add copy metadata from grpc-go

metadata/metadata_grpc.go

@@ -0,0 +1,271 @@
+//go:build exclude
+
+//TODO need compare with micro metadata
+package metadata
+
+import (
+	"context"
+	"fmt"
+	"strings"
+)
+
+// DecodeKeyValue returns k, v, nil.
+//
+// Deprecated: use k and v directly instead.
+func DecodeKeyValue(k, v string) (string, string, error) {
+	return k, v, nil
+}
+
+// MD is a mapping from metadata keys to values. Users should use the following
+// two convenience functions New and Pairs to generate MD.
+type MD map[string][]string
+
+// New creates an MD from a given key-value map.
+//
+// Only the following ASCII characters are allowed in keys:
+//   - digits: 0-9
+//   - uppercase letters: A-Z (normalized to lower)
+//   - lowercase letters: a-z
+//   - special characters: -_.
+//
+// Uppercase letters are automatically converted to lowercase.
+//
+// Keys beginning with "grpc-" are reserved for grpc-internal use only and may
+// result in errors if set in metadata.
+func New(m map[string]string) MD {
+	md := make(MD, len(m))
+	for k, val := range m {
+		key := strings.ToLower(k)
+		md[key] = append(md[key], val)
+	}
+	return md
+}
+
+// Pairs returns an MD formed by the mapping of key, value ...
+// Pairs panics if len(kv) is odd.
+//
+// Only the following ASCII characters are allowed in keys:
+//   - digits: 0-9
+//   - uppercase letters: A-Z (normalized to lower)
+//   - lowercase letters: a-z
+//   - special characters: -_.
+//
+// Uppercase letters are automatically converted to lowercase.
+//
+// Keys beginning with "grpc-" are reserved for grpc-internal use only and may
+// result in errors if set in metadata.
+func Pairs(kv ...string) MD {
+	if len(kv)%2 == 1 {
+		panic(fmt.Sprintf("metadata: Pairs got the odd number of input pairs for metadata: %d", len(kv)))
+	}
+	md := make(MD, len(kv)/2)
+	for i := 0; i < len(kv); i += 2 {
+		key := strings.ToLower(kv[i])
+		md[key] = append(md[key], kv[i+1])
+	}
+	return md
+}
+
+// Len returns the number of items in md.
+func (md MD) Len() int {
+	return len(md)
+}
+
+// Copy returns a copy of md.
+func (md MD) Copy() MD {
+	out := make(MD, len(md))
+	for k, v := range md {
+		out[k] = copyOf(v)
+	}
+	return out
+}
+
+// Get obtains the values for a given key.
+//
+// k is converted to lowercase before searching in md.
+func (md MD) Get(k string) []string {
+	k = strings.ToLower(k)
+	return md[k]
+}
+
+// Set sets the value of a given key with a slice of values.
+//
+// k is converted to lowercase before storing in md.
+func (md MD) Set(k string, vals ...string) {
+	if len(vals) == 0 {
+		return
+	}
+	k = strings.ToLower(k)
+	md[k] = vals
+}
+
+// Append adds the values to key k, not overwriting what was already stored at
+// that key.
+//
+// k is converted to lowercase before storing in md.
+func (md MD) Append(k string, vals ...string) {
+	if len(vals) == 0 {
+		return
+	}
+	k = strings.ToLower(k)
+	md[k] = append(md[k], vals...)
+}
+
+// Delete removes the values for a given key k which is converted to lowercase
+// before removing it from md.
+func (md MD) Delete(k string) {
+	k = strings.ToLower(k)
+	delete(md, k)
+}
+
+// Join joins any number of mds into a single MD.
+//
+// The order of values for each key is determined by the order in which the mds
+// containing those values are presented to Join.
+func Join(mds ...MD) MD {
+	out := MD{}
+	for _, md := range mds {
+		for k, v := range md {
+			out[k] = append(out[k], v...)
+		}
+	}
+	return out
+}
+
+type mdIncomingKey struct{}
+type mdOutgoingKey struct{}
+
+// NewIncomingContext creates a new context with incoming md attached. md must
+// not be modified after calling this function.
+func NewIncomingContext(ctx context.Context, md MD) context.Context {
+	return context.WithValue(ctx, mdIncomingKey{}, md)
+}
+
+// NewOutgoingContext creates a new context with outgoing md attached. If used
+// in conjunction with AppendToOutgoingContext, NewOutgoingContext will
+// overwrite any previously-appended metadata. md must not be modified after
+// calling this function.
