def delete_index_node(self, index_node):
block, index_node = self.find_index_block(index_node)
if block is None:
print("Fail")
return
successor_block, successor_node = self.find_successor(block, index_node)
if block == successor_block:
successor_node.set_index_block_pointer(index_node.get_index_block_pointer())
block.delete_index_node(index_node)
if len(block.get_index_nodes()) == 1:
if block.get_location() != self.get_root_block():
parent_location = block.get_parent_block()
if parent_location != -1:
parent = IndexBlock(parent_location, self._index_name, self._index_directory)
parent.read_block(self._fd)
for node in parent.get_index_nodes():
if node.get_index_block_pointer() == block.get_location():
node.set_index_block_pointer(block.get_index_nodes()[0].get_index_block_pointer())
parent.update_child_blocks(self._fd)
parent.write_block(self._fd)
block.delete_block(self._fd, self.get_free_block_pointer())
else:
block.write_block(self._fd)
else:
block.write_block(self._fd)
else :
successor_block.delete_index_node(successor_node)
block.delete_index_node(index_node)
successor_node.set_index_block_pointer(index_node.get_index_block_pointer())
block.add_index_node(successor_node)
block.write_block(self._fd)
if len(successor_block.get_index_nodes()) == 1:
if successor_block.get_location() != self.get_root_block():
parent_location = successor_block.get_parent_block()
if parent_location != -1:
parent = IndexBlock(parent_location, self._index_name, self._index_directory)
parent.read_block(self._fd)
for node in parent.get_index_nodes():
if node.get_index_block_pointer() == successor_block.get_location():
node.set_index_block_pointer(successor_block.get_index_nodes()[0].get_index_block_pointer())
parent.update_child_blocks(self._fd)
parent.write_block(self._fd)
successor_block.delete_block(self._fd, self.get_free_block_pointer())
else:
successor_block.write_block(self._fd)
else:
successor_block.write_block(self._fd)
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
