introduce `unifex::async_resource` #475

janondrusek · 2022-11-04T22:22:28Z

async_destroy CPO
returns a ptr-like object

…/master Merge from master to unstable

…/unstable Merge from unstable to broken-stdlib

This commit implements scheduler affinity -- aka "sticky" scheduling -- in `unifex::task<>`. The idea is that it is impossible for a child operation to cause the current coroutine to resume on the wrong execution context. * `task<>`-based coroutines track and propagate the current scheduler * `at_coroutine_exit` remembers current scheduler from when the cleanup action is scheduled * `schedule` always returns an instance of `sender_for<schedule, the_sender>`, which is also a `scheduler_provider` * scheduler affinity when co_await-ing senders in a `task<>`-returning coroutine * scheduler affinity when co_await-ing awaitables in a `task<>`-returning coroutine * awaitables and senders that are `blocking_kind::always_inline` don't get a thunk * More senders and awaitables support compile-time blocking queries * `co_await schedule(sched)` is magic in a `task<>`-returning coroutine: it changes execution context and schedules a cleanup action to transition back to the original scheduler

…/master Merge from master

…/unstable Merge from unstable

…/master Merge from master

…/create-sender add unifex::create for trivially wrapping a C-style async API, fixes facebookexperimental#294

* simpler than `unifex::v1::async_scope` (`nest()` and `join()`) * does not support cancellation Co-authored-by: Ian Petersen <[email protected]> Co-authored-by: Ian Petersen <[email protected]>

PR facebookexperimental#454 missed including `<unifex/continuations.hpp>` in `when_all_range.hpp` so let's fix that.

The existing operation state for `let_value_with` assumes that its *Sender* will always be an rvalue; this diff fixes the operation state's constructor to support lvalue *Senders*.

`unifex::nest()` is a CPO that delegates to either a `tag_invoke` customization taking a *Sender* and a "scope" reference, or to a member function on the given scope that takes a *Sender*. This diff wires `unifex::nest()` to the `nest()` member function on `v2::async_scope` and to the `attach()` member function on `v1::async_scope`.

…tal#470) This diff introduces a new algorithm, `unifex::spawn_detached()`. `spawn_detached` takes a sender, an "async scope", and an optional allocator. It nests the sender in the scope with `unifex::nest`, allocates and operation state using the allocator, and starts that operation. The given async scope may be anything that `nest()` supports, which currently includes both `v1::async_scope` and `v2::async_scope`.

With the introduction of `unifex::nest()` and `unifex::spawn_detached()`, we can simplify the implementation of `v1::async_scope`. This diff changes its `detached_spawn` to delegate to `unifex::spawn_detached()`.

…acebookexperimental#477) * Disable continuation visitations by default for binary size savings * Add unifex prefix to macro and fix async_trace * Fix unused variable error * Change ordering of field initializations * Address comments

* gcc 9,10 * clang 10,11,12

* rm absl and related polyfills * optional * utility * variant

This diff adds some `//` comments to the ends of some lines and then runs the result through `clang-format`.

…l#483) When trying to nest a `let_value_with_stop_token()` *Sender* inside a `unifex::v2::async_scope`, I discovered there were problems checking the constraints on a `const Sender&` when `Sender` was a `let_value_with_stop_token` *Sender* constructed with a `mutable` lambda. This diff fixes the above scenario and includes a regression test. The fixes include: - fixing the type calculations on `SuccessFactory` (e.g. we invoke an lvalue reference not an rvalue reference) - correcting the `noexcept` calculations (e.g. although we *construct* our copy of the `SuccessorFactory` in a value category-sensitive way, we always *invoke* the factory as a mutable lvalue) - standardizing value category casts (i.e. using `std::move()` for moves and `static_cast<DestType&&>()` for forwards) - adding some `static_assert`s to confirm the validity of the above fixes - made the operation state immovable

…mental#484) While writing `unifex::spawn_future()`, I discovered that waiting until the destructor of the `v2::async_scope`'s `nest()` operation to drop the scope reference is too late (it led to hangs). This diff adds an internal receiver to the nest operation so we can detect when the operation is complete (which is likely before the operation state is destroyed) and drop the reference as soon as we reach that state.

ispeters

More later…

include/unifex/async_destroy.hpp

include/unifex/async_resource.hpp

- async_destroy CPO - returns a `unique_ptr`-like object

ericniebler · 2023-02-21T18:10:00Z

Hi all! :-)

### `async_resource`

Provides _async RAII_ programming idiom. `async_resource_ptr<T>` is like
a `std::unique_ptr<T>` except that `async_resource_ptr<>`'s destructor destroys
its `T` asynchronously, in constrast to `unique_ptr<>`'s destructor's
synchronous invocation of `delete p_`. `async_resource` removes the need for
manual lifetime management of a `Resource` protected by an `async_scope` and
should be preferred over `async_scope`, if there is a need for one.

1. explicitly supports parent / child relationship modeled as a tree
2. allows for subtree removal / swap
3. each `Resource` managed by `async_resource` has an associated, managed _inner_
   `async_scope` without an explicit option to `join()`

I'm trying to wrap my head around the implications of this change. IIUC, "async resource" is a concept, and that there are generic algorithms/utilities that get constrained with it, and multiple concrete types that model the concept.

One such generic utility is async_resource_ptr, which is somehow simpler to use than async_scope. Can you point me to a before/after showing how code gets simpler with async_resource_ptr?

