micro/metadata/metadata.go

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// Package metadata is a way of defining message headers
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package metadata
import (
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"context"
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)
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type metaKey struct{}
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// Metadata is our way of representing request headers internally.
// They're used at the RPC level and translate back and forth
// from Transport headers.
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type Metadata map[string]string
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func Copy(md Metadata) Metadata {
cmd := make(Metadata)
for k, v := range md {
cmd[k] = v
}
return cmd
}
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func FromContext(ctx context.Context) (Metadata, bool) {
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md, ok := ctx.Value(metaKey{}).(Metadata)
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return md, ok
}
func NewContext(ctx context.Context, md Metadata) context.Context {
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return context.WithValue(ctx, metaKey{}, md)
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}
// PatchContext : will add/replace source metadata fields with given patch metadata fields
func PatchContext(ctx context.Context, patchMd Metadata) context.Context {
md, _ := ctx.Value(metaKey{}).(Metadata)
cmd := make(Metadata)
for k, v := range md {
cmd[k] = v
}
for k, v := range patchMd {
cmd[k] = v
}
return context.WithValue(ctx, metaKey{}, cmd)
}