Re: [asio-users] Problem with boost::asio::ssl when using multiple threads

[Christian H. <ha...@te...>]

Am 05.02.2013, 19:42 Uhr, schrieb Александр Бобров  
<bob...@gm...>:

> You can read here about openssl (the same issue):
>
> http://stackoverflow.com/questions/14467630/clarifying-openssl-0-9-8l-concurrency-support-can-ssl-instances-be-used-by-mul
>
> It seems that you run concurrently async_read / async_write on the same
> boost::asio::ssl::stream object (full duplex), so SSL_read and SSL_write
> can run concurrently.
>

That Stackoverflow article is quite interesting.
It seems that the boost::asio::ssl can't be used in a multithread  
environment unless you take special care not to async_send and  
async_receive at the same on the boost::asio::ssl_stream.
It took me quite a long time to figure it out. The documentation could be  
better there.

> Strands is only for IO operations completition handlers. async_read and
> async_write are composed from other asynchronous operations, and all
> intermediate handlers should be invoked using the same method as the  
> final
> handler.
>
> You should implement your own asio_handler_invoke like it's done in asio
> docs:
>
> http://www.boost.org/doc/libs/1_53_0/doc/html/boost_asio/reference/asio_handler_invoke.html
>

I don't understand how I could do this properly. Because I have one strand  
per object how can I set a different handler-invoker-hook for every  
async-operation?

Actually I am thinking of a workaround to protect the OpenSSL-Object by  
inserting a mutex in boost::asio::ssl::detail::io_op::operator(). I have  
to test the code more, though.


Regards,

Christian