Code size analysis

pw_async2: Cooperative async tasks for embedded

Core async2 implementation

The following table shows the code size cost of adding pw_async2 to a system. These size reports assume a baseline system with an RTOS which already uses a handful of core Pigweed components including HAL abstractions and pw_allocator.

The first row captures the core of pw_async2: the dispatcher, tasks, and wakers, using the pw::async2::BasicDispatcher. This is the minimum size cost a system must pay to adopt pw_async2. The following row demonstrates the cost of adding another task to this system. Of course, the majority of the cost of the task exists within its implementation — this simply shows that there is minimal internal overhead.

Label	Segment	Delta
Full cost of including pw_async2	FLASH +668 [section .rodata] +40 pw::containers::internal::GenericIntrusiveList<>::remove_if<>() +16 pw::containers::internal::GenericIntrusiveList<>::clear() +228 pw::async2::size_report::Measure() -2 pw::containers::internal::IntrusiveForwardListItem::DoGetPrevious() +14 pw::containers::internal::GenericIntrusiveList<>::remove() +4 vClearInterruptMaskFromISR NEW +228 pw::async2::Task::RunInDispatcher() NEW +164 pw::async2::Task::TryDeregister() NEW +100 pw::this_thread::sleep_for() NEW +84 pw::async2::Dispatcher::Post() NEW +82 pw::async2::Task::~Task() NEW +76 vTaskDelay NEW +72 pw::async2::Task::Wake() NEW +72 pw::async2::size_report::PendableValue<>::Get() NEW +60 pw::this_thread::get_id() NEW +56 pw::async2::Task::PostTo() NEW +56 pw::async2::Waker::operator=() NEW +56 pw::async2::internal::CloneWaker() NEW +52 pw::async2::Dispatcher::PopTaskToRun() NEW +52 pw::async2::size_report::MockTask::DoPend() NEW +50 pw::async2::Dispatcher::WakeTask() NEW +46 pw::async2::size_report::MockTask::~MockTask() NEW +42 pw::async2::Dispatcher::~Dispatcher() NEW +40 pw::async2::Dispatcher::Deregister() NEW +40 pw::async2::Dispatcher::PopTaskToRunLocked() NEW +40 pw::async2::Waker::InternalCloneIntoLocked() NEW +40 pw::async2::Waker::Wake() NEW +36 __atomic_exchange_1 NEW +32 __atomic_store_1 NEW +32 pw::async2::Dispatcher::PopAndRunAllReadyTasks() NEW +32 pw::async2::Waker::InsertIntoTaskWakerList() NEW +32 pw::async2::Waker::RemoveFromTaskWakerList() NEW +30 pw::async2::FuncTask<>::~FuncTask() NEW +28 pw::async2::BasicDispatcher NEW +28 pw::async2::Dispatcher::UnpostTaskList() NEW +28 pw::async2::RunnableDispatcher::RunToCompletion() NEW +26 pw::async2::Dispatcher::RunTask() NEW +26 pw::containers::internal::IntrusiveListItemBase<>::unlist() NEW +24 pw::async2::Task::Deregister() NEW +24 pw::async2::Waker::Waker() NEW +24 pw::async2::size_report::MockTask::DoPend()::{lambda()#1}::operator()() NEW +24 pw::async2::size_report::PendableValue<>::Get()::{lambda()#1}::operator()() NEW +22 pw::async2::BasicDispatcher::~BasicDispatcher() NEW +22 pw::async2::Task::RemoveAllWakersLocked() NEW +20 pw::async2::Dispatcher NEW +20 pw::async2::FuncTask<> NEW +20 pw::async2::Task NEW +20 pw::async2::size_report::MockTask NEW +18 pw::async2::FuncTask<>::DoPend() NEW +18 pw::async2::Task::RemoveWakerLocked() NEW +18 pw::containers::internal::LegacyIntrusiveList<>::Item::~Item() NEW +16 pw::async2::Waker::InsertIntoTaskWakerListLocked() NEW +16 pw::async2::Waker::RemoveFromTaskWakerListLocked() NEW +16 pw::async2::Waker::~Waker() NEW +16 pw::containers::internal::LegacyIntrusiveList<>::~LegacyIntrusiveList() NEW +14 pw::async2::Task::Unpost() NEW +12 pw::async2::(anonymous namespace)::YieldToAnyThread() NEW +12 pw::async2::BasicDispatcher::DoWaitForWake() NEW +12 pw::async2::Task::AddWakerLocked() NEW +12 pw::async2::internal::StoreWaker() NEW +10 pw::async2::BasicDispatcher::DoWake() NEW +8 pw::async2::RunnableDispatcher::DoRunUntilStalled()	+3,224
	RAM +8 [section .data] NEW +24 pw::async2::size_report::(anonymous namespace)::dispatcher NEW +8 pw::async2::internal::lock()::lock	+40
