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Asynchronously wait for the socket to become ready to read, ready to write, or to have pending error conditions.

    typename WaitHandler>
DEDUCED async_wait(
    wait_type w,
    WaitHandler && handler);

This function is used to perform an asynchronous wait for a socket to enter a ready to read, write or error condition state.



Specifies the desired socket state.


The handler to be called when the wait operation completes. Copies will be made of the handler as required. The function signature of the handler must be:

void handler(
  const boost::system::error_code& error // Result of operation

Regardless of whether the asynchronous operation completes immediately or not, the handler will not be invoked from within this function. Invocation of the handler will be performed in a manner equivalent to using boost::asio::io_context::post().

void wait_handler(const boost::system::error_code& error)
  if (!error)
    // Wait succeeded.


boost::asio::ip::tcp::socket socket(io_context);
socket.async_wait(boost::asio::ip::tcp::socket::wait_read, wait_handler);