From 7cdc3c1400f9bb4588a872fa0584dd0442938a92 Mon Sep 17 00:00:00 2001
From: Jarrod Johnson <jjohnson2@lenovo.com>
Date: Thu, 12 Jul 2018 08:48:07 -0400
Subject: [PATCH] Implement clear config rollback

Should something go awry during config
load, rollback the clear and load.
---
 .../confluent/collective/manager.py           | 28 +++++++++++-------
 .../confluent/config/configmanager.py         | 29 +++++++++++++++++--
 2 files changed, 43 insertions(+), 14 deletions(-)

diff --git a/confluent_server/confluent/collective/manager.py b/confluent_server/confluent/collective/manager.py
index ae9d3364..b05c4df3 100644
--- a/confluent_server/confluent/collective/manager.py
+++ b/confluent_server/confluent/collective/manager.py
@@ -103,15 +103,21 @@ def connect_to_leader(cert=None, name=None, leader=None):
                 dbjson += ndata
             cfm.cfgleader = None
             cfm.clear_configuration()
-            cfm._restore_keys(keydata, None, sync=False)
-            for c in colldata:
-                cfm._true_add_collective_member(c, colldata[c]['address'],
-                                                colldata[c]['fingerprint'],
-                                                sync=False)
-            for globvar in globaldata:
-                cfm.set_global(globvar, globaldata[globvar])
-            cfm._txcount = dbi.get('txcount', 0)
-            cfm.ConfigManager(tenant=None)._load_from_json(dbjson)
+            try:
+                cfm._restore_keys(keydata, None, sync=False)
+                for c in colldata:
+                    cfm._true_add_collective_member(c, colldata[c]['address'],
+                                                    colldata[c]['fingerprint'],
+                                                    sync=False)
+                for globvar in globaldata:
+                    cfm.set_global(globvar, globaldata[globvar])
+                cfm._txcount = dbi.get('txcount', 0)
+                cfm.ConfigManager(tenant=None)._load_from_json(dbjson,
+                                                               sync=False)
+                cfm.commit_clear()
+            except Exception:
+                cfm.rollback_clear()
+                raise
             currentleader = leader
         #spawn this as a thread...
         follower = eventlet.spawn(follow_leader, remote)
@@ -227,8 +233,8 @@ def handle_connection(connection, cert, request, local=False):
             f = open('/etc/confluent/cfg/myname', 'w')
             f.write(name)
             f.close()
-            cfm.clear_configuration()
-            eventlet.spawn_n(connect_to_leader, rsp['collective']['fingerprint'], name)
+            eventlet.spawn_n(connect_to_leader, rsp['collective'][
+                'fingerprint'], name)
     if 'enroll' == operation:
         #TODO(jjohnson2): error appropriately when asked to enroll, but the master is elsewhere
         mycert = util.get_certificate_from_file('/etc/confluent/srvcert.pem')
diff --git a/confluent_server/confluent/config/configmanager.py b/confluent_server/confluent/config/configmanager.py
index 7158e801..2d0b30e5 100644
--- a/confluent_server/confluent/config/configmanager.py
+++ b/confluent_server/confluent/config/configmanager.py
@@ -496,17 +496,39 @@ def stop_leading():
             pass  # may have already been deleted..
 
 
+_oldcfgstore = None
+_oldtxcount = 0
+
+
+def rollback_clear():
+    global _cfgstore
+    global _txcount
+    global _oldcfgstore
+    global _oldtxcount
+    _txcount = _oldtxcount
+    _cfgstore = _oldcfgstore
+    _oldtxcount = 0
+    _oldcfgstore = None
+
+
 def clear_configuration():
     global _cfgstore
     global _txcount
     _cfgstore = {}
-    todelete = _config_areas + ('globals', 'collective', 'transactioncount')
     _txcount = 0
+
+def commit_clear():
+    global _oldtxcount
+    global _oldcfgstore
+    _oldcfgstore = None
+    _oldtxcount = 0
+    todelete = _config_areas + ('globals', 'collective', 'transactioncount')
     for cfg in todelete:
         try:
             os.remove(os.path.join(ConfigManager._cfgdir, cfg))
         except OSError as oe:
             pass
+    self._bg_sync_to_file()
 
 cfgleader = None
 def follow_channel(channel):
@@ -1680,7 +1702,7 @@ class ConfigManager(object):
         self._bg_sync_to_file()
         #TODO: wait for synchronization to suceed/fail??)
 
-    def _load_from_json(self, jsondata):
+    def _load_from_json(self, jsondata, sync=True):
         """Load fresh configuration data from jsondata
 
         :param jsondata: String of jsondata
@@ -1751,7 +1773,8 @@ class ConfigManager(object):
                         self._cfgstore['users'][user]['cryptpass'] = \
                             tmpconfig[confarea][user]['cryptpass']
                         _mark_dirtykey('users', user, self.tenant)
-        self._bg_sync_to_file()
+        if sync:
+            self._bg_sync_to_file()
 
     def _dump_to_json(self, redact=None):
         """Dump the configuration in json form to output