ttree.cpp

一个功能强大的内存数据库源代码,c++编写,有详细的注释

//-< TTREE.CPP >-----------------------------------------------------*--------*
// FastDB                    Version 1.0         (c) 1999  GARRET    *     ?  *
// (Main Memory Database Management System)                          *   /\|  *
//                                                                   *  /  \  *
//                          Created:     20-Nov-98    K.A. Knizhnik  * / [] \ *
//                          Last update:  6-Jan-99    K.A. Knizhnik  * GARRET *
//-------------------------------------------------------------------*--------*
// T-Tree implementation
//-------------------------------------------------------------------*--------*

#define INSIDE_FASTDB

#include "fastdb.h"
#include "ttree.h"

#ifdef USE_LOCALE_SETTINGS
#ifdef IGNORE_CASE
#define strcmp(x, y) stricoll(x, y)
#else
#define strcmp(x, y) strcoll(x, y)
#endif
#else
#ifdef IGNORE_CASE
#define strcmp(x, y) stricmp(x, y)
#endif
#endif

inline int keycmp(void* p, void* q, int type, int sizeofType, dbUDTComparator comparator)
{
    switch (type) {
      case dbField::tpBool:
	return *(bool*)p - *(bool*)q;
      case dbField::tpInt1:
	return *(int1*)p - *(int1*)q;
      case dbField::tpInt2:
	return *(int2*)p - *(int2*)q;
      case dbField::tpInt4:
        return *(int4*)p < *(int4*)q ? -1 : *(int4*)p == *(int4*)q ? 0 : 1;
      case dbField::tpInt8:
        return *(db_int8*)p < *(db_int8*)q ? -1 : *(db_int8*)p == *(db_int8*)q ? 0 : 1;
      case dbField::tpReference:
        return *(oid_t*)p < *(oid_t*)q ? -1 : *(oid_t*)p == *(oid_t*)q ? 0 : 1;
      case dbField::tpReal4:
        return *(real4*)p < *(real4*)q ? -1 : *(real4*)p == *(real4*)q ? 0 : 1;
      case dbField::tpReal8:
        return *(real8*)p < *(real8*)q ? -1 : *(real8*)p == *(real8*)q ? 0 : 1;
      case dbField::tpRawBinary:
	return comparator(p, q, sizeofType);
      default:
	assert(false);
	return 0;
    }
}

void dbTtree::find(dbDatabase* db, oid_t treeId, dbSearchContext& sc)
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    if (rootId != 0) { 
	((dbTtreeNode*)db->get(rootId))->find(db, sc);
    }
}

oid_t dbTtree::allocate(dbDatabase* db)
{
    oid_t oid = db->allocateObject(dbTtreeMarker);
    dbTtree* tree = (dbTtree*)db->get(oid);
    tree->root = 0;
    return oid;
}

void dbTtree::insert(dbDatabase* db, oid_t treeId, oid_t recordId, 
		     int type, int sizeofType, dbUDTComparator comparator, int offs)
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    if (rootId == 0) {
	oid_t nodeId = dbTtreeNode::allocate(db, recordId);
	((dbTtree*)db->put(treeId))->root = nodeId;
    } else { 
	byte* rec = (byte*)db->getRow(recordId);
	byte* key = rec + offs;
	if (type == dbField::tpString) { 
	    key = rec + ((dbVarying*)key)->offs;
	}
	oid_t nodeId = rootId;
	dbTtreeNode::insert(db, nodeId, recordId, key, type, sizeofType, comparator, offs);
	if (rootId != nodeId) { 
	    ((dbTtree*)db->put(treeId))->root = nodeId;
	}
    }
}


void dbTtree::remove(dbDatabase* db, oid_t treeId, oid_t recordId, 
		     int type, int sizeofType, dbUDTComparator comparator, int offs)
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    byte* rec = (byte*)db->getRow(recordId);
    byte* key = rec + offs;
    if (type == dbField::tpString) { 
	key = rec + ((dbVarying*)key)->offs;
    }
    oid_t nodeId = rootId;
    int h = dbTtreeNode::remove(db, nodeId, recordId, key, type, sizeofType, comparator, offs);
    assert(h >= 0);
    if (nodeId != rootId) { 
	((dbTtree*)db->put(treeId))->root = nodeId;
    }
}   


void dbTtree::purge(dbDatabase* db, oid_t treeId) 
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    dbTtreeNode::purge(db, rootId);
    ((dbTtree*)db->put(treeId))->root = 0;
}
    
void dbTtree::drop(dbDatabase* db, oid_t treeId) 
{
    purge(db, treeId);
    db->freeObject(treeId);
}
    

void dbTtree::traverseForward(dbDatabase* db, oid_t treeId,
			      dbAnyCursor* cursor)
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    if (rootId != 0) { 
	((dbTtreeNode*)db->get(rootId))->traverseForward(db, cursor);
    }
}

