116 lines
2.5 KiB
Go
116 lines
2.5 KiB
Go
package metadata
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import (
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"context"
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"maps"
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"strings"
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)
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type metadataKey struct{}
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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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type Metadata map[string]string
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func canonicalMetadataKey(key string) string {
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return strings.ToLower(key)
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}
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func (md Metadata) Has(key string) bool {
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_, ok := md[canonicalMetadataKey(key)]
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return ok
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}
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func (md Metadata) Get(key string) (string, bool) {
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val, ok := md[canonicalMetadataKey(key)]
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return val, ok
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}
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func (md Metadata) Set(key, val string) {
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md[canonicalMetadataKey(key)] = val
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}
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func (md Metadata) Delete(key string) {
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delete(md, canonicalMetadataKey(key))
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}
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// Copy makes a copy of the metadata.
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func Copy(md Metadata) Metadata {
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cmd := make(Metadata, len(md))
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maps.Copy(cmd, md)
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return cmd
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}
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// Delete key from metadata.
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func Delete(ctx context.Context, k string) context.Context {
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return Set(ctx, k, "")
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}
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// Set add key with val to metadata.
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func Set(ctx context.Context, k, v 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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k = canonicalMetadataKey(k)
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if v == "" {
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delete(md, k)
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} else {
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md[k] = v
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}
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return context.WithValue(ctx, metadataKey{}, md)
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}
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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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key = canonicalMetadataKey(key)
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val, ok := md[canonicalMetadataKey(key)]
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return val, ok
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}
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// FromContext returns metadata from the given context.
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func FromContext(ctx context.Context) (Metadata, bool) {
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md, ok := ctx.Value(metadataKey{}).(Metadata)
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if !ok {
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return nil, ok
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}
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// capitalise all values
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newMD := make(Metadata, len(md))
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for k, v := range md {
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newMD[canonicalMetadataKey(k)] = v
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}
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return newMD, ok
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}
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// NewContext creates a new context with the given metadata.
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func NewContext(ctx context.Context, md Metadata) context.Context {
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return context.WithValue(ctx, metadataKey{}, md)
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}
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// MergeContext merges metadata to existing metadata, overwriting if specified.
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func MergeContext(ctx context.Context, patchMd Metadata, overwrite bool) context.Context {
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if ctx == nil {
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ctx = context.Background()
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}
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md, _ := ctx.Value(metadataKey{}).(Metadata)
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cmd := make(Metadata, len(md))
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maps.Copy(cmd, md)
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for k, v := range patchMd {
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if _, ok := cmd[k]; ok && !overwrite {
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// skip
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} else if v != "" {
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cmd[k] = v
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} else {
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delete(cmd, k)
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}
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}
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return context.WithValue(ctx, metadataKey{}, cmd)
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}
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