Guardo los nodos por recuperar al salir.

[z.facultad/75.52/treemulator.git] / src / btree.cpp

diff --git a/src/btree.cpp b/src/btree.cpp
index a88aae3baf98aa3acce5d7d8321e82db9ec0a1a3..e6dea5bc04b84efc1e8b82ed1df4f493042852af 100644 (file)
--- a/src/btree.cpp
+++ b/src/btree.cpp
@@ -1,9 +1,8 @@
 
 #include "btree.h"
 
 
 #include "btree.h"
 

-BTree::BTree (const std::string &name, unsigned int block_size, int kt, bool create_new_file)
+BTree::BTree (const std::string &name, unsigned int block_size, int tt, int kt, bool create_new_file)

 {
 {

-       key_type = kt;

        uchar *node;
        BTreeNodeHeader nh;
 
        uchar *node;
        BTreeNodeHeader nh;
 


@@ -18,6 +17,8 @@ BTree::BTree (const std::string &name, unsigned int block_size, int kt, bool cre
        
        /* Inicializo el header */
        header.block_size = block_size;
        
        /* Inicializo el header */
        header.block_size = block_size;

+       header.tree_type = tt;
+       header.key_type = kt;

        WriteFileHeader ();
 
        /* Creo el primer bloque vacio */
        WriteFileHeader ();
 
        /* Creo el primer bloque vacio */


@@ -32,9 +33,38 @@ BTree::BTree (const std::string &name, unsigned int block_size, int kt, bool cre
        delete [] node;
 }
 
        delete [] node;
 }
 

+BTree::BTree (const std::string &name)
+{
+       fp = fopen (name.c_str(), "rb+");
+       if (!fp) {
+               /* TODO : mandar una exception ? */
+               return;
+       }
+       ReadFileHeader ();
+}
+

 BTree::~BTree ()
 {
        fclose (fp);
 BTree::~BTree ()
 {
        fclose (fp);

+
+       std::string del = filename + ".del";
+
+       fp = fopen (del.c_str (), "wb");
+       std::list<uint>::iterator it = deleted_nodes.begin ();
+
+       while (it != deleted_nodes.end ()) {
+               uint i = *it;
+               fwrite (&i, 1, sizeof (uint), fp);
+               it++;
+       }
+
+       fclose (fp);
+}
+
+void BTree::ReadFileHeader ()
+{
+       fseek (fp, 0L, SEEK_SET);
+       fread (&header, 1, sizeof (BTreeFileHeader), fp);

 }
 
 void BTree::WriteFileHeader ()
 }
 
 void BTree::WriteFileHeader ()


@@ -53,7 +83,13 @@ void BTree::WriteBlock (uchar *block, uint num)
 void BTree::AddKey (const Clave &k)
 {
        uint left, right;
 void BTree::AddKey (const Clave &k)
 {
        uint left, right;

-       Clave *kout = AddKeyR (&k, 0, left, right);
+       Clave *kout;
+
+       try {
+               kout = AddKeyR (k.Clone (), 0, left, right);
+       } catch (Exception *e) {
+               throw e;
+       }

 
        if (kout) {
                unsigned short level;
 
        if (kout) {
                unsigned short level;


@@ -102,10 +138,19 @@ Clave* BTree::AddKeyR (const Clave *k, uint node_num, uint &left_child, uint &ri
        ReadNodoHeader (node, &node_header);
        delete [] node;
 
        ReadNodoHeader (node, &node_header);
        delete [] node;
 

-       if (node_header.level == 0)
-               return AddKeyLeafR (k, node_num, left_child, right_child);
+       if (node_header.level == 0) {
+               try {
+                       return AddKeyLeafR (k, node_num, left_child, right_child);
+               } catch (Exception *e) {
+                       throw e;
+               }
+       }

 
 

-       return AddKeyOtherR (k, node_num, left_child, right_child);
+       try {
+               return AddKeyOtherR (k, node_num, left_child, right_child);
+       } catch (Exception *e) {
+               throw e;
+       }

 }
 
 Clave* BTree::AddKeyLeafR (const Clave *k, uint node_num, uint &left_child, uint &right_child)
 }
 
