/* $Id: strcache.cpp 76553 2019-01-01 01:45:53Z vboxsync $ */ /** @file * IPRT - String Cache. */ /* * Copyright (C) 2009-2019 Oracle Corporation * * This file is part of VirtualBox Open Source Edition (OSE), as * available from http://www.virtualbox.org. This file is free software; * you can redistribute it and/or modify it under the terms of the GNU * General Public License (GPL) as published by the Free Software * Foundation, in version 2 as it comes in the "COPYING" file of the * VirtualBox OSE distribution. VirtualBox OSE is distributed in the * hope that it will be useful, but WITHOUT ANY WARRANTY of any kind. * * The contents of this file may alternatively be used under the terms * of the Common Development and Distribution License Version 1.0 * (CDDL) only, as it comes in the "COPYING.CDDL" file of the * VirtualBox OSE 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. */ /********************************************************************************************************************************* * Header Files * *********************************************************************************************************************************/ #include #include "internal/iprt.h" #include #include #include #include #include #include #include #include #include #include #include "internal/strhash.h" #include "internal/magics.h" /********************************************************************************************************************************* * Defined Constants And Macros * *********************************************************************************************************************************/ /** Special NIL pointer for the hash table. It differs from NULL in that it is * a valid hash table entry when doing a lookup. */ #define PRTSTRCACHEENTRY_NIL ((PRTSTRCACHEENTRY)~(uintptr_t)1) /** Calcuates the increment when handling a collision. * The current formula makes sure it's always odd so we cannot possibly end * up a cyclic loop with an even sized table. It also takes more bits from * the length part. */ #define RTSTRCACHE_COLLISION_INCR(uHashLen) ( ((uHashLen >> 8) | 1) ) /** The initial hash table size. Must be power of two. */ #define RTSTRCACHE_INITIAL_HASH_SIZE 512 /** The hash table growth factor. */ #define RTSTRCACHE_HASH_GROW_FACTOR 4 /** * The RTSTRCACHEENTRY size threshold at which we stop using our own allocator * and switch to the application heap, expressed as a power of two. * * Using a 1KB as a reasonable limit here. */ #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR # define RTSTRCACHE_HEAP_THRESHOLD_BIT 10 #else # define RTSTRCACHE_HEAP_THRESHOLD_BIT 9 #endif /** The RTSTRCACHE_HEAP_THRESHOLD_BIT as a byte limit. */ #define RTSTRCACHE_HEAP_THRESHOLD RT_BIT_32(RTSTRCACHE_HEAP_THRESHOLD_BIT) /** Big (heap) entry size alignment. */ #define RTSTRCACHE_HEAP_ENTRY_SIZE_ALIGN 16 #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR /** * The RTSTRCACHEENTRY size threshold at which we start using the merge free * list for allocations, expressed as a power of two. */ # define RTSTRCACHE_MERGED_THRESHOLD_BIT 6 /** The number of bytes (power of two) that the merged allocation lists should * be grown by. Must be much greater than RTSTRCACHE_MERGED_THRESHOLD. */ # define RTSTRCACHE_MERGED_GROW_SIZE _32K #endif /** The number of bytes (power of two) that the fixed allocation lists should * be grown by. */ #define RTSTRCACHE_FIXED_GROW_SIZE _32K /** The number of fixed sized lists. */ #define RTSTRCACHE_NUM_OF_FIXED_SIZES 12 /** Validates a string cache handle, translating RTSTRCACHE_DEFAULT when found, * and returns rc if not valid. */ #define RTSTRCACHE_VALID_RETURN_RC(pStrCache, rc) \ do { \ if ((pStrCache) == RTSTRCACHE_DEFAULT) \ { \ int rcOnce = RTOnce(&g_rtStrCacheOnce, rtStrCacheInitDefault, NULL); \ if (RT_FAILURE(rcOnce)) \ return (rc); \ (pStrCache) = g_hrtStrCacheDefault; \ } \ else \ { \ AssertPtrReturn((pStrCache), (rc)); \ AssertReturn((pStrCache)->u32Magic == RTSTRCACHE_MAGIC, (rc)); \ } \ } while (0) /********************************************************************************************************************************* * Structures and Typedefs * *********************************************************************************************************************************/ /** * String cache entry. */ typedef struct