/* Copyright (c) 1998 - 2005, Google Inc. * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are * met: * * * Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * Redistributions in binary form must reproduce the above * copyright notice, this list of conditions and the following disclaimer * in the documentation and/or other materials provided with the * distribution. * * Neither the name of Google Inc. nor the names of its * contributors may be used to endorse or promote products derived from * this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * * --- * Author: Craig Silverstein * * This library is intended to be used for in-memory hash tables, * though it provides rudimentary permanent-storage capabilities. * It attempts to be fast, portable, and small. The best algorithm * to fulfill these goals is an internal probing hashing algorithm, * as in Knuth, _Art of Computer Programming_, vol III. Unlike * chained (open) hashing, it doesn't require a pointer for every * item, yet it is still constant time lookup in practice. * * Also to save space, we let the contents (both data and key) that * you insert be a union: if the key/data is small, we store it * directly in the hashtable, otherwise we store a pointer to it. * To keep you from having to figure out which, use KEY_PTR and * PTR_KEY to convert between the arguments to these functions and * a pointer to the real data. For instance: * char key[] = "ab", *key2; * HTItem *bck; HashTable *ht; * HashInsert(ht, PTR_KEY(ht, key), 0); * bck = HashFind(ht, PTR_KEY(ht, "ab")); * key2 = KEY_PTR(ht, bck->key); * * There are a rich set of operations supported: * AllocateHashTable() -- Allocates a hashtable structure and * returns it. * cchKey: if it's a positive number, then each key is a * fixed-length record of that length. If it's 0, * the key is assumed to be a \0-terminated string. * fSaveKey: normally, you are responsible for allocating * space for the key. If this is 1, we make a * copy of the key for you. * ClearHashTable() -- Removes everything from a hashtable * FreeHashTable() -- Frees memory used by a hashtable * * HashFind() -- takes a key (use PTR_KEY) and returns the * HTItem containing that key, or NULL if the * key is not in the hashtable. * HashFindLast() -- returns the item found by last HashFind() * HashFindOrInsert() -- inserts the key/data pair if the key * is not already in the hashtable, or * returns the appropraite HTItem if it is. * HashFindOrInsertItem() -- takes key/data as an HTItem. * HashInsert() -- adds a key/data pair to the hashtable. What * it does if the key is already in the table * depends on the value of SAMEKEY_OVERWRITE. * HashInsertItem() -- takes key/data as an HTItem. * HashDelete() -- removes a key/data pair from the hashtable, * if it's there. RETURNS 1 if it was there, * 0 else. * If you use sparse tables and never delete, the full data * space is available. Otherwise we steal -2 (maybe -3), * so you can't have data fields with those values. * HashDeleteLast() -- deletes the item returned by the last Find(). * * HashFirstBucket() -- used to iterate over the buckets in a * hashtable. DON'T INSERT OR DELETE WHILE * ITERATING! You can't nest iterations. * HashNextBucket() -- RETURNS NULL at the end of iterating. * * HashSetDeltaGoalSize() -- if you're going to insert 1000 items * at once, call this fn with arg 1000. * It grows the table more intelligently. * * HashSave() -- saves the hashtable to a file. It saves keys ok, * but it doesn't know how to interpret the data field, * so if the data field is a pointer to some complex * structure, you must send a function that takes a * file pointer and a pointer to the structure, and * write whatever you want to write. It should return * the number of bytes written. If the file is NULL, * it should just return the number of bytes it would * write, without writing anything. * If your data field is just an integer, not a * pointer, just send NULL for the function. * HashLoad() -- loads a hashtable. It needs a function that takes * a file and the size of the structure, and expects * you to read in the structure and return a pointer * to it. You must do memory allocation, etc. If * the data is just a number, send NULL. * HashLoadKeys() -- unlike HashLoad(), doesn't load the data off disk * until needed. This saves memory, but if you look * up the same key a lot, it does a disk access each * time. * You can't do Insert() or Delete() on hashtables that were loaded * from disk. * * See libchash.h for parameters you can modify. Make sure LOG_WORD_SIZE * is defined correctly for your machine! (5 for 32 bit words, 6 for 64). */ #include #include #include /* for strcmp, memcmp, etc */ #include /* ULTRIX needs this for in.h */ #include /* for reading/writing hashtables */ #include #include "libchash.h" /* all the types */ /* if keys are stored directly but cchKey is less than sizeof(ulong), */ /* this cuts off the bits at the end */ char grgKeyTruncMask[sizeof(ulong)][sizeof(ulong)]; #define KEY_TRUNC(ht, key) \ ( STORES_PTR(ht) || (ht)->cchKey == sizeof(ulong) \ ? (key) : ((key) & *(ulong *)&(grgKeyTruncMask[(ht)->cchKey][0])) ) /* round num up to a multiple of wordsize. (LOG_WORD_SIZE-3 is in bytes) */ #define WORD_ROUND(num) ( ((num-1) | ((1<<(LOG_WORD_SIZE-3))-1)) + 1 ) #define NULL_TERMINATED 0 /* val of cchKey if keys are null-term strings */ /* Useful operations we do to keys: compare them, copy them, free them */ #define KEY_CMP(ht, key1, key2) ( !STORES_PTR(ht) ? (key1) - (key2) : \ (key1) == (key2) ? 0 : \ HashKeySize(ht) == NULL_TERMINATED ? \ strcmp((char *)key1, (char *)key2) :\ memcmp((void *)key1, (void *)key2, \ HashKeySize(ht)) ) #define COPY_KEY(ht, keyTo, keyFrom) do \ if ( !STORES_PTR(ht) || !