Base incremental cost of adding a task to an existing async system	FLASH +56 pw::async2::size_report::Measure() +8 vClearInterruptMaskFromISR	+64
Size of pw_async2’s C++ coroutine adapters	FLASH +160 [section .rodata] +116 pw::async2::size_report::Measure() +40 pw::Result<>::value() +2 pw::async2::size_report::MockTask::~MockTask() +2 pw::async2::FuncTask<>::~FuncTask() -6 operator delete() +4 vClearInterruptMaskFromISR +2 fit::internal::trivial_target_destroy() NEW +274 pw::async2::size_report::StoresFiveThenReturns() NEW +236 pw::async2::Coro<>::Pend() NEW +112 pw::async2::size_report::ImmediatelyReturnsFive() NEW +84 pw::async2::size_report::ExpectCoroTask::DoPend() NEW +70 pw::async2::internal::OwningCoroutineHandle<>::Release() NEW +68 pw::async2::internal::CoroPromiseType<>::SharedNew() NEW +52 pw::async2::internal::Awaitable<>::await_suspend() NEW +46 pw::async2::internal::Awaitable<>::PendFillReturnValue() NEW +40 _ZN2pw15internal_result12StatusOrDataIiLb1EEC2INS_6StatusETnNSt3__29enable_ifIXsr3std16is_constructibleIS4_OT_EE5valueEiE4typeELi0EEES8_ NEW +40 pw::async2::internal::CoroPromiseType<>::get_return_object() NEW +40 pw::internal_result::StatusOrData<>::AssignStatus<>() NEW +40 pw::internal_result::StatusOrData<>::operator=() NEW +36 _ZNSt3__216__variant_detail12__visitation6__base11__visit_altB9nqn230000IZNS0_6__dtorINS0_8__traitsIJN2pw6async24CoroINS6_6ResultIiEEEESA_EEELNS0_6_TraitE1EE9__destroyB9nqn230000EvEUlRT_E_JRSE_EEEDcOSF_DpOT0_ NEW +34 pw::async2::size_report::ExpectCoroTask::~ExpectCoroTask() NEW +32 pw::async2::internal::CoroPromiseType<>::get_return_object_on_allocation_failure() NEW +30 _ZNSt3__216__variant_detail12__assignmentINS0_8__traitsIJN2pw6async24CoroINS3_6ResultIiEEEES7_EEEE9__emplaceB9nqn230000ILj1EJS7_EEERDaDpOT0_ NEW +26 _ZNSt3__216__variant_detail12__assignmentINS0_8__traitsIJN2pw6async24CoroINS3_6ResultIiEEEES7_EEEE12__assign_altB9nqn230000ILj1ES7_S7_EEvRNS0_5__altIXT_ET0_EEOT1_ NEW +26 _ZNSt3__216__variant_detail6__dtorINS0_8__traitsIJN2pw6async24CoroINS3_6ResultIiEEEES7_EEELNS0_6_TraitE1EE9__destroyB9nqn230000Ev NEW +24 __aeabi_uread4 NEW +24 pw::async2::internal::LogCoroAllocationFailure() NEW +20 _ZNSt3__28optionalIN2pw6ResultIiEEEC2B9nqn230000INS1_6StatusETnNS_9enable_ifIXclsr22_CheckOptionalLikeCtorIT_OS8_EE17__enable_implicitIS8_EEEiE4typeELi0EEEONS0_IS8_EE NEW +20 fit::internal::target<>::ops NEW +20 pw::async2::size_report::ExpectCoroTask NEW +16 fit::internal::inline_trivial_target_move<>() NEW +16 pw::async2::internal::CoroPromiseType<>::operator new<>() NEW +14 _ZNSt3__223__optional_storage_baseIN2pw6ResultIiEELb0EE16__construct_fromB9nqn230000INS_8optionalINS1_6StatusEEEEEvOT_ NEW +14 pw::Result<>::Result() NEW +12 _ZNSt3__213__generic_getB9nqn230000ILj0ERNS_7variantIJN2pw6async24CoroINS2_6ResultIiEEEES6_EEEEEODaOT0_ NEW +12 _ZNSt3__213__generic_getB9nqn230000ILj1ERNS_7variantIJN2pw6async24CoroINS2_6ResultIiEEEES6_EEEEEODaOT0_ NEW +12 _ZNSt3__216__variant_detail6__implIJN2pw6async24CoroINS2_6ResultIiEEEES6_EE8__assignB9nqn230000ILj1ES6_EEvOT0_ NEW +12 _ZNSt3__223__optional_storage_baseIN2pw6ResultIiEELb0EE11__constructB9nqn230000IJNS1_6StatusEEEEvDpOT_ NEW +12 _ZNSt3__226__throw_bad_variant_accessB9nqn230000Ev NEW +10 _ZNSt3__216__variant_detail12__visitation6__base12__dispatcherIJLj0EEE10__dispatchB9nqn230000IOZNS0_6__dtorINS0_8__traitsIJN2pw6async24CoroINS8_6ResultIiEEEESC_EEELNS0_6_TraitE1EE9__destroyB9nqn230000EvEUlRT_E_JRNS0_6__baseILSF_1EJSD_SC_EEEEEEDcSH_DpT0_ NEW +10 pw::async2::internal::Awaitable<>::await_suspend()::{lambda()#1}::operator()() NEW +8 fit::internal::target<>::invoke() NEW +6 std::__2::__libcpp_verbose_abort() NEW +2 _ZNSt3__216__variant_detail12__visitation6__base12__dispatcherIJLj1EEE10__dispatchB9nqn230000IOZNS0_6__dtorINS0_8__traitsIJN2pw6async24CoroINS8_6ResultIiEEEESC_EEELNS0_6_TraitE1EE9__destroyB9nqn230000EvEUlRT_E_JRNS0_6__baseILSF_1EJSD_SC_EEEEEEDcSH_DpT0_ NEW +2 fit::internal::inline_target_get()	+1,872

