// A RawConn is a raw network connection.
type RawConn interface {
	// Control invokes f on the underlying connection's file
	// descriptor or handle.
	// The file descriptor fd is guaranteed to remain valid while
	// f executes but not after f returns.
	Control(f func(fd uintptr)) error

	// Read invokes f on the underlying connection's file
	// descriptor or handle; f is expected to try to read from the
	// file descriptor.
	// If f returns true, Read returns. Otherwise Read blocks
	// waiting for the connection to be ready for reading and
	// tries again repeatedly.
	// The file descriptor is guaranteed to remain valid while f
	// executes but not after f returns.
	Read(f func(fd uintptr) (done bool)) error

	// Write is like Read but for writing.
	Write(f func(fd uintptr) (done bool)) error

	// This is a new method.
	// OnRead registers a callback to handle the reading event.
	// If this callback is registered, users don't need to use
	// one goroutine for each conn and read it in a for-loop.
	OnRead(func(fd uintptr))

	// This is a new method.
	// OnWrite registers a callback to handle the writing event.
	OnWrite(func(fd uintptr))

	// This is a new method.
	// EnablePollWrite enables write event on the poller.
	// Users should cache the data unsent and call EnablePollWrite(true)
	// to enable the write event when Write fails, then the OnWrite 
	// callback will be called when the fd is writable;
	// Users should  call EnablePollWrite(false) to cancel the write
	// event after cached data has been sent.
	EnablePollWrite(enable bool)
}