Split election process into shorter methods to highlight logic.

git-svn-id: https://svn.erp5.org/repos/neo/trunk@1463 71dcc9de-d417-0410-9af5-da40c76e7ee4

neo/master/app.py

@@ -124,6 +124,7 @@ class Application(object):
                 # Reelect a new primary master.
                 self.electPrimary(bootstrap = False)
 
+
     def electPrimary(self, bootstrap = True):
         """Elect a primary master node.
 
@@ -136,24 +137,47 @@ class Application(object):
         self.unconnected_master_node_set = set()
         self.negotiating_master_node_set = set()
         self.listening_conn.setHandler(election.ServerElectionHandler(self))
-        client_handler = election.ClientElectionHandler(self)
-        em = self.em
-        nm = self.nm
 
-        for node in nm.getMasterList():
+        for node in self.nm.getMasterList():
             # For now, believe that every node should be available,
             # since down or broken nodes may be already repaired.
             node.setRunning()
 
-        while 1:
-            t = 0
-            self.primary = None
-            self.primary_master_node = None
+        try:
+            while True:
 
-            for node in nm.getMasterList():
+                # handle new connected masters
+                for node in self.nm.getMasterList():
                     if node.isRunning():
                         self.unconnected_master_node_set.add(node.getAddress())
 
+                # start the election process
+                self.primary = None
+                self.primary_master_node = None
+                self._doElection(bootstrap)
+
+                self.primary = self.primary is None
+                if self.primary:
+                    # i'm the primary, send the announcement
+                    self._announcePrimary()
+                else:
+                    # otherwise, wait for the primary announcement
+                    self._waitForPrimaryAnnouncement()
+                break
+        except ElectionFailure, m:
+            # something goes wrong, clean then restart
+            self._electionFailed(m)
+            bootstrap = False
+
+
+    def _doElection(self, bootstrap):
+        """
+            Start the election process:
+                - Try to connect to any known master node
+                - Wait a most for the timeout defined by bootstrap parameter
+            When done, the current process si defined either as primary or
+            secondary master node
+        """
         # Wait at most 20 seconds at bootstrap. Otherwise, wait at most
         # 10 seconds to avoid stopping the whole cluster for a long time.
         # Note that even if not all master are up in the first 20 seconds
@@ -163,13 +187,13 @@ class Application(object):
             expiration = 20
         else:
             expiration = 10
-
-            try:
-                while 1:
+        client_handler = election.ClientElectionHandler(self)
+        t = 0
+        while True:
             current_time = time()
             if current_time >= t + 1:
                 t = current_time
-                        for node in nm.getMasterList():
+                for node in self.nm.getMasterList():
                     if node.isTemporarilyDown() \
                             and node.getLastStateChange() + \
                             expiration < current_time:
@@ -181,64 +205,74 @@ class Application(object):
                 # Try to connect to master nodes.
                 if self.unconnected_master_node_set:
                     for addr in list(self.unconnected_master_node_set):
-                                ClientConnection(em, client_handler, addr=addr,
+                        ClientConnection(self.em, client_handler, addr=addr,
                              connector_handler=self.connector_handler)
-                    em.poll(1)
+            self.em.poll(1)
             if len(self.unconnected_master_node_set) == 0 \
                and len(self.negotiating_master_node_set) == 0:
                 break
 
-                # Now there are three situations:
-                #   - I am the primary master
-                #   - I am secondary but don't know who is primary
-                #   - I am secondary and know who is primary
-                if self.primary is None:
+
+    def _announcePrimary(self):
+        """
+            Broadcast the announce that I'm the primary
+        """
         # I am the primary.
-                    self.primary = True
         logging.debug('I am the primary, sending an announcement')
-                    for conn in em.getClientList():
+        for conn in self.em.getClientList():
             conn.notify(Packets.AnnouncePrimary())
             conn.abort()
         t = time()
-                    while em.getClientList():
-                        em.poll(1)
+        while self.em.getClientList():
+            self.em.poll(1)
             if t + 10 < time():
-                            for conn in em.getClientList():
+                for conn in self.em.getClientList():
                     conn.close()
                 break
-                else:
+
+
+    def _waitForPrimaryAnnouncement(self):
+        """
+            For for the primary announcement as i'm not the primary.
+            If this is too long, raise ElectionFailure to restart the whole
+            election process.
+        """
         # Wait for an announcement. If this is too long, probably
         # the primary master is down.
         t = time()
         while self.primary_master_node is None:
-                        em.poll(1)
+            self.em.poll(1)
             if t + 10 < time():
-                            raise ElectionFailure, 'no primary master elected'
+                # election timeout
+                raise ElectionFailure("Election timeout")
 
         # Now I need only a connection to the primary master node.
         primary = self.primary_master_node
         addr = primary.getAddress()
-                    for conn in em.getServerList():
+        for conn in self.em.getServerList():
             conn.close()
-                    for conn in em.getClientList():
+        for conn in self.em.getClientList():
             if conn.getAddress() != addr:
                 conn.close()
 
         # But if there is no such connection, something wrong
         # happened.
-                    for conn in em.getClientList():
+        for conn in self.em.getClientList():
             if conn.getAddress() == addr:
+                # primary master elected and connected
                 break
         else:
-                        raise ElectionFailure, 'no connection remains to ' \
-                                'the primary'
+            raise ElectionFailure('No connection remains to the primary')
 
-                return
-            except ElectionFailure, m:
-                logging.error('election failed; %s' % m)
+
+    def _electionFailed(self, m):
+        """
+            Ask other masters to reelect a primary after an election failure.
+        """
+        logging.error('election failed: %s', (m, ))
 
         # Ask all connected nodes to reelect a single primary master.
-                for conn in em.getClientList():
+        for conn in self.em.getClientList():
             conn.notify(Packets.ReelectPrimary())
             conn.abort()
 
@@ -246,9 +280,9 @@ class Application(object):
         self.primary = None
         self.primary_master_node = None
         t = time()
-                while em.getClientList():
+        while self.em.getClientList():
             try:
-                        em.poll(1)
+                self.em.poll(1)
             except ElectionFailure:
                 pass
             if time() > t + 10:
@@ -256,11 +290,11 @@ class Application(object):
                 break
 
         # Close all connections.
-                for conn in em.getClientList():
+        for conn in self.em.getClientList():
             conn.close()
-                for conn in em.getServerList():
+        for conn in self.em.getServerList():
             conn.close()
-                bootstrap = False
+
 
     def broadcastNodesInformation(self, node_list):
         """