genode/repos/os/include/input/root.h
Norman Feske 0ed68a56b7 Use signals for delivering input events
This patch changes both the Input::Session interface and the skeleton
for the server-side implementation of this interface
('input/component.h').

The Input::Session interface offers a new 'sigh' function, which can be
called be the client to register a signal handler. The signal handler
gets notified on the arrival of new input. This alleviates the need to
poll for input events at the client side.

The server-side skeleton for implementing input services underwent a
redesign to make it more modular and robust. I.e., there are no
global functions needed at the server side and the event-queue
enable/disable mechanism is implemented at a central place (in the root
component) rather than inside each driver.

Fixes #46
2014-06-06 14:54:07 +02:00

71 lines
1.7 KiB
C++

/*
* \brief Input root component
* \author Norman Feske
* \date 2014-05-31
*/
/*
* Copyright (C) 2014 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU General Public License version 2.
*/
#ifndef _INPUT__ROOT_H_
#define _INPUT__ROOT_H_
/* Genode includes */
#include <os/static_root.h>
#include <input/component.h>
namespace Input { class Root_component; }
/*
* This input root component tracks if the session has been opened. If a client
* is connected, the 'Event_queue::enabled' gets enabled. This is useful to
* omit the enqueuing of input events into the event queue before any client is
* interested in receiving input events. If we would not drop such early input
* events, the queue might overflow when input events are generated at boot
* times.
*/
class Input::Root_component : public Genode::Static_root<Input::Session>
{
private:
Genode::Rpc_entrypoint &_ep;
Input::Session_component &_session;
public:
Root_component(Genode::Rpc_entrypoint &ep, Input::Session_component &session)
:
Static_root<Input::Session>(ep.manage(&session)),
_ep(ep), _session(session)
{ }
~Root_component()
{
_ep.dissolve(&_session);
}
Genode::Capability<Genode::Session>
session(Genode::Root::Session_args const &args,
Genode::Affinity const &affinity) override
{
if (_session.event_queue().enabled())
throw Root::Unavailable();
_session.event_queue().enabled(true);
return Static_root<Input::Session>::session(args, affinity);
}
void close(Genode::Capability<Session>)
{
_session.event_queue().enabled(false);
}
};
#endif /* _INPUT__ROOT_H_ */