process: remove Future impl on Child #2796
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* This brings our APIs closer to those in std and it allows us to internally fuse the future so that repeated calls to `wait` result in the same value (similar to std) without forcing the caller to fuse the outer future * Also change `Child::id` to return an Option result to avoid allowing the caller to accidentally use the pid on Unix systems after the child has been repaed
Darksonn
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A-tokio
Darksonn
approved these changes
Sep 5, 2020
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Motivation
The
tokio::process::Childtype implementsFuturedirectly which makes it awkward to use, especially when coming from the synchronous version from the standard library. For example, it is impossible to check the status of the command from outside of async contexts.Solution
Futureimpl onChildin favor of an async.wait()method, which mirrors the stdlib API.try_wait()method similar to the stdlib one. This API will not register for wake ups and is safe to invoke from non-async codeChild::idmethod to return anOption<u32>to better note that once a child has been reaped, it may not be safe to reuse that identifier (e.g. if the caller wants to interact with the raw process directly). This is the only API which differs from the stdlibRefs #2432