(ht)->fSaveKeys ) \ (keyTo) = (keyFrom); /* just copy pointer or info */\ else if ( (ht)->cchKey == NULL_TERMINATED ) /* copy 0-term.ed str */\ { \ (keyTo) = (ulong)HTsmalloc( WORD_ROUND(strlen((char *)(keyFrom))+1) ); \ strcpy((char *)(keyTo), (char *)(keyFrom)); \ } \ else \ { \ (keyTo) = (ulong) HTsmalloc( WORD_ROUND((ht)->cchKey) ); \ memcpy( (char *)(keyTo), (char *)(keyFrom), (ht)->cchKey); \ } \ while ( 0 ) #define FREE_KEY(ht, key) do \ if ( STORES_PTR(ht) && (ht)->fSaveKeys ) \ if ( (ht)->cchKey == NULL_TERMINATED ) \ HTfree((char *)(key), WORD_ROUND(strlen((char *)(key))+1)); \ else \ HTfree((char *)(key), WORD_ROUND((ht)->cchKey)); \ while ( 0 ) /* the following are useful for bitmaps */ /* Format is like this (if 1 word = 4 bits): 3210 7654 ba98 fedc ... */ typedef ulong HTBitmapPart; /* this has to be unsigned, for >> */ typedef HTBitmapPart HTBitmap[1<> LOG_WORD_SIZE) << (LOG_WORD_SIZE-3) ) #define MOD2(i, logmod) ( (i) & ((1<<(logmod))-1) ) #define DIV_NUM_ENTRIES(i) ( (i) >> LOG_WORD_SIZE ) #define MOD_NUM_ENTRIES(i) ( MOD2(i, LOG_WORD_SIZE) ) #define MODBIT(i) ( ((ulong)1) << MOD_NUM_ENTRIES(i) ) #define TEST_BITMAP(bm, i) ( (bm)[DIV_NUM_ENTRIES(i)] & MODBIT(i) ? 1 : 0 ) #define SET_BITMAP(bm, i) (bm)[DIV_NUM_ENTRIES(i)] |= MODBIT(i) #define CLEAR_BITMAP(bm, i) (bm)[DIV_NUM_ENTRIES(i)] &= ~MODBIT(i) /* the following are useful for reading and writing hashtables */ #define READ_UL(fp, data) \ do { \ long _ul; \ fread(&_ul, sizeof(_ul), 1, (fp)); \ data = ntohl(_ul); \ } while (0) #define WRITE_UL(fp, data) \ do { \ long _ul = htonl((long)(data)); \ fwrite(&_ul, sizeof(_ul), 1, (fp)); \ } while (0) /* Moves data from disk to memory if necessary. Note dataRead cannot be * * NULL, because then we might as well (and do) load the data into memory */ #define LOAD_AND_RETURN(ht, loadCommand) /* lC returns an HTItem * */ \ if ( !(ht)->fpData ) /* data is stored in memory */ \ return (loadCommand); \ else /* must read data off of disk */ \ { \ int cchData; \ HTItem *bck; \ if ( (ht)->bckData.data ) free((char *)(ht)->bckData.data); \ ht->bckData.data = (ulong)NULL; /* needed if loadCommand fails */ \ bck = (loadCommand); \ if ( bck == NULL ) /* loadCommand failed: key not found */ \ return NULL; \ else \ (ht)->bckData = *bck; \ fseek(ht->fpData, (ht)->bckData.data, SEEK_SET); \ READ_UL((ht)->fpData, cchData); \ (ht)->bckData.data = (ulong)(ht)->dataRead((ht)->fpData, cchData); \ return &((ht)->bckData); \ } /* ======================================================================== */ /* UTILITY ROUTINES */ /* ---------------------- */ /* HTsmalloc() -- safe malloc * allocates memory, or crashes if the allocation fails. */ static void *HTsmalloc(unsigned long size) { void *retval; if ( size == 0 ) return NULL; retval = (void *)malloc(size); if ( !retval ) { fprintf(stderr, "HTsmalloc: Unable to allocate %lu bytes of memory\n", size); exit(1); } return retval; } /* HTscalloc() -- safe calloc * allocates memory and initializes it to 0, or crashes if * the allocation fails. */ static void *HTscalloc(unsigned long size) { void *retval; retval = (void *)calloc(size, 1); if ( !retval && size > 0 ) { fprintf(stderr, "HTscalloc: Unable to allocate %lu bytes of memory\n", size); exit(1); } return retval; } /* HTsrealloc() -- safe calloc * grows the amount of memory from a source, or crashes if * the allocation fails. */ static void *HTsrealloc(void *ptr, unsigned long new_size, long delta) { if ( ptr == NULL ) return HTsmalloc(new_size); ptr = realloc(ptr, new_size); if ( !ptr && new_size > 0 ) { fprintf(stderr, "HTsrealloc: Unable to reallocate %lu bytes of memory\n", new_size); exit(1); } return ptr; } /* HTfree() -- keep track of memory use * frees memory using free, but updates count of how much memory * is being used. */ static void HTfree(void *ptr, unsigned long size) { if ( size > 0 ) /* some systems seem to not like freeing NULL */ free(ptr); } /*************************************************************************\ | HTcopy() | | Sometimes we interpret data as a ulong. But ulongs must be | | aligned on some machines, so instead of casting we copy. | \*************************************************************************/ unsigned long HTcopy(char *ul) { unsigned long retval; memcpy(&retval, ul, sizeof(retval)); return retval; } /*************************************************************************\ | HTSetupKeyTrunc() | | If keys are stored directly but cchKey is less than | | sizeof(ulong), this cuts off the bits at the end. | \*************************************************************************/ static void HTSetupKeyTrunc(void) { int i, j; for ( i = 0; i < sizeof(unsigned long); i++ ) for ( j = 0; j < sizeof(unsigned long); j++ ) grgKeyTruncMask[i][j] = j < i ? 255 : 0; /* chars have 8 bits */ } /* ======================================================================== */ /* TABLE ROUTINES */ /* -------------------- */ /* The idea is that a hashtable with (logically) t buckets is divided * into t/M groups of M buckets each. (M is a constant set in * LOG_BM_WORDS for efficiency.) Each group is stored sparsely. * Thus, inserting into the table causes some array to grow, which is * slow but still constant time. Lookup involves doing a * logical-position-to-sparse-position lookup, which is also slow but * constant time. The larger M is, the slower these operations are * but the less overhead (slightly). * * To store the sparse array, we store a bitmap B, where B[i] = 1 iff * bucket i is non-empty. Then to look up bucket i we really look up * array[# of 1s before i in B]. This is constant time for fixed M. * * Terminology: the position of an item in the overall table (from * 1 .. t) is called its "location." The logical position in a group * (from 1 .. M ) is called its "position." The actual location in * the array (from 1 .. # of non-empty buckets in the group) is * called its "offset." * * The following operations are supported: * o Allocate an array with t buckets, all empty * o Free a array (but not whatever was stored in the buckets) * o Tell whether or not a bucket is empty * o Return a bucket with a given location * o Set the value of a bucket at a given location * o Iterate through all the buckets in the array * o Read and write an occupancy bitmap to disk * o Return how much memory is being allocated by the array structure */ #ifndef SparseBucket /* by default, each bucket holds an HTItem */ #define SparseBucket HTItem #endif typedef struct SparseBin { SparseBucket *binSparse; HTBitmap bmOccupied; /* bmOccupied[i] is 1 if bucket i has an item */ short cOccupied; /* size of binSparse; useful for iterators, eg */ } SparseBin; typedef struct SparseIterator { long posGroup; long posOffset; SparseBin *binSparse; /* state