Futures

Futures are the core abstraction in pw_async2, providing a standardized way of polling an asynchronous operation to completion.

The design of futures has some implications for code size:

• All futures are templated on the type of value they produce, which means that the compiler must generate separate code for each type.

• Additionally, futures use CRTP for compile-time polymorphism, so each concrete future type is a distinct class and may duplicate common behavior.

The following sections detail the code size of various future implementations and utilities.

ValueFuture

ValueFuture is the simplest future type, used to return a single result from an asynchronous operation. Its implementation contains effectively the minimal code required for a future, making it a good baseline for understanding the size cost of a future in pw_async2.

The table below shows the size of ValueFuture. The first row shows the base cost of using a single ValueFuture. The second row adds another ValueFuture with a different return type to demonstrate the incremental cost of template specialization. The third row shows the size of VoidFuture (alias for ValueFuture<void>), which is specialized to avoid storing a value.

Label	Segment	Delta
Size of ValueFuture	FLASH +280 [section .rodata] -88 pw::async2::size_report::Measure() +2 pw::containers::internal::GenericIntrusiveList<>::remove_if<>() DEL -72 pw::async2::size_report::PendableValue<>::Get() +2 pw::async2::size_report::MockTask::~MockTask() -2 pw::containers::internal::IntrusiveListItemBase<>::unlist() DEL -24 pw::async2::size_report::PendableValue<>::Get()::{lambda()#1}::operator()() +12 pw::async2::FuncTask<>::DoPend() +2 pw::containers::internal::GenericIntrusiveList<>::push_back() +4 vClearInterruptMaskFromISR NEW +148 pw::async2::size_report::SingleTypeValueFuture() NEW +88 pw::async2::FutureCore::DoPend<>() NEW +56 pw::async2::ValueProvider<>::Get() NEW +48 pw::async2::ValueFuture<>::ResolveLocked<>() NEW +44 _ZN2pw6async213ValueProviderIiE7ResolveIJiEiTnNSt3__29enable_ifIXntsr3stdE9is_void_vIT0_EEiE4typeELi0EEEvDpOT_ NEW +44 pw::async2::BaseFutureList::PushRequireEmpty() NEW +40 pw::async2::ValueFuture<>::Pend() NEW +40 pw::async2::ValueProvider<>::~ValueProvider() NEW +36 pw::async2::ValueFuture<>::~ValueFuture() NEW +24 pw::async2::FutureCore::DoPend<>()::{lambda()#1}::operator()() NEW +18 pw::async2::FutureCore::~FutureCore() NEW +16 pw::async2::FutureCore::WakeAndMarkReady() NEW +10 pw::async2::FutureCore::Unlist()	+728
	RAM NEW +8 pw::async2::internal::ValueProviderLock()::lock	+8
Cost of additional ValueFuture template specialization	FLASH +8 pw::async2::size_report::Measure() +88 pw::async2::FutureCore::DoPend<>() +56 pw::async2::ValueProvider<>::Get() +48 pw::async2::ValueFuture<>::ResolveLocked<>() +40 pw::async2::ValueFuture<>::Pend() +40 pw::async2::ValueProvider<>::~ValueProvider() +36 pw::async2::ValueFuture<>::~ValueFuture() +30 pw::async2::FuncTask<>::DoPend() +30 pw::async2::FuncTask<>::~FuncTask() +24 pw::async2::FutureCore::DoPend<>()::{lambda()#1}::operator()() +20 pw::async2::FuncTask<> -4 __bi_84 -8 vClearInterruptMaskFromISR NEW +156 pw::async2::size_report::MultiTypeValueFuture() NEW +80 __aeabi_f2iz NEW +44 _ZN2pw6async213ValueProviderIfE7ResolveIJfEfTnNSt3__29enable_ifIXntsr3stdE9is_void_vIT0_EEiE4typeELi0EEEvDpOT_	+688
Size of VoidFuture (ValueFuture<void>)	FLASH +268 [section .rodata] -88 pw::async2::size_report::Measure() +2 pw::containers::internal::GenericIntrusiveList<>::remove_if<>() DEL -72 pw::async2::size_report::PendableValue<>::Get() +2 pw::async2::size_report::MockTask::~MockTask() -2 pw::containers::internal::IntrusiveListItemBase<>::unlist() DEL -24 pw::async2::size_report::PendableValue<>::Get()::{lambda()#1}::operator()() -4 __bi_84 +2 pw::containers::internal::GenericIntrusiveList<>::push_back() NEW +128 pw::async2::size_report::VoidFutureReport() NEW +76 pw::async2::FutureCore::DoPend<>() NEW +52 pw::async2::ValueProvider<>::Get() NEW +44 pw::async2::BaseFutureList::PushRequireEmpty() NEW +40 pw::async2::ValueFuture<>::Pend() NEW +40 pw::async2::ValueProvider<>::~ValueProvider() NEW +36 pw::async2::ValueFuture<>::~ValueFuture() NEW +32 _ZN2pw6async213ValueProviderIvE7ResolveIvTnNSt3__29enable_ifIXsr3stdE9is_void_vIT_EEiE4typeELi0EEEvv NEW +24 pw::async2::FutureCore::DoPend<>()::{lambda()#1}::operator()() NEW +20 pw::async2::BaseFutureList::ResolveOne() NEW +18 pw::async2::FutureCore::~FutureCore() NEW +14 pw::async2::BaseFutureList::ResolveOneIfAvailable() NEW +14 pw::async2::FutureCore::WakeAndMarkReady() NEW +10 pw::async2::FutureCore::Unlist()	+632
	RAM NEW +8 pw::async2::internal::ValueProviderLock()::lock	+8

async2 utilities

Pigweed provides several utilities to simplify writing asynchronous code. Among these are combinators which operate over several futures, such as Join which waits for all futures to complete, and Select which waits for the first future to complete.

The table below demonstrates the code size impact of using these utilities. For both Join and Select, the report shows:

• The initial cost of using the utility with multiple futures of the same type.

• The incremental cost of adding a second call with futures of different types, which demonstrates the overhead of template specialization.

Additionally, the table includes a comparison showing the code size difference between using the Select helper versus manually polling each future.

