Thank you Chris and Klemens for great talk! At 17:30 step_2.cpp is_stopped() method is left not modified from previous example. I believe it should be: bool is_stopped() const { return stopped_; }
*Summary* *General Topic:* Exploring cancellation support in Asio, including the new per-operation cancellation. *1. [**0:52**] Basic Cancellation with a Watchdog Timer:* - [2:51] Add a timer and deadline to the proxy class. - [3:22] Implement a watchdog loop: - [3:32] Set timer expiry to deadline. - [3:38] Asynchronously wait for the timer. - [3:48] If deadline passed, stop the proxy by closing sockets; otherwise, continue looping. - [4:55] Start watchdog when read/write operations begin. - [4:47] Stop watchdog and initialize timer on shutdown. - [5:31] This approach is a "blunt tool" as it cancels everything after timeout. *2. [**10:30**] Using "cancel" and Handling Race Conditions:* - [10:41] Replaced "close" with "cancel" for finer control. - [11:12] Introduced a "stopped" flag to handle potential race conditions between operation completion and cancellation. - [12:29] Highlighted the race condition inherent in `async_write`, which composes multiple write operations. - [14:48] Demonstrated the use of a completion condition to check for cancellation between `async_write_some` calls. *3. [**19:10**] Per-Operation Cancellation with Signals and Slots:* - [19:29] Introduced the new per-operation cancellation feature. - [19:31] Added a heartbeat timer and associated cancellation signal. - [19:17] Modified server-to-client read operation: - [21:08] If canceled, send a heartbeat message instead. - [23:07] Connected the operation's cancellation slot to the heartbeat signal. - [23:14] Showcased how `bind_cancellation_slot` associates an operation's cancellation with a signal. *4. [**25:07**] Cancellation Slots: Low-Level Building Blocks:* - [25:14] Explained the signal/slot mechanism for per-operation cancellation: - [25:21] A signal is emitted to request cancellation. - [25:27] Operations are connected to signals through slots. - [25:27] Slots invoke registered handlers upon receiving a signal. - [27:20] Emphasized that cancellation slots are low-level mechanisms and shouldn't be managed directly in high-level code. *5. [**27:45**] Parallel Groups for Simplified Cancellation:* - [27:57] Replaced the separate heartbeat loop with `asio::parallel_group`. - [28:23] Demonstrated the use of a parallel group for concurrently running the read operation and the heartbeat timer. - [33:42] Highlighted `asio::make_parallel_group` for simplified cancellation management within the group. - [32:56] Illustrated how different wait options (e.g., `wait_for_all`, `wait_for_one`) influence cancellation behavior within the group. *6. [**36:19**] Customizing Cancellation in Asynchronous Operations:* - [37:05] Implemented a custom `async_wait_for_signal` operation. - [37:23] Demonstrated the use of `asio::async_initiate` for implementing custom operations. - [44:08] Illustrated how to integrate cancellation slots into custom operations: - [44:15] Retrieve the cancellation slot using `asio::get_associated_cancellation_slot`. - [44:49] Assign a cancellation handler to the slot if connected. *7. [**47:11**] Cancellation Types and Guarantees:* - [47:50] Explained different cancellation types: - [48:05] *Terminal:* Side effects may have occurred, rendering the object unusable. - [49:05] *Partial:* Some progress is made, the object's state is known, and the operation can potentially be resumed. - [50:00] *Total:* No observable side effects, allowing for operation repetition. - [55:38] Showcased adjusting cancellation behavior based on the requested cancellation type using `asio::cancellation_type`. - [55:38] Demonstrated building an operation (buffered message reading) supporting total cancellation on top of lower layers that only provide partial cancellation. *Key Takeaways:* * Asio offers various mechanisms for handling cancellation. * The `asio::cancellation_slot` is a powerful low-level building block for cancellation. * High-level constructs like co-routines and `asio::make_parallel_group` simplify cancellation management. * Cancellation guarantees (terminal, partial, total) provide information about the object's state after cancellation. i used gemini 1.5 pro to summarize the transcript
best video as a introduction to asio coroutines! had problems finding anything else
Thank you Chris and Klemens for great talk! At 17:30 step_2.cpp is_stopped() method is left not modified from previous example. I believe it should be:
bool is_stopped() const
{
return stopped_;
}
We're getting an introduction from the developer of Asio itself. Nice!
