Many hyperlinks are disabled.
Use anonymous login
to enable hyperlinks.
Overview
Comment: | Optimizations in the hash table module. (CVS 1896) |
---|---|
Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA1: |
d5b0269e0dd7c310460a7ffc4120ed45 |
User & Date: | drh 2004-08-20 14:08:51.000 |
Context
2004-08-20
| ||
16:02 | Add support for named wildcards in SQL statements. (CVS 1897) (check-in: d3be0b7c5a user: drh tags: trunk) | |
14:08 | Optimizations in the hash table module. (CVS 1896) (check-in: d5b0269e0d user: drh tags: trunk) | |
2004-08-19
| ||
15:12 | Enhance lemon so that a @X instead of just X in the code expands to the major token value rather than the minor token value. Use this to make the parser a few hundred bytes smaller. (CVS 1895) (check-in: 28215096e0 user: drh tags: trunk) | |
Changes
Changes to src/hash.c.
︙ | ︙ | |||
8 9 10 11 12 13 14 | ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This is the implementation of generic hash-tables ** used in SQLite. ** | | | > > > | < | 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 | ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This is the implementation of generic hash-tables ** used in SQLite. ** ** $Id: hash.c,v 1.15 2004/08/20 14:08:51 drh Exp $ */ #include "sqliteInt.h" #include <assert.h> /* Turn bulk memory into a hash table object by initializing the ** fields of the Hash structure. ** ** "pNew" is a pointer to the hash table that is to be initialized. ** keyClass is one of the constants SQLITE_HASH_INT, SQLITE_HASH_POINTER, ** SQLITE_HASH_BINARY, or SQLITE_HASH_STRING. The value of keyClass ** determines what kind of key the hash table will use. "copyKey" is ** true if the hash table should make its own private copy of keys and ** false if it should just use the supplied pointer. CopyKey only makes ** sense for SQLITE_HASH_STRING and SQLITE_HASH_BINARY and is ignored ** for other key classes. */ void sqlite3HashInit(Hash *pNew, int keyClass, int copyKey){ assert( pNew!=0 ); assert( keyClass>=SQLITE_HASH_STRING && keyClass<=SQLITE_HASH_BINARY ); pNew->keyClass = keyClass; #if 0 if( keyClass==SQLITE_HASH_POINTER || keyClass==SQLITE_HASH_INT ) copyKey = 0; #endif pNew->copyKey = copyKey; pNew->first = 0; pNew->count = 0; pNew->htsize = 0; pNew->ht = 0; } /* Remove all entries from a hash table. Reclaim all memory. |
︙ | ︙ | |||
95 96 97 98 99 100 101 | /* ** Hash and comparison functions when the mode is SQLITE_HASH_STRING */ static int strHash(const void *pKey, int nKey){ return sqlite3HashNoCase((const char*)pKey, nKey); } static int strCompare(const void *pKey1, int n1, const void *pKey2, int n2){ | | | > | | > > > > > > > > > | | > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > > < < < < < < < < < < < < < < < | > | | > > | | | | | | 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 257 258 259 260 261 262 263 264 265 266 267 268 269 270 271 272 273 274 275 276 277 278 279 280 281 282 283 284 285 286 287 288 289 290 | /* ** Hash and comparison functions when the mode is SQLITE_HASH_STRING */ static int strHash(const void *pKey, int nKey){ return sqlite3HashNoCase((const char*)pKey, nKey); } static int strCompare(const void *pKey1, int n1, const void *pKey2, int n2){ if( n1!=n2 ) return 1; return sqlite3StrNICmp((const char*)pKey1,(const char*)pKey2,n1); } /* ** Hash and comparison functions when the mode is SQLITE_HASH_BINARY */ static int binHash(const void *pKey, int nKey){ int h = 0; const char *z = (const char *)pKey; while( nKey-- > 0 ){ h = (h<<3) ^ h ^ *(z++); } return h & 0x7fffffff; } static int binCompare(const void *pKey1, int n1, const void *pKey2, int n2){ if( n1!