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/** @file
* IPRT - Hardened AVL tree slab allocator.
*/
/*
* Copyright (C) 2022-2025 Oracle and/or its affiliates.
*
* This file is part of VirtualBox base platform packages, as
* available from https://www.virtualbox.org.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation, in version 3 of the
* License.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, see <https://www.gnu.org/licenses>.
*
* The contents of this file may alternatively be used under the terms
* of the Common Development and Distribution License Version 1.0
* (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
* in the VirtualBox distribution, in which case the provisions of the
* CDDL are applicable instead of those of the GPL.
*
* You may elect to license modified versions of this file under the
* terms and conditions of either the GPL or the CDDL or both.
*
* SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
*/
#ifndef IPRT_INCLUDED_cpp_hardavlslaballocator_h
#define IPRT_INCLUDED_cpp_hardavlslaballocator_h
#ifndef RT_WITHOUT_PRAGMA_ONCE
# pragma once
#endif
#include <iprt/asm-mem.h>
#include <iprt/asm.h>
#include <iprt/assert.h>
#include <iprt/err.h>
#include <iprt/string.h>
/** @addtogroup grp_rt_cpp_hardavl
* @{
*/
/**
* Slab allocator for the hardened AVL tree.
*/
template<typename NodeType>
struct RTCHardAvlTreeSlabAllocator
{
/** Pointer to an array of nodes. */
NodeType *m_paNodes;
/** Node allocation bitmap: 1 = free, 0 = allocated. */
uint64_t *m_pbmAlloc;
/** Max number of nodes in m_paNodes and valid bits in m_pbmAlloc. */
uint32_t m_cNodes;
/** Pointer error counter. */
uint32_t m_cErrors;
/** Allocation hint. */
uint32_t m_idxAllocHint;
uint32_t m_uPadding;
enum
{
kNilIndex = 0,
kErr_IndexOutOfBound = -1,
kErr_PointerOutOfBound = -2,
kErr_MisalignedPointer = -3,
kErr_NodeIsFree = -4,
kErr_Last = kErr_NodeIsFree
};
RTCHardAvlTreeSlabAllocator() RT_NOEXCEPT
: m_paNodes(NULL)
, m_pbmAlloc(NULL)
, m_cNodes(0)
, m_cErrors(0)
, m_idxAllocHint(0)
, m_uPadding(0)
{}
inline void initSlabAllocator(uint32_t a_cNodes, NodeType *a_paNodes, uint64_t *a_pbmAlloc) RT_NOEXCEPT
{
m_cNodes = a_cNodes;
m_paNodes = a_paNodes;
m_pbmAlloc = a_pbmAlloc;
/* Initialize the allocation bit. */
RT_BZERO(a_pbmAlloc, (a_cNodes + 63) / 64 * 8);
ASMBitSetRange(a_pbmAlloc, 0, a_cNodes);
}
inline NodeType *ptrFromInt(uint32_t a_idxNode1) RT_NOEXCEPT
{
if (a_idxNode1 == (uint32_t)kNilIndex)
return NULL;
AssertMsgReturnStmt(a_idxNode1 <= m_cNodes, ("a_idxNode1=%#x m_cNodes=%#x\n", a_idxNode1, m_cNodes),
m_cErrors++, (NodeType *)(intptr_t)kErr_IndexOutOfBound);
AssertMsgReturnStmt(ASMBitTest(m_pbmAlloc, a_idxNode1 - 1) == false, ("a_idxNode1=%#x\n", a_idxNode1),
m_cErrors++, (NodeType *)(intptr_t)kErr_NodeIsFree);
return &m_paNodes[a_idxNode1 - 1];
}
static inline bool isPtrRetOkay(NodeType *a_pNode) RT_NOEXCEPT
{
return (uintptr_t)a_pNode < (uintptr_t)kErr_Last;
}
static inline int ptrErrToStatus(NodeType *a_pNode) RT_NOEXCEPT
