Pollster is an incredibly minimal async executor for Rust that lets you block a thread until a future completes.
use FutureExt as _; let my_fut = async ; let result = my_fut.block_on;
That's it. That's all it does. Nothing more, nothing less. No need to pull in 50 crates to evaluate a future.
Why is this useful?
async functions are stable, we're increasingly seeing libraries all over the Rust ecosystem expose
APIs. This is great for those wanting to build highly concurrent web applications!
However, many of us are not building highly concurrent web applications, but end up faced with an
that we can't easily call from synchronous code. If you're in this position, then
pollster is for you: it allows you
to evaluate a future in-place without spinning up a heavyweight runtime like
Pollster is built with the UNIX ethos in mind: do one thing, and do it well. It has no dependencies, compiles quickly, and is composed of only ~100 lines of well-audited code.
Pollster will synchronously block the thread until a future completes. It will not spin: instead, it will place the thread into a waiting state until the future has been polled to completion.
pollster will not work for all futures because some require a specific runtime or reactor. See
here for more
information about when and where
pollster may be used. However, if you're already pulling in the required dependencies
to create such a future in the first place, it's likely that you already have a version of
block_on in your dependency
tree that's designed to poll your future, so use that instead.
When using the
macro crate feature, an attribute-macro can be used to mark
async fn main():
Additionally if you have re-exported the crate with a different name then
pollster, you have to specify it:
You can also use
#[pollster::test] for tests.