diff -r 4a65cc85c4f3 -r fbd95db6a4e1 engine/sqlite/src/hash.cpp --- a/engine/sqlite/src/hash.cpp Wed Apr 28 13:20:05 2010 +0100 +++ /dev/null Thu Jan 01 00:00:00 1970 +0000 @@ -1,418 +0,0 @@ -/* -** 2001 September 22 -** -** The author disclaims copyright to this source code. In place of -** a legal notice, here is a blessing: -** -** May you do good and not evil. -** 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.cpp 1282 2008-11-13 09:31:33Z LarsPson $ -*/ -#include "sqliteInt.h" -#include - -/* 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. -** Call this routine to delete a hash table or to reset a hash table -** to the empty state. -*/ -void sqlite3HashClear(Hash *pH){ - HashElem *elem; /* For looping over all elements of the table */ - - assert( pH!=0 ); - elem = pH->first; - pH->first = 0; - if( pH->ht ) sqlite3_free(pH->ht); - pH->ht = 0; - pH->htsize = 0; - while( elem ){ - HashElem *next_elem = elem->next; - if( pH->copyKey && elem->pKey ){ - sqlite3_free(elem->pKey); - } - sqlite3_free(elem); - elem = next_elem; - } - pH->count = 0; -} - -#if 0 /* NOT USED */ -/* -** Hash and comparison functions when the mode is SQLITE_HASH_INT -*/ -static int intHash(const void *pKey, int nKey){ - return nKey ^ (nKey<<8) ^ (nKey>>8); -} -static int intCompare(const void *pKey1, int n1, const void *pKey2, int n2){ - return n2 - n1; -} -#endif - -#if 0 /* NOT USED */ -/* -** Hash and comparison functions when the mode is SQLITE_HASH_POINTER -*/ -static int ptrHash(const void *pKey, int nKey){ - uptr x = Addr(pKey); - return x ^ (x<<8) ^ (x>>8); -} -static int ptrCompare(const void *pKey1, int n1, const void *pKey2, int n2){ - if( pKey1==pKey2 ) return 0; - if( pKey1 0 ){ - h = (h<<3) ^ h ^ sqlite3UpperToLower[(unsigned char)*z++]; - nKey--; - } - return h & 0x7fffffff; -} -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 */ - Hash::_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 sqlite3_malloc() fails. -*/ -static void rehash(Hash *pH, int new_size){ - Hash::_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 ); - - /* There is a call to sqlite3_malloc() inside rehash(). If there is - ** already an allocation at pH->ht, then if this malloc() fails it - ** is benign (since failing to resize a hash table is a performance - ** hit only, not a fatal error). - */ - sqlite3MallocBenignFailure(pH->htsize>0); - - new_ht = (Hash::_ht *)sqlite3MallocZero( new_size*sizeof(Hash::_ht) ); - if( new_ht==0 ) return; - if( pH->ht ) sqlite3_free(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 ){ - Hash::_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 */ -){ - Hash::_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 ){ - sqlite3_free(elem->pKey); - } - sqlite3_free( elem ); - pH->count--; - if( pH->count<=0 ){ - assert( pH->first==0 ); - assert( pH->count==0 ); - sqlite3HashClear(pH); - } -} - -/* Attempt to locate an element of the hash table pH with a key -** that matches pKey,nKey. Return a pointer to the corresponding -** HashElem structure for this element if it is found, or NULL -** otherwise. -*/ -HashElem *sqlite3HashFindElem(const Hash *pH, const void *pKey, int nKey){ - int h; /* A hash on key */ - HashElem *elem; /* The element that matches key */ - int (*xHash)(const void*,int); /* The hash function */ - - if( pH==0 || pH->ht==0 ) return 0; - xHash = hashFunction(pH->keyClass); - assert( xHash!=0 ); - h = (*xHash)(pKey,nKey); - assert( (pH->htsize & (pH->htsize-1))==0 ); - elem = findElementGivenHash(pH,pKey,nKey, h & (pH->htsize-1)); - return elem; -} - -/* Attempt to locate an element of the hash table pH with a key -** that matches pKey,nKey. Return the data for this element if it is -** found, or NULL if there is no match. -*/ -void *sqlite3HashFind(const Hash *pH, const void *pKey, int nKey){ - HashElem *elem; /* The element that matches key */ - elem = sqlite3HashFindElem(pH, pKey, nKey); - return elem ? elem->data : 0; -} - -/* Insert an element into the hash table pH. The key is pKey,nKey -** and the data is "data". -** -** If no element exists with a matching key, then a new -** element is created. A copy of the key is made if the copyKey -** flag is set. NULL is returned. -** -** If another element already exists with the same key, then the -** new data replaces the old data and the old data is returned. -** The key is not copied in this instance. If a malloc fails, then -** the new data is returned and the hash table is unchanged. -** -** If the "data" parameter to this function is NULL, then the -** element corresponding to "key" is removed from the hash table. -*/ -void *sqlite3HashInsert(Hash *pH, const void *pKey, int nKey, void *data){ - int hraw; /* Raw hash value of the key */ - int h; /* the hash of the key modulo hash table size */ - HashElem *elem; /* Used to loop thru the element list */ - HashElem *new_elem; /* New element added to the pH */ - int (*xHash)(const void*,int); /* The hash function */ - - assert( pH!=0 ); - xHash = hashFunction(pH->keyClass); - assert( xHash!=0 ); - hraw = (*xHash)(pKey, nKey); - assert( (pH->htsize & (pH->htsize-1))==0 ); - h = hraw & (pH->htsize-1); - elem = findElementGivenHash(pH,pKey,nKey,h); - if( elem ){ - void *old_data = elem->data; - if( data==0 ){ - removeElementGivenHash(pH,elem,h); - }else{ - elem->data = data; - if( !pH->copyKey ){ - elem->pKey = (void *)pKey; - } - assert(nKey==elem->nKey); - } - return old_data; - } - if( data==0 ) return 0; - new_elem = (HashElem*)sqlite3_malloc( sizeof(HashElem) ); - if( new_elem==0 ) return data; - if( pH->copyKey && pKey!=0 ){ - new_elem->pKey = sqlite3_malloc( nKey ); - if( new_elem->pKey==0 ){ - sqlite3_free(new_elem); - return data; - } - 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; - if( pH->copyKey ){ - sqlite3_free(new_elem->pKey); - } - sqlite3_free(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; -}