{
return (int)(intptr_t)a_pNode - (VERR_HARDAVL_INDEX_OUT_OF_BOUNDS - kErr_IndexOutOfBound);
}
inline uint32_t ptrToInt(NodeType *a_pNode) RT_NOEXCEPT
{
if (a_pNode == NULL)
return 0;
uintptr_t const offNode = (uintptr_t)a_pNode - (uintptr_t)m_paNodes;
uintptr_t const idxNode0 = offNode / sizeof(m_paNodes[0]);
AssertMsgReturnStmt((offNode % sizeof(m_paNodes[0])) == 0,
("pNode=%p / offNode=%#zx vs m_paNodes=%p L %#x, each %#x bytes\n",
a_pNode, offNode, m_paNodes, m_cNodes, sizeof(m_paNodes[0])),
m_cErrors++, (uint32_t)kErr_MisalignedPointer);
AssertMsgReturnStmt(idxNode0 < m_cNodes,
("pNode=%p vs m_paNodes=%p L %#x\n", a_pNode, m_paNodes, m_cNodes),
m_cErrors++, (uint32_t)kErr_PointerOutOfBound);
AssertMsgReturnStmt(ASMBitTest(m_pbmAlloc, idxNode0) == false, ("a_pNode=%p idxNode0=%#x\n", a_pNode, idxNode0),
m_cErrors++, (uint32_t)kErr_NodeIsFree);
return idxNode0 + 1;
}
static inline bool isIdxRetOkay(uint32_t a_idxNode) RT_NOEXCEPT
{
return a_idxNode < (uint32_t)kErr_Last;
}
static inline int idxErrToStatus(uint32_t a_idxNode) RT_NOEXCEPT
{
return (int)a_idxNode - (VERR_HARDAVL_INDEX_OUT_OF_BOUNDS - kErr_IndexOutOfBound);
}
inline bool isIntValid(uint32_t a_idxNode1) RT_NOEXCEPT
{
return a_idxNode1 <= m_cNodes;
}
inline int freeNode(NodeType *a_pNode) RT_NOEXCEPT
{
uint32_t idxNode1 = ptrToInt(a_pNode);
if (idxNode1 == (uint32_t)kNilIndex)
return 0;
if (idxNode1 < (uint32_t)kErr_Last)
{
AssertMsgReturnStmt(ASMAtomicBitTestAndSet(m_pbmAlloc, idxNode1 - 1) == false,
("a_pNode=%p idxNode1=%#x\n", a_pNode, idxNode1),
m_cErrors++, kErr_NodeIsFree);
return 0;
}
return (int)idxNode1;
}
inline NodeType *allocateNode(void) RT_NOEXCEPT
{
/*
* Use the hint first, then scan the whole bitmap.
* Note! We don't expect concurrent allocation calls, so no need to repeat.
*/
uint32_t const idxHint = m_idxAllocHint;
uint32_t idxNode0;
if ( idxHint >= m_cNodes
|| (int32_t)(idxNode0 = (uint32_t)ASMBitNextSet(m_pbmAlloc, m_cNodes, idxHint)) < 0)
idxNode0 = (uint32_t)ASMBitFirstSet(m_pbmAlloc, m_cNodes);
if ((int32_t)idxNode0 >= 0)
{
if (ASMAtomicBitTestAndClear(m_pbmAlloc, idxNode0) == true)
{
m_idxAllocHint = idxNode0;
return &m_paNodes[idxNode0];
}
AssertMsgFailed(("idxNode0=%#x\n", idxNode0));
m_cErrors++;
}
return NULL;
}
};
/**
* Placeholder structure for ring-3 slab allocator.
*/
typedef struct RTCHardAvlTreeSlabAllocatorR3_T
{
/** Pointer to an array of nodes. */
RTR3PTR m_paNodes;
/** Node allocation bitmap: 1 = free, 0 = allocated. */
RTR3PTR m_pbmAlloc;
/** Max number of nodes in m_paNodes and valid bits in m_pbmAlloc. */
uint32_t m_cNodes;
/** Pointer error counter. */
uint32_t m_cErrors;
/** Allocation hint. */
uint32_t m_idxAllocHint;
uint32_t m_uPadding;
} RTCHardAvlTreeSlabAllocatorR3_T;
AssertCompileSize(RTCHardAvlTreeSlabAllocatorR3_T,
sizeof(RTCHardAvlTreeSlabAllocator<RTUINT128U>) - (sizeof(void *) - sizeof(RTR3PTR)) * 2);
/** @} */
#endif /* !IPRT_INCLUDED_cpp_hardavlslaballocator_h */
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