Sender Patterns to Wrangle Concurrency in Embedded Devices

Michael Caisse

michael.caisse@intel.com
@MichaelCaisse

The Environment

  • our program doesn't end
  • we don't use exceptions
  • we don't have a dynamic allocator
  • we don't have an rtos

STM32L432KC

  • 26 GPIO
  • 14 communication interfaces (USB, SAI, I2C, CAN, …)
  • Quad SPI memory interface
  • 11 Timers
  • 3 cap-sense channels
  • 1 ADC
  • 2 DAC

nucleo-32.png

Interrupts

Interrupts

Exercise

Producer ID 1

  1. Think of a colour
  2. Spell the colour name to Ben backwards one character at a time.
  3. When done, yell "End of Line"

Producer ID 2

  1. Count the number of people in your row.
  2. Tell Ben the count one digit at a time.
  3. When done, yell "End of Line"

async/concurrency

async/concurrency


Sender World View

Sender

Composition

Potential Energy

Do Something

Sender Chain Contains State

The Players

Intel Baremetal Senders


https://github.com/intel/cpp-baremetal-senders-and-receivers

Sender Factories

Functions that return senders.

  • just
  • just_result_of
  • just_error
  • just_error_result_of
  • just_stopped
auto sndr = async::just(42, 17);

Sender Factories

Functions that return senders.

  • just
  • just_result_of
  • just_error
  • just_error_result_of
  • just_stopped
auto sndr = async::just_result_of(
              [] { return 42; },
              [] { do_something(); },
              [] { return 17; });

Sender Factories

Functions that return senders.

  • schedule
auto sndr = sched.schedule();

Sender Adapters

Take one or more senders and returns a sender that is the composition.

  • continue_on
  • start_on
  • let_value
  • let_error
  • let_stopped
  • then
  • sequence
  • upon_error
  • upon_stopped
  • repeat
  • repeat_n
  • repeat_until
  • retry
  • retry_until
  • split
  • when_any
  • when_all
  • timeout_after

Sender Consumers

Functions that take senders and start the work.

  • start_detached
  • start_detached_unstoppable
  • sync_wait

Composition

auto comp =
    s1.schedule()
  | async::then([] { return 42; })
  | async::continue_on(s2)
  | async::then([] (int i) { return std::to_string(i); })
  ;

auto r = comp | async::sync_wait();

auto [str] = r.value_or(std::make_tuple(""_s));

Patterns

Timeout

  • Request a thing
  • Wait N units of time for thing
  • Timeout if not received

Timeout

auto timout =
  async::start_on(time_scheduler{5ms},
                  async::just_error(error{42}));

auto thing = async::when_any(get_thing, timeout);

auto s =
   | thing
   | async::then( [](auto v) { /* ... */ } )
   | async::upon_error( [](auto e) { /* ... */ } )
   ;

Timeout

auto s =
   | thing
   | async::timeout_after(5ms, error{42})
   | async::then( [](auto v) { /* ... */ } )
   | async::upon_error( [](auto e) { /* ... */ } )
   ;

Patterns

  • stop_detached
  • Schedulers
    • fixed_priority_scheduler
    • time_scheduler
    • trigger_scheduler




Robot Tubeman

LX-16A Communication




0x55 0x55 <id> <length> <cmd> <params> <checksum> 

auto request_temperature =
    msg::send(
      [](std::uint_8 id) {
        serial.send(servo_temp_request_t{"id"_f = id});
      }, 0x01)
  | msg::then_receive<"recv_temp", servo_temp_read_t>(
      [&](auto msg) { return msg.get("temp"_f); }
      )
  ;

auto temp_cycle =
    request_temperature
  | async::continue_on( disp_sched )
  | async::then( [](auto t){ display(t); } )
  | delay(1s)
  | async::repeat()
  | async::start_detached()
  ;

What is Going On?

The intuitive mind is a sacred gift and the rational mind is a faithful servant. We have created a society that honors the servant and has forgotten the gift.

