Reapply "Rework reconnection logic so RECONNECT_TIME is interpreted as a minimum, to avoid eating CPU if Avahi or NM becomes unstable (or if dbus-python has the buggy pre-0.82 watch_name_owner() implementation)."

This reverts commit ae18c6f3897ee10a2136b36061dab14d465198b1.

3 files changed, 50 insertions, 33 deletions

diff --git a/src/linklocal_plugin.py b/src/linklocal_plugin.py
index b60eb15..10924e1 100644
--- a/src/linklocal_plugin.py
+++ b/src/linklocal_plugin.py
@@ -68,15 +68,19 @@ class LinkLocalPlugin(TelepathyPlugin):
         if unique_name:
             self._have_avahi = True
             if not had_avahi:
-                _logger.info('Avahi appeared on the system bus (%s) - '
-                             'starting...', unique_name)
-                self.start()
+                if self._backoff_id > 0:
+                    _logger.info('Avahi appeared on the system bus (%s) - '
+                                 'will start when retry time is reached')
+                else:
+                    _logger.info('Avahi appeared on the system bus (%s) - '
+                                 'starting...', unique_name)
+                    self.start()
         else:
             self._have_avahi = False
             if had_avahi:
                 _logger.info('Avahi disappeared from the system bus - '
                              'stopping...')
-                self.stop()
+                self._stop()
 
     def cleanup(self):
         TelepathyPlugin.cleanup(self)
@@ -85,7 +89,7 @@ class LinkLocalPlugin(TelepathyPlugin):
         self._watch = None
 
     def _could_connect(self):
-        return self._have_avahi
+        return TelepathyPlugin._could_connect(self) and self._have_avahi
 
     def _get_account_info(self):
         """Retrieve connection manager parameters for this account
diff --git a/src/server_plugin.py b/src/server_plugin.py
index ab00be7..7c275b1 100644
--- a/src/server_plugin.py
+++ b/src/server_plugin.py
@@ -68,12 +68,12 @@ class ServerPlugin(TelepathyPlugin):
         if address:
             _logger.debug("::: valid IP4 address, conn_status %s",
                           self._conn_status)
-            if self._conn_status == CONNECTION_STATUS_DISCONNECTED:
-                _logger.debug("::: will connect")
+            # this is a no-op if starting would be inappropriate right now
+            if self._conn_status != CONNECTION_STATUS_DISCONNECTED:
                 self.start()
         else:
             _logger.debug("::: invalid IP4 address, will disconnect")
-            self.stop()
+            self._stop()
 
     def _get_account_info(self):
         """Retrieve connection manager parameters for this account
@@ -126,7 +126,8 @@ class ServerPlugin(TelepathyPlugin):
         return None
 
     def _could_connect(self):
-        return bool(self._ip4am.props.address)
+        return bool(self._ip4am.props.address and
+                    TelepathyPlugin._could_connect(self))
 
     def _server_is_trusted(self, hostname):
         """Return True if the server with the given hostname is trusted to
diff --git a/src/telepathy_plugin.py b/src/telepathy_plugin.py
index d28e6a3..a9ddfe0 100644
--- a/src/telepathy_plugin.py
+++ b/src/telepathy_plugin.py
@@ -112,8 +112,8 @@ class TelepathyPlugin(gobject.GObject):
         #: The connection's status
         self._conn_status = CONNECTION_STATUS_DISCONNECTED
 
-        #: GLib signal ID for reconnections
-        self._reconnect_id = 0
+        #: GLib source ID indicating when we may try to reconnect
+        self._backoff_id = 0
 
         #: Parameters for the connection manager
         self._account = self._get_account_info()
@@ -156,8 +156,16 @@ class TelepathyPlugin(gobject.GObject):
         raise NotImplementedError
 
     def _reconnect_cb(self):
-        """Attempt to reconnect to the server"""
+        """Attempt to reconnect to the server after the back-off time has
+        elapsed.
+        """
+        if self._backoff_id > 0:
+            gobject.source_remove(self._backoff_id)
+            self._backoff_id = 0
+
+        # this is a no-op unless _could_connect() returns True
         self.start()
+
         return False
 
     def _init_connection(self):
@@ -192,9 +200,11 @@ class TelepathyPlugin(gobject.GObject):
                 _logger.debug('%r: Connect() succeeded', self)
             def connect_error(e):
                 _logger.debug('%r: Connect() failed: %s', self, e)
-                if not self._reconnect_id:
-                    self._reconnect_id = gobject.timeout_add(self._RECONNECT_TIMEOUT,
-                            self._reconnect_cb)
+                # we don't allow ourselves to retry more often than this
+                if self._backoff_id != 0:
+                    gobject.source_remove(self._backoff_id)
+                self._backoff_id = gobject.timeout_add(self._RECONNECT_TIMEOUT,
+                        self._reconnect_cb)
 
             self._conn[CONN_INTERFACE].Connect(reply_handler=connect_reply,
                                                error_handler=connect_error)
@@ -228,26 +238,30 @@ class TelepathyPlugin(gobject.GObject):
             _logger.debug("%r: connected", self)
             self._connected_cb()
         elif status == CONNECTION_STATUS_DISCONNECTED:
-            self.stop()
+            self._conn = None
+            self._stop()
             _logger.debug("%r: disconnected (reason %r)", self, reason)
             if reason == CONNECTION_STATUS_REASON_AUTHENTICATION_FAILED:
                 # FIXME: handle connection failure; retry later?
                 pass
             else:
-                # If disconnected, but still have a network connection, retry
-                # If disconnected and no network connection, do nothing here
-                # and let the IP4AddressMonitor address-changed signal handle
-                # reconnection
-                if self._could_connect() and not self._reconnect_id:
-                    self._reconnect_id = gobject.timeout_add(self._RECONNECT_TIMEOUT,
+                # Try again later. We'll detect whether we have a network
+                # connection after the retry period elapses. The fact that
+                # this timer is running also serves as a marker to indicate
+                # that we shouldn't try to go back online yet.
+                if self._backoff_id:
+                    gobject.source_remove(self._backoff_id)
+                    self._backoff_id = gobject.timeout_add(self._RECONNECT_TIMEOUT,
                             self._reconnect_cb)
 
         self.emit('status', self._conn_status, int(reason))
 
     def _could_connect(self):
-        return True
+        # Don't allow connection unless the reconnect timeout has elapsed,
+        # or this is the first attempt
+        return (self._backoff_id == 0)
 
-    def stop(self):
+    def _stop(self):
         """If we still have a connection, disconnect it"""
 
         matches = self._matches
@@ -266,12 +280,12 @@ class TelepathyPlugin(gobject.GObject):
         if self._online_contacts:
             self._contacts_offline(self._online_contacts)
 
-        if self._reconnect_id > 0:
-            gobject.source_remove(self._reconnect_id)
-            self._reconnect_id = 0
-
     def cleanup(self):
-        self.stop()
+        self._stop()
+
+        if self._backoff_id > 0:
+            gobject.source_remove(self._backoff_id)
+            self._backoff_id = 0
 
     def _contacts_offline(self, handles):
         """Handle contacts going offline (send message, update set)"""
@@ -454,13 +468,11 @@ class TelepathyPlugin(gobject.GObject):
         otherwise initiate a connection and transfer control to
             _connect_reply_cb or _connect_error_cb
         """
+        if self._conn is not None:
+            return
 
         _logger.debug("%r: Starting up...", self)
 
-        if self._reconnect_id > 0:
-            gobject.source_remove(self._reconnect_id)
-            self._reconnect_id = 0
-
         # Only init connection if we have a valid IP address
         if self._could_connect():
             self._init_connection()