info, to avoid args for NextBucket() */ ulong cBuckets; } SparseIterator; #define LOG_LOW_BIN_SIZE ( LOG_BM_WORDS+LOG_WORD_SIZE ) #define SPARSE_GROUPS(cBuckets) ( (((cBuckets)-1) >> LOG_LOW_BIN_SIZE) + 1 ) /* we need a small function to figure out # of items set in the bm */ static HTOffset EntriesUpto(HTBitmapPart *bm, int i) { /* returns # of set bits in 0..i-1 */ HTOffset retval = 0; static HTOffset rgcBits[256] = /* # of bits set in one char */ {0, 1, 1, 2, 1, 2, 2, 3, 1, 2, 2, 3, 2, 3, 3, 4, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 1, 2, 2, 3, 2, 3, 3, 4, 2, 3, 3, 4, 3, 4, 4, 5, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 2, 3, 3, 4, 3, 4, 4, 5, 3, 4, 4, 5, 4, 5, 5, 6, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 3, 4, 4, 5, 4, 5, 5, 6, 4, 5, 5, 6, 5, 6, 6, 7, 4, 5, 5, 6, 5, 6, 6, 7, 5, 6, 6, 7, 6, 7, 7, 8}; if ( i == 0 ) return 0; for ( ; i > sizeof(*bm)*8; i -= sizeof(*bm)*8, bm++ ) { /* think of it as loop unrolling */ #if LOG_WORD_SIZE >= 3 /* 1 byte per word, or more */ retval += rgcBits[*bm & 255]; /* get the low byte */ #if LOG_WORD_SIZE >= 4 /* at least 2 bytes */ retval += rgcBits[(*bm >> 8) & 255]; #if LOG_WORD_SIZE >= 5 /* at least 4 bytes */ retval += rgcBits[(*bm >> 16) & 255]; retval += rgcBits[(*bm >> 24) & 255]; #if LOG_WORD_SIZE >= 6 /* 8 bytes! */ retval += rgcBits[(*bm >> 32) & 255]; retval += rgcBits[(*bm >> 40) & 255]; retval += rgcBits[(*bm >> 48) & 255]; retval += rgcBits[(*bm >> 56) & 255]; #if LOG_WORD_SIZE >= 7 /* not a concern for a while... */ #error Need to rewrite EntriesUpto to support such big words #endif /* >8 bytes */ #endif /* 8 bytes */ #endif /* 4 bytes */ #endif /* 2 bytes */ #endif /* 1 byte */ } switch ( i ) { /* from 0 to 63 */ case 0: return retval; #if LOG_WORD_SIZE >= 3 /* 1 byte per word, or more */ case 1: case 2: case 3: case 4: case 5: case 6: case 7: case 8: return (retval + rgcBits[*bm & ((1 << i)-1)]); #if LOG_WORD_SIZE >= 4 /* at least 2 bytes */ case 9: case 10: case 11: case 12: case 13: case 14: case 15: case 16: return (retval + rgcBits[*bm & 255] + rgcBits[(*bm >> 8) & ((1 << (i-8))-1)]); #if LOG_WORD_SIZE >= 5 /* at least 4 bytes */ case 17: case 18: case 19: case 20: case 21: case 22: case 23: case 24: return (retval + rgcBits[*bm & 255] + rgcBits[(*bm >> 8) & 255] + rgcBits[(*bm >> 16) & ((1 << (i-16))-1)]); case 25: case 26: case 27: case 28: case 29: case 30: case 31: case 32: return (retval + rgcBits[*bm & 255] + rgcBits[(*bm >> 8) & 255] + rgcBits[(*bm >> 16) & 255] + rgcBits[(*bm >> 24) & ((1 << (i-24))-1)]); #if LOG_WORD_SIZE >= 6 /* 8 bytes! */ case 33: case 34: case 35: case 36: case 37: case 38: case 39: case 40: return (retval + rgcBits[*bm & 255] + rgcBits[(*bm >> 8) & 255] + rgcBits[(*bm >> 16) & 255] + rgcBits[(*bm >> 24) & 255] + rgcBits[(*bm >> 32) & ((1 << (i-32))-1)]); case 41: case 42: case 43: case 44: case 45: case 46: case 47: case 48: return (retval + rgcBits[*bm & 255] + rgcBits[(*bm >> 8) & 255] + rgcBits[(*bm >> 16) & 255] + rgcBits[(*bm >> 24) & 255] + rgcBits[(*bm >> 32) & 255] + rgcBits[(*bm >> 40) & ((1 << (i-40))-1)]); case 49: case 50: case 51: case 52: case 53: case 54: case 55: case 56: return (retval + rgcBits[*bm & 255] + rgcBits[(*bm >> 8) & 255] + rgcBits[(*bm >> 16) & 255] + rgcBits[(*bm >> 24) & 255] + rgcBits[(*bm >> 32) & 255] + rgcBits[(*bm >> 40) & 255] + rgcBits[(*bm >> 48) & ((1 << (i-48))-1)]); case 57: case 58: case 59: case 60: case 61: case 62: case 63: case 64: return (retval + rgcBits[*bm & 255] + rgcBits[(*bm >> 8) & 255] + rgcBits[(*bm >> 16) & 255] + rgcBits[(*bm >> 24) & 255] + rgcBits[(*bm >> 32) & 255] + rgcBits[(*bm >> 40) & 255] + rgcBits[(*bm >> 48) & 255] + rgcBits[(*bm >> 56) & ((1 << (i-56))-1)]); #endif /* 8 bytes */ #endif /* 4 bytes */ #endif /* 2 bytes */ #endif /* 1 byte */ } assert("" == "word size is too big in EntriesUpto()"); return -1; } #define SPARSE_POS_TO_OFFSET(bm, i) ( EntriesUpto(&((bm)[0]), i) ) #define SPARSE_BUCKET(bin, location) \ ( (bin)[(location) >> LOG_LOW_BIN_SIZE].binSparse + \ SPARSE_POS_TO_OFFSET((bin)[(location)>>LOG_LOW_BIN_SIZE].bmOccupied, \ MOD2(location, LOG_LOW_BIN_SIZE)) ) /*************************************************************************\ | SparseAllocate() | | SparseFree() | | Allocates, sets-to-empty, and frees a sparse array. All you need | | to tell me is how many buckets you want. I return the number of | | buckets I actually allocated, setting the array as a parameter. | | Note that you have to set auxilliary parameters, like cOccupied. | \*************************************************************************/ static ulong SparseAllocate(SparseBin **pbinSparse, ulong cBuckets) { int cGroups = SPARSE_GROUPS(cBuckets); *pbinSparse = (SparseBin *) HTscalloc(sizeof(**pbinSparse) * cGroups); return cGroups << LOG_LOW_BIN_SIZE; } static SparseBin *SparseFree(SparseBin *binSparse, ulong cBuckets) { ulong iGroup, cGroups = SPARSE_GROUPS(cBuckets); for ( iGroup = 0; iGroup < cGroups; iGroup++ ) HTfree(binSparse[iGroup].binSparse, (sizeof(*binSparse[iGroup].binSparse) * binSparse[iGroup].cOccupied)); HTfree(binSparse, sizeof(*binSparse) * cGroups); return NULL; } /*************************************************************************\ | SparseIsEmpty() | | SparseFind() | | You give me a location (ie a number between 1 and t), and I | | return the bucket at that location, or NULL if the bucket is | | empty. It's OK to call Find() on an empty table. | \*************************************************************************/ static int SparseIsEmpty(SparseBin *binSparse, ulong location) { return !TEST_BITMAP(binSparse[location>>LOG_LOW_BIN_SIZE].bmOccupied, MOD2(location, LOG_LOW_BIN_SIZE)); } static SparseBucket *SparseFind(SparseBin *binSparse, ulong location) { if ( SparseIsEmpty(binSparse, location) ) return NULL; return SPARSE_BUCKET(binSparse, location); } /*************************************************************************\ | SparseInsert() | | You give me a location, and contents to put there, and I insert | | into that location and RETURN a pointer to the location. If | | bucket was already occupied, I write over the contents only if | | *pfOverwrite is 1. We set *pfOverwrite to 1 if there was someone | | there (whether or