第五课技术选型作业

import hashlib
class HashConsistency :
    def _init__(self,noteList, noteCount ):
        self._hashCircle = dict()
        self._virtualNodeCount = noteCount
        self._virtualNoteList =  noteList
        if noteList:
            for note in notelist:
                self.add_node(note)
    def add_node(self,node):
        for i in range(self._virtualNodeCount):
            node_str = "%s %s" %(node,i)
            key = self._gen_key(node_str)
            self._hashCircle[key] = node
            self._virtualNoteList.append(key)
        self._virtualNoteList.sort()
    def get_node(self,key_str):
        if self._virtualNoteList:
            key = self._gen_key(key_str)
            for node_key in self._virtualNoteList:
                if key <= node_key:
                    return self._hashCircle[node_key]
            return self._hashCircle[self._virtualNoteList[0]]
        else:
            return None
    def remove_node(self,node):
        for i in range(self._virtualNodeCount):
            node_str = "%s %s" % (node, i)
            key = self._gen_key(node_str)
            if key in self._hashCircle.keys():
                del self._hashCircle[key]
                self._virtualNoteList.remove(key)
                return
    @staticmethod
    def _gen_key(key_str):
        md5_str = hashlib.md5(key_str)
        return long(md5_str,16)