update to tokio 1.0

[astraw]

This updates the internal use of tokio to 1.0. As I note in the module-level docstring, the examples (and tests) are kept using tokio 0.3 because tokio itself has removed the Stream trait until it is added in std.

I don't think this is a breaking change because tokio is not part of the API. Thus, I believe this could be released as non-breaking semver version bump.

[codecov-io]

Codecov Report

Merging #9 (63decfb) into master (8292fac) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master       #9   +/-   ##
=======================================
  Coverage   81.21%   81.21%           
=======================================
  Files           3        3           
  Lines         165      165           
=======================================
  Hits          134      134           
  Misses         31       31           

Impacted Files	Coverage Δ
src/combinator.rs	75.00% <ø> (ø)
src/lib.rs	81.81% <ø> (ø)

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[jonhoo]

Hmm, I suppose since we're just using sync types, we probably work with any version of tokio, you're right. That's nice! Note that that wouldn't have been the case if we used tokio I/O types or spawning for example, even though no tokio types show up in the external API.

As for the tests, I'd prefer to keep them on the same version nonetheless. Can we leverage tokio-stream here?

[astraw]

Good point that although tokio does not show up in the external API, compatibility with older tokio versions is not necessarily guaranteed. I hadn't considered that and thus perhaps this should be investigated more closely before declaring that this does not require a semver bump. (My back-compat testing was limited to the tests in the crate.)

(For reference, my motivation for this PR was simply eliminating tokio 0.3 from my dependency tree and replacing it exclusively with tokio 1.0.)

Regarding keeping the tests using the same version of tokio as the implementation and the Stream trait issue: I agree it is a nice goal and I originally tried to do that. However, I realized that it will substantially complicate the tests to port them to tokio 1.0 while tokio 1.0 is missing streams. As far as I remember (I forget the details already), using tokio-stream will still require a lot of boilerplate for what should be a simple example. In the end I see two possibilities that seem OK: The first is to keep the examples using tokio 0.3 until the Stream definition is in std at which point tokio will also implement this. Unfortunately this will take some months. The second possibility is to demonstrate and test stream-cancel not on tokio streams but e.g. simple self-defined ones.

[jonhoo]

@astraw I think that should be helped by tokio-rs/tokio#3343, which adds back all the various Stream implementations for the tokio types into tokio-stream?

[astraw]

Yes, those are the boilerplate implementations that I thought didn't belong in the stream-cancel examples. I think the stream-cancel examples/tests could be updated once those tokio-stream changes are published.

Until then, in this pull request, I would be happy to rename tokio 0.3 to tokio03 and tokio 1.0 to just tokio. Then tokio03, which would exist only in the examples, would be completely replaced with tokio-stream when that was possible. (The current naming was chosen to change as little code as possible.) Since replacing tokio03 to tokio-stream would touch only the examples, I'm not sure it would merit a new release. Still, such a later change would be useful to get the updated examples into the docstrings.

How do you like that idea?

(Once Stream lands in std, a new version of stream-cancel with a major version bump can be released that depends on the std Stream definition. Presumably the examples could then once again use types directly from tokio, not tokio-stream.)

[astraw]

Actually my proposal resulted in fewer changes than I anticipated, so I went ahead and updated this pull request.

[jonhoo]

I think the tokio-stream changes have been published now :)

[astraw]

Yes, now I updated the tests and examples to use the tokio-stream wrappers introduced in 0.1.1.

[jonhoo]

Beautiful, thank you! Will release shortly.

[jonhoo]

Released as 0.8.0 🎉