Eric Niebler and others added 30 commits May 21, 2021 09:53

work around absence of type traits variable tempates

e6bad7b

work around missing <optional> header

4e0af79

use @mpark's variant when the stdlib doesn't provide one

797c04f

add a fallback implementation for std::invoke

81b9a05

add a fallback for std::apply

5de794b

provide a fallback when cstddef doesn't provide std::byte

1cc3036

Add an option to use Abseil for optional<> and variant<>

2a86276

work around the lack of std::as_const

cfe4d39

add a fallback for std::void_t

0678cc4

Fix std::invoke feature test macro

0ba525c

add a replacement for std::aligned_union_t

c9218c9

accommodate Abseil's in_place_type_t tag in any_unique

3b7c481

Merge pull request facebookexperimental#288 from facebookexperimental…

b25067f

…/master Merge from master to unstable

Merge pull request facebookexperimental#289 from facebookexperimental…

90b4f8a

…/unstable Merge from unstable to broken-stdlib

Merge branch 'master' into unstable

bd65da8

Merge branch 'unstable' into broken-stdlib

8b9d807

use unifex::bool_constant

01c8ccb

Merge pull request facebookexperimental#300 from facebookexperimental…

c9d3b2e

…/master Merge from master

Merge pull request facebookexperimental#301 from facebookexperimental…

aa4fdd2

…/unstable Merge from unstable

Merge remote-tracking branch 'origin/master' into scheduler-affinity

b00333a

back out change to awaiter_type_t

9e5d834

Merge pull request facebookexperimental#311 from facebookexperimental…

bb1e79f

…/master Merge from master

Merge pull request facebookexperimental#312 from facebookexperimental…

c39a429

…/master Merge from master

add unifex::create for trivially wrapping a C-style async API

46abded

Merge branch 'master' into unstable

b25e938

Merge branch 'create-sender-master' into create-sender

b05dc62

Merge pull request facebookexperimental#316 from facebookexperimental…

89f02fa

…/create-sender add unifex::create for trivially wrapping a C-style async API, fixes facebookexperimental#294

Merge branch 'master' into scheduler-affinity

979f656

avoid warning about missing braces in initializer

33e36a9

janondrusek and others added 8 commits September 27, 2022 19:20

fix tag_invoke(CPO) in async_scope

4c33630

add unifex::v2::async_scope (facebookexperimental#463)

cd5a019

* simpler than `unifex::v1::async_scope` (`nest()` and `join()`) * does not support cancellation Co-authored-by: Ian Petersen <[email protected]> Co-authored-by: Ian Petersen <[email protected]>

Add missing include to when_all_range.hpp

b232ad1

PR facebookexperimental#454 missed including `<unifex/continuations.hpp>` in `when_all_range.hpp` so let's fix that.

Support lvalue let_value_with senders (facebookexperimental#469)

7f55c36

The existing operation state for `let_value_with` assumes that its *Sender* will always be an rvalue; this diff fixes the operation state's constructor to support lvalue *Senders*.

Simplify v1::async_scope

7f67d67

With the introduction of `unifex::nest()` and `unifex::spawn_detached()`, we can simplify the implementation of `v1::async_scope`. This diff changes its `detached_spawn` to delegate to `unifex::spawn_detached()`.

fix variant_sender blocking kind

fa922b0

janondrusek requested review from lewissbaker and ispeters November 4, 2022 22:22

facebook-github-bot added the CLA Signed This label is managed by the Facebook bot. Authors need to sign the CLA before a PR can be reviewed. label Nov 4, 2022

janondrusek force-pushed the broken-stdlib branch from f22482c to 1161dfd Compare November 4, 2022 22:26

janondrusek force-pushed the broken-stdlib branch from 1161dfd to 80dd528 Compare November 18, 2022 23:31

jesswong and others added 6 commits November 29, 2022 16:13

use stable release os: ubuntu-20.04

7e4d9c8

* gcc 9,10 * clang 10,11,12

rm absl and related polyfills (facebookexperimental#480)

f99ed04

* rm absl and related polyfills * optional * utility * variant

Auto-format let_value_with_stop_token.hpp

a145c8f

This diff adds some `//` comments to the ends of some lines and then runs the result through `clang-format`.

janondrusek force-pushed the broken-stdlib branch 4 times, most recently from 80cb272 to 77bc100 Compare February 1, 2023 23:33

ispeters reviewed Feb 2, 2023

View reviewed changes

janondrusek force-pushed the broken-stdlib branch from 77bc100 to 434ad64 Compare February 3, 2023 23:56

janondrusek force-pushed the broken-stdlib branch from 434ad64 to 3622a98 Compare February 15, 2023 22:29

introduce unifex::async_resource

123ae48

- async_destroy CPO - returns a `unique_ptr`-like object

janondrusek force-pushed the broken-stdlib branch from 3622a98 to 123ae48 Compare February 15, 2023 23:55

janondrusek changed the base branch from broken-stdlib to main May 11, 2023 16:47

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introduce `unifex::async_resource` #475

introduce `unifex::async_resource` #475

janondrusek commented Nov 4, 2022

ispeters left a comment

ericniebler commented Feb 21, 2023

introduce unifex::async_resource #475

Are you sure you want to change the base?

introduce unifex::async_resource #475

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ericniebler commented Feb 21, 2023

introduce `unifex::async_resource` #475

introduce `unifex::async_resource` #475