 Clave* BTree::AddKeyLeafR (const Clave *k, uint node_num, uint &left_child, uint &right_child)


@@ -127,6 +172,14 @@ Clave* BTree::AddKeyLeafR (const Clave *k, uint node_num, uint &left_child, uint
 
                while (it != node_keys.end ()) {
                        datait = (*it);
 
                while (it != node_keys.end ()) {
                        datait = (*it);

+                       if (header.tree_type == TYPE_IDENTIFICACION) {
+                               /* Verifico que la clave no existea ya en el arbol */
+                               if ((*data) == (*datait)) {
+                                       throw new AddException ();
+                                       return NULL;
+                               }
+                       }
+       

                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;
                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;


@@ -160,6 +213,13 @@ Clave* BTree::AddKeyLeafR (const Clave *k, uint node_num, uint &left_child, uint
                while (it != node_keys.end ()) {
                        BTreeData *datait;
                        datait = (*it);
                while (it != node_keys.end ()) {
                        BTreeData *datait;
                        datait = (*it);

+                       if (header.tree_type == TYPE_IDENTIFICACION) {
+                               /* Verifico que la clave no existea ya en el arbol */
+                               if ((*data) == (*datait)) {
+                                       throw new AddException ();
+                                       return NULL;
+                               }
+                       }

                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;
                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;


@@ -199,7 +259,7 @@ Clave* BTree::AddKeyLeafR (const Clave *k, uint node_num, uint &left_child, uint
                        used += d->Size ();
                        it++;
                }
                        used += d->Size ();
                        it++;
                }

-               kout = (*it++)->getClave (); // Esta se retorna al "padre" para que se la agregue
+               kout = (*it++)->GetKey (); // Esta se retorna al "padre" para que se la agregue

 
                while (it != node_keys.end ()) {
                        BTreeData *d = (*it);
 
                while (it != node_keys.end ()) {
                        BTreeData *d = (*it);


@@ -253,6 +313,13 @@ Clave* BTree::AddKeyOtherR (const Clave *k, uint node_num, uint &left_child, uin
        posterior = it;
 
        while (it != node_keys.end ()) {
        posterior = it;
 
        while (it != node_keys.end ()) {

+               if (header.tree_type == TYPE_IDENTIFICACION) {
+                       /* Verifico que la clave no existea ya en el arbol */
+                       if ((*data) == (*(*it))) {
+                               throw new AddException ();
+                               return NULL;
+                       }
+               }

                if ((*data) < (*(*it)))
                        break;
                ultima = it;
                if ((*data) < (*(*it)))
                        break;
                ultima = it;


@@ -260,9 +327,9 @@ Clave* BTree::AddKeyOtherR (const Clave *k, uint node_num, uint &left_child, uin
        }
 
        if (it == posterior) {
        }
 
        if (it == posterior) {

-               k = AddKeyR (k, lchild->getChild (), left_child, right_child);
+               k = AddKeyR (k, lchild->GetChild (), left_child, right_child);

        } else {
        } else {

-               k = AddKeyR (k, (*ultima)->getChild (), left_child, right_child);
+               k = AddKeyR (k, (*ultima)->GetChild (), left_child, right_child);

        }
        DeleteKeys (node_keys);
 
        }
        DeleteKeys (node_keys);
 


@@ -282,6 +349,13 @@ Clave* BTree::AddKeyOtherR (const Clave *k, uint node_num, uint &left_child, uin
 
                while (it != node_keys.end ()) {
                        datait = (*it);
 
                while (it != node_keys.end ()) {
                        datait = (*it);

+                       if (header.tree_type == TYPE_IDENTIFICACION) {
+                               /* Verifico que la clave no existea ya en el arbol */
+                               if ((*data) == (*datait)) {
+                                       throw new AddException ();
+                                       return NULL;
+                               }
+                       }

                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;
                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;


@@ -317,6 +391,13 @@ Clave* BTree::AddKeyOtherR (const Clave *k, uint node_num, uint &left_child, uin
                while (it != node_keys.end ()) {
                        BTreeData *datait;
                        datait = (*it);
                while (it != node_keys.end ()) {
                        BTreeData *datait;
                        datait = (*it);

