From 7bb481fda9ecb134804b49c2ce77ca28f7eea583 Mon Sep 17 00:00:00 2001 From: Hans-Christoph Steiner Date: Fri, 30 Mar 2012 20:42:12 -0400 Subject: Imported Upstream version 2.0.3 --- src/rowset.c | 422 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 422 insertions(+) create mode 100644 src/rowset.c (limited to 'src/rowset.c') diff --git a/src/rowset.c b/src/rowset.c new file mode 100644 index 0000000..d84bb93 --- /dev/null +++ b/src/rowset.c @@ -0,0 +1,422 @@ +/* +** 2008 December 3 +** +** 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 module implements an object we call a "RowSet". +** +** The RowSet object is a collection of rowids. Rowids +** are inserted into the RowSet in an arbitrary order. Inserts +** can be intermixed with tests to see if a given rowid has been +** previously inserted into the RowSet. +** +** After all inserts are finished, it is possible to extract the +** elements of the RowSet in sorted order. Once this extraction +** process has started, no new elements may be inserted. +** +** Hence, the primitive operations for a RowSet are: +** +** CREATE +** INSERT +** TEST +** SMALLEST +** DESTROY +** +** The CREATE and DESTROY primitives are the constructor and destructor, +** obviously. The INSERT primitive adds a new element to the RowSet. +** TEST checks to see if an element is already in the RowSet. SMALLEST +** extracts the least value from the RowSet. +** +** The INSERT primitive might allocate additional memory. Memory is +** allocated in chunks so most INSERTs do no allocation. There is an +** upper bound on the size of allocated memory. No memory is freed +** until DESTROY. +** +** The TEST primitive includes a "batch" number. The TEST primitive +** will only see elements that were inserted before the last change +** in the batch number. In other words, if an INSERT occurs between +** two TESTs where the TESTs have the same batch nubmer, then the +** value added by the INSERT will not be visible to the second TEST. +** The initial batch number is zero, so if the very first TEST contains +** a non-zero batch number, it will see all prior INSERTs. +** +** No INSERTs may occurs after a SMALLEST. An assertion will fail if +** that is attempted. +** +** The cost of an INSERT is roughly constant. (Sometime new memory +** has to be allocated on an INSERT.) The cost of a TEST with a new +** batch number is O(NlogN) where N is the number of elements in the RowSet. +** The cost of a TEST using the same batch number is O(logN). The cost +** of the first SMALLEST is O(NlogN). Second and subsequent SMALLEST +** primitives are constant time. The cost of DESTROY is O(N). +** +** There is an added cost of O(N) when switching between TEST and +** SMALLEST primitives. +*/ +#include "sqliteInt.h" + + +/* +** Target size for allocation chunks. +*/ +#define ROWSET_ALLOCATION_SIZE 1024 + +/* +** The number of rowset entries per allocation chunk. +*/ +#define ROWSET_ENTRY_PER_CHUNK \ + ((ROWSET_ALLOCATION_SIZE-8)/sizeof(struct RowSetEntry)) + +/* +** Each entry in a RowSet is an instance of the following object. +*/ +struct RowSetEntry { + i64 v; /* ROWID value for this entry */ + struct RowSetEntry *pRight; /* Right subtree (larger entries) or list */ + struct RowSetEntry *pLeft; /* Left subtree (smaller entries) */ +}; + +/* +** RowSetEntry objects are allocated in large chunks (instances of the +** following structure) to reduce memory allocation overhead. The +** chunks are kept on a linked list so that they can be deallocated +** when the RowSet is destroyed. +*/ +struct RowSetChunk { + struct RowSetChunk *pNextChunk; /* Next chunk on list of them all */ + struct RowSetEntry aEntry[ROWSET_ENTRY_PER_CHUNK]; /* Allocated entries */ +}; + +/* +** A RowSet in an instance of the following structure. +** +** A typedef of this structure if found in sqliteInt.h. +*/ +struct RowSet { + struct RowSetChunk *pChunk; /* List of all chunk allocations */ + sqlite3 *db; /* The database connection */ + struct RowSetEntry *pEntry; /* List of entries using pRight */ + struct RowSetEntry *pLast; /* Last entry