not we overwrote) and 0 else. | \*************************************************************************/ static SparseBucket *SparseInsert(SparseBin *binSparse, SparseBucket *bckInsert, ulong location, int *pfOverwrite) { SparseBucket *bckPlace; HTOffset offset; bckPlace = SparseFind(binSparse, location); if ( bckPlace ) /* means we replace old contents */ { if ( *pfOverwrite ) *bckPlace = *bckInsert; *pfOverwrite = 1; return bckPlace; } binSparse += (location >> LOG_LOW_BIN_SIZE); offset = SPARSE_POS_TO_OFFSET(binSparse->bmOccupied, MOD2(location, LOG_LOW_BIN_SIZE)); binSparse->binSparse = (SparseBucket *) HTsrealloc(binSparse->binSparse, sizeof(*binSparse->binSparse) * ++binSparse->cOccupied, sizeof(*binSparse->binSparse)); memmove(binSparse->binSparse + offset+1, binSparse->binSparse + offset, (binSparse->cOccupied-1 - offset) * sizeof(*binSparse->binSparse)); binSparse->binSparse[offset] = *bckInsert; SET_BITMAP(binSparse->bmOccupied, MOD2(location, LOG_LOW_BIN_SIZE)); *pfOverwrite = 0; return binSparse->binSparse + offset; } /*************************************************************************\ | SparseFirstBucket() | | SparseNextBucket() | | SparseCurrentBit() | | Iterate through the occupied buckets of a dense hashtable. You | | must, of course, have allocated space yourself for the iterator. | \*************************************************************************/ static SparseBucket *SparseNextBucket(SparseIterator *iter) { if ( iter->posOffset != -1 && /* not called from FirstBucket()? */ (++iter->posOffset < iter->binSparse[iter->posGroup].cOccupied) ) return iter->binSparse[iter->posGroup].binSparse + iter->posOffset; iter->posOffset = 0; /* start the next group */ for ( iter->posGroup++; iter->posGroup < SPARSE_GROUPS(iter->cBuckets); iter->posGroup++ ) if ( iter->binSparse[iter->posGroup].cOccupied > 0 ) return iter->binSparse[iter->posGroup].binSparse; /* + 0 */ return NULL; /* all remaining groups were empty */ } static SparseBucket *SparseFirstBucket(SparseIterator *iter, SparseBin *binSparse, ulong cBuckets) { iter->binSparse = binSparse; /* set it up for NextBucket() */ iter->cBuckets = cBuckets; iter->posOffset = -1; /* when we advance, we're at 0 */ iter->posGroup = -1; return SparseNextBucket(iter); } /*************************************************************************\ | SparseWrite() | | SparseRead() | | These are routines for storing a sparse hashtable onto disk. We | | store the number of buckets and a bitmap indicating which buckets | | are allocated (occupied). The actual contents of the buckets | | must be stored separately. | \*************************************************************************/ static void SparseWrite(FILE *fp, SparseBin *binSparse, ulong cBuckets) { ulong i, j; WRITE_UL(fp, cBuckets); for ( i = 0; i < SPARSE_GROUPS(cBuckets); i++ ) for ( j = 0; j < (1<rgBuckets, cBuckets); } static ulong DenseAllocate(DenseBin **pbin, ulong cBuckets) { *pbin = (DenseBin *) HTsmalloc(sizeof(*pbin)); (*pbin)->rgBuckets = (DenseBucket *) HTsmalloc(sizeof(*(*pbin)->rgBuckets) * cBuckets); DenseClear(*pbin, cBuckets); return cBuckets; } static DenseBin *DenseFree(DenseBin *bin, ulong cBuckets) { HTfree(bin->rgBuckets, sizeof(*bin->rgBuckets) * cBuckets); HTfree(bin, sizeof(*bin)); return NULL; } static int DenseIsEmpty(DenseBin *bin, ulong location) { return DENSE_IS_EMPTY(bin->rgBuckets, location); } static DenseBucket *DenseFind(DenseBin *bin, ulong location) { if ( DenseIsEmpty(bin, location) ) return NULL; return bin->rgBuckets + location; } static DenseBucket *DenseInsert(DenseBin *bin, DenseBucket *bckInsert, ulong location, int *pfOverwrite) { DenseBucket *bckPlace; bckPlace = DenseFind(bin, location); if ( bckPlace ) /* means something is already there */ { if ( *pfOverwrite ) *bckPlace = *bckInsert; *pfOverwrite = 1; /* set to 1 to indicate someone was there */ return bckPlace; } else { bin->rgBuckets[location] = *bckInsert; *pfOverwrite = 0; return bin->rgBuckets + location; } } static DenseBucket *DenseNextBucket(DenseIterator *iter) { for ( iter->pos++; iter->pos < iter->cBuckets; iter->pos++ ) if ( !DenseIsEmpty(iter->bin, iter->pos) ) return iter->bin->rgBuckets + iter->pos; return NULL; /* all remaining groups were empty */ } static DenseBucket *DenseFirstBucket(DenseIterator *iter, DenseBin *bin, ulong cBuckets) { iter->bin = bin; /* set it up for NextBucket() */ iter->cBuckets = cBuckets; iter->pos = -1; /* thus the next bucket will be 0 */ return DenseNextBucket(iter); } static void DenseWrite(FILE *fp, DenseBin *bin, ulong cBuckets) { ulong pos = 0, bit, bm; WRITE_UL(fp, cBuckets); while ( pos < cBuckets ) { bm = 0; for ( bit = 0; bit < 8*sizeof(ulong); bit++ ) { if ( !DenseIsEmpty(bin, pos) ) SET_BITMAP(&bm, bit); /* in fks-hash.h */ if ( ++pos == cBuckets ) break; } WRITE_UL(fp, bm); } } static ulong DenseRead(FILE *fp, DenseBin **pbin) { ulong pos = 0, bit, bm, cBuckets; READ_UL(fp, cBuckets); cBuckets = DenseAllocate(pbin, cBuckets); while ( pos < cBuckets ) { READ_UL(fp, bm); for ( bit = 0; bit < 8*sizeof(ulong); bit++ ) { if ( TEST_BITMAP(&bm, bit) ) /* in fks-hash.h */ DENSE_SET_OCCUPIED((*pbin)->rgBuckets, pos); else DENSE_SET_EMPTY((*pbin)->rgBuckets, pos); if ( ++pos == cBuckets ) break; } } return cBuckets; } static ulong DenseMemory(ulong cBuckets, ulong cOccupied) { return cBuckets * sizeof(DenseBucket); } /* ======================================================================== */ /* HASHING ROUTINES */ /* ---------------------- */ /* Implements a simple quadratic hashing scheme. We have a single hash * table of size t and a single hash function h(x). When inserting an * item, first we try h(x) % t. If it's occupied, we try h(x) + * i*(i-1)/2 % t for increasing values of i until we hit a not-occupied * space. To make this dynamic, we double the size of the hash table as * soon as more than half the cells are occupied. When deleting, we can * choose to shrink the hashtable when less than a quarter of the * cells are occupied, or we can choose never to shrink the hashtable. * For lookup, we check h(x) + i*(i-1)/2 % t (starting with i=0) until * we get a match or we hit an empty space. Note that as a result, * we can't make a cell empty on deletion, or lookups