+                       if (header.tree_type == TYPE_IDENTIFICACION) {
+                               /* Verifico que la clave no existea ya en el arbol */
+                               if ((*data) == (*datait)) {
+                                       throw new AddException ();
+                                       return NULL;
+                               }
+                       }

                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;
                        if ((*data) < (*datait))
                                /* Me pase, lo agrego aca! */
                                break;


@@ -356,9 +437,9 @@ Clave* BTree::AddKeyOtherR (const Clave *k, uint node_num, uint &left_child, uin
                        used += d->Size ();
                        it++;
                }
                        used += d->Size ();
                        it++;
                }

-               kout = (*it)->getClave (); // Esta se retorna al "padre" para que se la agregue
+               kout = (*it)->GetKey (); // Esta se retorna al "padre" para que se la agregue

 
 

-               new_node_keys.push_back ( new BTreeChildData ((*it)->getChild ()));
+               new_node_keys.push_back ( new BTreeChildData ((*it)->GetChild ()));

                it++;
                while (it != node_keys.end ()) {
                        BTreeData *d = (*it);
                it++;
                while (it != node_keys.end ()) {
                        BTreeData *d = (*it);


@@ -422,18 +503,18 @@ void BTree::DelKeyR (BTreeData *k, uint node_num, uint padre)
                if ((*k) == (*(*it))) {
                        /* La encontre!, retorno */
                        if (node_header.level == 0) {
                if ((*k) == (*(*it))) {
                        /* La encontre!, retorno */
                        if (node_header.level == 0) {

-                               DelKeyFromLeaf (k->getClave (), node_num, padre);
+                               DelKeyFromLeaf (k->GetKey (), node_num, padre);

                        } else {
                                uint left, right;
                                if (it == posterior) {
                        } else {
                                uint left, right;
                                if (it == posterior) {

-                                       left = lchild->getChild ();
-                                       right = (*it)->getChild ();
+                                       left = lchild->GetChild ();
+                                       right = (*it)->GetChild ();

                                } else {
                                } else {

-                                       left = (*ultima)->getChild ();
-                                       right = (*it)->getChild ();
+                                       left = (*ultima)->GetChild ();
+                                       right = (*it)->GetChild ();

                                }
                                std::cout << "Eliminar de Nodo con hijos : " << left << " y " << right << std::endl;
                                }
                                std::cout << "Eliminar de Nodo con hijos : " << left << " y " << right << std::endl;

-                               DelKeyFromNode (k->getClave (), node_num, padre, left, right);
+                               DelKeyFromNode (k->GetKey (), node_num, padre, left, right);

                        }
                        DeleteKeys (node_keys);
                        delete [] node;
                        }
                        DeleteKeys (node_keys);
                        delete [] node;


@@ -456,9 +537,9 @@ void BTree::DelKeyR (BTreeData *k, uint node_num, uint padre)
 
        /* TODO: Aca faltaria liberar memoria */
        if (it == posterior) {
 
        /* TODO: Aca faltaria liberar memoria */
        if (it == posterior) {

-               DelKeyR (k, lchild->getChild (), node_num);
+               DelKeyR (k, lchild->GetChild (), node_num);

        } else {
        } else {

-               DelKeyR (k, (*ultima)->getChild (), node_num);
+               DelKeyR (k, (*ultima)->GetChild (), node_num);

        }
 }
 
        }
 }
 


@@ -602,22 +683,22 @@ void BTree::JoinNodes (uint node1, uint node2, uint padre, int tipohermano)
        Clave *cpadre;
        BTreeData *lchild = (*it++);
 
        Clave *cpadre;
        BTreeData *lchild = (*it++);
 

-       if (lchild->getChild () == node1) {
-               cpadre = (*it)->getClave ();
+       if (lchild->GetChild () == node1) {
+               cpadre = (*it)->GetKey ();

                borrar_padre = it;
        } else {
                while (it != nkpadre.end ()) {
                        if (tipohermano == 0) {
                borrar_padre = it;
        } else {
                while (it != nkpadre.end ()) {
                        if (tipohermano == 0) {

-                               if ((*it)->getChild () == node2)
+                               if ((*it)->GetChild () == node2)

                                        break;
                        } else {
                                        break;
                        } else {

-                               if ((*it)->getChild () == node1)
+                               if ((*it)->GetChild () == node1)

