Add RAFT stuff

MyRaft/messages.py

@@ -0,0 +1,129 @@
+""" This module holds the messages for raft to use.
+
+Message -- Base message class
+
+AppendEntries -- Message representing raft append entries.
+
+RequestVote -- Message representing raft request vote.
+
+RequestVoteReponse -- Message for responding to a request vote.
+
+Response -- Response to an append entries message.
+"""
+import umsgpack
+from enum import Enum
+
+class Messages(Enum):
+    AppendEntries = 1
+    RequestVote = 2
+    RequestVoteResponse = 3
+    AppendEntriesResponse = 4 
+
+class Message:
+    """The base class of all messages used in raft"""
+    _type = None
+
+    def __init__(self, sender, data = {}, term = 0):
+        self._sender = sender
+        self._data = data
+        self._term = term
+
+    @property
+    def sender(self):
+        return self._sender
+
+    @property
+    def type(self):
+        return self._type
+
+    def serialise(self):
+        """Serialises a Message object into a message pack byte array"""
+        raise NotImplementedError
+
+    @staticmethod
+    def deserialise(message):
+        """Deserialises from a byte array into a Message object
+
+        message -- Message to deserialise.
+
+        Returns -- Deserialised message object, None if incorrect input message. 
+        """
+        m = None
+        try:
+            m = umsgpack.unpackb(m)
+        except:
+            print("Could not decode message")
+            return m
+
+        m = Message('tbd')
+        raise NotImplementedError
+
+    def __eq__(self, other):
+        if not isinstance(other, Message):
+            return False
+
+        if other.type != self.type:
+            return False
+
+        if other._data != self._data:
+            return False
+
+        if other._sender != self._sender:
+            return False
+
+        return True
+        
+class AppendEntries(Message):
+    _type = "AppendEntries"
+
+    def __init__(self, term, leaderId, prevLogIndex, prevLogTerm, leaderCommit, entries = None):
+        self._data["term"] = term
+        self._data["leaderId"] = leaderId
+        self._data["prevLogIndex"] = prevLogIndex
+        self._data["prevLogTerm"] = prevLogTerm
+        self._data["entries"] = entries
+        self._data["leaderCommit"] = leaderCommit # Leader's commit index.
+
+
+class RequestVote(Message):
+    _type = "RequestVote"
+
+    def __init__(self, term, candidate_id, last_log_index, last_log_term):
+        self._data["candidateId"] = candidate_id
+        self._data["lastLogIndex"] = last_log_index
+        self._data["lastLogTerm"] = last_log_term
+
+    @property
+    def candidate_id(self):
+        return self._data["candidateId"]
+
+    @property
+    def last_log_index(self):
+        return self._data["lastLogIndex"]
+
+    @property
+    def last_log_term(self):
+        return self._data["lastLogTerm"]
+
+
+class RequestVoteResponse(Message):
+    _type = "RequestVoteResponse"
+
+    def __init__(self, term, vote_granted):
+        self._data["voteGranted"] = vote_granted
+
+    @property
+    def vote_granted(self):
+        return self._data["voteGranted"]
+
+class Response(Message):
+    _type = "Response"
+
+    def __init__(self, term, success):
+        self._data["success"] = success
+
+    @property
+    def success(self):
+        return self._data["success"]
+
+