Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator > Class Template Reference

#include <asio_async_ops.h>

Inheritance diagram for Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >:

Public Types
using	allocator_type = boost::asio::associated_allocator_t< Handler, Allocator >
using	executor_type = boost::asio::associated_executor_t< Handler, Executor1 >

Public Member Functions
allocator_type	get_allocator () const noexcept
executor_type	get_executor () const noexcept

Protected Member Functions
template<class HandlerT >
	AsyncBase (HandlerT &&handler, const Executor1 &executor)
template<class... Args>
void	complete_now (Args &&... args)

Protected Attributes
Handler	m_handler
boost::asio::executor_work_guard< Executor1 >	m_work_guard_1

Detailed Description

template<class Handler, class Executor1, class Allocator>
class Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >

Base class for asynchronous stream operations.

Asynchronous operations, used for example to implement an interface for boost::asio::async_read_some and boost::asio::async_write_some, are based on boost::asio::coroutines. Derived operations should implement a call operator and invoke it with the correct parameters upon construction. The call operator needs to make sure that the user-provided handler is not called directly. Typically, yield / reenter is used for this in the following fashion:

void operator()(boost::system::error_code ec, std::size_t bytes_transferred, bool isContinuation = true)
   {
   reenter(this)
      {
      // operation specific logic, repeatedly interacting with the stream_core and the next_layer (socket)
 
      // make sure intermediate initiating function is called
      if(!isContinuation)
         {
         yield next_layer.async_operation(empty_buffer, this);
         }
 
      // call the completion handler
      complete_now(error_code, bytes_transferred);
      }
   }

Once the operation is completed and ready to call the completion handler it checks if an intermediate initiating function has been called using the isContinuation parameter. If not, it will call an asynchronous operation, such as async_read_some, with and empty buffer, set the object itself as the handler, and yield. As a result, the call operator will be invoked again, this time as a continuation, and will jump to the location where it yielded before using reenter. It is now safe to call the handler function via complete_now.

Template Parameters

Handler	Type of the completion handler
Executor1	Type of the asio executor (usually derived from the lower layer)
Allocator	Type of the allocator to be used

Definition at line 68 of file asio_async_ops.h.

Member Typedef Documentation

allocator_type

template<class Handler , class Executor1 , class Allocator >

using Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::allocator_type = boost::asio::associated_allocator_t<Handler, Allocator>

Definition at line 70 of file asio_async_ops.h.

executor_type

template<class Handler , class Executor1 , class Allocator >

using Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::executor_type = boost::asio::associated_executor_t<Handler, Executor1>

Definition at line 71 of file asio_async_ops.h.

Constructor & Destructor Documentation

AsyncBase()

template<class Handler , class Executor1 , class Allocator >

template<class HandlerT >

Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::AsyncBase ( HandlerT &&  handler, const Executor1 &  executor  )

inlineprotected

Definition at line 81 of file asio_async_ops.h.

                                                               :
            m_handler(std::forward<HandlerT>(handler)), m_work_guard_1(executor) {}

Member Function Documentation

complete_now()

template<class Handler , class Executor1 , class Allocator >

template<class... Args>

void Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::complete_now ( Args &&...  args )

inlineprotected

Call the completion handler.

This function should only be called after an intermediate initiating function has been called.

Parameters

args	Arguments forwarded to the completion handler function.

Definition at line 92 of file asio_async_ops.h.

                                        {
         m_work_guard_1.reset();
         m_handler(std::forward<Args>(args)...);
      }

References Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::m_handler, and Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::m_work_guard_1.

Referenced by Botan::TLS::detail::AsyncReadOperation< Handler, Stream, MutableBufferSequence, Allocator >::operator()(), Botan::TLS::detail::AsyncWriteOperation< Handler, Stream, Allocator >::operator()(), and Botan::TLS::detail::AsyncHandshakeOperation< Handler, Stream, Allocator >::operator()().

get_allocator()

template<class Handler , class Executor1 , class Allocator >

allocator_type Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::get_allocator ( ) const

inlinenoexcept

Definition at line 73 of file asio_async_ops.h.

{ return boost::asio::get_associated_allocator(m_handler); }

References Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::m_handler.

get_executor()

template<class Handler , class Executor1 , class Allocator >

executor_type Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::get_executor ( ) const

inlinenoexcept

Definition at line 75 of file asio_async_ops.h.

                                                  {
         return boost::asio::get_associated_executor(m_handler, m_work_guard_1.get_executor());
      }

References Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::m_handler, and Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::m_work_guard_1.

Member Data Documentation

m_handler

template<class Handler , class Executor1 , class Allocator >

Handler Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::m_handler

protected

Definition at line 97 of file asio_async_ops.h.

Referenced by Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::complete_now(), Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::get_allocator(), and Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::get_executor().

m_work_guard_1

template<class Handler , class Executor1 , class Allocator >

boost::asio::executor_work_guard<Executor1> Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::m_work_guard_1

protected

Definition at line 98 of file asio_async_ops.h.

Referenced by Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::complete_now(), and Botan::TLS::detail::AsyncBase< Handler, Executor1, Allocator >::get_executor().

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The documentation for this class was generated from the following file:

• src/lib/tls/asio/asio_async_ops.h