=n2 ) return 1; return memcmp(pKey1,pKey2,n1); } /* ** Return a pointer to the appropriate hash function given the key class. ** ** The C syntax in this function definition may be unfamilar to some ** programmers, so we provide the following additional explanation: ** ** The name of the function is "hashFunction". The function takes a ** single parameter "keyClass". The return value of hashFunction() ** is a pointer to another function. Specifically, the return value ** of hashFunction() is a pointer to a function that takes two parameters ** with types "const void*" and "int" and returns an "int". */ static int (*hashFunction(int keyClass))(const void*,int){ #if 0 /* HASH_INT and HASH_POINTER are never used */ switch( keyClass ){ case SQLITE_HASH_INT: return &intHash; case SQLITE_HASH_POINTER: return &ptrHash; case SQLITE_HASH_STRING: return &strHash; case SQLITE_HASH_BINARY: return &binHash;; default: break; } return 0; #else if( keyClass==SQLITE_HASH_STRING ){ return &strHash; }else{ assert( keyClass==SQLITE_HASH_BINARY ); return &binHash; } #endif } /* ** Return a pointer to the appropriate hash function given the key class. ** ** For help in interpreted the obscure C code in the function definition, ** see the header comment on the previous function. */ static int (*compareFunction(int keyClass))(const void*,int,const void*,int){ #if 0 /* HASH_INT and HASH_POINTER are never used */ switch( keyClass ){ case SQLITE_HASH_INT: return &intCompare; case SQLITE_HASH_POINTER: return &ptrCompare; case SQLITE_HASH_STRING: return &strCompare; case SQLITE_HASH_BINARY: return &binCompare; default: break; } return 0; #else if( keyClass==SQLITE_HASH_STRING ){ return &strCompare; }else{ assert( keyClass==SQLITE_HASH_BINARY ); return &binCompare; } #endif } /* Link an element into the hash table */ static void insertElement( Hash *pH, /* The complete hash table */ struct _ht *pEntry, /* The entry into which pNew is inserted */ HashElem *pNew /* The element to be inserted */ ){ HashElem *pHead; /* First element already in pEntry */ pHead = pEntry->chain; if( pHead ){ pNew->next = pHead; pNew->prev = pHead->prev; if( pHead->prev ){ pHead->prev->next = pNew; } else { pH->first = pNew; } pHead->prev = pNew; }else{ pNew->next = pH->first; if( pH->first ){ pH->first->prev = pNew; } pNew->prev = 0; pH->first = pNew; } pEntry->count++; pEntry->chain = pNew; } /* Resize the hash table so that it cantains "new_size" buckets. ** "new_size" must be a power of 2. The hash table might fail ** to resize if sqliteMalloc() fails. */ static void rehash(Hash *pH, int new_size){ struct _ht *new_ht; /* The new hash table */ HashElem *elem, *next_elem; /* For looping over existing elements */ int (*xHash)(const void*,int); /* The hash function */ assert( (new_size & (new_size-1))==0 ); new_ht = (struct _ht *)sqliteMalloc( new_size*sizeof(struct _ht) ); if( new_ht==0 ) return; if( pH->ht ) sqliteFree(pH->ht); pH->ht = new_ht; pH->htsize = new_size; xHash = hashFunction(pH->keyClass); for(elem=pH->first, pH->first=0; elem; elem = next_elem){ int h = (*xHash)(elem->pKey, elem->nKey) & (new_size-1); next_elem = elem->next; insertElement(pH, &new_ht[h], elem); } } /* This function (for internal use only) locates an element in an ** hash table that matches the given key. The hash for this key has ** already been computed and is passed as the 4th parameter. */ static HashElem *findElementGivenHash( const Hash *pH, /* The pH to be searched */ const void *pKey, /* The key we are searching for */ int nKey, int h /* The hash for this key. */ ){ HashElem *elem; /* Used to loop thru the element list */ int count; /* Number of elements