– Albert Einstein

Add simple debug handler

namespace async_trace {

template <stdx::ct_string C, stdx::ct_string L, stdx::ct_string S, typename Ctx>
bool handled{};

struct debug_handler {
  template <stdx::ct_string C, stdx::ct_string L, stdx::ct_string S, typename Ctx>
  constexpr auto signal(auto ...) -> void {
    handled<C, L, S, Ctx> = true;
  }
};
}

template <>
inline auto async::injected_debug_handler<> = async_trace::debug_handler{};

demo sender

namespace things {
  int av = 0;

  auto a0 = async::just<"just-a0">(0);
  auto a1 = async::just<"just-a1">(1);
  auto a2 = async::just<"just-a2">(2) | async::then([](auto v){ things::av = v; });
  auto w  = async::when_all(a0, a1, a2);

  int var = 0;
  auto s =
      async::just<"link-start">(42)
    | async::then<"before-wa-then">([](auto v){ things::var = v; })
    | async::seq(w)
    | async::then<"last-then">([](auto ...){ ++things::var; })
    | async::repeat();
}

int main() {
  auto d = async::start_detached<"my_chain">(things::s);

  while(true) {}
}

fire up gdb

_ZN11async_trace7handledIXtlN4stdx2v19ct_stringILm9EEEtlNSt3__15arrayIcLm9EEEtlA9_cLc109ELc121E
Lc95ELc99ELc104ELc97ELc105ELc110EEEEEXtlNS3_ILm10EEEtlNS6_IcLm10EEEtlA10_cLc108ELc97ELc115ELc11
6ELc45ELc116ELc104ELc101ELc110EEEEEXtlS9_tlSA_tlSB_Lc115ELc101ELc116ELc95ELc118ELc97ELc108ELc11
7ELc101EEEEEN5async5_then8receiverIXtlS9_tlSA_tlSB_Lc108ELc97ELc115ELc116ELc45ELc116ELc104ELc10
1ELc110EEEEENSC_11set_value_tENSC_7_repeat8receiverINSG_8op_stateIXtlNS3_ILm7EEEtlNS6_IcLm7EEEt
lA7_cLc114ELc101ELc112ELc101ELc97ELc116EEEEENSD_6senderIXtlS9_tlSA_tlSB_Lc108ELc97ELc115ELc116E
Lc45ELc116ELc104ELc101ELc110EEEEESF_NSC_9_sequence6senderIXtlNS3_ILm4EEEtlNS6_IcLm4EEEtlA4_cLc1
15ELc101ELc113EEEEENSM_IXtlNS3_ILm15EEEtlNS6_IcLm15EEEtlA15_cLc98ELc101ELc102ELc111ELc114ELc101
ELc45ELc119ELc97ELc45ELc116ELc104ELc101ELc110EEEEESF_NSC_5_just6senderIXtlNS3_ILm11EEEtlNS6_IcL
m11EEEtlA11_cLc108ELc105ELc110ELc107ELc45ELc115ELc116ELc97ELc114ELc116EEEEESF_JiEEEJN6things3$_
1EEEENSN_6detail7wrapperINSC_9_when_all6senderIXtlS4_tlS7_tlS8_Lc119ELc104ELc101ELc110ELc95ELc9
7ELc108ELc108EEEEEJNS16_10sub_senderINSW_IXtlNS3_ILm8EEEtlNS6_IcLm8EEEtlA8_cLc106ELc117ELc115EL
c116ELc45ELc97ELc48EEEEESF_JiEEELm0EEENS18_INSW_IXtlS19_tlS1A_tlS1B_Lc106ELc117ELc115ELc116ELc4
5ELc97ELc49EEEEESF_JiEEELm1EEENS18_INSM_IXtlNS3_ILm5EEEtlNS6_IcLm5EEEtlA5_cLc116ELc104ELc101ELc
110EEEEESF_NSW_IXtlS19_tlS1A_tlS1B_Lc106ELc117ELc115ELc116ELc45ELc97ELc50EEEEESF_JiEEEJNS11_3$_
0EEEELm2EEEEEEEEEEJNS11_3$_2EEEENSC_15_start_detached8receiverINS1S_8op_stateINS2_5cts_tIXtlS4_
tlS7_tlS8_Lc109ELc121ELc95ELc99ELc104ELc97ELc105ELc110EEEEEEENSG_6senderIXtlSJ_tlSK_tlSL_Lc114E
Lc101ELc112ELc101ELc97ELc116EEEEES1R_NSG_3$_3EEENSC_15stack_allocatorENSC_19inplace_stop_source
ENSC_3envIJNSC_4propINSC_21get_debug_interface_tENSC_5debug15named_interfaceIXtlS4_tlS7_tlS8_Lc
109ELc121ELc95ELc99ELc104ELc97ELc105ELc110EEEEEJEEEEENS22_IJEEEEEEEEEES1Y_EES2C_EEJS1Q_EEEEE


