2016-12-14 18:41:48 +03:00
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// Package metadata is a way of defining message headers
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2016-01-28 20:55:28 +03:00
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package metadata
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import (
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2018-03-03 14:53:52 +03:00
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"context"
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2020-09-30 16:14:54 +03:00
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"net/textproto"
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2016-01-28 20:55:28 +03:00
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)
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2020-04-12 13:16:08 +03:00
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type metadataKey struct{}
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2016-01-28 20:55:28 +03:00
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2016-01-31 00:17:44 +03:00
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// Metadata is our way of representing request headers internally.
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// They're used at the RPC level and translate back and forth
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// from Transport headers.
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2016-01-28 20:55:28 +03:00
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type Metadata map[string]string
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2020-03-26 21:50:00 +03:00
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func (md Metadata) Get(key string) (string, bool) {
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2020-09-30 16:14:54 +03:00
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// fast path
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2020-03-26 21:50:00 +03:00
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val, ok := md[key]
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2020-09-30 16:14:54 +03:00
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if !ok {
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// slow path
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val, ok = md[textproto.CanonicalMIMEHeaderKey(key)]
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2020-03-26 21:50:00 +03:00
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}
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return val, ok
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}
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2020-04-12 13:17:23 +03:00
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func (md Metadata) Set(key, val string) {
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2020-09-30 16:14:54 +03:00
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md[textproto.CanonicalMIMEHeaderKey(key)] = val
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2020-04-12 13:17:23 +03:00
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}
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2020-09-30 16:14:54 +03:00
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func (md Metadata) Del(key string) {
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2020-09-30 16:21:47 +03:00
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// fast path
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if _, ok := md[key]; ok {
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delete(md, key)
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} else {
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// slow path
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delete(md, textproto.CanonicalMIMEHeaderKey(key))
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}
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2020-03-31 22:55:33 +03:00
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}
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2019-10-26 01:27:59 +03:00
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// Copy makes a copy of the metadata
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2019-01-17 12:40:49 +03:00
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func Copy(md Metadata) Metadata {
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2020-09-30 16:14:54 +03:00
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nmd := make(Metadata, len(md))
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2019-01-17 12:40:49 +03:00
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for k, v := range md {
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2020-09-30 16:14:54 +03:00
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nmd[k] = v
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2019-01-17 12:40:49 +03:00
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}
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2020-09-30 16:14:54 +03:00
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return nmd
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2019-01-17 12:40:49 +03:00
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}
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2020-09-30 16:14:54 +03:00
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func Del(ctx context.Context, key string) context.Context {
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md, ok := FromContext(ctx)
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if !ok {
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md = make(Metadata)
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}
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md.Del(key)
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return context.WithValue(ctx, metadataKey{}, md)
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2020-03-31 22:55:33 +03:00
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}
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2020-02-21 23:04:47 +03:00
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// Set add key with val to metadata
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2020-09-30 16:14:54 +03:00
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func Set(ctx context.Context, key, val string) context.Context {
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2020-02-21 23:04:47 +03:00
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md, ok := FromContext(ctx)
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if !ok {
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md = make(Metadata)
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}
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2020-09-30 16:14:54 +03:00
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md.Set(key, val)
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2020-04-12 13:16:08 +03:00
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return context.WithValue(ctx, metadataKey{}, md)
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2020-02-21 23:04:47 +03:00
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}
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2019-11-11 12:13:02 +03:00
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// Get returns a single value from metadata in the context
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func Get(ctx context.Context, key string) (string, bool) {
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md, ok := FromContext(ctx)
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if !ok {
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return "", ok
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}
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2020-09-30 16:14:54 +03:00
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return md.Get(key)
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2019-11-11 12:13:02 +03:00
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}
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2019-10-26 01:27:59 +03:00
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// FromContext returns metadata from the given context
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2016-01-28 20:55:28 +03:00
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func FromContext(ctx context.Context) (Metadata, bool) {
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2020-04-12 13:16:08 +03:00
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md, ok := ctx.Value(metadataKey{}).(Metadata)
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2020-09-30 16:14:54 +03:00
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return md, ok
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2016-01-28 20:55:28 +03:00
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}
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2019-10-26 01:27:59 +03:00
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// NewContext creates a new context with the given metadata
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2016-01-28 20:55:28 +03:00
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func NewContext(ctx context.Context, md Metadata) context.Context {
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2020-04-12 13:16:08 +03:00
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return context.WithValue(ctx, metadataKey{}, md)
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2016-01-28 20:55:28 +03:00
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}
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2019-10-25 03:51:54 +03:00
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2019-10-26 01:27:59 +03:00
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// MergeContext merges metadata to existing metadata, overwriting if specified
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2020-09-30 16:14:54 +03:00
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func MergeContext(ctx context.Context, pmd Metadata, overwrite bool) context.Context {
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2020-02-06 20:22:16 +03:00
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if ctx == nil {
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ctx = context.Background()
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}
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2020-09-30 16:14:54 +03:00
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md, ok := FromContext(ctx)
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if !ok {
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md = make(Metadata)
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}
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nmd := make(Metadata, len(md))
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for key, val := range md {
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nmd.Set(key, val)
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2019-10-25 03:51:54 +03:00
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}
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2020-09-30 16:14:54 +03:00
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for key, val := range pmd {
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if _, ok := nmd[key]; ok && !overwrite {
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2019-10-25 18:27:28 +03:00
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// skip
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2020-09-30 16:14:54 +03:00
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} else if val != "" {
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nmd.Set(key, val)
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2020-03-31 22:55:33 +03:00
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} else {
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2020-09-30 16:14:54 +03:00
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nmd.Del(key)
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2019-10-25 18:27:28 +03:00
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}
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2019-10-25 03:51:54 +03:00
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}
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2020-09-30 16:14:54 +03:00
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return context.WithValue(ctx, metadataKey{}, nmd)
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2019-10-25 03:51:54 +03:00
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}
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