RTSTRCACHEENTRY { /** The number of references. */ uint32_t volatile cRefs; /** The lower 16-bit hash value. */ uint16_t uHash; /** The string length (excluding the terminator). * If this is set to RTSTRCACHEENTRY_BIG_LEN, this is a BIG entry * (RTSTRCACHEBIGENTRY). */ uint16_t cchString; /** The string. */ char szString[8]; } RTSTRCACHEENTRY; AssertCompileSize(RTSTRCACHEENTRY, 16); /** Pointer to a string cache entry. */ typedef RTSTRCACHEENTRY *PRTSTRCACHEENTRY; /** Pointer to a const string cache entry. */ typedef RTSTRCACHEENTRY *PCRTSTRCACHEENTRY; /** RTSTCACHEENTRY::cchString value for big cache entries. */ #define RTSTRCACHEENTRY_BIG_LEN UINT16_MAX /** * Big string cache entry. * * These are allocated individually from the application heap. */ typedef struct RTSTRCACHEBIGENTRY { /** List entry. */ RTLISTNODE ListEntry; /** The string length. */ uint32_t cchString; /** The full hash value / padding. */ uint32_t uHash; /** The core entry. */ RTSTRCACHEENTRY Core; } RTSTRCACHEBIGENTRY; AssertCompileSize(RTSTRCACHEENTRY, 16); /** Pointer to a big string cache entry. */ typedef RTSTRCACHEBIGENTRY *PRTSTRCACHEBIGENTRY; /** Pointer to a const big string cache entry. */ typedef RTSTRCACHEBIGENTRY *PCRTSTRCACHEBIGENTRY; /** * A free string cache entry. */ typedef struct RTSTRCACHEFREE { /** Zero value indicating that it's a free entry (no refs, no hash). */ uint32_t uZero; /** Number of free bytes. Only used for > 32 byte allocations. */ uint32_t cbFree; /** Pointer to the next free item. */ struct RTSTRCACHEFREE *pNext; } RTSTRCACHEFREE; AssertCompileSize(RTSTRCACHEENTRY, 16); AssertCompileMembersAtSameOffset(RTSTRCACHEENTRY, cRefs, RTSTRCACHEFREE, uZero); AssertCompileMembersAtSameOffset(RTSTRCACHEENTRY, szString, RTSTRCACHEFREE, pNext); /** Pointer to a free string cache entry. */ typedef RTSTRCACHEFREE *PRTSTRCACHEFREE; #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR /** * A free string cache entry with merging. * * This differs from RTSTRCACHEFREE only in having a back pointer for more * efficient list management (doubly vs. singly linked lists). */ typedef struct RTSTRCACHEFREEMERGE { /** Marker that indicates what kind of entry this is, either . */ uint32_t uMarker; /** Number of free bytes. Only used for > 32 byte allocations. */ uint32_t cbFree; /** Pointer to the main node. NULL for main nodes. */ struct RTSTRCACHEFREEMERGE *pMain; /** The free list entry. */ RTLISTNODE ListEntry; /** Pads the size up to the minimum allocation unit for the merge list. * This both defines the minimum allocation unit and simplifies pointer * manipulation during merging and splitting. */ uint8_t abPadding[ARCH_BITS == 32 ? 44 : 32]; } RTSTRCACHEFREEMERGE; AssertCompileSize(RTSTRCACHEFREEMERGE, RT_BIT_32(RTSTRCACHE_MERGED_THRESHOLD_BIT)); /** Pointer to a free cache string in the merge list. */ typedef RTSTRCACHEFREEMERGE *PRTSTRCACHEFREEMERGE; /** RTSTRCACHEFREEMERGE::uMarker value indicating that it's the real free chunk * header. Must be something that's invalid UTF-8 for both little and big * endian system. */ # define RTSTRCACHEFREEMERGE_MAIN UINT32_C(0xfffffff1) /** RTSTRCACHEFREEMERGE::uMarker value indicating that it's part of a larger * chunk of free memory. Must be something that's invalid UTF-8 for both little * and big endian system. */ # define RTSTRCACHEFREEMERGE_PART UINT32_C(0xfffffff2) #endif /* RTSTRCACHE_WITH_MERGED_ALLOCATOR */ /** * Tracking structure chunk of memory used by the 16 byte or 32 byte * allocations. * * This occupies the first entry in the chunk. */ typedef struct RTSTRCACHECHUNK { /** The size of the chunk. */ size_t cb; /** Pointer to the next chunk. */ struct RTSTRCACHECHUNK *pNext; } RTSTRCACHECHUNK; AssertCompile(sizeof(RTSTRCACHECHUNK) <= sizeof(RTSTRCACHEENTRY)); /** Pointer to the chunk tracking structure. */ typedef RTSTRCACHECHUNK *PRTSTRCACHECHUNK; /** * Cache instance data. */ typedef struct RTSTRCACHEINT { /** The string cache magic (RTSTRCACHE_MAGIC). */ uint32_t u32Magic; /** Ref counter for the cache handle. */ uint32_t volatile cRefs; /** The number of strings currently entered in the cache. */ uint32_t cStrings; /** The size of the hash table. */ uint32_t cHashTab; /** Pointer to the hash table. */ PRTSTRCACHEENTRY *papHashTab; /** Free list for allocations of the sizes defined by g_acbFixedLists. */ PRTSTRCACHEFREE