on the pEntry list */ + struct RowSetEntry *pFresh; /* Source of new entry objects */ + struct RowSetEntry *pTree; /* Binary tree of entries */ + u16 nFresh; /* Number of objects on pFresh */ + u8 isSorted; /* True if pEntry is sorted */ + u8 iBatch; /* Current insert batch */ +}; + +/* +** Turn bulk memory into a RowSet object. N bytes of memory +** are available at pSpace. The db pointer is used as a memory context +** for any subsequent allocations that need to occur. +** Return a pointer to the new RowSet object. +** +** It must be the case that N is sufficient to make a Rowset. If not +** an assertion fault occurs. +** +** If N is larger than the minimum, use the surplus as an initial +** allocation of entries available to be filled. +*/ +RowSet *sqlite3RowSetInit(sqlite3 *db, void *pSpace, unsigned int N){ + RowSet *p; + assert( N >= ROUND8(sizeof(*p)) ); + p = pSpace; + p->pChunk = 0; + p->db = db; + p->pEntry = 0; + p->pLast = 0; + p->pTree = 0; + p->pFresh = (struct RowSetEntry*)(ROUND8(sizeof(*p)) + (char*)p); + p->nFresh = (u16)((N - ROUND8(sizeof(*p)))/sizeof(struct RowSetEntry)); + p->isSorted = 1; + p->iBatch = 0; + return p; +} + +/* +** Deallocate all chunks from a RowSet. This frees all memory that +** the RowSet has allocated over its lifetime. This routine is +** the destructor for the RowSet. +*/ +void sqlite3RowSetClear(RowSet *p){ + struct RowSetChunk *pChunk, *pNextChunk; + for(pChunk=p->pChunk; pChunk; pChunk = pNextChunk){ + pNextChunk = pChunk->pNextChunk; + sqlite3DbFree(p->db, pChunk); + } + p->pChunk = 0; + p->nFresh = 0; + p->pEntry = 0; + p->pLast = 0; + p->pTree = 0; + p->isSorted = 1; +} + +/* +** Insert a new value into a RowSet. +** +** The mallocFailed flag of the database connection is set if a +** memory allocation fails. +*/ +void sqlite3RowSetInsert(RowSet *p, i64 rowid){ + struct RowSetEntry *pEntry; /* The new entry */ + struct RowSetEntry *pLast; /* The last prior entry */ + assert( p!=0 ); + if( p->nFresh==0 ){ + struct RowSetChunk *pNew; + pNew = sqlite3DbMallocRaw(p->db, sizeof(*pNew)); + if( pNew==0 ){ + return; + } + pNew->pNextChunk = p->pChunk; + p->pChunk = pNew; + p->pFresh = pNew->aEntry; + p->nFresh = ROWSET_ENTRY_PER_CHUNK; + } + pEntry = p->pFresh++; + p->nFresh--; + pEntry->v = rowid; + pEntry->pRight = 0; + pLast = p->pLast; + if( pLast ){ + if( p->isSorted && rowid<=pLast->v ){ + p->isSorted = 0; + } + pLast->pRight = pEntry; + }else{ + assert( p->pEntry==0 ); /* Fires if INSERT after SMALLEST */ + p->pEntry = pEntry; + } + p->pLast = pEntry; +} + +/* +** Merge two lists of RowSetEntry objects. Remove duplicates. +** +** The input lists are connected via pRight pointers and are +** assumed to each already be in sorted order. +*/ +static struct RowSetEntry *rowSetMerge( + struct RowSetEntry *pA, /* First sorted list to be merged */ + struct RowSetEntry *pB /* Second sorted list to be merged */ +){ + struct RowSetEntry head; + struct RowSetEntry *pTail; + + pTail = &head; + while( pA && pB ){ + assert( pA->pRight==0 || pA->v<=pA->pRight->v ); + assert( pB->pRight==0 || pB->v<=pB->pRight->v ); + if( pA->vv ){ + pTail->pRight = pA; + pA = pA->pRight; + pTail = pTail->pRight; + }else if( pB->vv ){ + pTail->pRight = pB; + pB = pB->pRight; + pTail = pTail->pRight; + }else{ + pA = pA->pRight; + } + } + if( pA ){ + assert( pA->pRight==0 || pA->v<=pA->pRight->v ); + pTail->pRight = pA; + }else{ + assert( pB==0 || pB->pRight==0 || pB->v<=pB->pRight->v ); + pTail->pRight = pB; + } + return head.pRight; +} + +/* +** Sort all elements on the pEntry list of the RowSet into ascending order. +*/ +static void rowSetSort(RowSet *p){ + unsigned int i; + struct RowSetEntry *pEntry; + struct RowSetEntry *aBucket[40]; + + assert( p->isSorted==0 ); + memset(aBucket, 0, sizeof(aBucket)); + while( p->pEntry ){ + pEntry = p->pEntry; + p->pEntry = pEntry->pRight; + pEntry->pRight = 0; + for(i=0; aBucket[i]; i++){ + pEntry = rowSetMerge(aBucket[i], pEntry); + aBucket[i] = 0; + } + aBucket[i] = pEntry; + } + pEntry = 0; + for(i=0; ipEntry = pEntry; + p->pLast = 0; + p->isSorted = 1; +} + + +/* +** The input, pIn, is a binary tree (or subtree) of RowSetEntry objects. +** Convert this tree into a linked list connected by the pRight pointers +** and return pointers to the first and last elements of the new list. +*/ +static void rowSetTreeToList( + struct RowSetEntry *pIn, /* Root of the input tree */ + struct RowSetEntry **ppFirst, /* Write head of the output list here */ + struct RowSetEntry **ppLast /* Write tail of the output list here */ +){ + assert( pIn!