FSM for Feed

zipline/components/feed.py

@@ -3,13 +3,27 @@ from collections import Counter
 
 from zipline.core.component import Component
 from zipline.components.aggregator import Aggregate
+from zipline.utils.protocol_utils import Enum
 import zipline.protocol as zp
+from zipline.transitions import WorkflowMeta
 
 from zipline.protocol import CONTROL_PROTOCOL, COMPONENT_TYPE, \
     CONTROL_FRAME, CONTROL_UNFRAME
 
 LOGGER = logging.getLogger('ZiplineLogger')
 
+# FSM
+# ---
+
+INIT, READY, DRAINING = FEED_STATES = \
+Enum( 'INIT', 'READY', 'DRAINING')
+
+state_transitions = dict(
+    do_start = (-1    , INIT)     ,
+    do_run   = (INIT  , READY)    ,
+    do_drain = (READY , DRAINING) ,
+)
+
 class Feed(Aggregate):
     """
     Connects to N PULL sockets, publishing all messages received to a
@@ -18,20 +32,26 @@ class Feed(Aggregate):
     one execution context (thread, process, etc) and run in another.
     """
 
+    __metaclass__ = WorkflowMeta
+
+    states = list(FEED_STATES)
+    transitions = state_transitions
+    initial_state = -1
+
     def init(self):
         self.sent_count             = 0
         self.received_count         = 0
         self.draining               = False
         self.ds_finished_counter    = 0
 
-        # Depending on the size of this, might want to use a data
-        # structure with better asymptotics.
         self.data_buffer            = {}
 
         # source_id -> integer count
         self.sent_counters          = Counter()
         self.recv_counters          = Counter()
 
+        self.state = INIT
+
     @property
     def get_id(self):
         return "FEED"
@@ -71,6 +91,8 @@ class Feed(Aggregate):
         """
         Get the next message in chronological order.
         """
+
+        # is_full and draining defined in aggregator
         if not(self.is_full() or self.draining):
             return
 

zipline/components/passthrough.py

@@ -7,7 +7,7 @@ class PassthroughTransform(BaseTransform):
     """
 
     def init(self):
-        self.state = { 'name': 'PASSTHROUGH' }
+        self.props = { 'name': 'PASSTHROUGH' }
 
     #TODO, could save some cycles by skipping the _UNFRAME call
     # and just setting value to original msg string.