                                        break;
                        }
                        anterior = it;
                        it++;
                }
                                        break;
                        }
                        anterior = it;
                        it++;
                }

-               cpadre = (*it)->getClave ();
+               cpadre = (*it)->GetKey ();

                borrar_padre = it;
        }
        if (it == nkpadre.end ()) {
                borrar_padre = it;
        }
        if (it == nkpadre.end ()) {


@@ -632,14 +713,14 @@ void BTree::JoinNodes (uint node1, uint node2, uint padre, int tipohermano)
 
        i = nk1.begin ();
        while (i != nk1.end ()) {
 
        i = nk1.begin ();
        while (i != nk1.end ()) {

-               newkeys.push_back ( new BTreeLeafData ((*i)->getClave ()->Clone ()));
+               newkeys.push_back ( new BTreeLeafData ((*i)->GetKey ()->Clone ()));

                i++;
        }
        //if (tipohermano == 0)
                newkeys.push_back ( new BTreeLeafData (cpadre->Clone ()));
        i = nk2.begin ();
        while (i != nk2.end ()) {
                i++;
        }
        //if (tipohermano == 0)
                newkeys.push_back ( new BTreeLeafData (cpadre->Clone ()));
        i = nk2.begin ();
        while (i != nk2.end ()) {

-               newkeys.push_back ( new BTreeLeafData ((*i)->getClave ()->Clone ()));
+               newkeys.push_back ( new BTreeLeafData ((*i)->GetKey ()->Clone ()));

                i++;
        }
 
                i++;
        }
 


@@ -662,15 +743,17 @@ void BTree::JoinNodes (uint node1, uint node2, uint padre, int tipohermano)
                WriteNodoHeader (npadre, &nhp);
                WriteBlock (npadre, padre);
 
                WriteNodoHeader (npadre, &nhp);
                WriteBlock (npadre, padre);
 

-        /* TODO: Recuperar nodo1 y nodo2 */
+               deleted_nodes.push_back (node1);
+               deleted_nodes.push_back (node2);

        } else {
                WriteKeys (n1, nh1, newkeys);
                WriteNodoHeader (n1, &nh1);
                WriteBlock (n1, node1);
 
        } else {
                WriteKeys (n1, nh1, newkeys);
                WriteNodoHeader (n1, &nh1);
                WriteBlock (n1, node1);
 

-               /* TODO : Recuperar node2 */
+               deleted_nodes.push_back (node2);
+

                /* Actualizo punero al padre */
                /* Actualizo punero al padre */

-               (*anterior)->setChild (node1);
+               (*anterior)->SetChild (node1);

        
                nkpadre.erase (borrar_padre);
                WriteKeys (npadre, nhp, nkpadre);
        
                nkpadre.erase (borrar_padre);
                WriteKeys (npadre, nhp, nkpadre);


@@ -729,12 +812,12 @@ Clave *BTree::GetKey (uint node_num, char maxmin)
        }
 
        if (maxmin == 0) {
        }
 
        if (maxmin == 0) {

-               k = (*it)->getClave ()->Clone ();
+               k = (*it)->GetKey ()->Clone ();

                node_keys.erase (it);
        } else {
                it = node_keys.end ();
                it--;
                node_keys.erase (it);
        } else {
                it = node_keys.end ();
                it--;

-               k = (*it)->getClave ()->Clone ();
+               k = (*it)->GetKey ()->Clone ();

                node_keys.erase (it);
        }
 
                node_keys.erase (it);
        }
 


@@ -764,28 +847,28 @@ void BTree::FindBrothers (uint node_num, uint padre, uint &left, uint &right)
 
        BTreeData *lchild = (*it++);
 
 
        BTreeData *lchild = (*it++);
 

-       if (lchild->getChild () == node_num) {
+       if (lchild->GetChild () == node_num) {

                /* Solo tengo hermano derecho */
                std::cout << "Hermano Izquierdo : NO TENGO" << std::endl;
                left = 0;
                /* Solo tengo hermano derecho */
                std::cout << "Hermano Izquierdo : NO TENGO" << std::endl;
                left = 0;