=0 ); + if( pIn->pLeft ){ + struct RowSetEntry *p; + rowSetTreeToList(pIn->pLeft, ppFirst, &p); + p->pRight = pIn; + }else{ + *ppFirst = pIn; + } + if( pIn->pRight ){ + rowSetTreeToList(pIn->pRight, &pIn->pRight, ppLast); + }else{ + *ppLast = pIn; + } + assert( (*ppLast)->pRight==0 ); +} + + +/* +** Convert a sorted list of elements (connected by pRight) into a binary +** tree with depth of iDepth. A depth of 1 means the tree contains a single +** node taken from the head of *ppList. A depth of 2 means a tree with +** three nodes. And so forth. +** +** Use as many entries from the input list as required and update the +** *ppList to point to the unused elements of the list. If the input +** list contains too few elements, then construct an incomplete tree +** and leave *ppList set to NULL. +** +** Return a pointer to the root of the constructed binary tree. +*/ +static struct RowSetEntry *rowSetNDeepTree( + struct RowSetEntry **ppList, + int iDepth +){ + struct RowSetEntry *p; /* Root of the new tree */ + struct RowSetEntry *pLeft; /* Left subtree */ + if( *ppList==0 ){ + return 0; + } + if( iDepth==1 ){ + p = *ppList; + *ppList = p->pRight; + p->pLeft = p->pRight = 0; + return p; + } + pLeft = rowSetNDeepTree(ppList, iDepth-1); + p = *ppList; + if( p==0 ){ + return pLeft; + } + p->pLeft = pLeft; + *ppList = p->pRight; + p->pRight = rowSetNDeepTree(ppList, iDepth-1); + return p; +} + +/* +** Convert a sorted list of elements into a binary tree. Make the tree +** as deep as it needs to be in order to contain the entire list. +*/ +static struct RowSetEntry *rowSetListToTree(struct RowSetEntry *pList){ + int iDepth; /* Depth of the tree so far */ + struct RowSetEntry *p; /* Current tree root */ + struct RowSetEntry *pLeft; /* Left subtree */ + + assert( pList!=0 ); + p = pList; + pList = p->pRight; + p->pLeft = p->pRight = 0; + for(iDepth=1; pList; iDepth++){ + pLeft = p; + p = pList; + pList = p->pRight; + p->pLeft = pLeft; + p->pRight = rowSetNDeepTree(&pList, iDepth); + } + return p; +} + +/* +** Convert the list in p->pEntry into a sorted list if it is not +** sorted already. If there is a binary tree on p->pTree, then +** convert it into a list too and merge it into the p->pEntry list. +*/ +static void rowSetToList(RowSet *p){ + if( !p->isSorted ){ + rowSetSort(p); + } + if( p->pTree ){ + struct RowSetEntry *pHead, *pTail; + rowSetTreeToList(p->pTree, &pHead, &pTail); + p->pTree = 0; + p->pEntry = rowSetMerge(p->pEntry, pHead); + } +} + +/* +** Extract the smallest element from the RowSet. +** Write the element into *pRowid. Return 1 on success. Return +** 0 if the RowSet is already empty. +** +** After this routine has been called, the sqlite3RowSetInsert() +** routine may not be called again. +*/ +int sqlite3RowSetNext(RowSet *p, i64 *pRowid){ + rowSetToList(p); + if( p->pEntry ){ + *pRowid = p->pEntry->v; + p->pEntry = p->pEntry->pRight; + if( p->pEntry==0 ){ + sqlite3RowSetClear(p); + } + return 1; + }else{ + return 0; + } +} + +/* +** Check to see if element iRowid was inserted into the the rowset as +** part of any insert batch prior to iBatch. Return 1 or 0. +*/ +int sqlite3RowSetTest(RowSet *pRowSet, u8 iBatch, sqlite3_int64 iRowid){ + struct RowSetEntry *p; + if( iBatch!=pRowSet->iBatch ){ + if( pRowSet->pEntry ){ + rowSetToList(pRowSet); + pRowSet->pTree = rowSetListToTree(pRowSet->pEntry); + pRowSet->pEntry = 0; + pRowSet->pLast = 0; + } + pRowSet->iBatch = iBatch; + } + p = pRowSet->pTree; + while( p ){ + if( p->vpRight; + }else if( p->v>iRowid ){ + p = p->pLeft; + }else{ + return 1; + } + } + return 0; +} -- cgit v1.2.3