Label	Segment	Delta
Size of calling Select() with several futures of the same type	FLASH +128 [section .rodata] +8 pw::async2::size_report::Measure() +84 pw::async2::FuncTask<>::DoPend() +30 pw::async2::FuncTask<>::~FuncTask() +20 pw::async2::FuncTask<> +4 __bi_84 -4 main NEW +196 pw::async2::size_report::SingleTypeSelect() NEW +152 pw::async2::SelectFuture<>::PendFuture<>() NEW +140 pw::async2::SelectFuture<>::Pend() NEW +108 pw::OptionalTuple<>::value<>() NEW +36 _ZNSt3__212__tuple_implINS_18__integer_sequenceIjJLj0ELj1ELj2EEEEJN2pw6async211ValueFutureIiEES6_S6_EEC2B9nqn230000IJS6_S6_S6_EEENS_14__forward_argsEDpOT_ NEW +36 _ZNSt3__227__memberwise_forward_assignB9nqn230000INS_5tupleIJN2pw6async211ValueFutureIiEES5_S5_EEES6_JS5_S5_S5_EJLj0ELj1ELj2EEEEvRT_OT0_NS_11__type_listIJDpT1_EEENS_18__integer_sequenceIjJXspT2_EEEE NEW +36 pw::OptionalTuple<>::UninitializedMoveFrom<>() NEW +36 pw::async2::SelectFuture<>::PendAll<>() NEW +32 pw::async2::ValueFuture<>::is_complete() NEW +28 std::__2::__tuple_impl<>::~__tuple_impl() NEW +18 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEES4_S4_EEC2B9nqn230000IJS4_S4_S4_ETnNS_9enable_ifIXsr4_AndINS_17integral_constantIbXeqsZT_sZT_EEENS5_17_EnableUTypesCtorIJDpT_EEEEE5valueEiE4typeELi0EEEDpOSB_ NEW +18 pw::OptionalTuple<>::OptionalTuple() NEW +14 pw::async2::SelectFuture<>::SelectFuture() NEW +12 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEES4_S4_EEaSB9nqn230000EOS5_ NEW +12 _ZNSt3__28optionalIN2pw13OptionalTupleIJiiiEEEEC2B9nqn230000IS3_TnNS_9enable_ifIXclsr22_CheckOptionalArgsCtorIT_EE17__enable_implicitIS7_EEEiE4typeELi0EEEOS7_	+1,144
Size of an additional a call to Select() with futures of different types	FLASH +84 pw::async2::FuncTask<>::DoPend() +8 pw::async2::size_report::Measure() +144 pw::async2::SelectFuture<>::PendFuture<>() +138 pw::async2::SelectFuture<>::Pend() +108 pw::OptionalTuple<>::value<>() +30 pw::async2::FuncTask<>::~FuncTask() +20 pw::async2::FuncTask<> +36 pw::OptionalTuple<>::UninitializedMoveFrom<>() +36 pw::async2::SelectFuture<>::PendAll<>() +64 pw::async2::ValueFuture<>::is_complete() +26 std::__2::__tuple_impl<>::~__tuple_impl() +18 pw::OptionalTuple<>::OptionalTuple() -4 __bi_84 +14 pw::async2::SelectFuture<>::SelectFuture() NEW +192 pw::async2::size_report::MultiTypeSelect() NEW +36 _ZNSt3__227__memberwise_forward_assignB9nqn230000INS_5tupleIJN2pw6async211ValueFutureIiEENS4_IjEENS4_IcEEEEES8_JS5_S6_S7_EJLj0ELj1ELj2EEEEvRT_OT0_NS_11__type_listIJDpT1_EEENS_18__integer_sequenceIjJXspT2_EEEE NEW +34 _ZNSt3__212__tuple_implINS_18__integer_sequenceIjJLj0ELj1ELj2EEEEJN2pw6async211ValueFutureIiEENS5_IjEENS5_IcEEEEC2B9nqn230000IJS6_S7_S8_EEENS_14__forward_argsEDpOT_ NEW +16 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEENS3_IjEENS3_IcEEEEC2B9nqn230000IJS4_S5_S6_ETnNS_9enable_ifIXsr4_AndINS_17integral_constantIbXeqsZT_sZT_EEENS7_17_EnableUTypesCtorIJDpT_EEEEE5valueEiE4typeELi0EEEDpOSD_ NEW +12 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEENS3_IjEENS3_IcEEEEaSB9nqn230000EOS7_ NEW +12 _ZNSt3__28optionalIN2pw13OptionalTupleIJijcEEEEC2B9nqn230000IS3_TnNS_9enable_ifIXclsr22_CheckOptionalArgsCtorIT_EE17__enable_implicitIS7_EEEiE4typeELi0EEEOS7_	+1,024