-               std::cout << "Hermano Derecho   : " << (*it)->getChild () << std::endl;
-               right = (*it)->getChild ();
+               std::cout << "Hermano Derecho   : " << (*it)->GetChild () << std::endl;
+               right = (*it)->GetChild ();

                return;
        }
 
        while (it != node_keys.end ()) {
                return;
        }
 
        while (it != node_keys.end ()) {

-               if ((*it)->getChild () == node_num)
+               if ((*it)->GetChild () == node_num)

                        break;
                anterior = it;
                it++;
        }
        siguiente = it++;
 
                        break;
                anterior = it;
                it++;
        }
        siguiente = it++;
 

-       std::cout << "Hermano Izquierdo : " << (*anterior)->getChild () << std::endl;
-       left = (*anterior)->getChild ();
+       std::cout << "Hermano Izquierdo : " << (*anterior)->GetChild () << std::endl;
+       left = (*anterior)->GetChild ();

        if (siguiente != node_keys.end ()) {
        if (siguiente != node_keys.end ()) {

-               right = (*siguiente)->getChild ();
-               std::cout << "Hermano Derecho   : " << (*siguiente)->getChild () << std::endl;
+               right = (*siguiente)->GetChild ();
+               std::cout << "Hermano Derecho   : " << (*siguiente)->GetChild () << std::endl;

        } else {
                right = 0;
                std::cout << "Hermano Derecho   : NO TENGO" << std::endl;
        } else {
                right = 0;
                std::cout << "Hermano Derecho   : NO TENGO" << std::endl;


@@ -808,9 +891,9 @@ Clave *BTree::ReplaceKeyInFather (uint node_num, uint padre, Clave *k)
 
        BTreeData *lchild = (*it++);
 
 
        BTreeData *lchild = (*it++);
 

-       if (lchild->getChild () == node_num) {
-               Clave *ret = (*it)->getClave ();
-               (*it)->setClave (k);
+       if (lchild->GetChild () == node_num) {
+               Clave *ret = (*it)->GetKey ();
+               (*it)->SetKey (k);

 
                WriteKeys (node, node_header, node_keys);
                WriteNodoHeader (node, &node_header);
 
                WriteKeys (node, node_header, node_keys);
                WriteNodoHeader (node, &node_header);


@@ -822,14 +905,14 @@ Clave *BTree::ReplaceKeyInFather (uint node_num, uint padre, Clave *k)
        }
 
        while (it != node_keys.end ()) {
        }
 
        while (it != node_keys.end ()) {

-               if ((*it)->getChild () == node_num)
+               if ((*it)->GetChild () == node_num)

                        break;
                anterior = it;
                it++;
        }
 
                        break;
                anterior = it;
                it++;
        }
 

-       Clave *ret = (*it)->getClave ();
-       (*it)->setClave (k);
+       Clave *ret = (*it)->GetKey ();
+       (*it)->SetKey (k);

 
        WriteKeys (node, node_header, node_keys);
        WriteNodoHeader (node, &node_header);
 
        WriteKeys (node, node_header, node_keys);
        WriteNodoHeader (node, &node_header);


@@ -867,7 +950,7 @@ void BTree::DelKeyFromNode (Clave *k, uint node_num, uint padre, uint left, uint
                                node_keyr = ReadKeys (node_r, node_hr);
                                data_r = *(node_keyr.begin ());
                                padre_hijo = right;
                                node_keyr = ReadKeys (node_r, node_hr);
                                data_r = *(node_keyr.begin ());
                                padre_hijo = right;

-                               right = data_r->getChild ();
+                               right = data_r->GetChild ();

 
                                DeleteKeys (node_keyr);
                                delete [] node_r;
 
                                DeleteKeys (node_keyr);
                                delete [] node_r;


@@ -903,8 +986,8 @@ void BTree::DelKeyFromNode (Clave *k, uint node_num, uint padre, uint left, uint
                        PrintNode (node_num);
                        exit (1);
                }
                        PrintNode (node_num);
                        exit (1);
                }

-               (*it)->setClave (reemplazar->getClave ());
-               reemplazar->setClave (k->Clone ());
+               (*it)->SetKey (reemplazar->GetKey ());
+               reemplazar->SetKey (k->Clone ());

 
                std::cout << "Tengo todo reemplazado ...\n";
 
 
                std::cout << "Tengo todo reemplazado ...\n";
 