apFreeLists[RTSTRCACHE_NUM_OF_FIXED_SIZES]; #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR /** Free lists based on */ RTLISTANCHOR aMergedFreeLists[RTSTRCACHE_HEAP_THRESHOLD_BIT - RTSTRCACHE_MERGED_THRESHOLD_BIT + 1]; #endif /** List of allocated memory chunks. */ PRTSTRCACHECHUNK pChunkList; /** List of big cache entries. */ RTLISTANCHOR BigEntryList; /** @name Statistics * @{ */ /** The total size of all chunks. */ size_t cbChunks; /** The total length of all the strings, terminators included. */ size_t cbStrings; /** The total size of all the big entries. */ size_t cbBigEntries; /** Hash collisions. */ uint32_t cHashCollisions; /** Secondary hash collisions. */ uint32_t cHashCollisions2; /** The number of inserts to compare cHashCollisions to. */ uint32_t cHashInserts; /** The number of rehashes. */ uint32_t cRehashes; /** @} */ /** Critical section protecting the cache structures. */ RTCRITSECT CritSect; } RTSTRCACHEINT; /** Pointer to a cache instance. */ typedef RTSTRCACHEINT *PRTSTRCACHEINT; /********************************************************************************************************************************* * Global Variables * *********************************************************************************************************************************/ /** The entry sizes of the fixed lists (RTSTRCACHEINT::apFreeLists). */ static const uint32_t g_acbFixedLists[RTSTRCACHE_NUM_OF_FIXED_SIZES] = { 16, 32, 48, 64, 96, 128, 192, 256, 320, 384, 448, 512 }; /** Init once for the default string cache. */ static RTONCE g_rtStrCacheOnce = RTONCE_INITIALIZER; /** The default string cache. */ static RTSTRCACHE g_hrtStrCacheDefault = NIL_RTSTRCACHE; /** @callback_method_impl{FNRTONCE, Initializes g_hrtStrCacheDefault} */ static DECLCALLBACK(int) rtStrCacheInitDefault(void *pvUser) { NOREF(pvUser); return RTStrCacheCreate(&g_hrtStrCacheDefault, "Default"); } RTDECL(int) RTStrCacheCreate(PRTSTRCACHE phStrCache, const char *pszName) { int rc = VERR_NO_MEMORY; PRTSTRCACHEINT pThis = (PRTSTRCACHEINT)RTMemAllocZ(sizeof(*pThis)); if (pThis) { pThis->cHashTab = RTSTRCACHE_INITIAL_HASH_SIZE; pThis->papHashTab = (PRTSTRCACHEENTRY*)RTMemAllocZ(sizeof(pThis->papHashTab[0]) * pThis->cHashTab); if (pThis->papHashTab) { rc = RTCritSectInit(&pThis->CritSect); if (RT_SUCCESS(rc)) { RTListInit(&pThis->BigEntryList); #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR for (uint32_t i = 0; i < RT_ELEMENTS(pThis->aMergedFreeLists); i++) RTListInit(&pThis->aMergedFreeLists[i]); #endif pThis->cRefs = 1; pThis->u32Magic = RTSTRCACHE_MAGIC; *phStrCache = pThis; return VINF_SUCCESS; } RTMemFree(pThis->papHashTab); } RTMemFree(pThis); } RT_NOREF_PV(pszName); return rc; } RT_EXPORT_SYMBOL(RTStrCacheCreate); RTDECL(int) RTStrCacheDestroy(RTSTRCACHE hStrCache) { if ( hStrCache == NIL_RTSTRCACHE || hStrCache == RTSTRCACHE_DEFAULT) return VINF_SUCCESS; PRTSTRCACHEINT pThis = hStrCache; RTSTRCACHE_VALID_RETURN_RC(pThis, VERR_INVALID_HANDLE); /* * Invalidate it. Enter the crit sect just to be on the safe side. */ AssertReturn(ASMAtomicCmpXchgU32(&pThis->u32Magic, RTSTRCACHE_MAGIC_DEAD, RTSTRCACHE_MAGIC), VERR_INVALID_HANDLE); RTCritSectEnter(&pThis->CritSect); Assert(pThis->cRefs == 1); PRTSTRCACHECHUNK pChunk; while ((pChunk = pThis->pChunkList) != NULL) { pThis->pChunkList = pChunk->pNext; RTMemPageFree(pChunk, pChunk->cb); } RTMemFree(pThis->papHashTab); pThis->papHashTab = NULL; pThis->cHashTab = 0; PRTSTRCACHEBIGENTRY pCur, pNext; RTListForEachSafe(&pThis->BigEntryList, pCur, pNext, RTSTRCACHEBIGENTRY, ListEntry) { RTMemFree(pCur); } RTCritSectLeave(&pThis->CritSect); RTCritSectDelete(&pThis->CritSect); RTMemFree(pThis); return VINF_SUCCESS; } RT_EXPORT_SYMBOL(RTStrCacheDestroy); /** * Selects the fixed free list index for a given minimum entry size. * * @returns Free list index. * @param cbMin Minimum entry size. */ DECLINLINE(uint32_t) rtStrCacheSelectFixedList(uint32_t cbMin) { Assert(cbMin <= g_acbFixedLists[RT_ELEMENTS(g_acbFixedLists) - 1]); unsigned i = 0; while (cbMin > g_acbFixedLists[i]) i++; return i; } #ifdef RT_STRICT # define RTSTRCACHE_CHECK(a_pThis) do { rtStrCacheCheck(pThis); } while (0) /** * Internal cache check. */ static void rtStrCacheCheck(PRTSTRCACHEINT pThis) { # ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR for (uint32_t i = 0; i < RT_ELEMENTS(pThis->aMergedFreeLists); i++) { PRTSTRCACHEFREEMERGE