Cost of using Select() versus manually polling each future	FLASH +128 [section .rodata] +28 pw::async2::size_report::SelectComparisonTask::DoPend() +2 pw::containers::internal::IntrusiveListItemBase<>::~IntrusiveListItemBase() -4 vClearInterruptMaskFromISR NEW +144 pw::async2::SelectFuture<>::PendFuture<>() NEW +138 pw::async2::SelectFuture<>::Pend() NEW +108 pw::OptionalTuple<>::value<>() NEW +96 pw::async2::ValueFuture<>::is_complete() NEW +36 _ZNSt3__227__memberwise_forward_assignB9nqn230000INS_5tupleIJN2pw6async211ValueFutureIiEENS4_IjEENS4_IcEEEEES8_JS5_S6_S7_EJLj0ELj1ELj2EEEEvRT_OT0_NS_11__type_listIJDpT1_EEENS_18__integer_sequenceIjJXspT2_EEEE NEW +36 pw::OptionalTuple<>::UninitializedMoveFrom<>() NEW +36 pw::async2::SelectFuture<>::PendAll<>() NEW +34 _ZNSt3__212__tuple_implINS_18__integer_sequenceIjJLj0ELj1ELj2EEEEJN2pw6async211ValueFutureIiEENS5_IjEENS5_IcEEEEC2B9nqn230000IJS6_S7_S8_EEENS_14__forward_argsEDpOT_ NEW +26 std::__2::__tuple_impl<>::~__tuple_impl() NEW +18 pw::OptionalTuple<>::OptionalTuple() NEW +16 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEENS3_IjEENS3_IcEEEEC2B9nqn230000IJS4_S5_S6_ETnNS_9enable_ifIXsr4_AndINS_17integral_constantIbXeqsZT_sZT_EEENS7_17_EnableUTypesCtorIJDpT_EEEEE5valueEiE4typeELi0EEEDpOSD_ NEW +14 pw::async2::SelectFuture<>::SelectFuture() NEW +12 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEENS3_IjEENS3_IcEEEEaSB9nqn230000EOS7_ NEW +12 _ZNSt3__28optionalIN2pw13OptionalTupleIJijcEEEEC2B9nqn230000IS3_TnNS_9enable_ifIXclsr22_CheckOptionalArgsCtorIT_EE17__enable_implicitIS7_EEEiE4typeELi0EEEOS7_	+880
Size of calling Join() with several futures of the same type	FLASH +104 [section .rodata] +8 pw::async2::size_report::Measure() +34 pw::async2::FuncTask<>::DoPend() +30 pw::async2::FuncTask<>::~FuncTask() +20 pw::async2::FuncTask<> +4 vClearInterruptMaskFromISR +4 __bi_84 -4 main NEW +204 pw::async2::size_report::SingleTypeJoin() NEW +100 pw::async2::JoinFuture<>::PendElement<>() NEW +88 pw::async2::JoinFuture<>::Pend() NEW +52 pw::async2::JoinFuture<>::PendElements<>() NEW +40 _ZNSt3__223__optional_storage_baseINS_5tupleIJOiS2_S2_EEELb0EE13__assign_fromB9nqn230000INS_27__optional_move_assign_baseIS3_Lb0EEEEEvOT_ NEW +36 _ZNSt3__212__tuple_implINS_18__integer_sequenceIjJLj0ELj1ELj2EEEEJN2pw6async211ValueFutureIiEES6_S6_EEC2B9nqn230000IJS6_S6_S6_EEENS_14__forward_argsEDpOT_ NEW +28 _ZNSt3__227__memberwise_forward_assignB9nqn230000INS_5tupleIJOiS2_S2_EEES3_JS2_S2_S2_EJLj0ELj1ELj2EEEEvRT_OT0_NS_11__type_listIJDpT1_EEENS_18__integer_sequenceIjJXspT2_EEEE NEW +28 std::__2::__tuple_impl<>::~__tuple_impl() NEW +26 pw::async2::JoinFuture<>::JoinFuture() NEW +18 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEES4_S4_EEC2B9nqn230000IJS4_S4_S4_ETnNS_9enable_ifIXsr4_AndINS_17integral_constantIbXeqsZT_sZT_EEENS5_17_EnableUTypesCtorIJDpT_EEEEE5valueEiE4typeELi0EEEDpOSB_ NEW +12 _ZNSt3__25tupleIJOiS1_S1_EEaSB9nqn230000EOS2_	+832
Size of an additional a call to Join() with futures of different types	FLASH +8 pw::async2::size_report::Measure() +32 pw::async2::FuncTask<>::DoPend() +88 pw::async2::JoinFuture<>::PendElement<>() +88 pw::async2::JoinFuture<>::Pend() +30 pw::async2::FuncTask<>::~FuncTask() +52 pw::async2::JoinFuture<>::PendElements<>() -2 pw::async2::size_report::MockTask::~MockTask() +20 pw::async2::FuncTask<> +26 std::__2::__tuple_impl<>::~__tuple_impl() +26 pw::async2::JoinFuture<>::JoinFuture() -12 vClearInterruptMaskFromISR -4 __bi_84 NEW +208 pw::async2::size_report::MultiTypeJoin() NEW +40 _ZNSt3__223__optional_storage_baseINS_5tupleIJOiOjOcEEELb0EE13__assign_fromB9nqn230000INS_27__optional_move_assign_baseIS5_Lb0EEEEEvOT_ NEW +34 _ZNSt3__212__tuple_implINS_18__integer_sequenceIjJLj0ELj1ELj2EEEEJN2pw6async211ValueFutureIiEENS5_IjEENS5_IcEEEEC2B9nqn230000IJS6_S7_S8_EEENS_14__forward_argsEDpOT_ NEW +26 _ZNSt3__227__memberwise_forward_assignB9nqn230000INS_5tupleIJOiOjOcEEES5_JS2_S3_S4_EJLj0ELj1ELj2EEEEvRT_OT0_NS_11__type_listIJDpT1_EEENS_18__integer_sequenceIjJXspT2_EEEE NEW +16 _ZNSt3__25tupleIJN2pw6async211ValueFutureIiEENS3_IjEENS3_IcEEEEC2B9nqn230000IJS4_S5_S6_ETnNS_9enable_ifIXsr4_AndINS_17integral_constantIbXeqsZT_sZT_EEENS7_17_EnableUTypesCtorIJDpT_EEEEE5valueEiE4typeELi0EEEDpOSD_ NEW +12 _ZNSt3__25tupleIJOiOjOcEEaSB9nqn230000EOS4_	+688

