v2.8.0

Features

• Add agrpc::register_callback_rpc_handler for setting up request handling with agrpc::ServerRPCPtr, a dynamically allocated ServerRPC which can be used to implement non-coroutine based gRPC servers.
• Add experimental support for P2300R7 (std::execution) in the form of a new CMake target asio-grpc::asio-grpc-stdexec.
• Breaking change: Certain completion token like asio::experimental::use_promise might now return a different type due to the implementation of Asio's optional requirement on asynchronous operations: The operation's associated I/O executor may be exposed via the Initiation function object's executor_type type alias and get_executor() member function.

Fixes

• Removed all usage of pointer tagging. Although Asio uses it, it is technically undefined behavior.

Performance

• Use Asio's immediate_executor in ServerRPC::wait_for_done and Waiter::wait.

Documentation

• Use Asio's default completion token mechanism in examples.
• Avoid using asio::detached in examples since it swallows exceptions.
• Document how register_awaitable_rpc_handler and register_yield_rpc_handler obtain the executor used to spawn the coroutine.
• Removed documentation of deprecated CMake options.

Chore

• Remove codeql pipeline