genode/repos/base/include/base/session_object.h
Norman Feske eba9c15746 Follow practices suggested by "Effective C++"
The patch adjust the code of the base, base-<kernel>, and os repository.
To adapt existing components to fix violations of the best practices
suggested by "Effective C++" as reported by the -Weffc++ compiler
argument. The changes follow the patterns outlined below:

* A class with virtual functions can no longer publicly inherit base
  classed without a vtable. The inherited object may either be moved
  to a member variable, or inherited privately. The latter would be
  used for classes that inherit 'List::Element' or 'Avl_node'. In order
  to enable the 'List' and 'Avl_tree' to access the meta data, the
  'List' must become a friend.

* Instead of adding a virtual destructor to abstract base classes,
  we inherit the new 'Interface' class, which contains a virtual
  destructor. This way, single-line abstract base classes can stay
  as compact as they are now. The 'Interface' utility resides in
  base/include/util/interface.h.

* With the new warnings enabled, all member variables must be explicitly
  initialized. Basic types may be initialized with '='. All other types
  are initialized with braces '{ ... }' or as class initializers. If
  basic types and non-basic types appear in a row, it is nice to only
  use the brace syntax (also for basic types) and align the braces.

* If a class contains pointers as members, it must now also provide a
  copy constructor and assignment operator. In the most cases, one
  would make them private, effectively disallowing the objects to be
  copied. Unfortunately, this warning cannot be fixed be inheriting
  our existing 'Noncopyable' class (the compiler fails to detect that
  the inheriting class cannot be copied and still gives the error).
  For now, we have to manually add declarations for both the copy
  constructor and assignment operator as private class members. Those
  declarations should be prepended with a comment like this:

        /*
         * Noncopyable
         */
        Thread(Thread const &);
        Thread &operator = (Thread const &);

  In the future, we should revisit these places and try to replace
  the pointers with references. In the presence of at least one
  reference member, the compiler would no longer implicitly generate
  a copy constructor. So we could remove the manual declaration.

Issue #465
2018-01-17 12:14:35 +01:00

131 lines
3.1 KiB
C++

/*
* \brief RPC object that owns client-provided RAM and capability quotas
* \author Norman Feske
* \date 2017-04-28
*/
/*
* Copyright (C) 2017 Genode Labs GmbH
*
* This file is part of the Genode OS framework, which is distributed
* under the terms of the GNU Affero General Public License version 3.
*/
#ifndef _INCLUDE__BASE__SESSION_OBJECT_H_
#define _INCLUDE__BASE__SESSION_OBJECT_H_
#include <util/arg_string.h>
#include <base/entrypoint.h>
#include <session/session.h>
namespace Genode { template <typename, typename> struct Session_object; }
template <typename RPC_INTERFACE, typename SERVER = RPC_INTERFACE>
class Genode::Session_object : private Ram_quota_guard,
private Cap_quota_guard,
public Rpc_object<RPC_INTERFACE, SERVER>
{
public:
typedef Session::Label Label;
typedef Session::Diag Diag;
typedef Session::Resources Resources;
using Ram_quota_guard::withdraw;
using Cap_quota_guard::withdraw;
using Ram_quota_guard::replenish;
using Cap_quota_guard::replenish;
using Ram_quota_guard::upgrade;
using Cap_quota_guard::upgrade;
private:
Rpc_entrypoint &_ep;
Diag _diag;
protected:
Label const _label;
Ram_quota_guard &_ram_quota_guard() { return *this; }
Cap_quota_guard &_cap_quota_guard() { return *this; }
public:
/**
* Constructor
*/
Session_object(Entrypoint &ep, Resources const &resources,
Label const &label, Diag diag)
:
Session_object(ep.rpc_ep(), resources, label, diag)
{ }
/**
* Constructor
*
* \deprecated This constructor exists for backward compatibility only
* and will eventually be removed.
*/
Session_object(Rpc_entrypoint &ep, Resources const &resources,
Label const &label, Diag diag)
:
Ram_quota_guard(resources.ram_quota),
Cap_quota_guard(resources.cap_quota),
_ep(ep), _diag(diag), _label(label)
{
Cap_quota_guard::withdraw(Cap_quota{1});
_ep.manage(this);
}
~Session_object()
{
_ep.dissolve(this);
Cap_quota_guard::replenish(Cap_quota{1});
}
/**
* Hook called whenever the session quota was upgraded by the client
*/
virtual void session_quota_upgraded() { }
/**
* Return client-specific session label
*/
Label label() const { return _label; }
/**
* Output label-prefixed diagnostic message conditionally
*
* The method produces output only if the session is in diagnostic
* mode (defined via the 'diag' session argument).
*/
template <typename... ARGS>
void diag(ARGS &&... args)
{
if (_diag.enabled)
log(RPC_INTERFACE::service_name(), " (", _label, ") ", args...);
}
/**
* Output label-prefixed error message
*/
template <typename... ARGS>
void error(ARGS &&... args)
{
Genode::error(RPC_INTERFACE::service_name(), " (", _label, ") ", args...);
}
/**
* Output label-prefixed error message
*/
template <typename... ARGS>
void warning(ARGS &&... args)
{
Genode::warning(RPC_INTERFACE::service_name(), " (", _label, ") ", args...);
}
};
#endif /* _INCLUDE__BASE__SESSION_OBJECT_H_ */