async_trace::handled<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109,
(char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}},
stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)108, (char)97,
(char)115, (char)116, (char)45, (char)116, (char)104, (char)101, (char)110}}},
stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)115, (char)101,
(char)116, (char)95, (char)118, (char)97, (char)108, (char)117, (char)101}}},
async::_then::receiver<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_repeat::receiver<async::_repeat::op_state<stdx::v1::ct_string<7ul>{std::__1::array<char
, 7ul>{char [7]{(char)114, (char)101, (char)112, (char)101, (char)97, (char)116}}},
async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char
[4]{(char)115, (char)101, (char)113}}},
async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98,
(char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97,
(char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char
[11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97,
(char)114, (char)116}}}, async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::a
rray<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97,
(char)108, (char)108}}},
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}},
async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}},
async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char
, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106,
(char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>,
things::$_0>, 2ul>>>>, things::$_2>,
async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<stdx::v1::ct_
string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99,
(char)104, (char)97, (char)105, (char)110}}}>,
async::_repeat::sender<stdx::v1::ct_string<7ul>{std::__1::array<char, 7ul>{char [7]{(char)114,
(char)101, (char)112, (char)101, (char)97, (char)116}}},
async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char
[4]{(char)115, (char)101, (char)113}}},
async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98,
(char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97,
(char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char
[11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97,
(char)114, (char)116}}}, async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::a
rray<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97,
(char)108, (char)108}}}, async_trace::handled<stdx::v1::ct_string<9ul>{std::__1::array<char,
9ul>{char [9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105,
(char)110}}}, stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)108,
(char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101, (char)110}}},
stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)115, (char)101,
(char)116, (char)95, (char)118, (char)97, (char)108, (char)117, (char)101}}},
async::_then::receiver<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_repeat::receiver<async::_repeat::op_state<stdx::v1::ct_string<7ul>{std::__1::array<char
, 7ul>{char [7]{(char)114, (char)101, (char)112, (char)101, (char)97, (char)116}}},
async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char
[4]{(char)115, (char)101, (char)113}}},
async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98,
(char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97,
(char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char
[11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97,
(char)114, (char)116}}}, async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::a
rray<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97,
(char)108, (char)108}}},
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}},
async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}},
async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char
, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106,
(char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>,
things::$_0>, 2ul>>>>, things::$_2>,
async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<stdx::v1::ct_
string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99,
(char)104, (char)97, (char)105, (char)110}}}>,
async::_repeat::sender<stdx::v1::ct_string<7ul>{std::__1::array<char, 7ul>{char [7]{(char)114,
(char)101, (char)112, (char)101, (char)97, (char)116}}},
async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char
[4]{(char)115, (char)101, (char)113}}},
async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98,
(char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97,
(char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char
[11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97,
(char)114, (char)116}}}, async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::a
rray<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97,
(char)108, (char)108}}},
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}},
async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}},
async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char
, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106,
(char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>,
things::$_0>, 2ul>>>>, things::$_2>, async::_repeat::$_3>, async::stack_allocator,
async::inplace_stop_source, async::env<async::prop<async::get_debug_interface_t,
async::debug::named_interface<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char
[9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>>,
async::env<>>>>, async::_repeat::$_3>,
async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<stdx::v1::ct_
string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99,
(char)104, (char)97, (char)105, (char)110}}}>,
async::_repeat::sender<stdx::v1::ct_string<7ul>{std::__1::array<char, 7ul>{char [7]{(char)114,
(char)101, (char)112, (char)101, (char)97, (char)116}}},
async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char
[4]{(char)115, (char)101, (char)113}}},
async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98,
(char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97,
(char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char
[11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97,
(char)114, (char)116}}}, async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::a
rray<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97,
(char)108, (char)108}}},
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}},
async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}},
async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char
, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106,
(char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>,
things::$_0>, 2ul>>>>, things::$_2>, async::_repeat::$_3>, async::stack_allocator,
async::inplace_stop_source, async::env<async::prop<async::get_debug_interface_t,
async::debug::named_interface<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char
[9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>>,
async::env<>>>>>,
things::$_2>>async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__
1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97,
