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Note

This is a point-in-time snapshot of the API documentation from January 2026. Going forward, we will not be maintaining a public copy of these references, and recommend users to refer to the built-in signature helpers available in the Hack LSP instead for complete and up-to-date information.

Cancel Awaitable, if it's still pending

namespace HH\Asio;

function cancel<T>(
  Awaitable<T, mixed> $awaitable,
  \Exception $exception,
): bool;

If Awaitable has not been completed yet, fails Awaitable with $exception and returns true. Otherwise, returns false.

Throws InvalidArgumentException, if Awaitable does not support cancellation.

Parameters​

Returns​

  • bool