genode/repos/base/include/base/ram_allocator.h
Norman Feske e44f65f3b2 core: RAM service based on 'Session_object'
This patch reworks the implementation of core's RAM service to make use
of the 'Session_object' and to remove the distinction between the
"metadata" quota and the managed RAM quota. With the new implementation,
the session implicitly allocates its metadata from its own account. So
there is not need to handle 'Out_of_metadata' and 'Quota_exceeded' via
different exceptions. Instead, the new version solely uses the
'Out_of_ram' exception.

Furthermore, the 'Allocator::Out_of_memory' exception has become an alias
for 'Out_of_ram', which simplifies the error handling.

Issue #2398
2017-05-31 13:16:06 +02:00

120 lines
2.7 KiB
C++

/*
* \brief Interface for allocating RAM dataspaces
* \author Norman Feske
* \date 2017-05-02
*/
/*
* 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__RAM_ALLOCATOR_H_
#define _INCLUDE__BASE__RAM_ALLOCATOR_H_
#include <base/capability.h>
#include <base/quota_guard.h>
#include <base/cache.h>
#include <dataspace/dataspace.h>
namespace Genode {
struct Ram_dataspace : Dataspace { };
typedef Capability<Ram_dataspace> Ram_dataspace_capability;
struct Ram_allocator;
class Constrained_ram_allocator;
}
struct Genode::Ram_allocator
{
/**
* Allocate RAM dataspace
*
* \param size size of RAM dataspace
* \param cached selects cacheability attributes of the memory,
* uncached memory, i.e., for DMA buffers
*
* \throw Out_of_ram
* \throw Out_of_caps
*
* \return capability to new RAM dataspace
*/
virtual Ram_dataspace_capability alloc(size_t size,
Cache_attribute cached = CACHED) = 0;
/**
* Free RAM dataspace
*
* \param ds dataspace capability as returned by alloc
*/
virtual void free(Ram_dataspace_capability ds) = 0;
/**
* Return size of dataspace in bytes
*/
virtual size_t dataspace_size(Ram_dataspace_capability ds) const = 0;
};
/**
* Quota-bounds-checking wrapper of the 'Ram_allocator' interface
*/
class Genode::Constrained_ram_allocator : public Ram_allocator
{
private:
Ram_allocator &_ram_alloc;
Ram_quota_guard &_ram_guard;
Cap_quota_guard &_cap_guard;
public:
Constrained_ram_allocator(Ram_allocator &ram_alloc,
Ram_quota_guard &ram_guard,
Cap_quota_guard &cap_guard)
:
_ram_alloc(ram_alloc), _ram_guard(ram_guard), _cap_guard(cap_guard)
{ }
Ram_dataspace_capability alloc(size_t size, Cache_attribute cached) override
{
size_t page_aligned_size = align_addr(size, 12);
Ram_quota_guard::Reservation ram (_ram_guard, Ram_quota{page_aligned_size});
Cap_quota_guard::Reservation caps(_cap_guard, Cap_quota{1});
/*
* \throw Out_of_caps, Out_of_ram
*/
Ram_dataspace_capability ds = _ram_alloc.alloc(page_aligned_size, cached);
ram. acknowledge();
caps.acknowledge();
return ds;
}
void free(Ram_dataspace_capability ds) override
{
size_t const size = _ram_alloc.dataspace_size(ds);
_ram_alloc.free(ds);
_ram_guard.replenish(Ram_quota{size});
_cap_guard.replenish(Cap_quota{1});
}
size_t dataspace_size(Ram_dataspace_capability ds) const override
{
return _ram_alloc.dataspace_size(ds);
}
};
#endif /* _INCLUDE__BASE__RAM_ALLOCATOR_H_ */