39 lines
986 B
Go
39 lines
986 B
Go
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package log
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import (
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"context"
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"errors"
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)
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type key int
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const metadataKey key = 0
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// ContextWithLoggable returns a derived context which contains the provided
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// Loggable. Any Events logged with the derived context will include the
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// provided Loggable.
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func ContextWithLoggable(ctx context.Context, l Loggable) context.Context {
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existing, err := MetadataFromContext(ctx)
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if err != nil {
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// context does not contain meta. just set the new metadata
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child := context.WithValue(ctx, metadataKey, Metadata(l.Loggable()))
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return child
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}
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merged := DeepMerge(existing, l.Loggable())
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child := context.WithValue(ctx, metadataKey, merged)
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return child
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}
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// MetadataFromContext extracts Matadata from a given context's value.
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func MetadataFromContext(ctx context.Context) (Metadata, error) {
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value := ctx.Value(metadataKey)
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if value != nil {
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metadata, ok := value.(Metadata)
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if ok {
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return metadata, nil
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}
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}
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return nil, errors.New("context contains no metadata")
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}
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