Python3.x 环境下安装使用hash_ring库

冷不防 2022-03-18 14:10 297阅读 0赞

### hash\_ring库安装 ###

pip install hash_ring

### 修改使其在Python3.x 环境下能用 ###

安装成功后，在程序里直接加载hash\_ring库

from hash_ring import *

会报错如下:

Traceback (most recent call last):
    
      File "D:\ProgramData\Anaconda3\lib\site-packages\IPython\core\interactiveshell.py", line 2963, in run_code
        exec(code_obj, self.user_global_ns, self.user_ns)
      File "<ipython-input-1-00889c1e63f8>", line 1, in <module>
        runfile('E:/推荐系统/hash1.py', wdir='E:/推荐系统')
      File "D:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 705, in runfile
        execfile(filename, namespace)
      File "D:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
        exec(compile(f.read(), filename, 'exec'), namespace)
      File "E:/推荐系统/hash1.py", line 1, in <module>
        from hash_ring import *
      File "D:\ProgramData\Anaconda3\lib\site-packages\hash_ring\__init__.py", line 5
        except ImportError, e:
                          ^
    SyntaxError: invalid syntax

这是由于官方给出的（"D:\\ProgramData\\Anaconda3\\lib\\site-packages\\hash\_ring\\\_\_init\_\_.py"）文件代码是由Python2.x 版本实现的，而有些语法在Python3.x 中不再适用。打开该文件：

from hash_ring import HashRing
      
    try:
        from memcache_ring import MemcacheRing
    except ImportError,e:
        pass

手动修改为：

from hash_ring.hash_ring import HashRing
      
    try:
        from memcache_ring import MemcacheRing
    except ImportError as e:
        pass

再次运行，又发现新的问题：：

Traceback (most recent call last):
    
      File "<ipython-input-4-00889c1e63f8>", line 1, in <module>
        runfile('E:/推荐系统/hash1.py', wdir='E:/推荐系统')
      File "D:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 705, in runfile
        execfile(filename, namespace)
      File "D:\ProgramData\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
        exec(compile(f.read(), filename, 'exec'), namespace)
      File "E:/推荐系统/hash1.py", line 5, in <module>
        ring = HashRing(memcache_servers)
      File "D:\ProgramData\Anaconda3\lib\site-packages\hash_ring\hash_ring.py", line 62, in __init__
        self._generate_circle()
      File "D:\ProgramData\Anaconda3\lib\site-packages\hash_ring\hash_ring.py", line 79, in _generate_circle
        for j in xrange(0, int(factor)):
    NameError: name 'xrange' is not defined

这次是同样的问题，文件（"D:\\ProgramData\\Anaconda3\\lib\\site-packages\\hash\_ring\\hash\_ring.py"）中同样存在Python2.x 语法，修改为：

# -*- coding: utf-8 -*-
    """
        hash_ring
        ~~~~~~~~~~~~~~
        Implements consistent hashing that can be used when
        the number of server nodes can increase or decrease (like in memcached).
    
        Consistent hashing is a scheme that provides a hash table functionality
        in a way that the adding or removing of one slot
        does not significantly change the mapping of keys to slots.
    
        More information about consistent hashing can be read in these articles:
    
            "Web Caching with Consistent Hashing":
                http://www8.org/w8-papers/2a-webserver/caching/paper2.html
    
            "Consistent hashing and random trees:
            Distributed caching protocols for relieving hot spots on the World Wide Web (1997)":
                http://citeseerx.ist.psu.edu/legacymapper?did=38148
    
    
        Example of usage::
    
            memcache_servers = ['192.168.0.246:11212',
                                '192.168.0.247:11212',
                                '192.168.0.249:11212']
    
            ring = HashRing(memcache_servers)
            server = ring.get_node('my_key')
    
        :copyright: 2008 by Amir Salihefendic.
        :license: BSD
    """
    
    import math
    import sys
    from bisect import bisect
    
    if sys.version_info >= (2, 5):
        import hashlib
        md5_constructor = hashlib.md5
    else:
        import md5
        md5_constructor = md5.new
    
    class HashRing(object):
    
        def __init__(self, nodes=None, weights=None):
            """
            `nodes` is a list of objects that have a proper __str__ representation.
            `weights` is dictionary that sets weights to the nodes.  The default
            weight is that all nodes are equal.
            """
            self.ring = dict()
            self._sorted_keys = []
    
            self.nodes = nodes
    
            if not weights:
                weights = {}
            self.weights = weights
    
            self._generate_circle()
    
        def _generate_circle(self):
            """Generates the circle.
            """
            total_weight = 0
            for node in self.nodes:
                total_weight += self.weights.get(node, 1)
    
            for node in self.nodes:
                weight = 1
    
                if node in self.weights:
                    weight = self.weights.get(node)
    
                factor = math.floor((40*len(self.nodes)*weight) / total_weight);
    
                for j in range(0, int(factor)):  # 修改处2, xrange -> range
                    b_key = self._hash_digest( '%s-%s' % (node, j) )
    
                    for i in range(0, 3):
                        key = self._hash_val(b_key, lambda x: x+i*4)
                        self.ring[key] = node
                        self._sorted_keys.append(key)
    
            self._sorted_keys.sort()
    
        def get_node(self, string_key):
            """Given a string key a corresponding node in the hash ring is returned.
    
            If the hash ring is empty, `None` is returned.
            """
            pos = self.get_node_pos(string_key)
            if pos is None:
                return None
            return self.ring[ self._sorted_keys[pos] ]
    
        def get_node_pos(self, string_key):
            """Given a string key a corresponding node in the hash ring is returned
            along with it's position in the ring.
    
            If the hash ring is empty, (`None`, `None`) is returned.
            """
            if not self.ring:
                return None
    
            key = self.gen_key(string_key)
    
            nodes = self._sorted_keys
            pos = bisect(nodes, key)
    
            if pos == len(nodes):
                return 0
            else:
                return pos
    
        def iterate_nodes(self, string_key, distinct=True):
            """Given a string key it returns the nodes as a generator that can hold the key.
    
            The generator iterates one time through the ring
            starting at the correct position.
    
            if `distinct` is set, then the nodes returned will be unique,
            i.e. no virtual copies will be returned.
            """
            if not self.ring:
                yield None, None
    
            returned_values = set()
            def distinct_filter(value):
                if str(value) not in returned_values:
                    returned_values.add(str(value))
                    return value
    
            pos = self.get_node_pos(string_key)
            for key in self._sorted_keys[pos:]:
                val = distinct_filter(self.ring[key])
                if val:
                    yield val
    
            for i, key in enumerate(self._sorted_keys):
                if i < pos:
                    val = distinct_filter(self.ring[key])
                    if val:
                        yield val
    
        def gen_key(self, key):
            """Given a string key it returns a long value,
            this long value represents a place on the hash ring.
    
            md5 is currently used because it mixes well.
            """
            b_key = self._hash_digest(key)
            return self._hash_val(b_key, lambda x: x)
    
        def _hash_val(self, b_key, entry_fn):
            return (( b_key[entry_fn(3)] << 24)
                    |(b_key[entry_fn(2)] << 16)
                    |(b_key[entry_fn(1)] << 8)
                    | b_key[entry_fn(0)] )
    
        def _hash_digest(self, key):
            m = md5_constructor()
            m.update(key.encode('utf-8'))  # 修改处3,Unicode-objects must be encoded before hashing
    
            return list(map(ord,str(m.digest())))  # 修改处1,python3 'map' object is not subscriptable

至此，问题全部解决。