may end prematurely. * Instead we mark the cell as "deleted." We thus steal the value * DELETED as a possible "data" value. As long as data are pointers, * that's ok. * The hash increment we use, i(i-1)/2, is not the standard quadratic * hash increment, which is i^2. i(i-1)/2 covers the entire bucket space * when the hashtable size is a power of two, as it is for us. In fact, * the first n probes cover n distinct buckets; then it repeats. This * guarantees insertion will always succeed. * If you linear hashing, set JUMP in chash.h. You can also change * various other parameters there. */ /*************************************************************************\ | Hash() | | The hash function I use is due to Bob Jenkins (see | | http://ourworld.compuserve.com/homepages/bob_jenkins/evahash.htm). | | It takes 36 instructions, in 18 cycles if you're lucky. | | hashing depends on the fact the hashtable size is always a | | power of 2. cBuckets is probably ht->cBuckets. | \*************************************************************************/ #if LOG_WORD_SIZE == 5 /* 32 bit words */ #define mix(a,b,c) \ { \ a -= b; a -= c; a ^= (c>>13); \ b -= c; b -= a; b ^= (a<<8); \ c -= a; c -= b; c ^= (b>>13); \ a -= b; a -= c; a ^= (c>>12); \ b -= c; b -= a; b ^= (a<<16); \ c -= a; c -= b; c ^= (b>>5); \ a -= b; a -= c; a ^= (c>>3); \ b -= c; b -= a; b ^= (a<<10); \ c -= a; c -= b; c ^= (b>>15); \ } #ifdef WORD_HASH /* play with this on little-endian machines */ #define WORD_AT(ptr) ( *(ulong *)(ptr) ) #else #define WORD_AT(ptr) ( (ptr)[0] + ((ulong)(ptr)[1]<<8) + \ ((ulong)(ptr)[2]<<16) + ((ulong)(ptr)[3]<<24) ) #endif #elif LOG_WORD_SIZE == 6 /* 64 bit words */ #define mix(a,b,c) \ { \ a -= b; a -= c; a ^= (c>>43); \ b -= c; b -= a; b ^= (a<<9); \ c -= a; c -= b; c ^= (b>>8); \ a -= b; a -= c; a ^= (c>>38); \ b -= c; b -= a; b ^= (a<<23); \ c -= a; c -= b; c ^= (b>>5); \ a -= b; a -= c; a ^= (c>>35); \ b -= c; b -= a; b ^= (a<<49); \ c -= a; c -= b; c ^= (b>>11); \ a -= b; a -= c; a ^= (c>>12); \ b -= c; b -= a; b ^= (a<<18); \ c -= a; c -= b; c ^= (b>>22); \ } #ifdef WORD_HASH /* alpha is little-endian, btw */ #define WORD_AT(ptr) ( *(ulong *)(ptr) ) #else #define WORD_AT(ptr) ( (ptr)[0] + ((ulong)(ptr)[1]<<8) + \ ((ulong)(ptr)[2]<<16) + ((ulong)(ptr)[3]<<24) + \ ((ulong)(ptr)[4]<<32) + ((ulong)(ptr)[5]<<40) + \ ((ulong)(ptr)[6]<<48) + ((ulong)(ptr)[7]<<56) ) #endif #else /* neither 32 or 64 bit words */ #error This hash function can only hash 32 or 64 bit words. Sorry. #endif static ulong Hash(HashTable *ht, char *key, ulong cBuckets) { ulong a, b, c, cchKey, cchKeyOrig; cchKeyOrig = ht->cchKey == NULL_TERMINATED ? strlen(key) : ht->cchKey; a = b = c = 0x9e3779b9; /* the golden ratio; an arbitrary value */ for ( cchKey = cchKeyOrig; cchKey >= 3 * sizeof(ulong); cchKey -= 3 * sizeof(ulong), key += 3 * sizeof(ulong) ) { a += WORD_AT(key); b += WORD_AT(key + sizeof(ulong)); c += WORD_AT(key + sizeof(ulong)*2); mix(a,b,c); } c += cchKeyOrig; switch ( cchKey ) { /* deal with rest. Cases fall through */ #if LOG_WORD_SIZE == 5 case 11: c += (ulong)key[10]<<24; case 10: c += (ulong)key[9]<<16; case 9 : c += (ulong)key[8]<<8; /* the first byte of c is reserved for the length */ case 8 : b += WORD_AT(key+4); a+= WORD_AT(key); break; case 7 : b += (ulong)key[6]<<16; case 6 : b += (ulong)key[5]<<8; case 5 : b += key[4]; case 4 : a += WORD_AT(key); break; case 3 : a += (ulong)key[2]<<16; case 2 : a += (ulong)key[1]<<8; case 1 : a += key[0]; /* case 0 : nothing left to add */ #elif LOG_WORD_SIZE == 6 case 23: c += (ulong)key[22]<<56; case 22: c += (ulong)key[21]<<48; case 21: c += (ulong)key[20]<<40; case 20: c += (ulong)key[19]<<32; case 19: c += (ulong)key[18]<<24; case 18: c += (ulong)key[17]<<16; case 17: c += (ulong)key[16]<<8; /* the first byte of c is reserved for the length */ case 16: b += WORD_AT(key+8); a+= WORD_AT(key); break; case 15: b += (ulong)key[14]<<48; case 14: b += (ulong)key[13]<<40; case 13: b += (ulong)key[12]<<32; case 12: b += (ulong)key[11]<<24; case 11: b += (ulong)key[10]<<16; case 10: b += (ulong)key[ 9]<<8; case 9: b += (ulong)key[ 8]; case 8: a += WORD_AT(key); break; case 7: a += (ulong)key[ 6]<<48; case 6: a += (ulong)key[ 5]<<40; case 5: a += (ulong)key[ 4]<<32; case 4: a += (ulong)key[ 3]<<24; case 3: a += (ulong)key[ 2]<<16; case 2: a += (ulong)key[ 1]<<8; case 1: a += (ulong)key[ 0]; /* case 0: nothing left to add */ #endif } mix(a,b,c); return c & (cBuckets-1); } /*************************************************************************\ | Rehash() | | You give me a hashtable, a new size, and a bucket to follow, and | | I resize the hashtable's bin to be the new size, rehashing | | everything in it. I keep particular track of the bucket you pass | | in, and RETURN a pointer to where the item in the bucket got to. | | (If you pass in NULL, I return an arbitrary pointer.) | \*************************************************************************/ static HTItem *Rehash(HashTable *ht, ulong cNewBuckets, HTItem *bckWatch) { Table *tableNew; ulong iBucketFirst; HTItem *bck, *bckNew = NULL; ulong offset; /* the i in h(x) + i*(i-1)/2 */ int fOverwrite = 0; /* not an issue: there can be no collisions */ assert( ht->table ); cNewBuckets = Table(Allocate)(&tableNew, cNewBuckets); /* Since we RETURN the new position of bckWatch, we want * * to make sure it doesn't get moved due to some table * * rehashing that comes after it's inserted. Thus, we * * have to put it in last. This makes the loop weird. */ for ( bck = HashFirstBucket(ht); ; bck = HashNextBucket(ht) ) { if ( bck == NULL ) /* we're done iterating, so look at bckWatch */ { bck = bckWatch; if ( bck == NULL ) /* I guess bckWatch wasn't specified */ break; } else if ( bck == bckWatch ) continue; /* ignore if we see it during the iteration */ offset = 0; /* a new i for a new bucket */ for ( iBucketFirst = Hash(ht, KEY_PTR(ht, bck->key), cNewBuckets); !Table(IsEmpty)(tableNew, iBucketFirst); iBucketFirst = (iBucketFirst + JUMP(KEY_PTR(ht,bck->key), offset)) & (cNewBuckets-1) ) ; bckNew = Table(Insert)(tableNew, bck, iBucketFirst, &fOverwrite); if ( bck == bckWatch ) /* we're done with the last thing to do */ break; } Table(Free)(ht->table, ht->cBuckets); ht->table = tableNew; ht->cBuckets = cNewBuckets; ht->cDeletedItems = 0; return bckNew; /* new position of bckWatch, which was inserted last */ } /*************************************************************************\ | Find() | | Does the quadratic searching stuff. RETURNS NULL if we don't | | find an object with the given key, and a pointer to the Item | | holding the key, if we do. Also sets posLastFind. If piEmpty is | | non-NULL, we set it to the first open bucket we pass; helpful for | | doing a later insert if the search fails, for instance. | \*************************************************************************/ static HTItem *Find(HashTable *ht, ulong key, ulong *piEmpty) { ulong iBucketFirst; HTItem *item; ulong offset = 0; /* the i in h(x) + i*(i-1)/2 */ int fFoundEmpty = 0; /* set when we pass over an empty bucket */ ht->posLastFind = NULL; /* set up for failure: a new find starts */ if ( ht->table == NULL ) /* empty hash table: find is bound to fail */ return NULL; iBucketFirst = Hash(ht, KEY_PTR(ht, key), ht->cBuckets); while ( 1 ) /* now try all i > 0 */ { item = Table(Find)(ht->table, iBucketFirst); if ( item == NULL ) /* it's not in the table */ { if ( piEmpty && !fFoundEmpty ) *piEmpty = iBucketFirst; return NULL; } else { if ( IS_BCK_DELETED(item) ) /* always 0 ifdef INSERT_ONLY */ { if ( piEmpty && !fFoundEmpty ) { *piEmpty = iBucketFirst; fFoundEmpty = 1; } } else if ( !KEY_CMP(ht, key, item->key) ) /* must be occupied */ { ht->posLastFind = item; return item; /* we found it! */ } } iBucketFirst = ((iBucketFirst + JUMP(KEY_PTR(ht, key), offset)) & (ht->cBuckets-1)); } } /*************************************************************************\ | Insert() | | If an item with the key already exists in the hashtable, RETURNS | | a pointer to the item (replacing its data if fOverwrite is 1). | | If not, we find the first place-to-insert (which Find() is nice | | enough to set for us) and insert the item there, RETURNing a | | pointer to the item. We might grow the hashtable if it's getting | | full. Note we include buckets holding DELETED when determining | | fullness, because they slow down searching. | \*************************************************************************/ static ulong NextPow2(ulong x) /* returns next power of 2 > x, or 2^31 */ { if ( ((x << 1) >> 1) != x ) /* next power of 2 overflows */ x >>= 1; /* so we return highest power of 2 we can */ while ( (x & (x-1)) != 0 ) /* blacks out all but the top bit */ x &= (x-1); return x << 1; /* makes it the *next* power of 2 */ } static HTItem *Insert(HashTable *ht, ulong key, ulong data, int fOverwrite) { HTItem *item, bckInsert; ulong iEmpty; /* first empty bucket key probes */ if ( ht->table == NULL ) /* empty hash table: find is bound to fail */ return NULL; item = Find(ht, key, &iEmpty); ht->posLastFind = NULL; /* last operation is insert, not find */ if ( item ) { if ( fOverwrite ) item->data = data; /* key already matches */ return item; } COPY_KEY(ht, bckInsert.key, key); /* make our own copy of the key */ bckInsert.data = data; /* oh, and the data too */ item = Table(Insert)(ht->table, &bckInsert, iEmpty, &fOverwrite); if ( fOverwrite ) /* we overwrote a deleted bucket */ ht->cDeletedItems--; ht->cItems++; /* insert couldn't have overwritten */ if ( ht->cDeltaGoalSize > 0 ) /* closer to our goal size */ ht->cDeltaGoalSize--; if ( ht->cItems + ht->cDeletedItems >= ht->cBuckets * OCCUPANCY_PCT || ht->cDeltaGoalSize < 0 ) /* we must've overestimated # of deletes */ item = Rehash(ht, NextPow2((ulong)(((ht->cDeltaGoalSize > 0 ? ht->cDeltaGoalSize : 0) + ht->cItems) / OCCUPANCY_PCT)), item); return item; } /*************************************************************************\ | Delete() | | Removes the item from the hashtable, and if fShrink is 1, will | | shrink the hashtable if it's too small (ie even after halving, | | the ht would be less than half full, though in order to avoid | | oscillating table size, we insist that after halving the ht would | | be less than 40% full). RETURNS 1 if the item was found, 0 else. | | If fLastFindSet is true, then this function is basically | | DeleteLastFind. | \*************************************************************************/ static int Delete(HashTable *ht, ulong key, int fShrink, int fLastFindSet) { if ( !fLastFindSet && !Find(ht, key, NULL) ) return 0; SET_BCK_DELETED(ht, ht->posLastFind); /* find set this, how nice */ ht->cItems--; ht->cDeletedItems++; if ( ht->cDeltaGoalSize < 0 ) /* heading towards our goal of deletion */ ht->cDeltaGoalSize++; if ( fShrink && ht->cItems < ht->cBuckets * OCCUPANCY_PCT*0.4 && ht->cDeltaGoalSize >= 0 /* wait until we're done deleting */ && (ht->cBuckets >> 1) >= MIN_HASH_SIZE ) /* shrink */ Rehash(ht, NextPow2((ulong)((ht->cItems+ht->cDeltaGoalSize)/OCCUPANCY_PCT)), NULL); ht->posLastFind = NULL; /* last operation is delete, not find */ return 1; } /* ======================================================================== */ /* USER-VISIBLE API */ /* ---------------------- */ /*************************************************************************\ | AllocateHashTable() | | ClearHashTable() | | FreeHashTable() | | Allocate() allocates a hash table and sets up size parameters. | | Free() frees it. Clear() deletes all the items from the hash | | table, but frees not. | | cchKey is < 0 if the keys you send me are meant to be pointers | | to \0-terminated strings. Then -cchKey is the maximum key size. | | If cchKey < one word (ulong), the keys you send me are the keys | | themselves; else the keys you send me are pointers to the data. | | If fSaveKeys is 1, we copy any keys given to us to insert. We | | also free these keys when freeing the hash table. If it's 0, the | | user is responsible for key space management. | | AllocateHashTable() RETURNS a hash table; the others TAKE one. | \*************************************************************************/ HashTable *AllocateHashTable(int cchKey, int fSaveKeys) { HashTable *ht; ht = (HashTable *) HTsmalloc(sizeof(*ht)); /* set everything to 0 */ ht->cBuckets = Table(Allocate)(&ht->table, MIN_HASH_SIZE); ht->cchKey = cchKey <= 0 ? NULL_TERMINATED : cchKey; ht->cItems = 0; ht->cDeletedItems = 0; ht->fSaveKeys = fSaveKeys; ht->cDeltaGoalSize = 0; ht->iter = HTsmalloc( sizeof(TableIterator) ); ht->fpData = NULL; /* set by HashLoad, maybe */ ht->bckData.data = (ulong) NULL; /* this must be done */ HTSetupKeyTrunc(); /* in util.c */ return ht; } void ClearHashTable(HashTable *ht) { HTItem *bck; if ( STORES_PTR(ht) && ht->fSaveKeys ) /* need to free keys */ for ( bck = HashFirstBucket(ht); bck; bck = HashNextBucket(ht) ) { FREE_KEY(ht, bck->key); if ( ht->fSaveKeys == 2 ) /* this means key stored in one block */ break; /* ...so only free once */ } Table(Free)(ht->table, ht->cBuckets); ht->cBuckets = Table(Allocate)(&ht->table, MIN_HASH_SIZE); ht->cItems = 0; ht->cDeletedItems = 0; ht->cDeltaGoalSize = 0; ht->posLastFind = NULL; ht->fpData = NULL; /* no longer HashLoading */ if ( ht->bckData.data ) free( (char *)(ht)->bckData.data); ht->bckData.data = (ulong) NULL; } void FreeHashTable(HashTable *ht) { ClearHashTable(ht); if ( ht->iter ) HTfree(ht->iter, sizeof(TableIterator)); if ( ht->table ) Table(Free)(ht->table, ht->cBuckets); free(ht); } /*************************************************************************\ | HashFind() | | HashFindLast() | | HashFind(): looks in h(x) + i(i-1)/2 % t as i goes up from 0 | | until we either find the key or hit an empty bucket. RETURNS a | | pointer to the item in the hit bucket, if we find it, else | | RETURNS NULL. | | HashFindLast() returns the item returned by the last | | HashFind(), which may be NULL if the last HashFind() failed. | | LOAD_AND_RETURN reads the data from off disk, if necessary. | \*************************************************************************/ HTItem *HashFind(HashTable *ht, ulong key) { LOAD_AND_RETURN(ht, Find(ht, KEY_TRUNC(ht, key), NULL)); } HTItem *HashFindLast(HashTable *ht) { LOAD_AND_RETURN(ht, ht->posLastFind); } /*************************************************************************\ | HashFindOrInsert() | | HashFindOrInsertItem() | | HashInsert() | | HashInsertItem() | | HashDelete() | | HashDeleteLast() | | Pretty obvious what these guys do. Some take buckets (items), | | some take keys and data separately. All things RETURN the bucket | | (a pointer into the hashtable) if appropriate. | \*************************************************************************/ HTItem *HashFindOrInsert(HashTable *ht, ulong key, ulong dataInsert) { /* This is equivalent to Insert without samekey-overwrite */ return Insert(ht, KEY_TRUNC(ht, key), dataInsert, 0); } HTItem *HashFindOrInsertItem(HashTable *ht, HTItem *pItem) { return HashFindOrInsert(ht, pItem->key, pItem->data); } HTItem *HashInsert(HashTable *ht, ulong key, ulong data) { return Insert(ht, KEY_TRUNC(ht, key), data, SAMEKEY_OVERWRITE); } HTItem *HashInsertItem(HashTable *ht, HTItem *pItem) { return HashInsert(ht, pItem->key, pItem->data); } int HashDelete(HashTable *ht, ulong key) { return Delete(ht, KEY_TRUNC(ht, key), !FAST_DELETE, 0); } int HashDeleteLast(HashTable *ht) { if ( !ht->posLastFind ) /* last find failed */ return 0; return Delete(ht, 0, !FAST_DELETE, 1); /* no need to specify a key */ } /*************************************************************************\ | HashFirstBucket() | | HashNextBucket() | | Iterates through the items in the hashtable by iterating through | | the table. Since we know about deleted buckets and loading data | | off disk, and the table doesn't, our job is to take care of these | | things. RETURNS a bucket, or NULL after the last bucket. | \*************************************************************************/ HTItem *HashFirstBucket(HashTable *ht) { HTItem *retval; for ( retval = Table(FirstBucket)(ht->iter, ht->table, ht->cBuckets); retval; retval = Table(NextBucket)(ht->iter) ) if ( !IS_BCK_DELETED(retval) ) LOAD_AND_RETURN(ht, retval); return NULL; } HTItem *HashNextBucket(HashTable *ht) { HTItem *retval; while ( (retval=Table(NextBucket)(ht->iter)) ) if ( !IS_BCK_DELETED(retval) ) LOAD_AND_RETURN(ht, retval); return NULL; } /*************************************************************************\ | HashSetDeltaGoalSize() | | If we're going to insert 100 items, set the delta goal size to | | 100 and we take that into account when inserting. Likewise, if | | we're going to delete 10 items, set it to -100 and we won't | | rehash until all 100 have been done. It's ok to be wrong, but | | it's efficient to be right. Returns the delta value. | \*************************************************************************/ int HashSetDeltaGoalSize(HashTable *ht, int delta) { ht->cDeltaGoalSize = delta; #if FAST_DELETE == 1 || defined INSERT_ONLY if ( ht->cDeltaGoalSize < 0 ) /* for fast delete, we never */ ht->cDeltaGoalSize = 0; /* ...rehash after deletion */ #endif return ht->cDeltaGoalSize; } /*************************************************************************\ | HashSave() | | HashLoad() | | HashLoadKeys() | | Routines for saving and loading the hashtable from disk. We can | | then use the hashtable in two ways: loading it back into memory | | (HashLoad()) or loading only the keys into memory, in which case | | the data for a given key is loaded off disk when the key is | | retrieved. The data is freed when something new is retrieved in | | its place, so this is not a "lazy-load" scheme. | | The key is saved automatically and restored upon load, but the | | user needs to specify a routine for reading and writing the data. | | fSaveKeys is of course set to 1 when you read in a hashtable. | | HashLoad RETURNS a newly allocated hashtable. | | DATA_WRITE() takes an fp and a char * (representing the data | | field), and must perform two separate tasks. If fp is NULL, | | return the number of bytes written. If not, writes the data to | | disk at the place the fp points to. | | DATA_READ() takes an fp and the number of bytes in the data | | field, and returns a char * which points to wherever you've | | written the data. Thus, you must allocate memory for the data. | | Both dataRead and dataWrite may be NULL if you just wish to | | store the data field directly, as an integer. | \*************************************************************************/ void HashSave(FILE *fp, HashTable *ht, int (*dataWrite)(FILE *, char *)) { long cchData, posStart; HTItem *bck; /* File format: magic number (4 