@@ -983,9 +1066,9 @@ std::list<BTreeData *> BTree::ReadKeys (uchar *node, BTreeNodeHeader &node_heade
        for (uint i=0; i<count; i++) {
                BTreeData *data;
                if (node_header.level == 0) {
        for (uint i=0; i<count; i++) {
                BTreeData *data;
                if (node_header.level == 0) {

-                       data = new BTreeLeafData (node, key_type);
+                       data = new BTreeLeafData (node, header.key_type);

                } else {
                } else {

-                       data = new BTreeData (node, key_type);
+                       data = new BTreeData (node, header.key_type);

                }
                node += data->Size ();
                keys.push_back (data);
                }
                node += data->Size ();
                keys.push_back (data);


@@ -998,7 +1081,7 @@ std::list<BTreeData *> BTree::ReadKeys (uchar *node, BTreeNodeHeader &node_heade
 void BTree::AbrevKey (std::list<BTreeData *> &lst)
 {
        /* Claves Fijas No se abrevian */
 void BTree::AbrevKey (std::list<BTreeData *> &lst)
 {
        /* Claves Fijas No se abrevian */

-       if (key_type == KEY_FIXED) return;
+       if (header.key_type == KEY_FIXED) return;

 
        BTreeData *primera = NULL;
        std::list<BTreeData *>::iterator it = lst.begin ();
 
        BTreeData *primera = NULL;
        std::list<BTreeData *>::iterator it = lst.begin ();


@@ -1013,7 +1096,7 @@ void BTree::AbrevKey (std::list<BTreeData *> &lst)
 void BTree::DeAbrevKey (std::list<BTreeData *> &lst)
 {
        /* Claves Fijas No se abrevian */
 void BTree::DeAbrevKey (std::list<BTreeData *> &lst)
 {
        /* Claves Fijas No se abrevian */

-       if (key_type == KEY_FIXED) return;
+       if (header.key_type == KEY_FIXED) return;

 
        BTreeData *primera = NULL;
        std::list<BTreeData *>::iterator it = lst.begin ();
 
        BTreeData *primera = NULL;
        std::list<BTreeData *>::iterator it = lst.begin ();


@@ -1083,11 +1166,18 @@ uchar *BTree::NewBlock (uint &num)
        uchar *node;
        BTreeNodeHeader nh;
 
        uchar *node;
        BTreeNodeHeader nh;
 

-       fseek (fp, 0, SEEK_END);
-       filelen = ftell (fp);
+       std::list<uint>::iterator it;
+       it = deleted_nodes.begin ();

 
 

-       num = filelen/header.block_size - 1;
+       if (it != deleted_nodes.end ()) {
+               num = *it;
+               deleted_nodes.erase (it);
+       } else {
+               fseek (fp, 0, SEEK_END);
+               filelen = ftell (fp);

 
 

+               num = filelen/header.block_size - 1;
+       }

        node = new uchar[header.block_size];
        ReadNodoHeader (node, &nh);
        nh.level = 0;
        node = new uchar[header.block_size];
        ReadNodoHeader (node, &nh);
        nh.level = 0;


@@ -1164,9 +1254,9 @@ BTreeFindResult *BTree::FindKeyR (const Clave *k, uint node_num)
        /* TODO: Aca faltaria liberar memoria */
        BTreeFindResult *ret;
        if (it == posterior)
        /* TODO: Aca faltaria liberar memoria */
        BTreeFindResult *ret;
        if (it == posterior)

-               ret = FindKeyR (k, lchild->getChild ());
+               ret = FindKeyR (k, lchild->GetChild ());

        else
        else

-               ret = FindKeyR (k, (*ultima)->getChild ());
+               ret = FindKeyR (k, (*ultima)->GetChild ());

 
        DeleteKeys (node_keys);
        delete [] node;
 
        DeleteKeys (node_keys);
        delete [] node;


@@ -1183,3 +1273,8 @@ void BTree::DeleteKeys (std::list<BTreeData *> &keys)
                it++;
        }
 }
                it++;
        }
 }

+
+int BTree::type () const
+{
+       return header.key_type;
+}