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Add stdexec::spawn_future
This diff adds `stdexec::spawn_future` and some basic tests.
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8 files changed

+790
-136
lines changed

8 files changed

+790
-136
lines changed

‎include/stdexec/__detail/__spawn.hpp‎

Lines changed: 5 additions & 50 deletions
Original file line numberDiff line numberDiff line change
@@ -24,6 +24,7 @@
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#include "__receivers.hpp"
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#include "__scope_concepts.hpp"
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#include "__senders_core.hpp"
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#include "__spawn_common.hpp"
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#include "__type_traits.hpp"
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#include "__write_env.hpp"
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@@ -98,53 +99,6 @@ namespace stdexec {
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__assoc_t __assoc_;
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};
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struct __choose_alloc_fn {
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template <class _Env, class _SenderEnv>
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requires __callable<get_allocator_t, _Env>
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auto operator()(const _Env& __env, const _SenderEnv&) const {
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return get_allocator(__env);
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}
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template <class _Env, class _SenderEnv>
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requires(!__callable<get_allocator_t, const _Env&>)
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&& __callable<get_allocator_t, const _SenderEnv&>
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auto operator()(const _Env&, const _SenderEnv& __env) const {
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return get_allocator(__env);
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}
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template <class _Env, class _SenderEnv>
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requires(!__callable<get_allocator_t, const _Env&>)
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&& (!__callable<get_allocator_t, const _SenderEnv&>)
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std::allocator<void> operator()(const _Env&, const _SenderEnv&) const {
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return std::allocator<void>();
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}
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};
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inline constexpr __choose_alloc_fn __choose_alloc{};
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struct __choose_senv_fn {
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template <class _Env, class _SenderEnv>
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requires __callable<get_allocator_t, const _Env&>
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const _Env& operator()(const _Env& __env, const _SenderEnv&) const {
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return __env;
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}
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template <class _Env, class _SenderEnv>
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requires(!__callable<get_allocator_t, const _Env&>)
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&& __callable<get_allocator_t, const _SenderEnv&>
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auto operator()(const _Env& __env, const _SenderEnv& __sndrEnv) const {
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return __env::__join(prop(get_allocator, get_allocator(__sndrEnv)), __env);
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}
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template <class _Env, class _SenderEnv>
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requires(!__callable<get_allocator_t, const _Env&>)
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&& (!__callable<get_allocator_t, const _SenderEnv&>)
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const _Env& operator()(const _Env& __env, const _SenderEnv&) const {
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return __env;
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}
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};
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inline constexpr __choose_senv_fn __choose_senv{};
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struct spawn_t {
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template <sender _Sender, scope_token _Token>
@@ -157,15 +111,16 @@ namespace stdexec {
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auto wrappedSender = __tkn.wrap(static_cast<_Sender&&>(__sndr));
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auto sndrEnv = get_env(wrappedSender);
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160-
using raw_alloc = decltype(__choose_alloc(__env, sndrEnv));
114+
using raw_alloc = decltype(__spawn_common::__choose_alloc(__env, sndrEnv));
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162-
auto senderWithEnv = write_env(std::move(wrappedSender), __choose_senv(__env, sndrEnv));
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auto senderWithEnv =
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write_env(std::move(wrappedSender), __spawn_common::__choose_senv(__env, sndrEnv));
163118

164119
using spawn_state_t =
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__spawn_state<raw_alloc, std::remove_cvref_t<_Token>, decltype(senderWithEnv)>;
166121

167122
using traits = std::allocator_traits<raw_alloc>::template rebind_traits<spawn_state_t>;
168-
typename traits::allocator_type alloc(__choose_alloc(__env, sndrEnv));
123+
typename traits::allocator_type alloc(__spawn_common::__choose_alloc(__env, sndrEnv));
169124

170125
auto* op = traits::allocate(alloc, 1);
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‎include/stdexec/__detail/__spawn_common.hpp‎

