[feature] incoming processing flow

This class implements a process flow between the ones defined at #8881
and #8874. It uses a LoopingCall to keep running in a loop and accepts
IIncomingBoxConsumers defined by soledad users, such as leap mail.

- Resolves: #8874

1 files changed, 102 insertions, 0 deletions

diff --git a/src/leap/soledad/client/incoming.py b/src/leap/soledad/client/incoming.py
new file mode 100644
index 00000000..b029e5b8
--- /dev/null
+++ b/src/leap/soledad/client/incoming.py
@@ -0,0 +1,102 @@
+# -*- coding: utf-8 -*-
+# incoming.py
+# Copyright (C) 2014 LEAP
+#
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+"""
+Code to interact with Incoming Box feature.
+See: http://soledad.readthedocs.io/en/latest/incoming_box.html
+     or docs/incoming_box.rst
+"""
+import sys
+from twisted.logger import Logger
+from twisted.internet.task import LoopingCall
+from twisted.internet import defer
+log = Logger()
+
+
+class IncomingBoxProcessingLoop(object):
+    """
+    Implements the client-side processing flow for Incoming Box feature,
+    maintaining a loop that fetches incoming messages from remote replica,
+    delivers it to consumers and changes flags as necessary. This is defined at
+    "Processing Incoming Messages" section on Incoming Box Specifications:
+    http://soledad.readthedocs.io/en/latest/incoming_box.html
+    """
+
+    def __init__(self, incoming_box):
+        self.incoming_box = incoming_box
+        self.consumers = []
+        self._loop = LoopingCall(self._process)
+
+    def __call__(self):
+        return self._loop()
+
+    @property
+    def running(self):
+        return self._loop.running
+
+    def start(self, interval=30):
+        """
+        Starts the inner LoopingCall, triggering the loop.
+        :param interval: Time between interactions in seconds.
+        :type interval: int
+        """
+        return self._loop.start(interval)
+
+    def stop(self):
+        """
+        Stops the inner LoopingCall, stopping the loop.
+        """
+        return self._loop.stop()
+
+    def add_consumer(self, consumer):
+        """
+        Adds a consumer to the consumers list, so it can be used to process and
+        persist incoming box items.
+        :param consumer: Consumer implementation
+        :type consumer: leap.soledad.client.interfaces.IIncomingBoxConsumer
+        """
+        self.consumers.append(consumer)
+
+    @defer.inlineCallbacks
+    def _process(self):
+        pending = yield self.incoming_box.list_pending()
+        for item_id in pending:
+            item = yield self.incoming_box.fetch_for_processing(item_id)
+            if not item:
+                log.warn("Couldn't reserve item %s for processing, skipping.")
+                continue
+            failed = False
+            for consumer in self.consumers:
+                try:
+                    parts = yield consumer.process(item, item_id=item_id)
+                except:
+                    msg = "Consumer %s failed to process item %s: %s"
+                    msg %= (consumer.name, item_id, sys.exc_info()[0])
+                    log.error(msg)
+                    failed = True
+                    continue
+                yield self.incoming_box.set_processed(item_id)
+                try:
+                    yield consumer.save(parts, item_id=item_id)
+                except:
+                    msg = "Consumer %s failed to save item %s: %s"
+                    msg %= (consumer.name, item_id, sys.exc_info()[0])
+                    log.error(msg)
+                    failed = True
+            if failed:
+                yield self.incoming_box.set_failed(item_id)
+            else:
+                yield self.incoming_box.delete(item_id)