+func NewOutgoingContext(ctx context.Context, md MD) context.Context {
+	return context.WithValue(ctx, mdOutgoingKey{}, rawMD{md: md})
+}
+
+// AppendToOutgoingContext returns a new context with the provided kv merged
+// with any existing metadata in the context. Please refer to the documentation
+// of Pairs for a description of kv.
+func AppendToOutgoingContext(ctx context.Context, kv ...string) context.Context {
+	if len(kv)%2 == 1 {
+		panic(fmt.Sprintf("metadata: AppendToOutgoingContext got an odd number of input pairs for metadata: %d", len(kv)))
+	}
+	md, _ := ctx.Value(mdOutgoingKey{}).(rawMD)
+	added := make([][]string, len(md.added)+1)
+	copy(added, md.added)
+	kvCopy := make([]string, 0, len(kv))
+	for i := 0; i < len(kv); i += 2 {
+		kvCopy = append(kvCopy, strings.ToLower(kv[i]), kv[i+1])
+	}
+	added[len(added)-1] = kvCopy
+	return context.WithValue(ctx, mdOutgoingKey{}, rawMD{md: md.md, added: added})
+}
+
+// FromIncomingContext returns the incoming metadata in ctx if it exists.
+//
+// All keys in the returned MD are lowercase.
+func FromIncomingContext(ctx context.Context) (MD, bool) {
+	md, ok := ctx.Value(mdIncomingKey{}).(MD)
+	if !ok {
+		return nil, false
+	}
+	out := make(MD, len(md))
+	for k, v := range md {
+		// We need to manually convert all keys to lower case, because MD is a
+		// map, and there's no guarantee that the MD attached to the context is
+		// created using our helper functions.
+		key := strings.ToLower(k)
+		out[key] = copyOf(v)
+	}
+	return out, true
+}
+
+// ValueFromIncomingContext returns the metadata value corresponding to the metadata
+// key from the incoming metadata if it exists. Keys are matched in a case insensitive
+// manner.
+func ValueFromIncomingContext(ctx context.Context, key string) []string {
+	md, ok := ctx.Value(mdIncomingKey{}).(MD)
+	if !ok {
+		return nil
+	}
+
+	if v, ok := md[key]; ok {
+		return copyOf(v)
+	}
+	for k, v := range md {
+		// Case insensitive comparison: MD is a map, and there's no guarantee
+		// that the MD attached to the context is created using our helper
+		// functions.
+		if strings.EqualFold(k, key) {
+			return copyOf(v)
+		}
+	}
+	return nil
+}
+
+func copyOf(v []string) []string {
+	vals := make([]string, len(v))
+	copy(vals, v)
+	return vals
+}
+
+// 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
+// the extra kv pairs (AppendToOutgoingContext doesn't turn them into
+// lowercase).
+func fromOutgoingContextRaw(ctx context.Context) (MD, [][]string, bool) {
+	raw, ok := ctx.Value(mdOutgoingKey{}).(rawMD)
+	if !ok {
+		return nil, nil, false
+	}
+
+	return raw.md, raw.added, true
+}
+
+// FromOutgoingContext returns the outgoing metadata in ctx if it exists.
+//
+// All keys in the returned MD are lowercase.
+func FromOutgoingContext(ctx context.Context) (MD, bool) {
+	raw, ok := ctx.Value(mdOutgoingKey{}).(rawMD)
+	if !ok {
+		return nil, false
+	}
+
+	mdSize := len(raw.md)
+	for i := range raw.added {
+		mdSize += len(raw.added[i]) / 2
+	}
+
+	out := make(MD, mdSize)
+	for k, v := range raw.md {
+		// We need to manually convert all keys to lower case, because MD is a
+		// map, and there's no guarantee that the MD attached to the context is
+		// created using our helper functions.
+		key := strings.ToLower(k)
+		out[key] = copyOf(v)
+	}
+	for _, added := range raw.added {
+		if len(added)%2 == 1 {
+			panic(fmt.Sprintf("metadata: FromOutgoingContext got an odd number of input pairs for metadata: %d", len(added)))
+		}
+
+		for i := 0; i < len(added); i += 2 {
+			key := strings.ToLower(added[i])
+			out[key] = append(out[key], added[i+1])
+		}
+	}
+	return out, ok
+}
+
+type rawMD struct {
+	md    MD
+	added [][]string
+}