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Package writerset implements a mechanism to add and remove writers from a construct similar to io.MultiWriter.
type ErrPartialWrite struct {
Writer io.Writer
Err error
Expected, Wrote int
}ErrPartialWrite encapsulates an error from a WriterSet.
func (e ErrPartialWrite) Error() stringError returns the error string from the underlying error.
type WriterSet struct {
}WriterSet wraps multiple writers like io.MultiWriter, but such that individual writers are easy to add or remove as necessary.
func New() *WriterSetNew initializes a new empty writer set. This function is here for ease of use and backward compatibility, but a zero-value WriterSet is valid and ready for use.
func (ws *WriterSet) Add(w io.Writer) <-chan errorAdd ensures w is in the set. w must be a valid map key or Add will panic. The returned channel is written to if an error occurs writing to this writer, and in that case, the writer is removed from the set. The error will be of type ErrorPartialWrite. The channel is closed when the writer is removed from the set, with or without an error.
func (ws *WriterSet) Contains(w io.Writer) boolContains determines if w is in the set.
func (ws *WriterSet) Flush()Flush implements http.Flusher by calling flush on all the underlying writers if they are also http.Flushers.
func (ws *WriterSet) Remove(w io.Writer)Remove ensures w is not in the set. If it is in the set, the error channel associated with it will be closed.
func (ws *WriterSet) Write(b []byte) (int, error)Write writes data to each underlying writer. If an error occurs on an underlying writer, that writer is removed from the set. The error will be wrapped as an ErrPartialWrite and sent on the channel created when the writer was added.