isabella232 / eio

Erlang Flavored I/O for C++

Erlang Flavored I/O (for C++)

This library is a C++ wrapper for libevent, that lets you write programs with asynchronous I/O using some common Erlang idioms.

Most importantly, it provides a straight-forward way to use the {active, once} and {packet, 4} packet options that Erlang provides, so you don't have to write that logic. It also provies an efficient abstraction for packet data (based on evbuffers) that implement the zero-copy streams for google protocol buffers.

We only build it as a static library, since it's so small that it is better linked statically than depended upon in a system installation.

class ProtocolHandler : eio::Handler {
   void data( eio::StreamTransport& sock, std::string& packet ) {
       // handle incoming packet

       // send some data
       sock.send( " some data " );

       // make the sock active again after processing
       // i.e., read next 4-byte delimited packet
       sock.set_active( eio::ACTIVE_ONCE );
   }
   
   void connected( eio::StreamTransport &sock ) {
      cout << "did connect\n";
   }
};

void main() {
   eio::IO io;
   eio::TCPTransport sock(io, new ProtocolHandler());

   // use 4-byte network order header for packets
   sock.set_packet( 4 );
   
   // only read actively once
   sock.set_active( eio::ACTIVE_ONCE );
   
   // deliver packets as std::string.   
   sock.set_deliver( eio::STRING ); 

   // connect
   eio::SockAddr addr("localhost:8080");
   sock.connect(addr);

   io.dispatch()
}