genode/repos/base/include/util/reconstructible.h
Norman Feske 5ed5fddb7c base/os: remove deprecated APIs
This commit removes APIs that were previously marked as deprecated. This
change has the following implications:

- The use of the global 'env()' accessor is not possible anymore.
- Boolean accessor methods are no longer prefixed with 'is_'. E.g.,
  instead of 'is_valid()', use 'valid()'.
- The last traces of 'Ram_session' are gone now. The 'Env::ram()'
  accessor returns the 'Ram_allocator' interface, which is a subset of
  the 'Pd_session' interface.
- All connection constructors need the 'Env' as argument.
- The 'Reporter' constructor needs an 'Env' argument now because the
  reporter creates a report connection.
- The old overload 'Child_policy::resolve_session_request' that returned
  a 'Service' does not exist anymore.
- The base/printf.h header has been removed, use base/log.h instead.
- The old notion of 'Signal_dispatcher' is gone. Use 'Signal_handler'.
- Transitional headers like os/server.h, cap_session/,
  volatile_object.h, os/attached*_dataspace.h, signal_rpc_dispatcher.h
  have been removed.
- The distinction between 'Thread_state' and 'Thread_state_base' does
  not exist anymore.
- The header cpu_thread/capability.h along with the type definition of
  'Cpu_thread_capability' has been removed. Use the type
  'Thread_capability' define in cpu_session/cpu_session.h instead.
- Several XML utilities (i.e., at os/include/decorator) could be removed
  because their functionality is nowadays covered by util/xml_node.h.
- The 'os/ram_session_guard.h' has been removed.
  Use 'Constrained_ram_allocator' provided by base/ram_allocator.h instead.

Issue #1987
2019-02-26 14:44:15 +01:00

175 lines
3.9 KiB
C++

/*
* \brief Utility for in-place (re-)construction of objects
* \author Norman Feske
* \date 2014-01-10
*/
/*
* Copyright (C) 2014-2017 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__UTIL__RECONSTRUCTIBLE_H_
#define _INCLUDE__UTIL__RECONSTRUCTIBLE_H_
#include <util/construct_at.h>
#include <base/stdint.h>
#include <util/noncopyable.h>
namespace Genode {
template<typename> class Reconstructible;
template<typename> class Constructible;
}
/**
* Place holder for an object to be repeatedly constructed and destructed
*
* This class template acts as a smart pointer that refers to an object
* contained within the smart pointer itself. The contained object may be
* repeatedly constructed and destructed while staying in the same place. This
* is useful for replacing aggregated members during the lifetime of a compound
* object.
*
* \param MT type
*/
template <typename MT>
class Genode::Reconstructible : Noncopyable
{
private:
/**
* Static reservation of memory for the embedded object
*/
char _space[sizeof(MT)] __attribute__((aligned(sizeof(addr_t))));
/**
* True if the volatile object contains a constructed object
*/
bool _constructed = false;
template <typename... ARGS> void _do_construct(ARGS &&... args)
{
construct_at<MT>(_space, args...);
_constructed = true;
}
MT *_ptr() { return reinterpret_cast<MT *>(_space); }
MT const *_const_ptr() const { return reinterpret_cast<MT const *>(_space); }
void _check_constructed() const
{
if (!_constructed)
throw Deref_unconstructed_object();
}
protected:
/**
* Dummy type used as a hook for 'Constructible' to bypass the
* default constructor by invoking the 'Reconstructible(Lazy *)'
* constructor.
*/
struct Lazy { };
/**
* Constructor that omits the initial construction of the object
*/
Reconstructible(Lazy *) { }
public:
class Deref_unconstructed_object { };
/**
* Constructor
*
* The arguments are forwarded to the constructor of the embedded
* object.
*/
template <typename... ARGS>
Reconstructible(ARGS &&... args)
{
_do_construct(args...);
}
~Reconstructible() { destruct(); }
/**
* Construct new object in place
*
* If the 'Reconstructible' already hosts a constructed object, the old
* object will be destructed first.
*/
template <typename... ARGS>
void construct(ARGS &&... args)
{
destruct();
_do_construct(args...);
}
/**
* Destruct object
*/
void destruct()
{
if (!_constructed)
return;
/* invoke destructor */
_ptr()->~MT();
_constructed = false;
}
/**
* Return true of volatile object contains a constructed object
*/
bool constructed() const { return _constructed; }
/**
* Construct or destruct volatile object according to 'condition'
*/
template <typename... ARGS>
void conditional(bool condition, ARGS &&... args)
{
if (condition && !constructed())
construct(args...);
if (!condition && constructed())
destruct();
}
/**
* Access contained object
*/
MT *operator -> () { _check_constructed(); return _ptr(); }
MT const *operator -> () const { _check_constructed(); return _const_ptr(); }
MT &operator * () { _check_constructed(); return *_ptr(); }
MT const &operator * () const { _check_constructed(); return *_const_ptr(); }
void print(Output &out) const
{
if (_constructed)
_const_ptr()->print(out);
else
out.out_string("<unconstructed>");
}
};
/**
* Reconstructible object that holds no initially constructed object
*/
template <typename MT>
struct Genode::Constructible : Reconstructible<MT>
{
Constructible()
: Reconstructible<MT>((typename Reconstructible<MT>::Lazy *)nullptr) { }
};
#endif /* _INCLUDE__UTIL__RECONSTRUCTIBLE_H_ */