Expose support for asynchronous interactions

[jboynes]

Servlet 3.1 and frameworks like Spring 4 support non-blocking request execution. This partially supported by the raw Storage API which exposes its HttpRequest objects with their executeAsync() operation. However, this does not support non-blocking transfers.

Full async support would allow an application to transfer data to/from Cloud Storage without having to consume a Thread while waiting for IO to complete.

[aozarov]

I doubt that will change while using google-api-java-client (did you create a feature request there we can link too?), so the current plan is to support it for every service that is available via gRPC.

[aozarov]

@jgeewax I don't this should not be a Needed for public announcement blocker but rather more of a future enhancement (when service supports it).

[jgeewax]

I can buy that. We could add these later pretty easily. Moving out the of the milestone.

[susanlinsfu]

+1

[lesv]

Turns out that AppEngine Standard has async support, Jetty 3.1 in Flex supports Async (at Top of Trunk), for generic Java, there is Apache's HttpAsyncClient

[garrettjonesgoogle]

I think we should just naturally surface the async functionality as we move each API to gRPC instead of having an old tracking issue. Closing this out.

[dminkovsky]

Has this been addressed elsewhere? I'm not finding another issue with this topic.

What is currently the best way to stream a file from storage with Netty? As in https://github.com/netty/netty/blob/60250f3795d4082e59df6806dade2966ec583859/example/src/main/java/io/netty/example/http/file/HttpStaticFileServerHandler.java#L188-L202.

[dminkovsky]

The way I have this working now is:

ReadChannel reader = storage.reader("bucket", "blob");
InputStream in = Channels.newInputStream(reader);
ChunkedStream stream = new ChunkedStream(in);
HttpChunkedInput input = new HttpChunkedInput(stream);

I send the HttpChunkedInput stream through the Netty channel and ChuckedWriteHandler writes the stream out in chunks to the client.

I wonder, though: the ReadChannel reader, is it non-blocking? I looked at the code and there are some functions that sleep the thread.

[oripwk]

Is there anything new with this?

Should we still work with GCS in a fully blocking manner? Or is there a solution?

Thanks

[frankyn]

@oripwk we don't currently have a plan for async in the GCS library. Could you file an issue against https://github.com/googleapis/java-storage/issues so we don't lose track of your request? Thank you!

[oripwk]

@frankyn opened here: googleapis/java-storage#638

[agentgt]

For download you only need to block on generating the download url. e.g: Storage.signUrl

Then you can use whatever Http client that is non blocking.

Storage.signUrl on code inspection appears to be non blocking as there doesn't seem to be any IO.

[danielcompton]

This is available now in v2.2.3.