bytes) : cchKey (one word) : cItems (one word) : cDeletedItems (one word) : table info (buckets and a bitmap) : cchAllKeys (one word) Then the keys, in a block. If cchKey is NULL_TERMINATED, the keys are null-terminated too, otherwise this takes up cchKey*cItems bytes. Note that keys are not written for DELETED buckets. Then the data: : EITHER DELETED (one word) to indicate it's a deleted bucket, : OR number of bytes for this (non-empty) bucket's data (one word). This is not stored if dataWrite == NULL since the size is known to be sizeof(ul). Plus: : the data for this bucket (variable length) All words are in network byte order. */ fprintf(fp, "%s", MAGIC_KEY); WRITE_UL(fp, ht->cchKey); /* WRITE_UL, READ_UL, etc in fks-hash.h */ WRITE_UL(fp, ht->cItems); WRITE_UL(fp, ht->cDeletedItems); Table(Write)(fp, ht->table, ht->cBuckets); /* writes cBuckets too */ WRITE_UL(fp, 0); /* to be replaced with sizeof(key block) */ posStart = ftell(fp); for ( bck = HashFirstBucket(ht); bck; bck = HashNextBucket(ht) ) fwrite(KEY_PTR(ht, bck->key), 1, (ht->cchKey == NULL_TERMINATED ? strlen(KEY_PTR(ht, bck->key))+1 : ht->cchKey), fp); cchData = ftell(fp) - posStart; fseek(fp, posStart - sizeof(unsigned long), SEEK_SET); WRITE_UL(fp, cchData); fseek(fp, 0, SEEK_END); /* done with our sojourn at the header */ /* Unlike HashFirstBucket, TableFirstBucket iters through deleted bcks */ for ( bck = Table(FirstBucket)(ht->iter, ht->table, ht->cBuckets); bck; bck = Table(NextBucket)(ht->iter) ) if ( dataWrite == NULL || IS_BCK_DELETED(bck) ) WRITE_UL(fp, bck->data); else /* write cchData followed by the data */ { WRITE_UL(fp, (*dataWrite)(NULL, (char *)bck->data)); (*dataWrite)(fp, (char *)bck->data); } } static HashTable *HashDoLoad(FILE *fp, char * (*dataRead)(FILE *, int), HashTable *ht) { ulong cchKey; char szMagicKey[4], *rgchKeys; HTItem *bck; fread(szMagicKey, 1, 4, fp); if ( strncmp(szMagicKey, MAGIC_KEY, 4) ) { fprintf(stderr, "ERROR: not a hash table (magic key is %4.4s, not %s)\n", szMagicKey, MAGIC_KEY); exit(3); } Table(Free)(ht->table, ht->cBuckets); /* allocated in AllocateHashTable */ READ_UL(fp, ht->cchKey); READ_UL(fp, ht->cItems); READ_UL(fp, ht->cDeletedItems); ht->cBuckets = Table(Read)(fp, &ht->table); /* next is the table info */ READ_UL(fp, cchKey); rgchKeys = (char *) HTsmalloc( cchKey ); /* stores all the keys */ fread(rgchKeys, 1, cchKey, fp); /* We use the table iterator so we don't try to LOAD_AND_RETURN */ for ( bck = Table(FirstBucket)(ht->iter, ht->table, ht->cBuckets); bck; bck = Table(NextBucket)(ht->iter) ) { READ_UL(fp, bck->data); /* all we need if dataRead is NULL */ if ( IS_BCK_DELETED(bck) ) /* always 0 if defined(INSERT_ONLY) */ continue; /* this is why we read the data first */ if ( dataRead != NULL ) /* if it's null, we're done */ if ( !ht->fpData ) /* load data into memory */ bck->data = (ulong)dataRead(fp, bck->data); else /* store location of data on disk */ { fseek(fp, bck->data, SEEK_CUR); /* bck->data held size of data */ bck->data = ftell(fp) - bck->data - sizeof(unsigned long); } if ( ht->cchKey == NULL_TERMINATED ) /* now read the key */ { bck->key = (ulong) rgchKeys; rgchKeys = strchr(rgchKeys, '\0') + 1; /* read past the string */ } else { if ( STORES_PTR(ht) ) /* small keys stored directly */ bck->key = (ulong) rgchKeys; else memcpy(&bck->key, rgchKeys, ht->cchKey); rgchKeys += ht->cchKey; } } if ( !STORES_PTR(ht) ) /* keys are stored directly */ HTfree(rgchKeys - cchKey, cchKey); /* we've advanced rgchK to end */ return ht; } HashTable *HashLoad(FILE *fp, char * (*dataRead)(FILE *, int)) { HashTable *ht; ht = AllocateHashTable(0, 2); /* cchKey set later, fSaveKey should be 2! */ return HashDoLoad(fp, dataRead, ht); } HashTable *HashLoadKeys(FILE *fp, char * (*dataRead)(FILE *, int)) { HashTable *ht; if ( dataRead == NULL ) return HashLoad(fp, NULL); /* no reason not to load the data here */ ht = AllocateHashTable(0, 2); /* cchKey set later, fSaveKey should be 2! */ ht->fpData = fp; /* tells HashDoLoad() to only load keys */ ht->dataRead = dataRead; return HashDoLoad(fp, dataRead, ht); } /*************************************************************************\ | PrintHashTable() | | A debugging tool. Prints the entire contents of the hash table, | | like so: : key of the contents. Returns number of bytes | | allocated. If time is not -1, we print it as the time required | | for the hash. If iForm is 0, we just print the stats. If it's | | 1, we print the keys and data too, but the keys are printed as | | ulongs. If it's 2, we print the keys correctly (as long numbers | | or as strings). | \*************************************************************************/ ulong PrintHashTable(HashTable *ht, double time, int iForm) { ulong cbData = 0, cbBin = 0, cItems = 0, cOccupied = 0; HTItem *item; printf("HASH TABLE.\n"); if ( time > -1.0 ) { printf("----------\n"); printf("Time: %27.2f\n", time); } for ( item = Table(FirstBucket)(ht->iter, ht->table, ht->cBuckets); item; item = Table(NextBucket)(ht->iter) ) { cOccupied++; /* this includes deleted buckets */ if ( IS_BCK_DELETED(item) ) /* we don't need you for anything else */ continue; cItems++; /* this is for a sanity check */ if ( STORES_PTR(ht) ) cbData += ht->cchKey == NULL_TERMINATED ? WORD_ROUND(strlen((char *)item->key)+1) : ht->cchKey; else cbBin -= sizeof(item->key), cbData += sizeof(item->key); cbBin -= sizeof(item->data), cbData += sizeof(item->data); if ( iForm != 0 ) /* we want the actual contents */ { if ( iForm == 2 && ht->cchKey == NULL_TERMINATED ) printf("%s/%lu\n", (char *)item->key, item->data); else if ( iForm == 2 && STORES_PTR(ht) ) printf("%.*s/%lu\n", (int)ht->cchKey, (char *)item->key, item->data); else /* either key actually is a ulong, or iForm == 1 */ printf("%lu/%lu\n", item->key, item->data); } } assert( cItems == ht->cItems ); /* sanity check */ cbBin = Table(Memory)(ht->cBuckets, cOccupied); printf("----------\n"); printf("%lu buckets (%lu bytes). %lu empty. %lu hold deleted items.\n" "%lu items (%lu bytes).\n" "%lu bytes total. %lu bytes (%2.1f%%) of this is ht overhead.\n", ht->cBuckets, cbBin, ht->cBuckets - cOccupied, cOccupied - ht->cItems, ht->cItems, cbData, cbData + cbBin, cbBin, cbBin*100.0/(cbBin+cbData)); return cbData + cbBin; }