Lines changed: 106 additions & 0 deletions
Original file line numberDiff line numberDiff line change
@@ -0,0 +1,106 @@
1+
/*
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* Copyright (c) 2025 Ian Petersen
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* Copyright (c) 2025 NVIDIA Corporation
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*
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* Licensed under the Apache License Version 2.0 with LLVM Exceptions
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* (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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*
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* https://llvm.org/LICENSE.txt
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#pragma once
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#include "__execution_fwd.hpp"
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#include "__concepts.hpp"
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#include "__env.hpp"
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#include "__queries.hpp"
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#include <memory>
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namespace stdexec {
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////////////////////////////////////////////////////////////////////////////////////////////////
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// [exec.spawn] paragraph 9
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// [exec.spawn.future] paragraph 15
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//
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// spawn and spawn_future both have to choose an allocator and an injected environment, and they
33+
// do it in the same way; this namespace provides a couple of functions for making those choices
34+
namespace __spawn_common {
35+
struct __choose_alloc_fn {
36+
// [exec.spawn] paragraph 9
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// [exec.spawn.future] paragraph 15
38+
// (9/15.1) -- if the expression get_allocator(env) is well-formed, then alloc is
39+
// the result of get_allocator(env)
40+
template <class _Env, class _SenderEnv>
41+
requires __callable<get_allocator_t, _Env>
42+
auto operator()(const _Env& __env, const _SenderEnv&) const {
43+
return get_allocator(__env);
44+
}
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46+
// [exec.spawn] paragraph 9
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// [exec.spawn.future] paragraph 15
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// (9/15.2) -- otherwise, if the expression get_allocator(get_env(new_sender)) is
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// well-formed, then alloc is the result of get_allocator(get_env(new_sender))
50+
template <class _Env, class _SenderEnv>
51+
requires(!__callable<get_allocator_t, const _Env&>)
52+
&& __callable<get_allocator_t, const _SenderEnv&>
53+
auto operator()(const _Env&, const _SenderEnv& __env) const {
54+
return get_allocator(__env);
55+
}
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57+
// [exec.spawn] paragraph 9
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// [exec.spawn.future] paragraph 15
59+
// (9/15.3) -- otherwise, alloc is allocator<void>()
60+
template <class _Env, class _SenderEnv>
61+
requires(!__callable<get_allocator_t, const _Env&>)
62+
&& (!__callable<get_allocator_t, const _SenderEnv&>)
63+
std::allocator<void> operator()(const _Env&, const _SenderEnv&) const {
64+
return std::allocator<void>();
65+
}
66+
};
67+
68+
inline constexpr __choose_alloc_fn __choose_alloc{};
69+
70+
struct __choose_senv_fn {
71+
// [exec.spawn] paragraph 9
72+
// [exec.spawn.future] paragraph 15
73+
// (9/15.1) -- if the expression get_allocator(env) is well-formed, then ...
74+
// senv is the expression env;
75+
template <class _Env, class _SenderEnv>
76+
requires __callable<get_allocator_t, const _Env&>
77+
const _Env& operator()(const _Env& __env, const _SenderEnv&) const {
78+
return __env;
79+
}
80+
81+
// [exec.spawn] paragraph 9
82+
// [exec.spawn.future] paragraph 15
83+
// (9/15.2) -- otherwise, if the expression get_allocator(get_env(new_sender)) is
84+
// well-formed, then ... senv is the expression
85+
// JOIN-ENV(prop(get_allocator, alloc), env);
86+
template <class _Env, class _SenderEnv>
87+
requires(!__callable<get_allocator_t, const _Env&>)
88+
&& __callable<get_allocator_t, const _SenderEnv&>
89+
auto operator()(const _Env& __env, const _SenderEnv& __sndrEnv) const {
90+
return __env::__join(prop(get_allocator, get_allocator(__sndrEnv)), __env);
91+
}
92+
93+
// [exec.spawn] paragraph 9
94+
// [exec.spawn.future] paragraph 15
95+
// (9/15.3) -- otherwise, ... senv is the expression env.
96+
template <class _Env, class _SenderEnv>
97+
requires(!__callable<get_allocator_t, const _Env&>)
98+
&& (!__callable<get_allocator_t, const _SenderEnv&>)
99+
const _Env& operator()(const _Env& __env, const _SenderEnv&) const {
100+
return __env;
101+
}
102+
};
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104+
inline constexpr __choose_senv_fn __choose_senv{};
105+
} // namespace __spawn_common
106+
} // namespace stdexec

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