50 lines
1.1 KiB
Go
50 lines
1.1 KiB
Go
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// Package metadata is a way of defining message headers
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package metadata
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import (
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"context"
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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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if ctx == nil {
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return nil, false
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}
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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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nmd := Copy(md)
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return nmd, 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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if ctx == nil {
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ctx = context.Background()
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}
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return context.WithValue(ctx, metadataKey{}, Copy(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, pmd 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, ok := FromContext(ctx)
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if !ok {
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return context.WithValue(ctx, metadataKey{}, Copy(pmd))
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}
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nmd := Copy(md)
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for key, val := range pmd {
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if _, ok := nmd[key]; ok && !overwrite {
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// skip
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} else if val != "" {
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nmd.Set(key, val)
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} else {
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nmd.Del(key)
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}
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}
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return context.WithValue(ctx, metadataKey{}, nmd)
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}
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