Writer should accept Buffer

[Xuanwo]

Write API Design

We want to implement the follwing APIs upon Writer:

• write(buf): feat(core): Implement write and write_from for Writer #4482
• into_sink() -> BufferSink (make this internal first)
• write_from(bytes:buf): feat(core): Implement write and write_from for Writer #4482
• into_bytes_sink() -> FuturesBytesSink
• replace sink API with into_bytes_sink
• into_futures_async_write() -> FuturesAsyncWriter

The name is still being decided, but the semantics should be fine as they are.

In general, we will provide three kinds of API:

• Buffer native (the best performance API without extra copy): write and into_sink
• Bytes based: write_from and into_bytes_sink
• Async Write based: into_futures_async_write

[zjregee]

Can I try some of them like write and write_from?

[Xuanwo]

Can I try some of them like write and write_from?

Welcome to have a try!

[tisonkun]

@Xuanwo there is no copy_from and pipe_from now?

[Xuanwo]

@Xuanwo there is no copy_from and pipe_from now?

Yes, not implemented.

[tisonkun]

@Xuanwo could you then update the issue description and add related source code any contributor can start from?

[tisonkun]

@Xuanwo any dangling APIs here? I saw #4498 do something for this issue.

[Xuanwo]

The only API left is into_sink and into_bytes_sink. They can replace the existing sink API.

---

I'm still hesitate about the into_sink API. We can keep it internal use only.

[tisonkun]

The API design is still quite abstract. As a developer unfamiliar with this scope, what does it mean BufferSink and FuturesBytesSink? Which trait should they implement? What APIs do they want to replace?

[Xuanwo]

what does it mean BufferSink and FuturesBytesSink?

• BufferSink is a Sink that accept Buffer. It should implement Sink<Buffer, Error=opendal::Error>. It's the opposite of BufferStream which returns a Buffer.
• FuturesBytesSink is a Sink that accept Bytes. It should implement Sink<Bytes, Error=std::io::Error>. It's the opposite of FuturesBytesStream which returns a Bytes.

Also, into_bytes_sink() -> FuturesBytesSink will replace existing sink(&mut self, sink_from: S).