Channel

pw_async2 channels are the primary mechanism for communicating between async tasks and threads.

The following size report shows the base cost of using static and dynamic channels, as well as the marginal cost of adding a new channel of a trivial or non-trivial type.

Label	Segment	Delta
Size of static MpmcChannel	FLASH +436 [section .rodata] DEL -244 pw::async2::size_report::Measure() +2 pw::containers::internal::GenericIntrusiveList<>::remove_if<>() DEL -72 pw::async2::size_report::PendableValue<>::Get() DEL -56 pw::async2::Waker::operator=() DEL -52 pw::async2::size_report::MockTask::DoPend() DEL -46 pw::async2::size_report::MockTask::~MockTask() +30 pw::async2::FuncTask<>::~FuncTask() DEL -28 pw::async2::RunnableDispatcher::RunToCompletion() -2 pw::Allocator::Resize() -2 pw::containers::internal::IntrusiveListItemBase<>::unlist() DEL -24 pw::async2::size_report::MockTask::DoPend()::{lambda()#1}::operator()() DEL -24 pw::async2::size_report::PendableValue<>::Get()::{lambda()#1}::operator()() +20 pw::async2::FuncTask<> DEL -20 pw::async2::size_report::MockTask +2 pw::async2::FuncTask<>::DoPend() +2 pw::async2::Waker::RemoveFromTaskWakerListLocked() -2 pw::async2::internal::StoreWaker() +4 vClearInterruptMaskFromISR +4 main NEW +272 pw::async2::size_report::MeasureStatic<>() NEW +144 pw::async2::SendFuture<>::DoPend() NEW +132 pw::async2::ReceiveFuture<>::DoPend() NEW +110 pw::async2::internal::BaseChannelFuture::BaseChannelFuture() NEW +100 pw::async2::internal::BaseChannelFuture::StoreWakerForReceiveIfOpen() NEW +88 pw::async2::internal::BaseChannel::remove_object() NEW +76 pw::async2::internal::BaseChannel::~BaseChannel() NEW +76 pw::async2::internal::BaseChannelFuture::StoreWakerForSend() NEW +68 pw::async2::CreateMpmcChannel<>() NEW +52 pw::async2::internal::BaseChannel::add_object() NEW +46 pw::async2::size_report::MeasureStatic<>()::{lambda()#1}::operator()() NEW +44 pw::async2::ChannelHandle<>::CreateReceiver() NEW +44 pw::async2::ChannelHandle<>::CreateSender() NEW +44 pw::async2::internal::BaseChannel::add_ref() NEW +44 pw::containers::internal::GenericDeque<>::front() NEW +44 pw::containers::internal::GenericDeque<>::pop_front() NEW +42 pw::async2::internal::Channel<>::CreateReceiver() NEW +42 pw::async2::internal::Channel<>::CreateSender() NEW +42 pw::async2::size_report::MeasureStatic<>()::{lambda()#2}::operator()() NEW +40 pw::async2::internal::BaseChannel::BaseChannel() NEW +40 pw::async2::internal::ChannelFuture<>::Pend() NEW +40 pw::containers::internal::GenericDeque<>::push_back() NEW +38 pw::containers::internal::GenericDeque<>::try_emplace_back<>() NEW +36 pw::async2::internal::BaseChannel::RemoveRefAndDestroyIfUnreferenced() NEW +34 pw::async2::internal::BaseChannelFuture::StoreAndAddRefIfNonnull() NEW +32 pw::FixedDeque<>::~FixedDeque() NEW +32 pw::async2::ChannelStorage<>::ChannelStorage() NEW +32 pw::async2::internal::Channel<>::Channel<>() NEW +32 pw::async2::internal::Channel<>::PopAndWake() NEW +32 pw::async2::internal::Channel<>::~Channel() NEW +30 pw::async2::internal::BaseChannelFuture::RemoveFromChannel() NEW +28 pw::async2::internal::BaseChannel::should_close() NEW +26 pw::async2::BaseFutureList::ResolveAll() NEW +24 pw::async2::internal::BaseChannel::CloseLocked() NEW +24 pw::containers::internal::GenericDequeBase<>::PopFront() NEW +24 pw::containers::internal::GenericDequeBase<>::PushBack() NEW +20 pw::async2::BaseFutureList::ResolveOne() NEW +20 pw::async2::Receiver<>::Disconnect() NEW +20 pw::async2::SendFuture<>::SendFuture() NEW +20 pw::async2::Sender<>::Disconnect() NEW +20 pw::async2::internal::BaseChannelHandle::Release() NEW +20 pw::async2::internal::Channel<>::PushAndWake() NEW +20 pw::containers::internal::GenericDeque<>::EmplaceBackUnchecked<>() NEW +18 pw::async2::FutureCore::~FutureCore() NEW +18 pw::async2::ReceiveFuture<>::~ReceiveFuture() NEW +18 pw::async2::Receiver<>::~Receiver() NEW +18 pw::async2::SendFuture<>::~SendFuture() NEW +18 pw::async2::Sender<>::~Sender() NEW +16 pw::async2::internal::BaseChannelFuture::Complete() NEW +14 pw::async2::BaseFutureList::ResolveOneIfAvailable() NEW +14 pw::async2::FutureCore::WakeAndMarkReady() NEW +14 pw::async2::internal::BaseChannel::add_handle() NEW +12 pw::async2::ChannelStorage<> NEW +12 pw::async2::internal::BaseChannel NEW +12 pw::async2::internal::BaseChannel::add_receiver() NEW +12 pw::async2::internal::BaseChannel::add_sender() NEW +12 pw::async2::internal::BaseChannel::remove_handle() NEW +12 pw::async2::internal::BaseChannel::remove_receiver() NEW +12 pw::async2::internal::BaseChannel::remove_sender() NEW +12 pw::async2::internal::Channel<> NEW +10 pw::async2::FutureCore::Unlist() NEW +10 pw::async2::ReceiveFuture<>::ReceiveFuture() NEW +10 pw::async2::Receiver<>::Receive() NEW +10 pw::async2::Sender<>::Send<>() NEW +2 pw::async2::internal::BaseChannel::Destroy()	+2,408
	RAM -8 [section .data] DEL -24 pw::async2::size_report::(anonymous namespace)::dispatcher	-32
