Poll
poll is the Rust Future operation that advances an asynchronous computation and returns Poll::Ready with its output or Poll::Pending.
Rust Servers, Services, and Apps
Poll is a Rust result type that indicates whether a polled asynchronous computation is ready with a value or still pending.
- How it is used
- Signals a future's progress to the Tokio executor so it can schedule other tasks or receive a completed value.
- How deep it goes
- Works through the poll signature, both variants, wakeups, and a custom timer; defers detailed Pin mechanics.
- Examples
- Uses a custom future that stays pending, a repeated-wakeup experiment, and an expiration timer that becomes ready.
- What you can do after
- Build it from scratch by implementing a Future that returns Pending until its timer expires, then Ready with a String.
Learn Rust in a Month of Lunches
poll is the operation by which an asynchronous runtime advances a future toward completion and obtains its current state or output.
- How it is used
- Explains how awaiting a Future obtains its output while an async runtime manages checks for readiness.
- How deep it goes
- Defines Pending and Ready, shows the Future method signature, and defers a deep explanation of Pin.
- Examples
- Uses an async function returning u8, compiler errors for misplaced .await, and a working Tokio main function.
- What you can do after
- Apply it via .await and Tokio to obtain a future’s output without calling poll manually.
Related concepts
- executorused by · An executor is a software component or interface that accepts tasks or actions and arranges for their execution by an appropriate runtime or worker.
- futureuses · A future is an abstraction representing an asynchronous computation or its result, which may not be complete or available yet.
- async/awaitused by · Async/await is language syntax for expressing asynchronous computations that suspend at awaited operations and resume when they can proceed without blocking the execution thread.
- Tokioused by · Tokio is a Rust asynchronous runtime and library for scheduling tasks, polling futures, and performing nonblocking I/O.
- pollingused by · Polling is the repeated checking or querying of a resource, system, or condition, often at intervals, to detect data, events, or state changes.
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