pFree; RTListForEach(&pThis->aMergedFreeLists[i], pFree, RTSTRCACHEFREEMERGE, ListEntry) { Assert(pFree->uMarker == RTSTRCACHEFREEMERGE_MAIN); Assert(pFree->cbFree > 0); Assert(RT_ALIGN_32(pFree->cbFree, sizeof(*pFree)) == pFree->cbFree); } } # endif RT_NOREF_PV(pThis); } #else # define RTSTRCACHE_CHECK(a_pThis) do { } while (0) #endif /** * Finds the first empty hash table entry given a hash+length value. * * ASSUMES that the hash table isn't full. * * @returns Hash table index. * @param pThis The string cache instance. * @param uHashLen The hash + length (not RTSTRCACHEENTRY_BIG_LEN). */ static uint32_t rtStrCacheFindEmptyHashTabEntry(PRTSTRCACHEINT pThis, uint32_t uHashLen) { uint32_t iHash = uHashLen % pThis->cHashTab; for (;;) { PRTSTRCACHEENTRY pEntry = pThis->papHashTab[iHash]; if (pEntry == NULL || pEntry == PRTSTRCACHEENTRY_NIL) return iHash; /* Advance. */ iHash += RTSTRCACHE_COLLISION_INCR(uHashLen); iHash %= pThis->cHashTab; } } /** * Grows the hash table. * * @returns vINF_SUCCESS or VERR_NO_MEMORY. * @param pThis The string cache instance. */ static int rtStrCacheGrowHashTab(PRTSTRCACHEINT pThis) { /* * Allocate a new hash table two times the size of the old one. */ uint32_t cNew = pThis->cHashTab * RTSTRCACHE_HASH_GROW_FACTOR; PRTSTRCACHEENTRY *papNew = (PRTSTRCACHEENTRY *)RTMemAllocZ(sizeof(papNew[0]) * cNew); if (papNew == NULL) return VERR_NO_MEMORY; /* * Install the new table and move the items from the old table and into the new one. */ PRTSTRCACHEENTRY *papOld = pThis->papHashTab; uint32_t iOld = pThis->cHashTab; pThis->papHashTab = papNew; pThis->cHashTab = cNew; pThis->cRehashes++; while (iOld-- > 0) { PRTSTRCACHEENTRY pEntry = papOld[iOld]; if (pEntry != NULL && pEntry != PRTSTRCACHEENTRY_NIL) { uint32_t cchString = pEntry->cchString; if (cchString == RTSTRCACHEENTRY_BIG_LEN) cchString = RT_FROM_MEMBER(pEntry, RTSTRCACHEBIGENTRY, Core)->cchString; uint32_t iHash = rtStrCacheFindEmptyHashTabEntry(pThis, RT_MAKE_U32(pEntry->uHash, cchString)); pThis->papHashTab[iHash] = pEntry; } } /* * Free the old hash table. */ RTMemFree(papOld); return VINF_SUCCESS; } #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR /** * Link/Relink into the free right list. * * @param pThis The string cache instance. * @param pFree The free string entry. */ static void rtStrCacheRelinkMerged(PRTSTRCACHEINT pThis, PRTSTRCACHEFREEMERGE pFree) { Assert(pFree->uMarker == RTSTRCACHEFREEMERGE_MAIN); Assert(pFree->cbFree > 0); Assert(RT_ALIGN_32(pFree->cbFree, sizeof(*pFree)) == pFree->cbFree); if (!RTListIsEmpty(&pFree->ListEntry)) RTListNodeRemove(&pFree->ListEntry); uint32_t iList = (ASMBitLastSetU32(pFree->cbFree) - 1) - RTSTRCACHE_MERGED_THRESHOLD_BIT; if (iList >= RT_ELEMENTS(pThis->aMergedFreeLists)) iList = RT_ELEMENTS(pThis->aMergedFreeLists) - 1; RTListPrepend(&pThis->aMergedFreeLists[iList], &pFree->ListEntry); } /** * Allocate a cache entry from the merged free lists. * * @returns Pointer to the cache entry on success, NULL on allocation error. * @param pThis The string cache instance. * @param uHash The full hash of the string. * @param pchString The string. * @param cchString The string length. * @param cbEntry The required entry size. */ static PRTSTRCACHEENTRY rtStrCacheAllocMergedEntry(PRTSTRCACHEINT pThis, uint32_t uHash, const char *pchString, uint32_t cchString, uint32_t cbEntry) { cbEntry = RT_ALIGN_32(cbEntry, sizeof(RTSTRCACHEFREEMERGE)); Assert(cbEntry > cchString); /* * Search the list heads first. */ PRTSTRCACHEFREEMERGE pFree = NULL; uint32_t iList = ASMBitLastSetU32(cbEntry) - 1; if (!RT_IS_POWER_OF_TWO(cbEntry)) iList++; iList -= RTSTRCACHE_MERGED_THRESHOLD_BIT; while (iList < RT_ELEMENTS(pThis->aMergedFreeLists)) { pFree = RTListGetFirst(&pThis->aMergedFreeLists[iList], RTSTRCACHEFREEMERGE, ListEntry); if (pFree) { /* * Found something. Should we we split it? We split from the end * to avoid having to update all the sub entries. */ Assert(pFree->uMarker == RTSTRCACHEFREEMERGE_MAIN); Assert(pFree->cbFree >= cbEntry); Assert(RT_ALIGN_32(pFree->cbFree, sizeof(*pFree)) == pFree->cbFree); if (pFree->cbFree == cbEntry) RTListNodeRemove(&pFree->ListEntry); else { uint32_t cRemainder = (pFree->cbFree - cbEntry) / sizeof(*pFree); PRTSTRCACHEFREEMERGE pRemainder = pFree; pFree += cRemainder; Assert((pRemainder->cbFree - cbEntry) == cRemainder * sizeof(*pFree)); pRemainder->cbFree = cRemainder * sizeof(*pFree); rtStrCacheRelinkMerged(pThis, pRemainder); } break; } iList++; } if (!pFree) { /* * Allocate a new block. (We could search the list below in some * cases, but it's too much effort to write and execute). */ size_t const cbChunk = RTSTRCACHE_MERGED_GROW_SIZE; AssertReturn(cbChunk > cbEntry * 2, NULL); PRTSTRCACHECHUNK pChunk = (PRTSTRCACHECHUNK)RTMemPageAlloc(cbChunk); if (!pChunk) return NULL; pChunk->cb = cbChunk; pChunk->pNext = pThis->pChunkList; pThis->pChunkList = pChunk; pThis->cbChunks += cbChunk; AssertCompile(sizeof(*pChunk) <= sizeof(*pFree)); /* * Get one node for the allocation at hand. */ pFree = (PRTSTRCACHEFREEMERGE)((uintptr_t)pChunk + sizeof(*pFree)); /* * Create a free block out of the remainder (always a reminder). */ PRTSTRCACHEFREEMERGE pNewFree = (PRTSTRCACHEFREEMERGE)((uintptr_t)pFree + cbEntry); pNewFree->uMarker = RTSTRCACHEFREEMERGE_MAIN; pNewFree->cbFree = cbChunk - sizeof(*pNewFree) - cbEntry; Assert(pNewFree->cbFree < cbChunk && pNewFree->cbFree > 0); pNewFree->pMain = NULL; RTListInit(&pNewFree->ListEntry); uint32_t iInternalBlock = pNewFree->cbFree / sizeof(*pNewFree); while (iInternalBlock-- > 1) { pNewFree[iInternalBlock].uMarker = RTSTRCACHEFREEMERGE_PART; pNewFree[iInternalBlock].cbFree = 0; pNewFree[iInternalBlock].pMain = pNewFree; } rtStrCacheRelinkMerged(pThis, pNewFree); } /* * Initialize the entry. We zero all bytes we don't use so they cannot * accidentally be mistaken for a free entry. */ ASMCompilerBarrier(); PRTSTRCACHEENTRY pEntry = (PRTSTRCACHEENTRY)pFree; pEntry->cRefs = 1; pEntry->uHash = (uint16_t)uHash; pEntry->cchString = (uint16_t)cchString; memcpy(pEntry->szString, pchString, cchString); RT_BZERO(&pEntry->szString[cchString], cbEntry - RT_UOFFSETOF(RTSTRCACHEENTRY, szString) - cchString); RTSTRCACHE_CHECK(pThis); return pEntry; } #endif /* RTSTRCACHE_WITH_MERGED_ALLOCATOR */ /** * Allocate a cache entry from the heap. * * @returns Pointer to the cache entry on success, NULL on allocation error. * @param pThis The string cache instance. * @param uHash The full hash of the string. * @param pchString The string. * @param cchString The string length. */ static PRTSTRCACHEENTRY rtStrCacheAllocHeapEntry(PRTSTRCACHEINT pThis, uint32_t uHash, const char *pchString, uint32_t cchString) { /* * Allocate a heap block for storing the string. We do some size aligning * here to encourage the heap to give us optimal alignment. */ size_t cbEntry = RT_UOFFSETOF_DYN(RTSTRCACHEBIGENTRY, Core.szString[cchString + 1]); PRTSTRCACHEBIGENTRY pBigEntry = (PRTSTRCACHEBIGENTRY)RTMemAlloc(RT_ALIGN_Z(cbEntry, RTSTRCACHE_HEAP_ENTRY_SIZE_ALIGN)); if (!pBigEntry) return NULL; /* * Initialize the block. */ RTListAppend(&pThis->BigEntryList, &pBigEntry->ListEntry); pThis->cbBigEntries += cbEntry; pBigEntry->cchString = cchString; pBigEntry->uHash = uHash; pBigEntry->Core.cRefs = 1; pBigEntry->Core.uHash = (uint16_t)uHash; pBigEntry->Core.cchString = RTSTRCACHEENTRY_BIG_LEN; /* The following is to try avoid gcc warnings/errors regarding array bounds: */ char *pszDst = (char *)memcpy(pBigEntry->Core.szString, pchString, cchString); pszDst[cchString] = '\0'; ASMCompilerBarrier(); return &pBigEntry->Core; } /** * Allocate a cache entry from a fixed size free list. * * @returns Pointer to the cache entry on success, NULL on allocation error. * @param pThis The string cache instance. * @param uHash The full hash of the string. * @param pchString The string. * @param cchString The string length. * @param iFreeList Which free list. */ static PRTSTRCACHEENTRY rtStrCacheAllocFixedEntry(PRTSTRCACHEINT pThis, uint32_t uHash, const char *pchString, uint32_t cchString, uint32_t iFreeList) { /* * Get an entry from the free list. If empty, allocate another chunk of * memory and split it up into free entries of the desired size. */ PRTSTRCACHEFREE pFree = pThis->apFreeLists[iFreeList]; if (!pFree) { PRTSTRCACHECHUNK pChunk = (PRTSTRCACHECHUNK)RTMemPageAlloc(RTSTRCACHE_FIXED_GROW_SIZE); if (!pChunk) return NULL; pChunk->cb = RTSTRCACHE_FIXED_GROW_SIZE; pChunk->pNext = pThis->pChunkList; pThis->pChunkList = pChunk; pThis->cbChunks += RTSTRCACHE_FIXED_GROW_SIZE; PRTSTRCACHEFREE pPrev = NULL; uint32_t const cbEntry = g_acbFixedLists[iFreeList]; uint32_t cLeft = RTSTRCACHE_FIXED_GROW_SIZE / cbEntry - 1; pFree = (PRTSTRCACHEFREE)((uintptr_t)pChunk + cbEntry); Assert(sizeof(*pChunk) <= cbEntry); Assert(sizeof(*pFree) <= cbEntry); Assert(cbEntry < RTSTRCACHE_FIXED_GROW_SIZE / 16); while (cLeft-- > 0) { pFree->uZero = 0; pFree->cbFree = cbEntry; pFree->pNext = pPrev; pPrev = pFree; pFree = (PRTSTRCACHEFREE)((uintptr_t)pFree + cbEntry); } Assert(pPrev); pThis->apFreeLists[iFreeList] = pFree = pPrev; } /* * Unlink it. */ pThis->apFreeLists[iFreeList] = pFree->pNext; ASMCompilerBarrier(); /* * Initialize the entry. */ PRTSTRCACHEENTRY pEntry = (PRTSTRCACHEENTRY)pFree; pEntry->cRefs = 1; pEntry->uHash = (uint16_t)uHash; pEntry->cchString = (uint16_t)cchString; memcpy(pEntry->szString, pchString, cchString); pEntry->szString[cchString] = '\0'; return pEntry; } /** * Looks up a string in the hash table. * * @returns Pointer to the string cache entry, NULL + piFreeHashTabEntry if not * found. * @param pThis The string cache instance. * @param uHashLen The hash + length (not RTSTRCACHEENTRY_BIG_LEN). * @param cchString The real length. * @param pchString The string. * @param piFreeHashTabEntry Where to store the index insertion index if NULL * is returned (same as what * rtStrCacheFindEmptyHashTabEntry would return). * @param pcCollisions Where to return a collision counter. */ static PRTSTRCACHEENTRY rtStrCacheLookUp(PRTSTRCACHEINT pThis, uint32_t uHashLen, uint32_t cchString, const char *pchString, uint32_t *piFreeHashTabEntry, uint32_t *pcCollisions) { *piFreeHashTabEntry = UINT32_MAX; *pcCollisions = 0; uint16_t cchStringFirst = RT_UOFFSETOF_DYN(RTSTRCACHEENTRY, szString[cchString + 1]) < RTSTRCACHE_HEAP_THRESHOLD ? (uint16_t)cchString : RTSTRCACHEENTRY_BIG_LEN; uint32_t iHash = uHashLen % pThis->cHashTab; for (;;) { PRTSTRCACHEENTRY pEntry = pThis->papHashTab[iHash]; /* Give up if NULL, but record the index for insertion. */ if (pEntry == NULL) { if (*piFreeHashTabEntry == UINT32_MAX) *piFreeHashTabEntry = iHash; return NULL; } if (pEntry != PRTSTRCACHEENTRY_NIL) { /* Compare. */ if ( pEntry->uHash == (uint16_t)uHashLen && pEntry->cchString == cchStringFirst) { if (pEntry->cchString != RTSTRCACHEENTRY_BIG_LEN) { if ( !memcmp(pEntry->szString, pchString, cchString) && pEntry->szString[cchString] == '\0') return pEntry; } else { PRTSTRCACHEBIGENTRY pBigEntry = RT_FROM_MEMBER(pEntry, RTSTRCACHEBIGENTRY, Core); if ( pBigEntry->cchString == cchString && !memcmp(pBigEntry->Core.szString, pchString, cchString)) return &pBigEntry->Core; } } if (*piFreeHashTabEntry == UINT32_MAX) *pcCollisions += 1; } /* Record the first NIL index for insertion in case we don't get a hit. */ else if (*piFreeHashTabEntry == UINT32_MAX) *piFreeHashTabEntry = iHash; /* Advance. */ iHash += RTSTRCACHE_COLLISION_INCR(uHashLen); iHash %= pThis->cHashTab; } } RTDECL(const char *) RTStrCacheEnterN(RTSTRCACHE hStrCache, const char *pchString, size_t cchString) { PRTSTRCACHEINT pThis = hStrCache; RTSTRCACHE_VALID_RETURN_RC(pThis, NULL); /* * Calculate the hash and figure the exact string length, then look for an existing entry. */ uint32_t const uHash = sdbmN(pchString, cchString, &cchString); uint32_t const uHashLen = RT_MAKE_U32(uHash, cchString); AssertReturn(cchString < _1G, NULL); uint32_t const cchString32 = (uint32_t)cchString; RTCritSectEnter(&pThis->CritSect); RTSTRCACHE_CHECK(pThis); uint32_t cCollisions; uint32_t iFreeHashTabEntry; PRTSTRCACHEENTRY pEntry = rtStrCacheLookUp(pThis, uHashLen, cchString32, pchString, &iFreeHashTabEntry, &cCollisions); if (pEntry) { uint32_t cRefs = ASMAtomicIncU32(&pEntry->cRefs); Assert(cRefs < UINT32_MAX / 2); NOREF(cRefs); } else { /* * Allocate a new entry. */ uint32_t cbEntry = cchString32 + 1U + RT_UOFFSETOF(RTSTRCACHEENTRY, szString); if (cbEntry >= RTSTRCACHE_HEAP_THRESHOLD) pEntry = rtStrCacheAllocHeapEntry(pThis, uHash, pchString, cchString32); #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR else if (cbEntry >= RTSTRCACHE_MERGED_THRESHOLD_BIT) pEntry = rtStrCacheAllocMergedEntry(pThis, uHash, pchString, cchString32, cbEntry); #endif else pEntry = rtStrCacheAllocFixedEntry(pThis, uHash, pchString, cchString32, rtStrCacheSelectFixedList(cbEntry)); if (!pEntry) { RTSTRCACHE_CHECK(pThis); RTCritSectLeave(&pThis->CritSect); return NULL; } /* * Insert it into the hash table. */ if (pThis->cHashTab - pThis->cStrings < pThis->cHashTab / 2) { int rc = rtStrCacheGrowHashTab(pThis); if (RT_SUCCESS(rc)) iFreeHashTabEntry = rtStrCacheFindEmptyHashTabEntry(pThis, uHashLen); else if (pThis->cHashTab - pThis->cStrings <= pThis->cHashTab / 8) /* 12.5% full => error */ { pThis->papHashTab[iFreeHashTabEntry] = pEntry; pThis->cStrings++; pThis->cHashInserts++; pThis->cHashCollisions += cCollisions > 0; pThis->cHashCollisions2 += cCollisions > 1; pThis->cbStrings += cchString32 + 1; RTStrCacheRelease(hStrCache, pEntry->szString); RTSTRCACHE_CHECK(pThis); RTCritSectLeave(&pThis->CritSect); return NULL; } } pThis->papHashTab[iFreeHashTabEntry] = pEntry; pThis->cStrings++; pThis->cHashInserts++; pThis->cHashCollisions += cCollisions > 0; pThis->cHashCollisions2 += cCollisions > 1; pThis->cbStrings += cchString32 + 1; Assert(pThis->cStrings < pThis->cHashTab && pThis->cStrings > 0); } RTSTRCACHE_CHECK(pThis); RTCritSectLeave(&pThis->CritSect); return pEntry->szString; } RT_EXPORT_SYMBOL(RTStrCacheEnterN); RTDECL(const char *) RTStrCacheEnter(RTSTRCACHE hStrCache, const char *psz) { return RTStrCacheEnterN(hStrCache, psz, strlen(psz)); } RT_EXPORT_SYMBOL(RTStrCacheEnter); static const char *rtStrCacheEnterLowerWorker(PRTSTRCACHEINT pThis, const char *pchString, size_t cchString) { /* * Try use a dynamic heap buffer first. */ if (cchString < 512) { char *pszStackBuf = (char *)alloca(cchString + 1); if (pszStackBuf) { memcpy(pszStackBuf, pchString, cchString); pszStackBuf[cchString] = '\0'; RTStrToLower(pszStackBuf); return RTStrCacheEnterN(pThis, pszStackBuf, cchString); } } /* * Fall back on heap. */ char *pszHeapBuf = (char *)RTMemTmpAlloc(cchString + 1); if (!pszHeapBuf) return NULL; memcpy(pszHeapBuf, pchString, cchString); pszHeapBuf[cchString] = '\0'; RTStrToLower(pszHeapBuf); const char *pszRet = RTStrCacheEnterN(pThis, pszHeapBuf, cchString); RTMemTmpFree(pszHeapBuf); return pszRet; } RTDECL(const char *) RTStrCacheEnterLowerN(RTSTRCACHE hStrCache, const char *pchString, size_t cchString) { PRTSTRCACHEINT pThis = hStrCache; RTSTRCACHE_VALID_RETURN_RC(pThis, NULL); return rtStrCacheEnterLowerWorker(pThis, pchString, RTStrNLen(pchString, cchString)); } RT_EXPORT_SYMBOL(RTStrCacheEnterLowerN); RTDECL(const char *) RTStrCacheEnterLower(RTSTRCACHE hStrCache, const char *psz) { PRTSTRCACHEINT pThis = hStrCache; RTSTRCACHE_VALID_RETURN_RC(pThis, NULL); return rtStrCacheEnterLowerWorker(pThis, psz, strlen(psz)); } RT_EXPORT_SYMBOL(RTStrCacheEnterLower); RTDECL(uint32_t) RTStrCacheRetain(const char *psz) { AssertPtr(psz); PRTSTRCACHEENTRY pStr = RT_FROM_MEMBER(psz, RTSTRCACHEENTRY, szString); Assert(!((uintptr_t)pStr & 15) || pStr->cchString == RTSTRCACHEENTRY_BIG_LEN); uint32_t cRefs = ASMAtomicIncU32(&pStr->cRefs); Assert(cRefs > 1); Assert(cRefs < UINT32_MAX / 2); return cRefs; } RT_EXPORT_SYMBOL(RTStrCacheRetain); static uint32_t rtStrCacheFreeEntry(PRTSTRCACHEINT pThis, PRTSTRCACHEENTRY pStr) { RTCritSectEnter(&pThis->CritSect); RTSTRCACHE_CHECK(pThis); /* Remove it from the hash table. */ uint32_t cchString = pStr->cchString == RTSTRCACHEENTRY_BIG_LEN ? RT_FROM_MEMBER(pStr, RTSTRCACHEBIGENTRY, Core)->cchString : pStr->cchString; uint32_t uHashLen = RT_MAKE_U32(pStr->uHash, cchString); uint32_t iHash = uHashLen % pThis->cHashTab; if (pThis->papHashTab[iHash] == pStr) pThis->papHashTab[iHash] = PRTSTRCACHEENTRY_NIL; else { do { AssertBreak(pThis->papHashTab[iHash] != NULL); iHash += RTSTRCACHE_COLLISION_INCR(uHashLen); iHash %= pThis->cHashTab; } while (pThis->papHashTab[iHash] != pStr); if (RT_LIKELY(pThis->papHashTab[iHash] == pStr)) pThis->papHashTab[iHash] = PRTSTRCACHEENTRY_NIL; else { AssertFailed(); iHash = pThis->cHashTab; while (iHash-- > 0) if (pThis->papHashTab[iHash] == pStr) break; AssertMsgFailed(("iHash=%u cHashTab=%u\n", iHash, pThis->cHashTab)); } } pThis->cStrings--; pThis->cbStrings -= cchString; Assert(pThis->cStrings < pThis->cHashTab); /* Free it. */ if (pStr->cchString != RTSTRCACHEENTRY_BIG_LEN) { uint32_t const cbMin = pStr->cchString + 1U + RT_UOFFSETOF(RTSTRCACHEENTRY, szString); #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR if (cbMin <= RTSTRCACHE_MAX_FIXED) #endif { /* * No merging, just add it to the list. */ uint32_t const iFreeList = rtStrCacheSelectFixedList(cbMin); ASMCompilerBarrier(); PRTSTRCACHEFREE pFreeStr = (PRTSTRCACHEFREE)pStr; pFreeStr->cbFree = cbMin; pFreeStr->uZero = 0; pFreeStr->pNext = pThis->apFreeLists[iFreeList]; pThis->apFreeLists[iFreeList] = pFreeStr; } #ifdef RTSTRCACHE_WITH_MERGED_ALLOCATOR