void dbTtree::traverseBackward(dbDatabase* db, oid_t treeId,
			      dbAnyCursor* cursor)
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    if (rootId != 0) { 
	((dbTtreeNode*)db->get(rootId))->traverseBackward(db, cursor);
    }
}


void dbTtree::traverseForward(dbDatabase* db, oid_t treeId,
			     dbAnyCursor* cursor, dbExprNode* condition)
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    if (rootId != 0) { 
	((dbTtreeNode*)db->get(rootId))->traverseForward(db, cursor,condition);
    }
}


void dbTtree::traverseBackward(dbDatabase* db, oid_t treeId,
			      dbAnyCursor* cursor, dbExprNode* condition)
{
    oid_t rootId = ((dbTtree*)db->get(treeId))->root;
    if (rootId != 0) { 
	((dbTtreeNode*)db->get(rootId))->traverseBackward(db,cursor,condition);
    }
}




bool dbTtreeNode::find(dbDatabase* db, dbSearchContext& sc)
{
    char* rec;
    int   diff;
    int   l, r, m, n = nItems;

    sc.probes += 1;
    dbTable* table = (dbTable*)db->getRow(sc.cursor->table->tableId);

    if (sc.type == dbField::tpString) { 
	if (sc.firstKey != NULL) { 
	    rec = (char*)db->getRow(item[0]);
	    diff = strcmp(sc.firstKey, rec+((dbVarying*)(rec+sc.offs))->offs);
	    if (diff >= sc.firstKeyInclusion) {	    
		rec = (char*)db->getRow(item[n-1]);
		diff = strcmp(sc.firstKey, 
			      rec+((dbVarying*)(rec+sc.offs))->offs);
		if (diff >= sc.firstKeyInclusion) { 
		    if (right != 0) { 
			return ((dbTtreeNode*)db->get(right))->find(db, sc); 
		    } 
		    return true;
		}
		for (l = 0, r = n; l < r;) { 
		    m = (l + r) >> 1;
		    rec = (char*)db->getRow(item[m]);
		    diff = strcmp(sc.firstKey, 
				  rec + ((dbVarying*)(rec+sc.offs))->offs);
		    if (diff >= sc.firstKeyInclusion) {
			l = m+1;
		    } else { 
			r = m;
		    }
		}
		while (r < n) { 
		    rec = (char*)db->getRow(item[r]);
		    if (sc.lastKey != NULL 
			&& strcmp(rec + ((dbVarying*)(rec+sc.offs))->offs,
				  sc.lastKey) >= sc.lastKeyInclusion) 
		    { 
			return false;
		    }
		    if (!sc.condition 
			|| db->evaluate(sc.condition, item[r], table, sc.cursor)) 
                    {
			if (!sc.cursor->add(item[r])) { 
			    return false;
			}
		    }
		    r += 1;
		}
		if (right != 0) { 
		    return ((dbTtreeNode*)db->get(right))->find(db, sc); 
		} 
		return true;	
	    }
	}	
	if (left != 0) { 
	    if (!((dbTtreeNode*)db->get(left))->find(db, sc)) { 
		return false;
	    }
	}
	for (l = 0; l < n; l++) { 
	    rec = (char*)db->getRow(item[l]);
	    if (sc.lastKey != NULL 
		&& strcmp(rec + ((dbVarying*)(rec+sc.offs))->offs, 
			  sc.lastKey) >= sc.lastKeyInclusion) 
	    {
		return false;
	    }
	    if (!sc.condition || db->evaluate(sc.condition, item[l], table, sc.cursor)) {
		if (!sc.cursor->add(item[l])) { 
		    return false;
		}
	    }
	}
	if (right != 0) { 
	    return ((dbTtreeNode*)db->get(right))->find(db, sc);
	} 
    } else { 
	if (sc.firstKey != NULL) { 
	    rec = (char*)db->getRow(item[0]);
	    diff = keycmp(sc.firstKey, rec+sc.offs, sc.type, sc.sizeofType, sc.comparator);
	    if (diff >= sc.firstKeyInclusion) {	    
		rec = (char*)db->getRow(item[n-1]);
		diff = keycmp(sc.firstKey, rec+sc.offs, sc.type, sc.sizeofType, sc.comparator);
		if (diff >= sc.firstKeyInclusion) {
		    if (right != 0) { 
			return ((dbTtreeNode*)db->get(right))->find(db, sc); 
		    } 
		    return true;
		}
		for (l = 0, r = n; l < r;) { 
		    m = (l + r) >> 1;
		    rec = (char*)db->getRow(item[m]);
		    diff = keycmp(sc.firstKey, rec+sc.offs, sc.type, sc.sizeofType, sc.comparator);
		    if (diff >= sc.firstKeyInclusion) {
			l = m+1;
		    } else { 
			r = m;
		    }
		}
		while (r < n) { 
		    rec = (char*)db->getRow(item[r]);
		    if (sc.lastKey != NULL 
			&& keycmp(rec+sc.offs, sc.lastKey, sc.type, sc.sizeofType, sc.comparator) 
			   >= sc.lastKeyInclusion) 
		    { 
			return false;
		    }
		    if (!sc.condition 
			|| db->evaluate(sc.condition, item[r], table, sc.cursor)) 
		    {
			if (!sc.cursor->add(item[r])) { 
			    return false;
			}
		    }
		    r += 1;
		}
		if (right != 0) { 
		    return ((dbTtreeNode*)db->get(right))->find(db, sc); 
		} 
		return true;	
	    }
	}	
	if (left != 0) { 
	    if (!((dbTtreeNode*)db->get(left))->find(db, sc)) { 
		return false;
	    }
	}
	for (l = 0; l < n; l++) { 
	    rec = (char*)db->getRow(item[l]);
	    if (sc.lastKey != NULL && keycmp(rec+sc.offs, sc.lastKey, sc.type, sc.sizeofType, sc.comparator) 
		>= sc.lastKeyInclusion) 
	    {
		return false;
	    }
	    if (!sc.condition || db->evaluate(sc.condition, item[l], table, sc.cursor)) { 
		if (!sc.cursor->add(item[l])) { 
		    return false;
		}
	    }
	}
	if (right != 0) { 
	    return ((dbTtreeNode*)db->get(right))->find(db, sc);
	} 
    }
    return true;
}