(char)48}}}, async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}},
async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char
, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106,
(char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>,
things::$_0>, 2ul>>>>, things::$_2>, async::_repeat::$_3>, async::stack_allocator,
async::inplace_stop_source, async::env<async::prop<async::get_debug_interface_t,
async::debug::named_interface<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char
[9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>>,
async::env<>>>>, async::_repeat::$_3>,
async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<stdx::v1::ct_
string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99,
(char)104, (char)97, (char)105, (char)110}}}>,
async::_repeat::sender<stdx::v1::ct_string<7ul>{std::__1::array<char, 7ul>{char [7]{(char)114,
(char)101, (char)112, (char)101, (char)97, (char)116}}},
async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char
[10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101,
(char)110}}}, async::set_value_t,
async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char
[4]{(char)115, (char)101, (char)113}}},
async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98,
(char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97,
(char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char
[11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97,
(char)114, (char)116}}}, async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::a
rray<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97,
(char)108, (char)108}}},
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}},
async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char
, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}},
async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char
, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t,
async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106,
(char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>,
things::$_0>, 2ul>>>>, things::$_2>, async::_repeat::$_3>, async::stack_allocator,
async::inplace_stop_source, async::env<async::prop<async::get_debug_interface_t,
async::debug::named_interface<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char
[9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>>,
async::env<>>>>>, things::$_2>>
async_trace::handled<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}, stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101, (char)110}}}, stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)115, (char)101, (char)116, (char)95, (char)118, (char)97, (char)108, (char)117, (char)101}}}, async::_then::receiver<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_repeat::receiver<async::_repeat::op_state<stdx::v1::ct_string<7ul>{std::__1::array<char, 7ul>{char [7]{(char)114, (char)101, (char)112, (char)101, (char)97, (char)116}}}, async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char [4]{(char)115, (char)101, (char)113}}}, async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98, (char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97, (char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char [11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97, (char)114, (char)116}}}, async::set_value_t, int>, things::$_1>, async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97, (char)108, (char)108}}}, async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}}, async::set_value_t, int>, 0ul>, async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}}, async::set_value_t, int>, 1ul>, async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>, async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>, async::_repeat::sender<stdx::v1::ct_string<7ul>{std::__1::array<char, 7ul>{char [7]{(char)114, (char)101, (char)112, (char)101, (char)97, (char)116}}}, async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char [4]{(char)115, (char)101, (char)113}}}, async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98, (char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97, (char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char [11]{(char)108, (char)105, (char)110, (char)107, (char)45, (char)115, (char)116, (char)97, (char)114, (char)116}}}, async::set_value_t, int>, things::$_1>, async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97, (char)108, (char)108}}}, async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}}, async::set_value_t, int>, 0ul>, async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}}, async::set_value_t, int>, 1ul>, async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>, async::_repeat::$_3>, async::stack_allocator, async::inplace_stop_source, async::env<async::prop<async::get_debug_interface_t, async::debug::named_interface<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>>, async::env<>>>>, async::_repeat::$_3>, async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>, async::_repeat::sender<stdx::v1::ct_string<7ul>{std::__1::array<char, 7ul>{char [7]{(char)114, (char)101, (char)112, (char)101, (char)97, (char)116}}}, async::_then::sender<stdx::v1::ct_string<10ul>{std::__1::array<char, 10ul>{char [10]{(char)108, (char)97, (char)115, (char)116, (char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_sequence::sender<stdx::v1::ct_string<4ul>{std::__1::array<char, 4ul>{char [4]{(char)115, (char)101, (char)113}}}, async::_then::sender<stdx::v1::ct_string<15ul>{std::__1::array<char, 15ul>{char [15]{(char)98, (char)101, (char)102, (char)111, (char)114, (char)101, (char)45, (char)119, (char)97, (char)45, (char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_just::sender<stdx::v1::ct_string<11ul>{std::__1::array<char, 11ul>{char [11]{(char)108, (char)105, (char)110--Type <RET> for more, q to quit, c to continue without paging--c
, (char)107, (char)45, (char)115, (char)116, (char)97, (char)114, (char)116}}}, async::set_value_t, int>, things::$_1>, async::_sequence::detail::wrapper<async::_when_all::sender<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)119, (char)104, (char)101, (char)110, (char)95, (char)97, (char)108, (char)108}}}, async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)48}}}, async::set_value_t, int>, 0ul>, async::_when_all::sub_sender<async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)49}}}, async::set_value_t, int>, 1ul>, async::_when_all::sub_sender<async::_then::sender<stdx::v1::ct_string<5ul>{std::__1::array<char, 5ul>{char [5]{(char)116, (char)104, (char)101, (char)110}}}, async::set_value_t, async::_just::sender<stdx::v1::ct_string<8ul>{std::__1::array<char, 8ul>{char [8]{(char)106, (char)117, (char)115, (char)116, (char)45, (char)97, (char)50}}}, async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>, async::_repeat::$_3>, async::stack_allocator, async::inplace_stop_source, async::env<async::prop<async::get_debug_interface_t, async::debug::named_interface<stdx::v1::ct_string<9ul>{std::__1::array<char, 9ul>{char [9]{(char)109, (char)121, (char)95, (char)99, (char)104, (char)97, (char)105, (char)110}}}>>, async::env<>>>>>, things::$_2>>

