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