From 646f7c4e4e4237caeaeb52a5d63580406df955b4 Mon Sep 17 00:00:00 2001
From: drebs <drebs@leap.se>
Date: Fri, 6 Feb 2015 16:48:13 -0200
Subject: Retry watching dirs if failed for some reason (closes #6687).

---
 ...6687_log-and-retry-when-watched-dirs-dont-exist |  1 +
 src/leap/mx/mail_receiver.py                       | 68 +++++++++++++++++-----
 2 files changed, 53 insertions(+), 16 deletions(-)
 create mode 100644 changes/bug_6687_log-and-retry-when-watched-dirs-dont-exist

diff --git a/changes/bug_6687_log-and-retry-when-watched-dirs-dont-exist b/changes/bug_6687_log-and-retry-when-watched-dirs-dont-exist
new file mode 100644
index 0000000..bddba01
--- /dev/null
+++ b/changes/bug_6687_log-and-retry-when-watched-dirs-dont-exist
@@ -0,0 +1 @@
+  o MX log and retry when delivery directories don't exist. Closes #6687.
diff --git a/src/leap/mx/mail_receiver.py b/src/leap/mx/mail_receiver.py
index 5fa3863..630c982 100644
--- a/src/leap/mx/mail_receiver.py
+++ b/src/leap/mx/mail_receiver.py
@@ -143,6 +143,12 @@ class MailReceiver(Service):
     ERROR_DECRYPTING_KEY = "errdecr"
     PROCESS_SKIPPED_INTERVAL = 60 * 30  # every half an hour
 
+    """
+    If there's a failure when trying to watch a directory for file creation,
+    the service will schedule a retry delayed by the following amount of time.
+    """
+    RETRY_DIR_WATCH_DELAY = 60 * 5  # 5 minutes
+
     def __init__(self, mail_couch_url, users_cdb, directories, bounce_from,
                  bounce_subject):
         """
@@ -165,20 +171,15 @@ class MailReceiver(Service):
         :param bounce_subject: Subject line used in the bounced mail
         :type bounce_subject: str
         """
-        # Service doesn't define an __init__
+        # IService doesn't define an __init__
         self._mail_couch_url = mail_couch_url
         self._users_cdb = users_cdb
         self._directories = directories
-        self._domain = socket.gethostbyaddr(socket.gethostname())[0]
-        self._processing_skipped = False
-
         self._bounce_from = bounce_from
         self._bounce_subject = bounce_subject
 
-        def _signal_handler(sig_num, stack_frame):
-            self._process_skipped()
-
-        signal.signal(signal.SIGUSR1, _signal_handler)
+        self._domain = socket.gethostbyaddr(socket.gethostname())[0]
+        self._processing_skipped = False
 
     def startService(self):
         """
@@ -188,19 +189,55 @@ class MailReceiver(Service):
         self.wm = inotify.INotify()
         self.wm.startReading()
 
-        # watch the mail directory for new files and process incoming mail
-        mask = inotify.IN_CREATE
+        # watch mail directories for new files to trigger processing of
+        # incoming mail
         for directory, recursive in self._directories:
-            log.msg("Watching %r --- Recursive: %r" % (directory, recursive))
-            self.wm.watch(filepath.FilePath(directory), mask,
-                          callbacks=[self._process_incoming_email],
-                          recursive=recursive)
+            self._start_watching_dir(directory, recursive)
 
-        # schedule a periodic task to process skipped mail, but also run it
+        # schedule a periodic task to process skipped mail, and also run it
         # immediatelly
         self._lcall = task.LoopingCall(self._process_skipped)
         self._lcall.start(interval=self.PROCESS_SKIPPED_INTERVAL, now=True)
 
+        # catch SIGUSR1 to trigger processing of skipped mail
+        signal.signal(
+            signal.SIGUSR1,
+            lambda *_: self._process_skipped())
+
+    def stopService(self):
+        """
+        Stop the MailReceiver service
+        """
+        self.wm.stopReading()
+        self._lcall.stop()
+
+    def _start_watching_dir(self, dirname, recursive):
+        """
+        Start watching a directory to trigger processing of newly created
+        files.
+
+        Will also add a delayed call to retry when failed for some reason.
+        """
+        directory = filepath.FilePath(dirname)
+        try:
+            if not directory.isdir():
+                raise OSError("Not a directory: '%s'" % directory.path)
+            self.wm.watch(
+                directory,
+                inotify.IN_CREATE,
+                callbacks=[self._process_incoming_email],
+                recursive=recursive)
+            log.msg("Watching %r --- Recursive: %r" % (directory, recursive))
+        except Exception as e:
+            log.msg(
+                "Failed adding watch to %s, will try again in %s seconds: %s"
+                % (directory, self.RETRY_DIR_WATCH_DELAY, e))
+            reactor.callLater(
+                self.RETRY_DIR_WATCH_DELAY,
+                self._start_watching_dir,
+                dirname,
+                recursive)
+
     def _encrypt_message(self, pubkey, message):
         """
         Given a public key and a message, it encrypts the message to
@@ -380,7 +417,6 @@ class MailReceiver(Service):
 
         :rtype: twisted.internet.defer.Deferred
         """
-        from twisted.internet import reactor
         d = defer.Deferred()
         reactor.callLater(secs, d.callback, None)
         return d
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