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package wasi:io@0.2.1;
/// A poll API intended to let users wait for I/O events on multiple handles
/// at once.
@since(version = 0.2.0)
interface poll {
/// `pollable` represents a single I/O event which may be ready, or not.
@since(version = 0.2.0)
resource pollable {
/// Return the readiness of a pollable. This function never blocks.
///
/// Returns `true` when the pollable is ready, and `false` otherwise.
@since(version = 0.2.0)
ready: func() -> bool;
/// `block` returns immediately if the pollable is ready, and otherwise
/// blocks until ready.
///
/// This function is equivalent to calling `poll.poll` on a list
/// containing only this pollable.
@since(version = 0.2.0)
block: func();
}
/// Poll for completion on a set of pollables.
///
/// This function takes a list of pollables, which identify I/O sources of
/// interest, and waits until one or more of the events is ready for I/O.
///
/// The result `list<u32>` contains one or more indices of handles in the
/// argument list that is ready for I/O.
///
/// This function traps if either:
/// - the list is empty, or:
/// - the list contains more elements than can be indexed with a `u32` value.
///
/// A timeout can be implemented by adding a pollable from the
/// wasi-clocks API to the list.
///
/// This function does not return a `result`; polling in itself does not
/// do any I/O so it doesn't fail. If any of the I/O sources identified by
/// the pollables has an error, it is indicated by marking the source as
/// being ready for I/O.
@since(version = 0.2.0)
poll: func(in: list<borrow<pollable>>) -> list<u32>;
}
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