class ConsistentHasher:
def __init__(self):
self.nodes = BST()
self.id_to_node = dict()
def hash(self, item, limit=4294967295):
id_hash = hashlib.sha512(item.encode())
id_hash_int = int.from_bytes(id_hash.digest(), 'big')
final_id = id_hash_int % limit
return final_id
def add_node(self, node_name):
hash_id = self.hash(node_name)
self.nodes.insert(hash_id)
self.id_to_node[hash_id] = node_name
def remove_node(self, node_name):
hash_id = self.hash(node_name)
removed = self.nodes.remove(hash_id)
print('Removed %s: %r' % (node_name, removed))
return self.id_to_node.pop(hash_id, None)
def assign_key_to_node(self, key):
key_hash_id = self.hash(key)
assigned_node_id = self.nodes.find_next_bigger_elem(key_hash_id)
if assigned_node_id is None:
print('Failed to assign key %s (hash = %d) to any node!' %
(key, key_hash_id))
return
# print('Key %s was hashed to value %d, and was assigned to node %s with id %d' % (key, key_hash_id, self.id_to_node[assigned_node_id], assigned_node_id))
return self.id_to_node[assigned_node_id]
def test_bst(self):
numbers = [10, 15, 3, 6, 12, 20, 1, 0]
bst = BST()
for num in numbers:
bst.insert(num)
ordered_nums = bst.traverse_inorder()
print(ordered_nums)
for num in numbers:
successor = bst.find_next_bigger_elem(num)
if successor is not None:
print('Successor of %d is %d' % (num, successor))
else:
print('Successor of %d is %s' % (num, 'None'))
predecessor = bst.find_previous_smaller_elem(num)
if predecessor is not None:
print('Predecessor of %d is %d' % (num, predecessor))
else:
print('Predecessor of %d is %s' % (num, 'None'))
print('\n')
num = -1 # Does not exist in the list
successor = bst.find_next_bigger_elem(num)
if successor is not None:
print('Successor of %d is %d' % (num, successor))
else:
print('Successor of %d is %s' % (num, 'None'))
print('\n')
num = 1
removed = bst.remove(num)
if removed is not None:
print('%d removed from tree: %s' %
(num, " ".join(str(x) for x in bst.traverse_inorder())))
else:
print('%d was not found in the tree' % num)
class ConsistentHasher:
def __init__(self):
self.nodes = BST()
self.id_to_node = dict()
# Note: we need a deterministic hash function. Python hashlib's hash() is not deterministic, and will return
# a different hash value on different runs.
def hash(self, item, limit=4294967295):
id_hash = hashlib.sha512(item.encode())
id_hash_int = int.from_bytes(
id_hash.digest(), 'big'
) # Uses explicit byteorder for system-agnostic reproducibility
final_id = id_hash_int % limit
return final_id
def hash2(self, item):
return zlib.adler32(str.encode(item)) & 0xffffffff
def add_node(self, node_name):
hash_id = self.hash(node_name)
self.nodes.insert(hash_id)
self.id_to_node[hash_id] = node_name
def remove_node(self, node_name):
hash_id = self.hash(node_name)
removed = self.nodes.remove(hash_id)
print('Removed %s: %r' % (node_name, removed))
return self.id_to_node.pop(hash_id, None)
def assign_key_to_node(self, key):
key_hash_id = self.hash(key)
assigned_node_id = self.nodes.find_next_bigger_elem(key_hash_id)
if assigned_node_id is None:
print('Failed to assign key %s (hash = %d) to any node!' %
(key, key_hash_id))
return
# print('Key %s was hashed to value %d, and was assigned to node %s with id %d' % (key, key_hash_id, self.id_to_node[assigned_node_id], assigned_node_id))
return self.id_to_node[assigned_node_id]