Pretty print the ct_string


async_trace::handled<"my_chain", "last-then", "set_value", async::_then::receiver<"last-then",
async::set_value_t, async::_repeat::receiver<async::_repeat::op_state<"repeat",
async::_then::sender<"last-then", async::set_value_t, async::_sequence::sender<"seq",
async::_then::sender<"before-wa-then", async::set_value_t, async::_just::sender<"link-start",
async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<"when_all",
async::_when_all::sub_sender<async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<"then", async::set_value_t,
async::_just::sender<"just-a2", async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>,
async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<"my_chain">,
async::_repeat::sender<"repeat", async::_then::sender<"last-then", async::set_value_t,
async::_sequence::sender<"seq", async::_then::sender<"before-wa-then", async::set_value_t,
async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<"when_all",
async::_when_all::sub_sender<async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<"then", async::set_value_t,
async::_just::sender<"just-a2", async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>,
async::_repeat::$_3>, async::stack_allocator, async::inplace_stop_source,
async::env<async::prop<async::get_debug_interface_t,
async::debug::named_interface<"my_chain">>, async::env<>>>>, async::_repeat::$_3>,
async::_start_detached::receiver<async::_start_detached::op_state<stdx::v1::cts_t<"my_chain">,
async::_repeat::sender<"repeat", async::_then::sender<"last-then", async::set_value_t,
async::_sequence::sender<"seq", async::_then::sender<"before-wa-then", async::set_value_t,
async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<"when_all",
async::_when_all::sub_sender<async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<"then", async::set_value_t,
async::_just::sender<"just-a2", async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>,
async::_repeat::$_3>, async::stack_allocator, async::inplace_stop_source,
async::env<async::prop<async::get_debug_interface_t,
async::debug::named_interface<"my_chain">>, async::env<>>>>>, things::$_2>>

