Request the strand to invoke the given handler and return immediately.
template< typename CompletionHandler> void-or-deduced post( CompletionHandler && handler);
This function is used to ask the strand to execute the given handler, but without allowing the strand to call the handler from inside this function.
The strand object guarantees that handlers posted or dispatched through
the strand will not be executed concurrently. The strand's guarantee
is in addition to the guarantee provided by the underlying
io_service guarantees that the
handler will only be called in a thread in which the io_service's run
member function is currently being invoked.
The handler to be called. The strand will make a copy of the handler object as required. The function signature of the handler must be: