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/* $Id: handletable.h $ */
/** @file
* IPRT - Handle Tables, internal header.
*/
/*
* Copyright (C) 2008-2023 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_SRC_common_misc_handletable_h
#define IPRT_INCLUDED_SRC_common_misc_handletable_h
#ifndef RT_WITHOUT_PRAGMA_ONCE
# pragma once
#endif
/*******************************************************************************
* Defined Constants And Macros *
*******************************************************************************/
/** The number of entries in the 2nd level lookup table. */
#define RTHT_LEVEL2_ENTRIES 2048
/** The number of (max) 1st level entries requiring dynamic allocation of the
* 1st level table. If the max number is below this threshold, the 1st level
* table will be allocated as part of the handle table structure. */
#define RTHT_LEVEL1_DYN_ALLOC_THRESHOLD 256
/** Checks whether a object pointer is really a free entry or not. */
#define RTHT_IS_FREE(pvObj) ( ((uintptr_t)(pvObj) & 3) == 3 )
/** Sets RTHTENTRYFREE::iNext. */
#define RTHT_SET_FREE_IDX(pFree, idx) \
do { \
(pFree)->iNext = ((uintptr_t)((uint32_t)(idx)) << 2) | 3U; \
} while (0)
/** Gets the index part of RTHTENTRYFREE::iNext. */
#define RTHT_GET_FREE_IDX(pFree) ( (uint32_t)((pFree)->iNext >> 2) )
/** @def NIL_RTHT_INDEX
* The NIL handle index for use in the free list. (The difference between
* 32-bit and 64-bit hosts here comes down to the shifting performed for
* RTHTENTRYFREE::iNext.) */
#if ARCH_BITS == 32
# define NIL_RTHT_INDEX ( UINT32_C(0x3fffffff) )
#elif ARCH_BITS >= 34
# define NIL_RTHT_INDEX ( UINT32_C(0xffffffff) )
#else
# error "Missing or unsupported ARCH_BITS."
#endif
/*******************************************************************************
* Structures and Typedefs *
*******************************************************************************/
/**
* Handle table entry, simple variant.
*/
typedef struct RTHTENTRY
{
/** The object. */
void *pvObj;
} RTHTENTRY;
/** Pointer to a handle table entry, simple variant. */
typedef RTHTENTRY *PRTHTENTRY;
/**
* Handle table entry, context variant.
*/
typedef struct RTHTENTRYCTX
{
/** The object. */
void *pvObj;
/** The context. */
void *pvCtx;
} RTHTENTRYCTX;
/** Pointer to a handle table entry, context variant. */
typedef RTHTENTRYCTX *PRTHTENTRYCTX;
/**
* Free handle table entry, shared by all variants.
*/
typedef struct RTHTENTRYFREE
{
/** The index of the next handle, special format.
* In order to distinguish free and used handle table entries we exploit
* the heap alignment and use the lower two bits to do this. Used entries
* will have these bits set to 0, while free entries will have tem set
* to 3. Use the RTHT_GET_FREE_IDX and RTHT_SET_FREE_IDX macros to access
* this field. */
uintptr_t iNext;
} RTHTENTRYFREE;
/** Pointer to a free handle table entry. */
typedef RTHTENTRYFREE *PRTHTENTRYFREE;
AssertCompile(sizeof(RTHTENTRYFREE) <= sizeof(RTHTENTRY));
AssertCompile(sizeof(RTHTENTRYFREE) <= sizeof(RTHTENTRYCTX));
AssertCompileMemberOffset(RTHTENTRYFREE, iNext, 0);
AssertCompileMemberOffset(RTHTENTRY, pvObj, 0);
AssertCompileMemberOffset(RTHTENTRYCTX, pvObj, 0);
/**
* Internal handle table structure.
