metadata: move FromOutgoingContextRaw() to internal

internal/internal.go

@@ -188,6 +188,9 @@ var (
 	ExitIdleModeForTesting any // func(*grpc.ClientConn) error
 
 	ChannelzTurnOffForTesting func()
+
+  // Gets the function definition from metadata package
+	FromOutgoingContextRaw any // func(context.Context) (metadata.MD, [][]string, bool)
 )
 
 // HealthChecker defines the signature of the client-side LB channel health checking function.

internal/transport/http2_client.go

@@ -568,7 +568,8 @@ func (t *http2Client) createHeaderFields(ctx context.Context, callHdr *CallHdr)
 		headerFields = append(headerFields, hpack.HeaderField{Name: "grpc-trace-bin", Value: encodeBinHeader(b)})
 	}
 
-	if md, added, ok := metadata.FromOutgoingContextRaw(ctx); ok {
+	fromOutgoingCtxRaw := internal.FromOutgoingContextRaw.(func(context.Context) (metadata.MD, [][]string, bool))
+	if md, added, ok := fromOutgoingCtxRaw(ctx); ok {
 		var k string
 		for k, vv := range md {
 			// HTTP doesn't allow you to set pseudoheaders after non pseudoheaders were set.

metadata/metadata.go

@@ -25,8 +25,14 @@ import (
 	"context"
 	"fmt"
 	"strings"
+
+	"google.golang.org/grpc/internal"
 )
 
+func init() {
+	internal.FromOutgoingContextRaw = fromOutgoingContextRaw
+}
+
 // DecodeKeyValue returns k, v, nil.
 //
 // Deprecated: use k and v directly instead.
@@ -238,7 +244,7 @@ func copyOf(v []string) []string {
 	return vals
 }
 
-// FromOutgoingContextRaw returns the un-merged, intermediary contents of rawMD.
+// fromOutgoingContextRaw returns the un-merged, intermediary contents of rawMD.
 //
 // Remember to perform strings.ToLower on the keys, for both the returned MD (MD
 // is a map, there's no guarantee it's created using our helper functions) and
@@ -247,7 +253,7 @@ func copyOf(v []string) []string {
 //
 // This is intended for gRPC-internal use ONLY. Users should use
 // FromOutgoingContext instead.
-func FromOutgoingContextRaw(ctx context.Context) (MD, [][]string, bool) {
+func fromOutgoingContextRaw(ctx context.Context) (MD, [][]string, bool) {
 	raw, ok := ctx.Value(mdOutgoingKey{}).(rawMD)
 	if !ok {
 		return nil, nil, false

stream.go

@@ -184,7 +184,8 @@ func newClientStream(ctx context.Context, desc *StreamDesc, cc *ClientConn, meth
 	// when the RPC completes.
 	opts = append([]CallOption{OnFinish(func(error) { cc.idlenessMgr.OnCallEnd() })}, opts...)
 
-	if md, added, ok := metadata.FromOutgoingContextRaw(ctx); ok {
+	fromOutgoingCtxRaw := internal.FromOutgoingContextRaw.(func(context.Context) (metadata.MD, [][]string, bool))
+	if md, added, ok := fromOutgoingCtxRaw(ctx); ok {
 		// validate md
 		if err := imetadata.Validate(md); err != nil {
 			return nil, status.Error(codes.Internal, err.Error())