TLA  Line data    Source code

       1                 : //
       2                 : // Copyright (c) 2025 Vinnie Falco (vinnie.falco@gmail.com)
       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/capy
       8                 : //
       9                 : 
      10                 : #ifndef BOOST_CAPY_WRITE_HPP
      11                 : #define BOOST_CAPY_WRITE_HPP
      12                 : 
      13                 : #include <boost/capy/detail/config.hpp>
      14                 : #include <boost/capy/io_task.hpp>
      15                 : #include <boost/capy/buffers.hpp>
      16                 : #include <boost/capy/buffers/buffer_slice.hpp>
      17                 : #include <boost/capy/concept/write_stream.hpp>
      18                 : #include <system_error>
      19                 : 
      20                 : #include <cstddef>
      21                 : 
      22                 : namespace boost {
      23                 : namespace capy {
      24                 : 
      25                 : /** Write an entire buffer sequence to a stream.
      26                 : 
      27                 :     @par Await-effects
      28                 : 
      29                 :     Writes the contents of `buffers` to `stream` via awaiting on
      30                 :     `stream.write_some` with consecutive portions of data from `buffers`
      31                 :     until:
      32                 : 
      33                 :     @li either the full content of @c buffers is processed,
      34                 :     @li or a contingency occurs.
      35                 : 
      36                 :     If `buffer_size(buffers) == 0` then no awaiting on `stream.write_some`
      37                 :     is performed. This is not a contingency.
      38                 : 
      39                 : 
      40                 :     @par Await-returns
      41                 : 
      42                 :     An object of type `io_result<std::size_t>` destructuring as `[ec, n]`.
      43                 : 
      44                 :     Upon a contingency, `n` represents the number of bytes written
      45                 :     so far.
      46                 : 
      47                 :     Otherwise `n` represents the number of bytes written.
      48                 : 
      49                 :     Contingencies:
      50                 : 
      51                 :     @li The first contingency reported from
      52                 :     awaiting on @c stream.write_some .
      53                 : 
      54                 :     Notable conditions:
      55                 : 
      56                 :     @li @c cond::canceled — Operation was cancelled,
      57                 :     @li @c std::errc::broken_pipe — Peer closed connection.
      58                 : 
      59                 : 
      60                 :     @par Await-postcondition
      61                 : 
      62                 :     `ec || n == buffer_size(buffers)`.
      63                 : 
      64                 : 
      65                 :     @par Cancellation
      66                 :     Supports cancellation via `stop_token` propagated through the
      67                 :     `IoAwaitable` protocol. When cancelled, returns with `cond::canceled`.
      68                 : 
      69                 :     @param stream The stream to write to. If the lifetime of `stream` ends
      70                 :     before the coroutine finishes, the behavior is undefined.
      71                 : 
      72                 :     @param buffers The buffer sequence to write. If the lifetime of the buffer
      73                 :     sequence represented by `buffers` ends
      74                 :     before the coroutine finishes, the behavior is undefined.
      75                 : 
      76                 : 
      77                 :     @par Example
      78                 : 
      79                 :     @code
      80                 :     capy::task<> send_response(capy::WriteStream auto& stream, std::string_view body)
      81                 :     {
      82                 :         auto [ec, n] = co_await capy::write(stream, capy::make_buffer(body));
      83                 :         if (ec)
      84                 :             throw std::system_error(ec);
      85                 : 
      86                 :         // All bytes written successfully
      87                 :     }
      88                 :     @endcode
      89                 : 
      90                 :     @return
      91                 : 
      92                 :     @see WriteStream, ConstBufferSequence, IoAwaitable, io_result, cond.
      93                 : */
      94                 : template <WriteStream S, ConstBufferSequence CB>
      95 HIT          50 : auto write(S& stream, CB buffers) -> io_task<std::size_t>
      96                 : {
      97                 :     auto consuming = buffer_slice(buffers);
      98                 :     std::size_t const total_size = buffer_size(buffers);
      99                 :     std::size_t total_written = 0;
     100                 : 
     101                 :     while(total_written < total_size)
     102                 :     {
     103                 :         auto [ec, n] = co_await stream.write_some(consuming.data());
     104                 :         consuming.remove_prefix(n);
     105                 :         total_written += n;
     106                 :         if(ec)
     107                 :             co_return {ec, total_written};
     108                 :     }
     109                 : 
     110                 :     co_return {{}, total_written};
     111             100 : }
     112                 : 
     113                 : } // namespace capy
     114                 : } // namespace boost
     115                 : 
     116                 : #endif