64 lines
1.8 KiB
Go
64 lines
1.8 KiB
Go
package eventstreamapi
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import (
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"github.com/aws/aws-sdk-go/private/protocol"
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"github.com/aws/aws-sdk-go/private/protocol/eventstream"
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)
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// Marshaler provides a marshaling interface for event types to event stream
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// messages.
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type Marshaler interface {
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MarshalEvent(protocol.PayloadMarshaler) (eventstream.Message, error)
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}
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// Encoder is an stream encoder that will encode an event stream message for
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// the transport.
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type Encoder interface {
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Encode(eventstream.Message) error
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}
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// EventWriter provides a wrapper around the underlying event stream encoder
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// for an io.WriteCloser.
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type EventWriter struct {
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encoder Encoder
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payloadMarshaler protocol.PayloadMarshaler
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eventTypeFor func(Marshaler) (string, error)
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}
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// NewEventWriter returns a new event stream writer, that will write to the
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// writer provided. Use the WriteEvent method to write an event to the stream.
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func NewEventWriter(encoder Encoder, pm protocol.PayloadMarshaler, eventTypeFor func(Marshaler) (string, error),
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) *EventWriter {
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return &EventWriter{
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encoder: encoder,
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payloadMarshaler: pm,
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eventTypeFor: eventTypeFor,
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}
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}
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// WriteEvent writes an event to the stream. Returns an error if the event
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// fails to marshal into a message, or writing to the underlying writer fails.
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func (w *EventWriter) WriteEvent(event Marshaler) error {
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msg, err := w.marshal(event)
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if err != nil {
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return err
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}
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return w.encoder.Encode(msg)
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}
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func (w *EventWriter) marshal(event Marshaler) (eventstream.Message, error) {
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eventType, err := w.eventTypeFor(event)
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if err != nil {
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return eventstream.Message{}, err
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}
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msg, err := event.MarshalEvent(w.payloadMarshaler)
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if err != nil {
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return eventstream.Message{}, err
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}
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msg.Headers.Set(EventTypeHeader, eventstream.StringValue(eventType))
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return msg, nil
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}
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