[Boost-users] Boost.ASIO calling handler guarantees

Subject: [Boost-users] Boost.ASIO calling handler guarantees
From: æ£ÄÏÒ ôÒÕÛËÉÎ (ted-xp_at_[hidden])
Date: 2014-08-22 08:20:10

Hello, Dear All,

I'm playing with Boost.ASIO framework and failed to find a complete answer on the following question.

Under which circumstances is it guaranteed that asynchronous operation completion handler is called?

Plainly speaking, is this example code correct?

void my_handler(const error_code &ec)
{
   if(!ec) { /* process successful operation */ }
   else { /* process failed operation */ }

   try {
      async_write(port, my_handler2)
   }
   catch(...) {
       // processing failure to execute asynchronous operation
   }
}

Obviously here I rely heavily upon the above mentioned guarantee.

Looking at least at async_write() implementation, it cannot be relied upon:
 - async_write executes a chain of boost::asio::detail::write_op() operations:
 - if asio_handler_allocate() may throw then
 - write_op::stream_.async_write_some() may throw then
 - write_op.handler_() might never be called

So, either we should never rely on this assumption, or there's a bug in async_write().
Not relying on this assumption what is the reliable way of building applications with Boost.Asio?

Sincerely yours,
Fedor Trushkin