ehmry/genode
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Add support for specialized session interfaces

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This patch introduces principal support for extending session interfaces
with specialized functionality in a clean way. For example, an 'Uart'
interface may implement the 'Terminal' interface but also offers
additional functions for setting the baud rate. A service that
implements the 'Uart' service will then automatically announce both the
'Uart' and 'Terminal' services.
This commit is contained in:
Norman Feske 2012-10-29 12:18:24 +01:00
parent cb8910b40c
commit 0c76bc9cfd
3 changed files with 198 additions and 114 deletions
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22
base/include/base/rpc.h
View File

@ -80,7 +80,8 @@
#define GENODE_RPC_INTERFACE_INHERIT(base, ...) \
typedef ::Genode::Meta::Append<base::Rpc_functions, \
GENODE_TYPE_LIST(__VA_ARGS__) >::Type \
Rpc_functions;
Rpc_functions; \
typedef base Rpc_inherited_interface;
namespace Genode {
@ -282,6 +283,25 @@ namespace Genode {
struct Rpc_interface_msg_size {
typedef typename RPC_IF::Rpc_functions Rpc_functions;
enum { Value = Rpc_function_list_msg_size<Rpc_functions, MSG_TYPE>::Value }; };
/**
* Determine if a RPC interface is inherited
*/
template <typename INTERFACE>
struct Rpc_interface_is_inherited
{
typedef char yes[1];
typedef char no[2];
template <typename IF>
static yes &test(typename IF::Rpc_inherited_interface *);
template <typename>
static no &test(...);
enum { VALUE = sizeof(test<INTERFACE>(0)) == sizeof(yes) };
};
}
#endif /* _INCLUDE__BASE__RPC_H_ */

63
base/include/parent/parent.h
View File

@ -23,8 +23,30 @@
namespace Genode {
struct Parent
class Parent
{
private:
/**
* Recursively announce inherited service interfaces
*
* At compile time, the 'ROOT' type is inspected for the presence
* of the 'Rpc_inherited_interface' type in the corresponding
* session interface. If present, the session type gets announced.
* This works recursively.
*/
template <typename ROOT>
void _announce_base(Capability<ROOT> const &, Meta::Bool_to_type<false> *) { }
/*
* This overload gets selected if the ROOT interface corresponds to
* an inherited session type.
*/
template <typename ROOT>
inline void _announce_base(Capability<ROOT> const &, Meta::Bool_to_type<true> *);
public:
/*********************
** Exception types **
*********************/
@ -52,6 +74,7 @@ namespace Genode {
virtual void announce(Service_name const &service_name,
Root_capability service_root) = 0;
/**
* Announce service to the parent
*
@ -66,7 +89,17 @@ namespace Genode {
template <typename ROOT_INTERFACE>
void announce(Capability<ROOT_INTERFACE> const &service_root)
{
announce(ROOT_INTERFACE::Session_type::service_name(), service_root);
typedef typename ROOT_INTERFACE::Session_type Session;
announce(Session::service_name(), service_root);
/*
* Announce inherited session types
*
* Select the overload based on the presence of the type
* 'Rpc_inherited_interface' within the session type.
*/
_announce_base(service_root,
(Meta::Bool_to_type<Rpc_interface_is_inherited<Session>::VALUE> *)0);
}
/**
@ -155,4 +188,30 @@ namespace Genode {
};
}
template <typename ROOT_INTERFACE>
void
Genode::Parent::_announce_base(Genode::Capability<ROOT_INTERFACE> const &service_root,
Genode::Meta::Bool_to_type<true> *)
{
/* shortcut for inherited session type */
typedef typename ROOT_INTERFACE::Session_type::Rpc_inherited_interface
Session_type_inherited;
/* shortcut for root interface type matching the inherited session type */
typedef Typed_root<Session_type_inherited> Root_inherited;
/* convert root capability to match the inherited session type */
Capability<Root> root = service_root;
Capability<Root_inherited> root_inherited = static_cap_cast<Root_inherited>(root);
/* announce inherited service type */
announce(Session_type_inherited::service_name(), root_inherited);
/* recursively announce further inherited session types */
_announce_base(root_inherited,
(Meta::Bool_to_type<Rpc_interface_is_inherited<Session_type_inherited>::VALUE> *)0);
}
#endif /* _INCLUDE__PARENT__PARENT_H_ */

5
base/include/util/meta.h
View File

@ -637,6 +637,11 @@ namespace Genode {
Overload_selector() { }
};
/**
* Convert boolean value to type
*/
template <bool VALUE> struct Bool_to_type { enum { V = VALUE }; };
} /* namespace Meta */
}