Ah.
Two things:
1) If the stream is dropped without done() ever having been called, you
know at least that the data is incomplete.
2) Usually, I would recommend that the method you call to say "write data
to this stream" should not return until all data is written.
get @0 (filename :Text, stream :ByteStream);
# Writes the content of the given file to the given stream. Returns
once all data is written
# and stream.done() has completed successfully.
-Kenton
On Tue, May 23, 2017 at 12:56 PM, Ian Denhardt <[email protected]> wrote:
> I'm talking about reporting an error to the receiver of the data, not
> the caller of write(). E.g. I have a capnp interface for a remote
> filesystem, and I want to read data from a file. I pass the server a
> ByteStream to use to send me the data. How does the server report an
> error *to me*?
>
> Quoting Kenton Varda (2017-05-23 11:42:44)
> > Hi Ian,
> > I'm not sure I understand. write() can throw an exception. Does that
> > not solve the problem?
> > -Kenton
> > On Mon, May 22, 2017 at 5:01 PM, Ian Denhardt <[1][email protected]>
> > wrote:
> >
> > Are there established best practices for handling errors that occur
> > with
> > async/push style interfaces, such as sandstorm's Util.ByteStream[1]?
> > That interface doesn't seem to supply a way to report e.g. an IO
> > error
> > that occurs while streaming, and since the call that obtained the
> > ByteStream has already completed, the error can't be reported via
> > the
> > rpc protocol's exception mechanism.
> > I suppose one could just add a method for reporting the error. But I
> > wanted to poll to see if there was any standard pattern for this.
> > [1]: [2]https://github.com/sandstorm-io/sandstorm/blob/
> master/src/sa
> > ndstorm/util.capnp#L69
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> >
> > Verweise
> >
> > 1. mailto:[email protected]
> > 2. https://github.com/sandstorm-io/sandstorm/blob/master/src/
> sandstorm/util.capnp#L69
> > 3. mailto:capnproto%[email protected]
> > 4. https://groups.google.com/group/capnproto
>
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