else { /* * Complicated mode, we merge with adjecent nodes. */ ASMCompilerBarrier(); PRTSTRCACHEFREEMERGE pFreeStr = (PRTSTRCACHEFREEMERGE)pStr; pFreeStr->cbFree = RT_ALIGN_32(cbMin, sizeof(*pFreeStr)); pFreeStr->uMarker = RTSTRCACHEFREEMERGE_MAIN; pFreeStr->pMain = NULL; RTListInit(&pFreeStr->ListEntry); /* * Merge with previous? * (Reading one block back is safe because there is always the * RTSTRCACHECHUNK structure at the head of each memory chunk.) */ uint32_t cInternalBlocks = pFreeStr->cbFree / sizeof(*pFreeStr); PRTSTRCACHEFREEMERGE pMain = pFreeStr - 1; if ( pMain->uMarker == RTSTRCACHEFREEMERGE_MAIN || pMain->uMarker == RTSTRCACHEFREEMERGE_PART) { while (pMain->uMarker != RTSTRCACHEFREEMERGE_MAIN) pMain--; pMain->cbFree += pFreeStr->cbFree; } else { pMain = pFreeStr; pFreeStr++; cInternalBlocks--; } /* * Mark internal blocks in the string we're freeing. */ while (cInternalBlocks-- > 0) { pFreeStr->uMarker = RTSTRCACHEFREEMERGE_PART; pFreeStr->cbFree = 0; pFreeStr->pMain = pMain; RTListInit(&pFreeStr->ListEntry); pFreeStr++; } /* * Merge with next? Limitation: We won't try cross page boundraries. * (pFreeStr points to the next first free enter after the string now.) */ if ( PAGE_ADDRESS(pFreeStr) == PAGE_ADDRESS(&pFreeStr[-1]) && pFreeStr->uMarker == RTSTRCACHEFREEMERGE_MAIN) { pMain->cbFree += pFreeStr->cbFree; cInternalBlocks = pFreeStr->cbFree / sizeof(*pFreeStr); Assert(cInternalBlocks > 0); /* Update the main block we merge with. */ pFreeStr->cbFree = 0; pFreeStr->uMarker = RTSTRCACHEFREEMERGE_PART; RTListNodeRemove(&pFreeStr->ListEntry); RTListInit(&pFreeStr->ListEntry); /* Change the internal blocks we merged in. */ cInternalBlocks--; while (cInternalBlocks-- > 0) { pFreeStr++; pFreeStr->pMain = pMain; Assert(pFreeStr->uMarker == RTSTRCACHEFREEMERGE_PART); Assert(!pFreeStr->cbFree); } } /* * Add/relink into the appropriate free list. */ rtStrCacheRelinkMerged(pThis, pMain); } #endif /* RTSTRCACHE_WITH_MERGED_ALLOCATOR */ RTSTRCACHE_CHECK(pThis); RTCritSectLeave(&pThis->CritSect); } else { /* Big string. */ PRTSTRCACHEBIGENTRY pBigStr = RT_FROM_MEMBER(pStr, RTSTRCACHEBIGENTRY, Core); RTListNodeRemove(&pBigStr->ListEntry); pThis->cbBigEntries -= RT_ALIGN_32(RT_UOFFSETOF_DYN(RTSTRCACHEBIGENTRY, Core.szString[cchString + 1]), RTSTRCACHE_HEAP_ENTRY_SIZE_ALIGN); RTSTRCACHE_CHECK(pThis); RTCritSectLeave(&pThis->CritSect); RTMemFree(pBigStr); } return 0; } RTDECL(uint32_t) RTStrCacheRelease(RTSTRCACHE hStrCache, const char *psz) { if (!psz) return 0; PRTSTRCACHEINT pThis = hStrCache; RTSTRCACHE_VALID_RETURN_RC(pThis, UINT32_MAX); AssertPtr(psz); PRTSTRCACHEENTRY pStr = RT_FROM_MEMBER(psz, RTSTRCACHEENTRY, szString); Assert(!((uintptr_t)pStr & 15) || pStr->cchString == RTSTRCACHEENTRY_BIG_LEN); /* * Drop a reference and maybe free the entry. */ uint32_t cRefs = ASMAtomicDecU32(&pStr->cRefs); Assert(cRefs < UINT32_MAX / 2); if (!cRefs) return rtStrCacheFreeEntry(pThis, pStr); return cRefs; } RT_EXPORT_SYMBOL(RTStrCacheRelease); RTDECL(size_t) RTStrCacheLength(const char *psz) { if (!psz) return 0; AssertPtr(psz); PRTSTRCACHEENTRY pStr = RT_FROM_MEMBER(psz, RTSTRCACHEENTRY, szString); if (pStr->cchString == RTSTRCACHEENTRY_BIG_LEN) { PRTSTRCACHEBIGENTRY pBigStr = RT_FROM_MEMBER(psz, RTSTRCACHEBIGENTRY, Core.szString); return pBigStr->cchString; } Assert(!((uintptr_t)pStr & 15)); return pStr->cchString; } RT_EXPORT_SYMBOL(RTStrCacheLength); RTDECL(bool) RTStrCacheIsRealImpl(void) { return true; } RT_EXPORT_SYMBOL(RTStrCacheIsRealImpl); RTDECL(uint32_t) RTStrCacheGetStats(RTSTRCACHE hStrCache, size_t *pcbStrings, size_t *pcbChunks, size_t *pcbBigEntries, uint32_t *pcHashCollisions, uint32_t *pcHashCollisions2, uint32_t *pcHashInserts, uint32_t *pcRehashes) { PRTSTRCACHEINT pThis = hStrCache; RTSTRCACHE_VALID_RETURN_RC(pThis, UINT32_MAX); RTCritSectEnter(&pThis->CritSect); if (pcbStrings) *pcbStrings = pThis->cbStrings; if (pcbChunks) *pcbChunks = pThis->cbChunks; if (pcbBigEntries) *pcbBigEntries = pThis->cbBigEntries; if (pcHashCollisions) *pcHashCollisions = pThis->cHashCollisions; if (pcHashCollisions2) *pcHashCollisions2 = pThis->cHashCollisions2; if (pcHashInserts) *pcHashInserts = pThis->cHashInserts; if (pcRehashes) *pcRehashes = pThis->cRehashes; uint32_t cStrings = pThis->cStrings; RTCritSectLeave(&pThis->CritSect); return cStrings; } RT_EXPORT_SYMBOL(RTStrCacheRelease);