oid_t dbTtreeNode::allocate(dbDatabase* db, oid_t recordId)
{
    oid_t nodeId = db->allocateObject(dbTtreeNodeMarker);
    dbTtreeNode* node = (dbTtreeNode*)db->get(nodeId);
    node->nItems = 1;
    node->item[0] = recordId;
    node->left = node->right = 0;
    node->balance = 0;
    return nodeId;
}

bool dbTtreeNode::insert(dbDatabase* db, oid_t& nodeId, oid_t recordId, 
			 void* key, int type, int sizeofType, dbUDTComparator comparator, int offs)
{
    dbTtreeNode* node = (dbTtreeNode*)db->get(nodeId);
    char* rec = (char*)db->getRow(node->item[0]);
    int n = node->nItems;
    int diff = (type == dbField::tpString)
	? strcmp((char*)key, rec + ((dbVarying*)(rec+offs))->offs)
	: keycmp(key, rec+offs, type, sizeofType, comparator);
    
    if (diff <= 0) { 
	oid_t leftId = node->left;
	if ((leftId == 0 || diff == 0) && node->nItems != pageSize) { 
	    node = (dbTtreeNode*)db->put(nodeId);
	    for (int i = n; i > 0; i--) node->item[i] = node->item[i-1];
	    node->item[0] = recordId;
	    node->nItems += 1;
	    return false;
	} 
	if (leftId == 0) { 
	    leftId = allocate(db, recordId);
	    node = (dbTtreeNode*)db->put(nodeId);
	    node->left = leftId;
	} else {
	    oid_t childId = leftId;
	    bool grow = insert(db, childId, recordId, key, type, sizeofType, comparator, offs);
	    if (childId != leftId) { 
		((dbTtreeNode*)db->put(nodeId))->left = leftId = childId;
	    }
	    if (!grow) return false;
	}
	node = (dbTtreeNode*)db->put(nodeId);
	if (node->balance > 0) { 
	    node->balance = 0;
	    return false;
	} else if (node->balance == 0) { 
	    node->balance = -1;
	    return true;
	} else { 
	    dbTtreeNode* left = (dbTtreeNode*)db->put(leftId);
	    node = (dbTtreeNode*)db->get(nodeId);
	    if (left->balance < 0) { // single LL turn
		node->left = left->right;
		left->right = nodeId;
		node->balance = 0;
		left->balance = 0;
		nodeId = leftId;
	    } else { // double LR turn
		oid_t rightId = left->right;
		dbTtreeNode* right = (dbTtreeNode*)db->put(rightId);
		left = (dbTtreeNode*)db->get(leftId);
		node = (dbTtreeNode*)db->get(nodeId);
		left->right = right->left;
		right->left = leftId;
		node->left = right->right;
		right->right = nodeId;
		node->balance = (right->balance < 0) ? 1 : 0;
		left->balance = (right->balance > 0) ? -1 : 0;
		right->balance = 0;
		nodeId = rightId;
	    }
	    return false;
	}
    } 
    rec = (char*)db->getRow(node->item[n-1]);
    diff = (type == dbField::tpString)
	? strcmp((char*)key, rec + ((dbVarying*)(rec+offs))->offs)
	: keycmp(key, rec+offs, type, sizeofType, comparator);
    if (diff >= 0) { 
	oid_t rightId = node->right;
	if ((rightId == 0 || diff == 0) && node->nItems != pageSize) { 
	    node = (dbTtreeNode*)db->put(nodeId);
	    node->item[n] = recordId;
	    node->nItems += 1;
	    return false;
	}
	if (rightId == 0) { 
	    rightId = allocate(db, recordId);
	    node = (dbTtreeNode*)db->put(nodeId);
	    node->right = rightId;