Add smol as an executor #3790
Add smol as an executor #3790
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# Conflicts: # .github/workflows/sqlx.yml
martin-kolarik
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| } else if #[cfg(feature = "_rt-smol")] { | ||
| use smol::net::resolve; | ||
| use smol::Async; | ||
| use std::net::TcpStream; | ||
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| let mut last_err = None; | ||
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| // Loop through all the Socket Addresses that the hostname resolves to | ||
| for socket_addr in resolve((host, port)).await? { | ||
| let stream = Async::<TcpStream>::connect(socket_addr) | ||
| .await | ||
| .and_then(|s| { | ||
| s.get_ref().set_nodelay(true)?; | ||
| Ok(s) | ||
| }); | ||
| match stream { | ||
| Ok(stream) => return Ok(with_socket.with_socket(stream).await), | ||
| Err(e) => last_err = Some(e), | ||
| } | ||
| } | ||
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| #[cfg(not(feature = "_rt-async-std"))] | ||
| { | ||
| crate::rt::missing_rt((host, port, with_socket)) | ||
| // If we reach this point, it means we failed to connect to any of the addresses. | ||
| // Return the last error we encountered, or a custom error if the hostname didn't resolve to any address. | ||
| Err(match last_err { | ||
| Some(err) => err, | ||
| None => io::Error::new( | ||
| io::ErrorKind::AddrNotAvailable, | ||
| "Hostname did not resolve to any addresses", | ||
| ), | ||
| } | ||
| .into()) |
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Actually, this code duplication isn't really necessary. Since async-std and smol both use async-io, the async-std block should work for both with a few tweaks. And then the async-global-executor impl can share the same code path as well (async-net just wraps async-io).
The difference between async_std::net::ToSocketAddrs and smol::net::resolve() seems significant, but in fact, they both simply invoke std::net::ToSocketAddrs in a blocking task:
- Smol via
async-net: https://docs.rs/async-net/2.0.0/src/async_net/addr.rs.html#150-153 async-stdvia a bespoke implementation: https://docs.rs/async-std/latest/src/async_std/net/addr.rs.html#217-221
Funnily enough, Tokio does the exact same thing: https://docs.rs/tokio/latest/src/tokio/net/addr.rs.html#219-221
They all also have a fast path for when the hostname can be parsed as an IP address that skips the blocking task.
This would be easy enough to implement ourselves in a single code path using our own spawn_blocking abstraction. Then only runtime-specific part would be deciding which TcpStream type to use.
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Implemented, but it looks that TLS test are failing after this changed. Do not know why so far, even going back does not help.
The issue is that |
As of This is likely going to be delayed until the 0.9.0 release anyway since a whole new runtime feature is a bit much to add in a point release. |
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Next question: if 0.9.0 is a target, will sqlx's MSRV be lifted to +1.81? If yes, then the split between |
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After all changes (in |
This PR adds
smolas a third async executor, to overcomeasync_stdobsolescence.async_stdremains working, but it is replaced withsmolin CI, to reduce number of run tasks.Adding
smolis not a breaking change.