/* $Id: handletable.h 98103 2023-01-17 14:15:46Z vboxsync $ */ /** @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 . * * 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 */