*Summary*
*General Topic:* Exploring cancellation support in Asio, including the new per-operation cancellation.
*1. [**0:52**] Basic Cancellation with a Watchdog Timer:*
- [2:51] Add a timer and deadline to the proxy class.
- [3:22] Implement a watchdog loop:
- [3:32] Set timer expiry to deadline.
- [3:38] Asynchronously wait for the timer.
- [3:48] If deadline passed, stop the proxy by closing sockets; otherwise, continue looping.
- [4:55] Start watchdog when read/write operations begin.
- [4:47] Stop watchdog and initialize timer on shutdown.
- [5:31] This approach is a "blunt tool" as it cancels everything after timeout.
*2. [**10:30**] Using "cancel" and Handling Race Conditions:*
- [10:41] Replaced "close" with "cancel" for finer control.
- [11:12] Introduced a "stopped" flag to handle potential race conditions between operation completion and cancellation.
- [12:29] Highlighted the race condition inherent in `async_write`, which composes multiple write operations.
- [14:48] Demonstrated the use of a completion condition to check for cancellation between `async_write_some` calls.
*3. [**19:10**] Per-Operation Cancellation with Signals and Slots:*
- [19:29] Introduced the new per-operation cancellation feature.
- [19:31] Added a heartbeat timer and associated cancellation signal.
- [19:17] Modified server-to-client read operation:
- [21:08] If canceled, send a heartbeat message instead.
- [23:07] Connected the operation's cancellation slot to the heartbeat signal.
- [23:14] Showcased how `bind_cancellation_slot` associates an operation's cancellation with a signal.
*4. [**25:07**] Cancellation Slots: Low-Level Building Blocks:*
- [25:14] Explained the signal/slot mechanism for per-operation cancellation:
- [25:21] A signal is emitted to request cancellation.
- [25:27] Operations are connected to signals through slots.
- [25:27] Slots invoke registered handlers upon receiving a signal.
- [27:20] Emphasized that cancellation slots are low-level mechanisms and shouldn't be managed directly in high-level code.
*5. [**27:45**] Parallel Groups for Simplified Cancellation:*
- [27:57] Replaced the separate heartbeat loop with `asio::parallel_group`.
- [28:23] Demonstrated the use of a parallel group for concurrently running the read operation and the heartbeat timer.
- [33:42] Highlighted `asio::make_parallel_group` for simplified cancellation management within the group.
- [32:56] Illustrated how different wait options (e.g., `wait_for_all`, `wait_for_one`) influence cancellation behavior within the group.
*6. [**36:19**] Customizing Cancellation in Asynchronous Operations:*
- [37:05] Implemented a custom `async_wait_for_signal` operation.
- [37:23] Demonstrated the use of `asio::async_initiate` for implementing custom operations.
- [44:08] Illustrated how to integrate cancellation slots into custom operations:
- [44:15] Retrieve the cancellation slot using `asio::get_associated_cancellation_slot`.
- [44:49] Assign a cancellation handler to the slot if connected.
*7. [**47:11**] Cancellation Types and Guarantees:*
- [47:50] Explained different cancellation types:
- [48:05] *Terminal:* Side effects may have occurred, rendering the object unusable.
- [49:05] *Partial:* Some progress is made, the object's state is known, and the operation can potentially be resumed.
- [50:00] *Total:* No observable side effects, allowing for operation repetition.
- [55:38] Showcased adjusting cancellation behavior based on the requested cancellation type using `asio::cancellation_type`.
- [55:38] Demonstrated building an operation (buffered message reading) supporting total cancellation on top of lower layers that only provide partial cancellation.
*Key Takeaways:*
* Asio offers various mechanisms for handling cancellation.
* The `asio::cancellation_slot` is a powerful low-level building block for cancellation.
* High-level constructs like co-routines and `asio::make_parallel_group` simplify cancellation management.
* Cancellation guarantees (terminal, partial, total) provide information about the object's state after cancellation.
i used gemini 1.5 pro to summarize the transcript
This video feels like some portal into the future. I really have to watch it carefully to learn the new ASIO ways and co_await!
When will we be able to expect a new episode? Very much enjoyed the first two.
Fantastic talk, Klemens especially asks great questions!
Thanks for amazing content!
Are you going to cover some advanced multithread-wise stuff in next episodes?
Audio is better, thanks! Now I need to watch very focused, it's not an easy topic........