Find start_detached

async_trace::handled<"my_chain", "start_detached", "start",
async::_start_detached::op_state<stdx::v1::cts_t<"my_chain">, async::_repeat::sender<"repeat",
async::_then::sender<"last-then", async::set_value_t, async::_sequence::sender<"seq",
async::_then::sender<"before-wa-then", async::set_value_t, async::_just::sender<"link-start",
async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<"when_all",
async::_when_all::sub_sender<async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<"then", async::set_value_t,
async::_just::sender<"just-a2", async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>,
async::_repeat::$_3>, async::stack_allocator, async::inplace_stop_source,
async::env<async::prop<async::get_debug_interface_t,
async::debug::named_interface<"my_chain">>, async::env<>>>>

start_detached contained sender

async::_repeat::sender<"repeat",
async::_then::sender<"last-then", async::set_value_t, async::_sequence::sender<"seq",
async::_then::sender<"before-wa-then", async::set_value_t, async::_just::sender<"link-start",
async::set_value_t, int>, things::$_1>,
async::_sequence::detail::wrapper<async::_when_all::sender<"when_all",
async::_when_all::sub_sender<async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
async::_when_all::sub_sender<async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
async::_when_all::sub_sender<async::_then::sender<"then", async::set_value_t,
async::_just::sender<"just-a2", async::set_value_t, int>, things::$_0>, 2ul>>>>, things::$_2>,
async::_repeat::$_3>

start_detached

async::_repeat::sender<"repeat",
  async::_then::sender<"last-then", async::set_value_t,
    async::_sequence::sender<"seq",
      async::_then::sender<"before-wa-then", async::set_value_t,
        async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
      async::_sequence::detail::wrapper<
        async::_when_all::sender<"when_all",
          async::_when_all::sub_sender<
            async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
          async::_when_all::sub_sender<
            async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
          async::_when_all::sub_sender<
            async::_then::sender<"then", async::set_value_t,
              async::_just::sender<"just-a2", async::set_value_t, int>,
              things::$_0>,
            2ul>>>>,
    things::$_2>,
  async::_repeat::$_3>


async::_repeat::sender<"repeat",
  async::_then::sender<"last-then", async::set_value_t,
    async::_sequence::sender<"seq",
      async::_then::sender<"before-wa-then", async::set_value_t,
        async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
      async::_sequence::detail::wrapper<
        async::_when_all::sender<"when_all",
          async::_when_all::sub_sender<
            async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
          async::_when_all::sub_sender<
            async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
          async::_when_all::sub_sender<
            async::_then::sender<"then", async::set_value_t,
              async::_just::sender<"just-a2", async::set_value_t, int>,
              things::$_0>,
            2ul>>>>,
    things::$_2>,
  async::_repeat::$_3>

Lark, Transformers, and Python


def async_debug():
    async_debug_re = re.compile(r"async_trace::handled")
    start_detached_op_state_re = re.compile(r"async::_start_detached::op_state")
    start_detached_context_re = re.compile(r"async_trace::context<async_trace::start_detached_t")

    frame = gdb.selected_frame()
    block = frame.block()
    debug_symbols = set()

    while block:
        for symbol in block:
            name = symbol.name
            demangled_name = cxxfilt.demangle(name)
            if async_debug_re.search(demangled_name):
                debug_symbols.add((symbol, demangled_name))
        block = block.superblock

    handled_states = []

    for (debug_symbol, demangled_name) in debug_symbols:
        pretty_name = stdx.prettify_ct_strings(demangled_name)
        add_symbol(debug_symbol)
        if start_detached_op_state_re.search(pretty_name) or start_detached_context_re.search(pretty_name):
            try:
                h = Handled(pretty_name)
                h.set_gdb_symbol(debug_symbol)
                handled_states.append(h)
            except:
                pass
    return handled_states

from .gdb_wedge import get_symbols

class DotColorMapper:
    """
    Signals have priority. The highest priority signal that is set
    will dictate the color
    """
    signal_priority_map = (
        ("set_error","orangered"),
        ("set_stopped","lightgrey"),
        ("set_value","dodgerblue"),
        ("start","mediumseagreen"),
        ("eval_predicate", "tan"))

    def __init__(self, chain_name, frame):
        self.chain_name = chain_name
        self.frame = frame

    def map(self, node_identifier):
        if not node_identifier or not self.frame:
            return {}

        syms = get_symbols(self.chain_name, **node_identifier)

        mapped_color = 'ghostwhite'
        for (sig, color) in self.signal_priority_map:
            sig_values = [s.get_value(self.frame) for s in syms if s.signal_name == sig]
            if any(sig_values):
                mapped_color = color
                break

