TLA  Line data    Source code

       1                 : //
       2                 : // Copyright (c) 2026 Steve Gerbino
       3                 : //
       4                 : // Distributed under the Boost Software License, Version 1.0. (See accompanying
       5                 : // file LICENSE_1_0.txt or copy at http://www.boost.org/LICENSE_1_0.txt)
       6                 : //
       7                 : // Official repository: https://github.com/cppalliance/corosio
       8                 : //
       9                 : 
      10                 : #ifndef BOOST_COROSIO_IO_IO_READ_STREAM_HPP
      11                 : #define BOOST_COROSIO_IO_IO_READ_STREAM_HPP
      12                 : 
      13                 : #include <boost/corosio/detail/config.hpp>
      14                 : #include <boost/corosio/detail/op_base.hpp>
      15                 : #include <boost/corosio/io/io_object.hpp>
      16                 : #include <boost/corosio/detail/buffer_param.hpp>
      17                 : #include <boost/capy/io_result.hpp>
      18                 : #include <boost/capy/ex/executor_ref.hpp>
      19                 : #include <boost/capy/ex/io_env.hpp>
      20                 : 
      21                 : #include <coroutine>
      22                 : #include <cstddef>
      23                 : #include <stop_token>
      24                 : #include <system_error>
      25                 : 
      26                 : namespace boost::corosio {
      27                 : 
      28                 : /** Abstract base for streams that support async reads.
      29                 : 
      30                 :     Provides the `read_some` operation via a pure virtual
      31                 :     `do_read_some` dispatch point. Concrete classes override
      32                 :     `do_read_some` to route through their implementation.
      33                 : 
      34                 :     Uses virtual inheritance from @ref io_object so that
      35                 :     @ref io_stream can combine this with @ref io_write_stream
      36                 :     without duplicating the `io_object` base.
      37                 : 
      38                 :     @par Thread Safety
      39                 :     Distinct objects: Safe.
      40                 :     Shared objects: Unsafe.
      41                 : 
      42                 :     @see io_write_stream, io_stream, io_object
      43                 : */
      44                 : class BOOST_COROSIO_DECL io_read_stream : virtual public io_object
      45                 : {
      46                 : protected:
      47                 :     /// Awaitable for async read operations.
      48                 :     template<class MutableBufferSequence>
      49                 :     struct read_some_awaitable
      50                 :         : detail::bytes_op_base<read_some_awaitable<MutableBufferSequence>>
      51                 :     {
      52                 :         io_read_stream& ios_;
      53                 :         MutableBufferSequence buffers_;
      54                 : 
      55 HIT      203207 :         read_some_awaitable(
      56                 :             io_read_stream& ios, MutableBufferSequence buffers) noexcept
      57          203207 :             : ios_(ios), buffers_(std::move(buffers)) {}
      58                 : 
      59          203207 :         std::coroutine_handle<> dispatch(
      60                 :             std::coroutine_handle<> h, capy::executor_ref ex) const
      61                 :         {
      62          406414 :             return ios_.do_read_some(
      63          609621 :                 h, ex, buffers_, this->token_, &this->ec_, &this->bytes_);
      64                 :         }
      65                 :     };
      66                 : 
      67                 :     /** Dispatch a read through the concrete implementation.
      68                 : 
      69                 :         @param h Coroutine handle to resume on completion.
      70                 :         @param ex Executor for dispatching the completion.
      71                 :         @param buffers Target buffer sequence.
      72                 :         @param token Stop token for cancellation.
      73                 :         @param ec Output error code.
      74                 :         @param bytes Output bytes transferred.
      75                 : 
      76                 :         @return Coroutine handle to resume immediately.
      77                 :     */
      78                 :     virtual std::coroutine_handle<> do_read_some(
      79                 :         std::coroutine_handle<>,
      80                 :         capy::executor_ref,
      81                 :         buffer_param,
      82                 :         std::stop_token,
      83                 :         std::error_code*,
      84                 :         std::size_t*) = 0;
      85                 : 
      86           17384 :     io_read_stream() noexcept = default;
      87                 : 
      88                 :     /// Construct from a handle.
      89                 :     explicit io_read_stream(handle h) noexcept : io_object(std::move(h)) {}
      90                 : 
      91                 :     io_read_stream(io_read_stream&&) noexcept            = default;
      92                 :     io_read_stream& operator=(io_read_stream&&) noexcept = delete;
      93                 :     io_read_stream(io_read_stream const&)                = delete;
      94                 :     io_read_stream& operator=(io_read_stream const&)     = delete;
      95                 : 
      96                 : public:
      97                 :     /** Asynchronously read data from the stream.
      98                 : 
      99                 :         Suspends the calling coroutine and initiates a kernel-level
     100                 :         read. The coroutine resumes when at least one byte is read,
     101                 :         an error occurs, or the operation is cancelled.
     102                 : 
     103                 :         This stream must outlive the returned awaitable. The memory
     104                 :         referenced by @p buffers must remain valid until the operation
     105                 :         completes.
     106                 : 
     107                 :         @param buffers The buffer sequence to read data into.
     108                 : 
     109                 :         @return An awaitable yielding `(error_code, std::size_t)`.
     110                 : 
     111                 :         @see io_stream::write_some
     112                 :     */
     113                 :     template<capy::MutableBufferSequence MB>
     114          203207 :     auto read_some(MB const& buffers)
     115                 :     {
     116          203207 :         return read_some_awaitable<MB>(*this, buffers);
     117                 :     }
     118                 : };
     119                 : 
     120                 : } // namespace boost::corosio
     121                 : 
     122                 : #endif