left to test */ int (*xCompare)(const void*,int,const void*,int); /* comparison function */ if( pH->ht ){ struct _ht *pEntry = &pH->ht[h]; elem = pEntry->chain; count = pEntry->count; xCompare = compareFunction(pH->keyClass); while( count-- && elem ){ if( (*xCompare)(elem->pKey,elem->nKey,pKey,nKey)==0 ){ return elem; } elem = elem->next; } } return 0; } /* Remove a single entry from the hash table given a pointer to that ** element and a hash on the element's key. */ static void removeElementGivenHash( Hash *pH, /* The pH containing "elem" */ HashElem* elem, /* The element to be removed from the pH */ int h /* Hash value for the element */ ){ struct _ht *pEntry; if( elem->prev ){ elem->prev->next = elem->next; }else{ pH->first = elem->next; } if( elem->next ){ elem->next->prev = elem->prev; } pEntry = &pH->ht[h]; if( pEntry->chain==elem ){ pEntry->chain = elem->next; } pEntry->count--; if( pEntry->count<=0 ){ pEntry->chain = 0; } if( pH->copyKey && elem->pKey ){ sqliteFree(elem->pKey); } sqliteFree( elem ); pH->count--; } |
︙ | ︙ | |||
323 324 325 326 327 328 329 | } memcpy((void*)new_elem->pKey, pKey, nKey); }else{ new_elem->pKey = (void*)pKey; } new_elem->nKey = nKey; pH->count++; | | > | | | | > > < < < < < < < < < < < < < | < | 356 357 358 359 360 361 362 363 364 365 366 367 368 369 370 371 372 373 374 375 376 377 378 379 380 | } memcpy((void*)new_elem->pKey, pKey, nKey); }else{ new_elem->pKey = (void*)pKey; } new_elem->nKey = nKey; pH->count++; if( pH->htsize==0 ){ rehash(pH,8); if( pH->htsize==0 ){ pH->count = 0; sqliteFree(new_elem); return data; } } if( pH->count > pH->htsize ){ rehash(pH,pH->htsize*2); } assert( pH->htsize>0 ); assert( (pH->htsize & (pH->htsize-1))==0 ); h = hraw & (pH->htsize-1); insertElement(pH, &pH->ht[h], new_elem); new_elem->data = data; return 0; } |
Changes to src/hash.h.
︙ | ︙ | |||
8 9 10 11 12 13 14 | ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This is the header file for the generic hash-table implemenation ** used in SQLite. ** | | | 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 | ** May you find forgiveness for yourself and forgive others. ** May you share freely, never taking more than you give. ** ************************************************************************* ** This is the header file for the generic hash-table implemenation ** used in SQLite. ** ** $Id: hash.h,v 1.8 2004/08/20 14:08:51 drh Exp $ */ #ifndef _SQLITE_HASH_H_ #define _SQLITE_HASH_H_ /* Forward declarations of structures. */ typedef struct Hash Hash; typedef struct HashElem HashElem; |
︙ | ︙ | |||
66 67 68 69 70 71 72 | ** ** SQLITE_HASH_BINARY pKey points to binary data nKey bytes long. ** memcmp() is used to compare keys. ** ** A copy of the key is made for SQLITE_HASH_STRING and SQLITE_HASH_BINARY ** if the copyKey parameter to HashInit is 1. */ | | | 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 | ** ** SQLITE_HASH_BINARY pKey points to binary data nKey bytes long. ** memcmp() is used to compare keys. ** ** A copy of the key is made for SQLITE_HASH_STRING and SQLITE_HASH_BINARY ** if the copyKey parameter to HashInit is 1. */ /* #define SQLITE_HASH_INT 1 // NOT USED */ /* #define SQLITE_HASH_POINTER 2 // NOT USED */ #define SQLITE_HASH_STRING 3 #define SQLITE_HASH_BINARY 4 /* ** Access routines. To delete, insert a NULL pointer. */ |
︙ | ︙ | |||
103 104 105 106 107 108 109 | /* ** Number of entries in a hash table */ #define sqliteHashCount(H) ((H)->count) #endif /* _SQLITE_HASH_H_ */ | < < < | 103 104 105 106 107 108 109 | /* ** Number of entries in a hash table */ #define sqliteHashCount(H) ((H)->count) #endif /* _SQLITE_HASH_H_ */ |