diff options
Diffstat (limited to 'vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/eventstreamapi/api.go')
-rw-r--r-- | vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/eventstreamapi/api.go | 160 |
1 files changed, 160 insertions, 0 deletions
diff --git a/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/eventstreamapi/api.go b/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/eventstreamapi/api.go new file mode 100644 index 0000000..4a4e64c --- /dev/null +++ b/vendor/github.com/aws/aws-sdk-go/private/protocol/eventstream/eventstreamapi/api.go @@ -0,0 +1,160 @@ +package eventstreamapi + +import ( + "fmt" + "io" + + "github.com/aws/aws-sdk-go/aws" + "github.com/aws/aws-sdk-go/private/protocol" + "github.com/aws/aws-sdk-go/private/protocol/eventstream" +) + +// Unmarshaler provides the interface for unmarshaling a EventStream +// message into a SDK type. +type Unmarshaler interface { + UnmarshalEvent(protocol.PayloadUnmarshaler, eventstream.Message) error +} + +// EventStream headers with specific meaning to async API functionality. +const ( + MessageTypeHeader = `:message-type` // Identifies type of message. + EventMessageType = `event` + ErrorMessageType = `error` + ExceptionMessageType = `exception` + + // Message Events + EventTypeHeader = `:event-type` // Identifies message event type e.g. "Stats". + + // Message Error + ErrorCodeHeader = `:error-code` + ErrorMessageHeader = `:error-message` + + // Message Exception + ExceptionTypeHeader = `:exception-type` +) + +// EventReader provides reading from the EventStream of an reader. +type EventReader struct { + reader io.ReadCloser + decoder *eventstream.Decoder + + unmarshalerForEventType func(string) (Unmarshaler, error) + payloadUnmarshaler protocol.PayloadUnmarshaler + + payloadBuf []byte +} + +// NewEventReader returns a EventReader built from the reader and unmarshaler +// provided. Use ReadStream method to start reading from the EventStream. +func NewEventReader( + reader io.ReadCloser, + payloadUnmarshaler protocol.PayloadUnmarshaler, + unmarshalerForEventType func(string) (Unmarshaler, error), +) *EventReader { + return &EventReader{ + reader: reader, + decoder: eventstream.NewDecoder(reader), + payloadUnmarshaler: payloadUnmarshaler, + unmarshalerForEventType: unmarshalerForEventType, + payloadBuf: make([]byte, 10*1024), + } +} + +// UseLogger instructs the EventReader to use the logger and log level +// specified. +func (r *EventReader) UseLogger(logger aws.Logger, logLevel aws.LogLevelType) { + if logger != nil && logLevel.Matches(aws.LogDebugWithEventStreamBody) { + r.decoder.UseLogger(logger) + } +} + +// ReadEvent attempts to read a message from the EventStream and return the +// unmarshaled event value that the message is for. +// +// For EventStream API errors check if the returned error satisfies the +// awserr.Error interface to get the error's Code and Message components. +// +// EventUnmarshalers called with EventStream messages must take copies of the +// message's Payload. The payload will is reused between events read. +func (r *EventReader) ReadEvent() (event interface{}, err error) { + msg, err := r.decoder.Decode(r.payloadBuf) + if err != nil { + return nil, err + } + defer func() { + // Reclaim payload buffer for next message read. + r.payloadBuf = msg.Payload[0:0] + }() + + typ, err := GetHeaderString(msg, MessageTypeHeader) + if err != nil { + return nil, err + } + + switch typ { + case EventMessageType: + return r.unmarshalEventMessage(msg) + case ErrorMessageType: + return nil, r.unmarshalErrorMessage(msg) + default: + return nil, fmt.Errorf("unknown eventstream message type, %v", typ) + } +} + +func (r *EventReader) unmarshalEventMessage( + msg eventstream.Message, +) (event interface{}, err error) { + eventType, err := GetHeaderString(msg, EventTypeHeader) + if err != nil { + return nil, err + } + + ev, err := r.unmarshalerForEventType(eventType) + if err != nil { + return nil, err + } + + err = ev.UnmarshalEvent(r.payloadUnmarshaler, msg) + if err != nil { + return nil, err + } + + return ev, nil +} + +func (r *EventReader) unmarshalErrorMessage(msg eventstream.Message) (err error) { + var msgErr messageError + + msgErr.code, err = GetHeaderString(msg, ErrorCodeHeader) + if err != nil { + return err + } + + msgErr.msg, err = GetHeaderString(msg, ErrorMessageHeader) + if err != nil { + return err + } + + return msgErr +} + +// Close closes the EventReader's EventStream reader. +func (r *EventReader) Close() error { + return r.reader.Close() +} + +// GetHeaderString returns the value of the header as a string. If the header +// is not set or the value is not a string an error will be returned. +func GetHeaderString(msg eventstream.Message, headerName string) (string, error) { + headerVal := msg.Headers.Get(headerName) + if headerVal == nil { + return "", fmt.Errorf("error header %s not present", headerName) + } + + v, ok := headerVal.Get().(string) + if !ok { + return "", fmt.Errorf("error header value is not a string, %T", headerVal) + } + + return v, nil +} |