*/
typedef struct RTHANDLETABLEINT
{
/** Magic value (RTHANDLETABLE_MAGIC). */
uint32_t u32Magic;
/** The handle table flags specified to RTHandleTableCreateEx. */
uint32_t fFlags;
/** The base handle value (i.e. the first handle). */
uint32_t uBase;
/** The current number of handle table entries. */
uint32_t cCur;
/** The spinlock handle (NIL if RTHANDLETABLE_FLAGS_LOCKED wasn't used). */
RTSPINLOCK hSpinlock;
/** The level one lookup table. */
void **papvLevel1;
/** The retainer callback. Can be NULL. */
PFNRTHANDLETABLERETAIN pfnRetain;
/** The user argument to the retainer. */
void *pvRetainUser;
/** The max number of handles. */
uint32_t cMax;
/** The number of handles currently allocated. (for optimizing destruction) */
uint32_t cCurAllocated;
/** The current number of 1st level entries. */
uint32_t cLevel1;
/** Head of the list of free handle entires (index). */
uint32_t iFreeHead;
/** Tail of the list of free handle entires (index). */
uint32_t iFreeTail;
} RTHANDLETABLEINT;
/** Pointer to an handle table structure. */
typedef RTHANDLETABLEINT *PRTHANDLETABLEINT;
/**
* Looks up a simple index.
*
* @returns Pointer to the handle table entry on success, NULL on failure.
* @param pThis The handle table structure.
* @param i The index to look up.
*/
DECLINLINE(PRTHTENTRY) rtHandleTableLookupSimpleIdx(PRTHANDLETABLEINT pThis, uint32_t i)
{
if (i < pThis->cCur)
{
PRTHTENTRY paTable = (PRTHTENTRY)pThis->papvLevel1[i / RTHT_LEVEL2_ENTRIES];
if (paTable)
return &paTable[i % RTHT_LEVEL2_ENTRIES];
}
return NULL;
}
/**
* Looks up a simple handle.
*
* @returns Pointer to the handle table entry on success, NULL on failure.
* @param pThis The handle table structure.
* @param h The handle to look up.
*/
DECLINLINE(PRTHTENTRY) rtHandleTableLookupSimple(PRTHANDLETABLEINT pThis, uint32_t h)
{
return rtHandleTableLookupSimpleIdx(pThis, h - pThis->uBase);
}
/**
* Looks up a context index.
*
* @returns Pointer to the handle table entry on success, NULL on failure.
* @param pThis The handle table structure.
* @param i The index to look up.
*/
DECLINLINE(PRTHTENTRYCTX) rtHandleTableLookupWithCtxIdx(PRTHANDLETABLEINT pThis, uint32_t i)
{
if (i < pThis->cCur)
{
PRTHTENTRYCTX paTable = (PRTHTENTRYCTX)pThis->papvLevel1[i / RTHT_LEVEL2_ENTRIES];
if (paTable)
return &paTable[i % RTHT_LEVEL2_ENTRIES];
}
return NULL;
}
/**
* Looks up a context handle.
*
* @returns Pointer to the handle table entry on success, NULL on failure.
* @param pThis The handle table structure.
* @param h The handle to look up.
*/
DECLINLINE(PRTHTENTRYCTX) rtHandleTableLookupWithCtx(PRTHANDLETABLEINT pThis, uint32_t h)
{
return rtHandleTableLookupWithCtxIdx(pThis, h - pThis->uBase);
}
/**
* Locks the handle table.
*
* @param pThis The handle table structure.
*/
DECLINLINE(void) rtHandleTableLock(PRTHANDLETABLEINT pThis)
{
if (pThis->hSpinlock != NIL_RTSPINLOCK)
RTSpinlockAcquire(pThis->hSpinlock);
}
/**
* Locks the handle table.
*
* @param pThis The handle table structure.
*/
DECLINLINE(void) rtHandleTableUnlock(PRTHANDLETABLEINT pThis)
{
if (pThis->hSpinlock != NIL_RTSPINLOCK)
RTSpinlockRelease(pThis->hSpinlock);
}
#endif /* !IPRT_INCLUDED_SRC_common_misc_handletable_h */
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