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coroutine generator cannot be moved or composed. #1789

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jsong785 opened this issue Aug 15, 2023 · 1 comment · May be fixed by #2354
Open

coroutine generator cannot be moved or composed. #1789

jsong785 opened this issue Aug 15, 2023 · 1 comment · May be fixed by #2354
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@tchaikov

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@jsong785
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jsong785 commented Aug 15, 2023 •
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I am just learning this framework and cpp20; excuse me if this is a known issue/problem.

It seems like there may be an issue in seastar::coroutine::experimental::generator; where both the move constructor and assignment operator do not update the promise object's generator.

Obvious things like this seem to fail. It seems like it is fixed with a couple of lines of changes to the generator class.

auto gen = create_generator(...);
auto gen_moved = std::move(gen);

// usage of gen_moved creates error

However, I seem to get a crash on/off here no matter what. Perhaps my knowledge of coroutines is faulty.

auto gen1 = create1(...);
auto gen2 = create2(..., std::move(gen1));
auto gen3 = create3(..., std::move(gen2));
auto gen4 = create2(..., std::move(gen3));

// start using gen4, which will start gen 1/2/3 upstream.
@tchaikov
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@jsong785 thank you for your bug report! this is not a known issue, AFAICT. actually, i never tried to move the generator. will give it a try later on.

@tchaikov tchaikov self-assigned this Aug 29, 2023
bhalevy added a commit to bhalevy/seastar that referenced this issue Jul 17, 2024
@bhalevy
coroutine: experimental: generator: implement move and swap
1d7a876 
The coroutine generator move ctor, move assignment operator,
and swap override were never fully implemented.

This patch completes their implementation
and adds unit tests to cover move and swap
and also moving not-drained generator (to test
moving of their buffered value(s)).

Fixes scylladb#1789

Signed-off-by: Benny Halevy <[email protected]>
@bhalevy bhalevy linked a pull request Jul 17, 2024 that will close this issue
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bhalevy added a commit to bhalevy/seastar that referenced this issue Jul 17, 2024
@bhalevy
coroutine: experimental: generator: implement move and swap
311c33d 
The coroutine generator move ctor, move assignment operator,
and swap override were never fully implemented.

This patch completes their implementation
and adds unit tests to cover move and swap
and also moving not-drained generator (to test
moving of their buffered value(s)).

Fixes scylladb#1789

Signed-off-by: Benny Halevy <[email protected]>
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coroutine: experimental: generator: implement move and swap bhalevy/seastar
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@tchaikov @jsong785