Mio – Metal I/O
Mio is a fast, low-level I/O library for Rust focusing on non-blocking APIs and event notification for building high performance I/O apps with as little overhead as possible over the OS abstractions.
This is a low level library, if you are looking for something easier to get started with, see Tokio.
mio, first add this to your
 = "0.8"
Next we can start using Mio. The following is quick introduction using
TcpStream. Note that
features = ["os-poll", "net"] must be
specified for this example.
use Error; use ; use ; // Some tokens to allow us to identify which event is for which socket. const SERVER: Token = Token; const CLIENT: Token = Token;
- Non-blocking TCP, UDP
- I/O event queue backed by epoll, kqueue, and IOCP
- Zero allocations at runtime
- Platform specific extensions
The following are specifically omitted from Mio and are left to the user or higher-level libraries.
- File operations
- Thread pools / multi-threaded event loop
Currently supported platforms:
- Android (API level 21)
- DragonFly BSD
There are potentially others. If you find that Mio works on another platform, submit a PR to update the list!
Mio can handle interfacing with each of the event systems of the aforementioned
platforms. The details of their implementation are further discussed in the
Poll type of the API documentation (see above).
The Windows implementation for polling sockets is using the wepoll strategy. This uses the Windows AFD system to access socket readiness events.
Mio uses different implementations to support the same functionality depending on the platform. Mio generally uses the "best" implementation possible, where "best" usually means most efficient for Mio's use case. However this means that the implementation is often specific to a limited number of platforms, meaning we often have multiple implementations for the same functionality. In some cases it might be required to not use the "best" implementation, but another implementation Mio supports (on other platforms). Mio does not officially support secondary implementations on platforms, however we do have various cfg flags to force another implementation for these situations.
mio_unsupported_force_poll_poll, uses an implementation based on
mio_unsupported_force_waker_pipe, uses an implementation based on
Again, Mio does not officially supports this. Furthermore these flags may disappear in the future.
Interested in getting involved? We would love to help you! For simple bug fixes, just submit a PR with the fix and we can discuss the fix directly in the PR. If the fix is more complex, start with an issue.
If you want to propose an API change, create an issue to start a discussion with the community. Also, feel free to talk with us in Discord.
Finally, be kind. We support the Rust Code of Conduct.