        return {'style': 'filled', 'fillcolor': mapped_color}

import graphviz

class BaseColorMapper:
    def map(self, node_identifier):
        return {}

class DotGraphBuilder:
    def __init__(self, dot=None, color_mapper=None, **kwargs):
        if not dot:
            u_graph_attr = kwargs.get('graph_attr', {})
            graph_attr={'compound': 'true', **u_graph_attr}
            kwargs = {**kwargs, 'graph_attr': graph_attr}
            dot = graphviz.Digraph(**kwargs)

        self.dot = dot
        self.color_mapper = color_mapper if color_mapper else BaseColorMapper()

    def add_node(self, name, label, node_identifier=None, **kwargs):
        color_spec = self.color_mapper.map(node_identifier)
        extra_args = {**color_spec, **kwargs}
        self.dot.node(name, label, **extra_args)

    def add_edge(self, a, b, **kwargs):
        self.dot.edge(a, b, **kwargs)

        def subgraph(self, name, label, node_identifier=None, **kwargs):
        color_spec = self.color_mapper.map(node_identifier)
        style = kwargs.get('style', 'striped')
        sub = DotGraphBuilder(name=f"cluster_{name}", graph_attr={'label': f'{label}', 'style': style, **color_spec}, color_mapper=self.color_mapper)
        sub.add_node(name=name, label="", shape="point", style="invis")
        return sub

    def add_subgraph(self, g, node_identifier=None, **kwargs):
        color_spec = {} #self.color_mapper.map(node_identifier)
        extra_args = {**color_spec, **kwargs}
        self.dot.subgraph(g.dot, **extra_args)

    def display(self):
        self.dot.render("./foo.gv", view=True)

Demo Time

repeat doesn't clear

It is a simple matter of programming.

– Ben Deane

Templates are Pattern Matching

async::_repeat::sender<"repeat",
  async::_then::sender<"last-then", async::set_value_t,
    async::_sequence::sender<"seq",
      async::_then::sender<"before-wa-then", async::set_value_t,
        async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
      async::_sequence::detail::wrapper<
        async::_when_all::sender<"when_all",
          async::_when_all::sub_sender<
            async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
          async::_when_all::sub_sender<
            async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
          async::_when_all::sub_sender<
            async::_then::sender<"then", async::set_value_t,
              async::_just::sender<"just-a2", async::set_value_t, int>,
              things::$_0>,
            2ul>>>>,
    things::$_2>,
  async::_repeat::$_3>

Rework the debug_handler

namespace async_trace {

template <stdx::ct_string C, stdx::ct_string L, stdx::ct_string S, typename Ctx>
bool handled{};

struct debug_handler {
  template <stdx::ct_string C, stdx::ct_string L, stdx::ct_string S,
            typename Ctx, typename... Args>
  constexpr auto signal(Args &&...) -> void {
    handled<C, L, S, Ctx> = true;
  }
};
}

template <>
inline auto async::injected_debug_handler<> = async_trace::debug_handler{};

Rework the debug_handler

struct debug_handler {
  template <stdx::ct_string C, stdx::ct_string L, stdx::ct_string S,
            typename Ctx, typename... Args>
  constexpr auto signal(Args &&...) -> void {
    using context_t = extract_context_t<Ctx>;
    using tag_t = typename context_t::tag_t;
    using sndrs_t = typename context_t::sndrs_t;

    if constexpr (S == stdx::ct_string("start") && contains_v<reset_recursively_t, tag_t>) {
      recursively_reset_handled<C, context_t, sndrs_t>();
    }

    handled<C, L, S, context_t> = true;
  }
};

Recursively Walk the Type Onion

template <stdx::ct_string C, typename Ctx, typename Graph>
auto recursively_reset_handled = [](){

  reset_handled<C, Ctx>();

  using sub_nodes_t = sub_senders_t<Graph>;

  []<template <class...> class List, typename... Subs>(List<Subs...>){
    (..., recursively_reset_handled<C, extract_context_t<Subs>, Subs>());
  }(sub_nodes_t{});
 };

