[k2] add await set primitive (#1418)

Author: astrophysik

runtime-light/coroutine/await-set.h

@@ -0,0 +1,82 @@
+// Compiler for PHP (aka KPHP)
+// Copyright (c) 2025 LLC «V Kontakte»
+// Distributed under the GPL v3 License, see LICENSE.notice.txt
+
+#pragma once
+
+#include <cstddef>
+#include <memory>
+#include <type_traits>
+
+#include "runtime-common/core/allocator/script-allocator.h"
+#include "runtime-common/core/std/containers.h"
+#include "runtime-light/coroutine/async-stack.h"
+#include "runtime-light/coroutine/concepts.h"
+#include "runtime-light/coroutine/coroutine-state.h"
+#include "runtime-light/coroutine/detail/await-set.h"
+#include "runtime-light/coroutine/type-traits.h"
+
+namespace kphp::coro {
+
+template<typename return_type>
+class await_set {
+  kphp::stl::list<detail::await_set::await_set_task<return_type>, kphp::memory::script_allocator> m_tasks_storage{};
+  std::unique_ptr<detail::await_set::await_broker<return_type>> m_await_broker;
+  kphp::coro::async_stack_root& m_coroutine_stack_root;
+
+  template<typename T>
+  friend class kphp::coro::detail::await_set::await_broker;
+
+  void clear() noexcept {
+    m_await_broker.release();
+    m_tasks_storage.clear();
+  }
+
+public:
+  explicit await_set() noexcept
+      : m_await_broker(std::make_unique<detail::await_set::await_broker<return_type>>(*this)),
+        m_coroutine_stack_root(CoroutineInstanceState::get().coroutine_stack_root) {}
+
+  await_set(await_set&& other) noexcept
+      : m_tasks_storage(std::move(other.m_tasks_storage)),
+        m_await_broker(std::move(other.m_await_broker)),
+        m_coroutine_stack_root(other.m_coroutine_stack_root) {}
+
+  await_set& operator=(await_set&& other) noexcept {
+    if (this != std::addressof(other)) {
+      clear();
+      m_tasks_storage = std::move(other.m_tasks_storage);
+      m_await_broker = std::move(other.m_await_broker);
+      m_coroutine_stack_root = other.m_coroutine_stack_root;
+    }
+    return *this;
+  }
+
+  await_set(const await_set&) = delete;
+  await_set& operator=(const await_set&) = delete;
+
+  template<typename awaitable_type>
+  requires kphp::coro::concepts::awaitable<awaitable_type> && std::is_same_v<typename awaitable_traits<awaitable_type>::awaiter_return_type, return_type>
+  void push(awaitable_type awaitable) noexcept {
+    auto task_iterator{m_tasks_storage.insert(m_tasks_storage.begin(), detail::await_set::make_await_set_task(std::move(awaitable)))};
+    task_iterator->start(*m_await_broker.get(), task_iterator, m_coroutine_stack_root, STACK_RETURN_ADDRESS);
+  }
+
+  auto next() noexcept {
+    return detail::await_set::await_set_awaitable<return_type>{*m_await_broker.get()};
+  }
+
+  bool empty() const noexcept {
+    return len() == 0;
+  }
+
+  size_t len() const noexcept {
+    return m_tasks_storage.size();
+  }
+
+  ~await_set() {
+    clear();
+  }
+};
+
+} // namespace kphp::coro