reactor-file-async-read.cc

reactor-file-async-read.cc

#include <boost/asio.hpp>
#include <boost/system/error_code.hpp>
#include <iostream>
#include <memory>
#include <string>

// Import function and types or define alias.
using boost::asio::buffer;
using boost::asio::null_buffers;
using ErrorCode = boost::system::error_code;
using IoContext = boost::asio::io_context;
using PosixStream = boost::asio::posix::stream_descriptor;
using PosixStreamPtr = std::shared_ptr<PosixStream>;

// The module scope stream pointer.
static PosixStreamPtr stream;

// Callback for read ready.
static void read_ready(ErrorCode const &e, size_t s)
{
  if (!e)
  {
    char buf[1024];
    // Actual read the data to buffer.
    size_t n = stream->read_some(buffer(buf, sizeof(buf)));
    // Process the readed data, like print out, etc.
    std::cout << "Buffer: [" << std::string(buf, n) << "]\n";
    // Wait for next read ready.
    stream->async_read_some(null_buffers(), read_ready);
  }
}

int main(int argc, char **argv)
{
  IoContext io;
  // Create a posix stream via stdin file descriptor.
  stream = std::move(std::make_shared<PosixStream>(io, STDIN_FILENO));
  // Enable nonblocking access.
  stream->non_blocking(true);
  // Wait for read ready.
  stream->async_read_some(null_buffers(), read_ready);
  // Running the io.
  io.run();
  // Exited from the io loop.
  return 0;
}