Recursively Walk the Type Onion

template <typename ...T>
using sub_senders_t =
  mp11::mp_flatten<
    mp11::mp_list< typename sub_senders<T>::type... >>;

default

template <typename T>
struct sub_senders {
  using type = mp11::mp_list<>;
};

async::_repeat::sender<"repeat",
  async::_then::sender<"last-then", async::set_value_t,
    async::_sequence::sender<"seq",
      async::_then::sender<"before-wa-then", async::set_value_t,
        async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
      async::_sequence::detail::wrapper<
        async::_when_all::sender<"when_all",
          async::_when_all::sub_sender<
            async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
          async::_when_all::sub_sender<
            async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
          async::_when_all::sub_sender<
            async::_then::sender<"then", async::set_value_t,
              async::_just::sender<"just-a2", async::set_value_t, int>,
              things::$_0>,
            2ul>>>>,
    things::$_2>,
  async::_repeat::$_3>

_then

template <stdx::ct_string Name, typename Tag, typename Sndr, typename... Ts>
struct sub_senders <async::_then::sender<Name, Tag, Sndr, Ts...>> {
  using type = mp11::mp_list<Sndr>;
};

async::_repeat::sender<"repeat",
  async::_then::sender<"last-then", async::set_value_t,
    async::_sequence::sender<"seq",
      async::_then::sender<"before-wa-then", async::set_value_t,
        async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
      async::_sequence::detail::wrapper<
        async::_when_all::sender<"when_all",
          async::_when_all::sub_sender<
            async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
          async::_when_all::sub_sender<
            async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
          async::_when_all::sub_sender<
            async::_then::sender<"then", async::set_value_t,
              async::_just::sender<"just-a2", async::set_value_t, int>,
              things::$_0>,
            2ul>>>>,
    things::$_2>,
  async::_repeat::$_3>

_sequence

template <stdx::ct_string Name, typename SndrA, typename SndrB>
struct sub_senders <async::_sequence::sender<Name,
                                             SndrA,
                                             async::_sequence::detail::wrapper<SndrB>>>{
  using type = mp11::mp_list<SndrA, SndrB>;
};

async::_repeat::sender<"repeat",
  async::_then::sender<"last-then", async::set_value_t,
    async::_sequence::sender<"seq",
      async::_then::sender<"before-wa-then", async::set_value_t,
        async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
      async::_sequence::detail::wrapper<
        async::_when_all::sender<"when_all",
          async::_when_all::sub_sender<
            async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
          async::_when_all::sub_sender<
            async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
          async::_when_all::sub_sender<
            async::_then::sender<"then", async::set_value_t,
              async::_just::sender<"just-a2", async::set_value_t, int>,
              things::$_0>,
            2ul>>>>,
    things::$_2>,
  async::_repeat::$_3>

_when_all

template <stdx::ct_string Name, typename... Sndrs, size_t ... N>
struct sub_senders <async::_when_all::sender<Name, async::_when_all::sub_sender<Sndrs, N>...>> {
  using type = mp11::mp_list<Sndrs...>;
};

async::_repeat::sender<"repeat",
  async::_then::sender<"last-then", async::set_value_t,
    async::_sequence::sender<"seq",
      async::_then::sender<"before-wa-then", async::set_value_t,
        async::_just::sender<"link-start", async::set_value_t, int>, things::$_1>,
      async::_sequence::detail::wrapper<
        async::_when_all::sender<"when_all",
          async::_when_all::sub_sender<
            async::_just::sender<"just-a0", async::set_value_t, int>, 0ul>,
          async::_when_all::sub_sender<
            async::_just::sender<"just-a1", async::set_value_t, int>, 1ul>,
          async::_when_all::sub_sender<
            async::_then::sender<"then", async::set_value_t,
              async::_just::sender<"just-a2", async::set_value_t, int>,
              things::$_0>,
            2ul>>>>,
    things::$_2>,
  async::_repeat::$_3>

demo with reset

demo with multiple threads

Will formalize the Ctx protocol

Summary

Sender Value Proposition

  • Expressions not Statements
  • Localized reasoning of concurrency
  • Brings the events to the state

Raising the Level of Abstraction

Enabled:

  • Structured concurrency
  • "Structured" debugging
  • "Structured" monitoring



Thank you

Questions?