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template< typename MutableBufferSequence, typename ReadToken = default_completion_token_t<executor_type>> DEDUCED async_read_some( const MutableBufferSequence & buffers, ReadToken && token = default_completion_token_t< executor_type >());
This function is used to asynchronously read one or more bytes of data from the stream. It is an initiating function for an asynchronous operation, and always returns immediately.
The buffers into which the data will be read. Although the buffers object may be copied as necessary, ownership of the underlying buffers is retained by the caller, which must guarantee that they remain valid until the completion handler is called.
The completion
token that will be used to produce a completion handler, which
will be called when the read completes. Potential completion tokens
include use_future,
use_awaitable,
yield_context,
or a function object with the correct completion signature. The function
signature of the completion handler must be:
void handler( const asio::error_code& error, // Result of operation. std::size_t bytes_transferred // Number of bytes read. );
Regardless of whether the asynchronous operation completes immediately
or not, the completion handler will not be invoked from within this
function. On immediate completion, invocation of the handler will
be performed in a manner equivalent to using post.
void(asio::error_code, std::size_t)
The async_read_some operation may not read all of the requested number
of bytes. Consider using the async_read function if you need
to ensure that the requested amount of data is read before the asynchronous
operation completes.
This asynchronous operation supports cancellation for the following cancellation_type
values:
cancellation_type::terminal
cancellation_type::partial
if they are also supported by the Stream
type's async_read_some
and async_write_some operations.