Update hyper to 0.12

[c0gent]

I see that this PR has been sitting for a while. I'd like to make the changes necessary to update hyper. I want to remove the rest of tokio-core from Parity due to its deprecation (migrate to tokio) and I'll need to update the reactor Handle to do that.

Is there anything in particular I should to be concerned about? Has anyone else looked into this?

[tomusdrw]

Thanks for jumping on it, I started the migration some time ago (just pushed td-hyper branch), there is some work involved in changing the way we handle headers (hyper removed the typed headers), but everything should be doable.

[c0gent]

Yep, I'm already about half way through it. I'll have a look at that branch. Thanks :)

[c0gent]

Is there any particular reason to keep the RpcEventLoop single threaded (i.e. using a single Tokio Reactor all by itself) in the Spawned configuration? It's usually sub-optimal except maybe in micro-benchmarks and other special cases.

This may be something you guys have tested already and maybe there is some particular reason you want to stay single threaded. If that's the case I can make sure that all jsonrpc tasks stay that way without much trouble. I'll be removing the CpuPool from Parity and its reactor will be paired with a thread pool automatically so when RpcEventLoop is in the Shared configuration tasks will be running on a thread pool anyway (unless jsonrpc needs special treatment).

Otherwise I'll proceed with converting it to the standard tokio configuration (using a Runtime i.e. multi-threaded).

[tomusdrw]

We wanted to have a handle that closes the server when dropped. And to simplify spawning a new server if you don't really care that much for async/tokio stuff.

It's fine to convert it to Runtime, I can review the changes even if unfinished if you are unsure about the approach.

[c0gent]

So far the only API change I was planning to make is simply renaming server_utils::reactor::Remote to Executor. I'm not sure about that though. It's ability to close the server, etc. remains unchanged. I might rename the reactor module. No functionality anywhere will be removed or significantly changed.

You can see the changes on this branch. So far, I've mostly finished changes to the server-utils and tcp crates. tcp provides the best example of what will change (virtually nothing from the outside). I got slowed down working on ipc due to the changes I had to make to tokio-named-pipes and parity-tokio-ipc but the changes to ipc and http, etc. will be mostly along the same lines as those in tcp. A fairly straightforward migration.

[c0gent]

Just an update: I haven't had time to work on this since last week and I have some travel coming up soon but I'm pretty much down to the final pieces and I'll do my best to get a PR submitted within in the next few days.

[jackcmay]

Is this still in motion?

[c0gent]

PR is here: #303

Integrating similar changes into Parity (to properly test the changes made by #303) is largely blocked by: openethereum/parity-ethereum#9533

A WIP branch for those changes is: https://github.com/poanetwork/parity-ethereum/tree/c0gent-tokio