Support asio::cancel_after

[anarthal]

This is a very handy token, but it requires the initiation function object to have a bound executor. The following should work:

redis::connection conn (ctx);
co_await conn.async_exec(req, res, asio::cancel_after(10s));

[mzimbres]

I tried to implement cancelation for async_exec here:

redis/include/boost/redis/detail/connection_base.hpp

Line 149 in d910557

if (is_cancelled(self)) {

At the moment I am considering removing as it is hard and I am not sure there is a good use cases for it. Do you think this is worth doing?

[anarthal]

Yes, there are good reasons. Without cancellation, you can't run a request with a timeout, for instance.