def add_index(self, index_node, block=None):
key = index_node.get_key()
root_block_location = self.get_root_block()
if block is None:
block = self.find_leaf_block(key, root_block_location)
parent = block.get_parent_block()
block.add_index_node(index_node)
if block.get_size() < self._block_size:
block.write_block(self._fd)
if root_block_location == -1:
self.set_root_block(block.get_location())
return
new_block, median_node = self.split_block(block)
if parent != -1:
parent = IndexBlock(parent, self._index_name, self._index_directory)
parent.read_block(self._fd)
block.write_block(self._fd)
new_block.write_block(self._fd)
self.add_index(median_node, parent)
else:
root_block = IndexBlock(self.get_free_block_pointer(), self._index_name, self._index_directory)
root_block.create_dummy_node()
root_block.get_index_nodes()[-1].set_index_block_pointer(block.get_location())
root_block.add_index_node(median_node)
block.set_parent_block(root_block.get_location())
new_block.set_parent_block(root_block.get_location())
self.set_root_block(root_block.get_location())
root_block.write_block(self._fd)
new_block.write_block(self._fd)
block.write_block(self._fd)
def find_leaf_block(self, key, root):
if root == -1:
block = IndexBlock(self.get_free_block_pointer(), self._index_name, self._index_directory)
block.create_dummy_node()
return block
block = self.read_block(root)
parent = -1
while not block.is_leaf():
parent = block.get_location()
index_nodes = block.get_index_nodes()
flag = 0
for node in index_nodes:
if key < node.get_key():
flag = 1
block_location = node.get_index_block_pointer()
break
if flag == 0:
block_location = block.get_dummy_node_pointer()
if block_location == -1:
return self.read_block(parent)
if block_location == None:
x = 1
block = self.read_block(block_location)
return block
def find_leaf_block(self, key, root):
if root == -1:
block = IndexBlock(self.get_free_block_pointer(), self._index_name, self._index_directory)
block.create_dummy_node()
return block
block = IndexBlock(root, self._index_name, self._index_directory)
parent = -1
block.read_block(self._fd)
while not block.is_leaf():
parent = block.get_location()
index_nodes = block.get_index_nodes()
for node in index_nodes:
if key < node.get_key():
block = IndexBlock(node.get_index_block_pointer(), self._index_name, self._index_directory)
break
if block.get_location() == -1:
return parent
block.read_block(self._fd)
return block
def split_block(self, block):
index_nodes = block.get_index_nodes()
median = int(len(index_nodes)/2 - 1)
median_node = index_nodes[median]
new_block = IndexBlock(self.get_free_block_pointer(), self._index_name, self._index_directory)
new_block.create_dummy_node()
i = 0
while i < median:
new_block.add_index_node(index_nodes[i])
i += 1
new_block.get_index_nodes()[-1].set_index_block_pointer(median_node.get_index_block_pointer())
i = 0
while i <= median:
block.delete_index_node(index_nodes[0])
i += 1
new_block.update_child_blocks(self._fd)
median_node.set_index_block_pointer(new_block.get_location())
new_block.set_parent_block(block.get_parent_block())
return new_block, median_node