Defined in header
template< class AsyncReadStream, class DynamicBuffer, bool isRequest, class Derived, class ReadHandler> void-or-deduced async_read_header( AsyncReadStream& stream, DynamicBuffer& buffer, basic_parser< isRequest, Derived >& parser, ReadHandler&& handler);
This function is used to asynchronously read a header from a stream into
a subclass of
http::basic_parser. The function call
always returns immediately. The asynchronous operation will continue until
one of the following conditions is true:
This operation is implemented in terms of one or more calls to the stream's
and is known as a composed operation. The program must
ensure that the stream performs no other reads until this operation completes.
The implementation may read additional octets that lie past the end of the
message being read. This additional data is stored in the dynamic buffer,
which must be retained for subsequent reads.
If the stream returns the error
the end of file during a read, the error returned from this function will
The stream from which the data is to be read. The type must support the AsyncReadStream concept.
A DynamicBuffer holding additional bytes read by the implementation from the stream. This is both an input and an output parameter; on entry, any data in the dynamic buffer's input sequence will be given to the parser first.
The parser to use. The object must remain valid at least until the handler is called; ownership is not transferred.
The handler to be called when the request completes. Copies will be made of the handler as required. The equivalent function signature of the handler must be:
void handler( error_code const& error, // result of operation, std::size_t bytes_transferred // the number of bytes transferred to the parser );
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
The implementation will call
http::basic_parser::eager with the value
false on the parser passed in.