Cost of additional static MpmcChannel<unsigned> instantiation	FLASH +272 pw::async2::size_report::MeasureStatic<>() +144 pw::async2::SendFuture<>::DoPend() +132 pw::async2::ReceiveFuture<>::DoPend() +68 pw::async2::CreateMpmcChannel<>() +60 pw::async2::FuncTask<>::~FuncTask() +46 pw::async2::size_report::MeasureStatic<>()::{lambda()#1}::operator()() +44 pw::async2::ChannelHandle<>::CreateReceiver() +44 pw::async2::ChannelHandle<>::CreateSender() +44 pw::containers::internal::GenericDeque<>::front() +44 pw::containers::internal::GenericDeque<>::pop_front() +42 pw::async2::internal::Channel<>::CreateReceiver() +42 pw::async2::internal::Channel<>::CreateSender() +40 pw::async2::size_report::MeasureStatic<>()::{lambda()#2}::operator()() +40 pw::async2::FuncTask<> +40 pw::async2::internal::ChannelFuture<>::Pend() +40 pw::containers::internal::GenericDeque<>::push_back() +38 pw::containers::internal::GenericDeque<>::try_emplace_back<>() +32 pw::FixedDeque<>::~FixedDeque() +32 pw::async2::ChannelStorage<>::ChannelStorage() +32 pw::async2::internal::Channel<>::Channel<>() +32 pw::async2::internal::Channel<>::PopAndWake() +32 pw::async2::internal::Channel<>::~Channel() +20 pw::async2::FuncTask<>::DoPend() +20 pw::async2::Receiver<>::Disconnect() +20 pw::async2::SendFuture<>::SendFuture() +20 pw::async2::Sender<>::Disconnect() +20 pw::async2::internal::Channel<>::PushAndWake() +20 pw::containers::internal::GenericDeque<>::EmplaceBackUnchecked<>() +18 pw::async2::ReceiveFuture<>::~ReceiveFuture() +18 pw::async2::Receiver<>::~Receiver() +18 pw::async2::SendFuture<>::~SendFuture() +18 pw::async2::Sender<>::~Sender() -8 vClearInterruptMaskFromISR +4 main +12 pw::async2::ChannelStorage<> +12 pw::async2::internal::Channel<> +12 pw::async2::ReceiveFuture<>::ReceiveFuture() +10 pw::async2::Receiver<>::Receive() +10 pw::async2::Sender<>::Send<>()	+1,584
Cost of additional static MpmcChannel<MoveOnly> instantiation	FLASH +272 pw::async2::size_report::MeasureStatic<>() +144 pw::async2::SendFuture<>::DoPend() +132 pw::async2::ReceiveFuture<>::DoPend() +68 pw::async2::CreateMpmcChannel<>() +60 pw::async2::FuncTask<>::~FuncTask() +46 pw::async2::size_report::MeasureStatic<>()::{lambda()#1}::operator()() +44 pw::async2::ChannelHandle<>::CreateReceiver() +44 pw::async2::ChannelHandle<>::CreateSender() +44 pw::containers::internal::GenericDeque<>::front() +44 pw::containers::internal::GenericDeque<>::pop_front() +42 pw::async2::internal::Channel<>::CreateReceiver() +42 pw::async2::internal::Channel<>::CreateSender() +40 pw::async2::size_report::MeasureStatic<>()::{lambda()#2}::operator()() +40 pw::async2::FuncTask<> +40 pw::async2::internal::ChannelFuture<>::Pend() +40 pw::containers::internal::GenericDeque<>::push_back() +38 pw::containers::internal::GenericDeque<>::try_emplace_back<>() +32 pw::FixedDeque<>::~FixedDeque() +32 pw::async2::ChannelStorage<>::ChannelStorage() +32 pw::async2::internal::Channel<>::Channel<>() +32 pw::async2::internal::Channel<>::PopAndWake() +32 pw::async2::internal::Channel<>::~Channel() +20 pw::async2::FuncTask<>::DoPend() +20 pw::async2::Receiver<>::Disconnect() +20 pw::async2::SendFuture<>::SendFuture() +20 pw::async2::Sender<>::Disconnect() +20 pw::async2::internal::Channel<>::PushAndWake() +20 pw::containers::internal::GenericDeque<>::EmplaceBackUnchecked<>() +18 pw::async2::ReceiveFuture<>::~ReceiveFuture() +18 pw::async2::Receiver<>::~Receiver() +18 pw::async2::SendFuture<>::~SendFuture() +18 pw::async2::Sender<>::~Sender() -8 vClearInterruptMaskFromISR +4 main +12 pw::async2::ChannelStorage<> +12 pw::async2::internal::Channel<> +12 pw::async2::ReceiveFuture<>::ReceiveFuture() +10 pw::async2::Receiver<>::Receive() +10 pw::async2::Sender<>::Send<>()	+1,584
Size of dynamic MpmcChannel	FLASH +416 [section .rodata] DEL -244 pw::async2::size_report::Measure() +2 pw::containers::internal::GenericIntrusiveList<>::remove_if<>() DEL -72 pw::async2::size_report::PendableValue<>::Get() DEL -56 pw::async2::Waker::operator=() DEL -52 pw::async2::size_report::MockTask::DoPend() DEL -46 pw::async2::size_report::MockTask::~MockTask() +30 pw::async2::FuncTask<>::~FuncTask() DEL -28 pw::async2::RunnableDispatcher::RunToCompletion() -2 pw::Allocator::Resize() -2 pw::containers::internal::IntrusiveListItemBase<>::unlist() DEL -24 pw::async2::size_report::MockTask::DoPend()::{lambda()#1}::operator()() DEL -24 pw::async2::size_report::PendableValue<>::Get()::{lambda()#1}::operator()() +20 pw::async2::FuncTask<> DEL -20 pw::async2::size_report::MockTask +68 pw::async2::FuncTask<>::DoPend() -4 __bi_84 +2 pw::async2::Waker::RemoveFromTaskWakerListLocked() -2 pw::async2::BasicDispatcher::DoWaitForWake() -2 pw::async2::internal::StoreWaker() -4 vClearInterruptMaskFromISR +2 main NEW +268 pw::async2::size_report::MeasureDynamic() NEW +144 pw::async2::SendFuture<>::DoPend() NEW +132 pw::async2::ReceiveFuture<>::DoPend() NEW +108 pw::async2::internal::BaseChannelFuture::BaseChannelFuture() NEW +100 pw::async2::internal::BaseChannelFuture::StoreWakerForReceiveIfOpen() NEW +88 pw::async2::internal::BaseChannel::remove_object() NEW +76 pw::async2::internal::BaseChannel::~BaseChannel() NEW +76 pw::async2::internal::BaseChannelFuture::StoreWakerForSend() NEW +64 pw::FixedDeque<>::TryAllocate() NEW +64 pw::async2::CreateMpmcChannel<>() NEW +52 pw::async2::internal::BaseChannel::add_object() NEW +48 pw::async2::internal::DynamicChannel<>::Allocate() NEW +44 pw::Deque<>::Aligned::Align() NEW +44 pw::async2::ChannelHandle<>::CreateReceiver() NEW +44 pw::async2::ChannelHandle<>::CreateSender() NEW +44 pw::async2::internal::BaseChannel::add_ref() NEW +44 pw::containers::internal::GenericDeque<>::front() NEW +44 pw::containers::internal::GenericDeque<>::pop_front() NEW +42 pw::async2::internal::Channel<>::CreateReceiver() NEW +42 pw::async2::internal::Channel<>::CreateSender() NEW +40 pw::async2::internal::BaseChannel::BaseChannel() NEW +40 pw::async2::internal::ChannelFuture<>::Pend() NEW +40 pw::containers::internal::GenericDeque<>::push_back() NEW +38 pw::containers::internal::GenericDeque<>::try_emplace_back<>() NEW +36 pw::async2::internal::BaseChannel::RemoveRefAndDestroyIfUnreferenced() NEW +36 pw::async2::internal::Channel<>::Channel() NEW +34 pw::FixedDeque<>::FixedDeque() NEW +34 pw::async2::internal::BaseChannelFuture::StoreAndAddRefIfNonnull() NEW +32 pw::FixedDeque<>::~FixedDeque() NEW +32 pw::async2::internal::Channel<>::PopAndWake() NEW +32 pw::async2::internal::Channel<>::~Channel() NEW +30 pw::Deque<>::Deque() NEW +30 pw::async2::internal::BaseChannelFuture::RemoveFromChannel() NEW +30 pw::containers::internal::GenericDequeBase<>::MoveAssignIndices() NEW +28 pw::async2::internal::BaseChannel::should_close() NEW +26 _ZN2pw9Allocator3NewINS_6async28internal14DynamicChannelIiEETpTnRiJEJNS_10FixedDequeIiLj4294967295EtEEEEENSt3__29enable_ifIXntsr3stdE10is_array_vIT_EEPSB_E4typeEDpOT1_ NEW +26 pw::async2::BaseFutureList::ResolveAll() NEW +24 pw::async2::internal::BaseChannel::CloseLocked() NEW +24 pw::async2::internal::DynamicChannel<>::Destroy() NEW +24 pw::containers::internal::GenericDequeBase<>::PopFront() NEW +24 pw::containers::internal::GenericDequeBase<>::PushBack() NEW +22 pw::allocator::Layout::Of<>() NEW +20 _ZNSt3__224__optional_destruct_baseIN2pw6async217MpmcChannelHandleIiEELb0EED2B9nqn230000Ev NEW +20 pw::async2::BaseFutureList::ResolveOne() NEW +20 pw::async2::Receiver<>::Disconnect() NEW +20 pw::async2::SendFuture<>::SendFuture() NEW +20 pw::async2::Sender<>::Disconnect() NEW +20 pw::async2::internal::BaseChannelHandle::Release() NEW +20 pw::async2::internal::Channel<>::PushAndWake() NEW +20 pw::async2::internal::DynamicChannel<>::DynamicChannel() NEW +20 pw::containers::internal::GenericDeque<>::EmplaceBackUnchecked<>() NEW +18 pw::async2::FutureCore::~FutureCore() NEW +18 pw::async2::ReceiveFuture<>::~ReceiveFuture() NEW +18 pw::async2::Receiver<>::~Receiver() NEW +18 pw::async2::SendFuture<>::~SendFuture() NEW +18 pw::async2::Sender<>::~Sender() NEW +16 pw::Deque<>::MoveBufferFrom() NEW +16 pw::async2::internal::BaseChannelFuture::Complete() NEW +14 pw::async2::BaseFutureList::ResolveOneIfAvailable() NEW +14 pw::async2::FutureCore::WakeAndMarkReady() NEW +12 pw::async2::internal::BaseChannel NEW +12 pw::async2::internal::BaseChannel::add_handle() NEW +12 pw::async2::internal::BaseChannel::add_receiver() NEW +12 pw::async2::internal::BaseChannel::add_sender() NEW +12 pw::async2::internal::BaseChannel::remove_handle() NEW +12 pw::async2::internal::BaseChannel::remove_receiver() NEW +12 pw::async2::internal::BaseChannel::remove_sender() NEW +12 pw::async2::internal::Channel<> NEW +12 pw::async2::internal::DynamicChannel<> NEW +10 pw::async2::FutureCore::Unlist() NEW +10 pw::async2::ReceiveFuture<>::ReceiveFuture() NEW +10 pw::async2::Receiver<>::Receive() NEW +10 pw::async2::Sender<>::Send<>() NEW +2 pw::async2::internal::BaseChannel::Destroy()	+2,688
	RAM -8 [section .data] DEL -24 pw::async2::size_report::(anonymous namespace)::dispatcher	-32
Cost of static MpmcChannel when dynamic of same type is present	FLASH +20 [section .rodata] +20 pw::async2::FuncTask<>::DoPend() +68 pw::async2::CreateMpmcChannel<>() +60 pw::async2::FuncTask<>::~FuncTask() +40 pw::async2::FuncTask<> -2 pw::containers::internal::GenericDequeBase<>::MoveAssignIndices() +2 pw::async2::internal::BaseChannel::add_handle() +6 main +2 pw::async2::BasicDispatcher::DoWaitForWake() +12 vClearInterruptMaskFromISR NEW +272 pw::async2::size_report::MeasureStatic<>() NEW +46 pw::async2::size_report::MeasureStatic<>()::{lambda()#1}::operator()() NEW +42 pw::async2::size_report::MeasureStatic<>()::{lambda()#2}::operator()() NEW +32 pw::async2::ChannelStorage<>::ChannelStorage() NEW +32 pw::async2::internal::Channel<>::Channel<>() NEW +12 pw::async2::ChannelStorage<>	+664