			},
 		},
+		{
+			name: "from: populated, to: populated, clobbered",
+			from: func() context.Context {
+				n := node.Node{
+					OTEL: &node.OTELClient{
+						ServiceName: "from",
+					},
+				}
+				return node.EmbedInCtx(context.Background(), &n)
+			},
+			to: func() context.Context {
+				n := node.Node{
+					OTEL: &node.OTELClient{
+						ServiceName: "to",
+					},
+				}
+				return node.EmbedInCtx(context.Background(), &n)
+			},
+			clobber: true,
+			assert: func(t *testing.T, ctx context.Context) {
+				n := node.FromCtx(ctx)
+				require.NotNil(t, n.OTEL)
+				assert.Equal(t, "from", n.OTEL.ServiceName)
+			},
+		},
 	}
 	for _, test := range table {
 		t.Run(test.name, func(t *testing.T) {
-			result := Inherit(test.from(), test.to())
+			result := Inherit(test.from(), test.to(), test.clobber)
 			require.NotNil(t, result)
 			test.assert(t, result)
 		})

ctats/ctats.go

@@ -72,7 +72,11 @@ func Initialize(ctx context.Context) (context.Context, error) {
 // is available for request-bound conetxts, such as in a http server pattern.
 //
 // If the 'to' context already contains an initialized ctats, no change is made.
-func Inherit(from, to context.Context) context.Context {
+// Callers can force a 'from' ctats to override a 'to' ctats by setting clobber=true.
+func Inherit(
+	from, to context.Context,
+	clobber bool,
+) context.Context {
 	fromBus := fromCtx(from)
 	toBus := fromCtx(to)
 
@@ -81,7 +85,7 @@ func Inherit(from, to context.Context) context.Context {
 	}
 
 	// return the 'to' context unmodified if we won't update the context.
-	if fromBus == nil || toBus != nil {
+	if fromBus == nil || (toBus != nil && !clobber) {
 		return to
 	}
 

ctats/ctats_test.go

@@ -78,10 +78,11 @@ func TestInherit(t *testing.T) {
 	stubBus2 := &bus{}
 
 	table := []struct {
-		name   string
-		from   func() context.Context
-		to     func() context.Context
-		assert func(t *testing.T, ctx context.Context)
+		name    string
+		from    func() context.Context
+		to      func() context.Context
+		clobber bool
+		assert  func(t *testing.T, ctx context.Context)
 	}{
 		{
 			name: "from: nil, to: nil",
@@ -181,10 +182,25 @@ func TestInherit(t *testing.T) {
 				assert.Equal(t, stubBus2, b)
 			},
 		},
+		{
+			name: "from: populated, to: populated, clobbered",
+			from: func() context.Context {
+				return embedInCtx(context.Background(), stubBus1)
+			},
+			to: func() context.Context {
+				return embedInCtx(context.Background(), stubBus2)
+			},
+			clobber: true,
+			assert: func(t *testing.T, ctx context.Context) {
+				b := fromCtx(ctx)
+				require.NotNil(t, b)
+				assert.Equal(t, stubBus1, b)
+			},
+		},
 	}
 	for _, test := range table {
 		t.Run(test.name, func(t *testing.T) {
-			result := Inherit(test.from(), test.to())
+			result := Inherit(test.from(), test.to(), test.clobber)
 			require.NotNil(t, result)
 			test.assert(t, result)
 		})