1 files changed, 35 insertions, 47 deletions

diff --git a/src/mailman/app/workflow.py b/src/mailman/workflows/base.py
index 92b78c184..8153bf77d 100644
--- a/src/mailman/app/workflow.py
+++ b/src/mailman/workflows/base.py
@@ -22,9 +22,12 @@ import json
 import logging
 
 from collections import deque
-from mailman.interfaces.workflow import IWorkflowStateManager
+
+from mailman.interfaces.workflows import IWorkflow, IWorkflowStateManager
+from mailman.utilities.modules import abstract_component
 from public import public
 from zope.component import getUtility
+from zope.interface import implementer
 
 
 COMMASPACE = ', '
@@ -32,38 +35,27 @@ log = logging.getLogger('mailman.error')
 
 
 @public
+@abstract_component
+@implementer(IWorkflow)
 class Workflow:
     """Generic workflow."""
 
-    SAVE_ATTRIBUTES = ()
-    INITIAL_STATE = None
+    initial_state = None
+    save_attributes = ()
 
     def __init__(self):
         self.token = None
         self._next = deque()
-        self.push(self.INITIAL_STATE)
+        self.push(self.initial_state)
         self.debug = False
         self._count = 0
 
-    @property
-    def name(self):
-        return self.__class__.__name__
-
     def __iter__(self):
+        """See `IWorkflow`."""
         return self
 
-    def push(self, step):
-        self._next.append(step)
-
-    def _pop(self):
-        name = self._next.popleft()
-        step = getattr(self, '_step_{}'.format(name))
-        self._count += 1
-        if self.debug:                              # pragma: nocover
-            print('[{:02d}] -> {}'.format(self._count, name), file=sys.stderr)
-        return name, step
-
     def __next__(self):
+        """See `IWorkflow`."""
         try:
             name, step = self._pop()
             return step()
@@ -73,13 +65,20 @@ class Workflow:
             log.exception('deque: {}'.format(COMMASPACE.join(self._next)))
             raise
 
-    def run_thru(self, stop_after):
-        """Run the state machine through and including the given step.
+    def push(self, step):
+        """See `IWorkflow`."""
+        self._next.append(step)
+
+    def _pop(self):
+        name = self._next.pop()
+        step = getattr(self, '_step_{}'.format(name))
+        self._count += 1
+        if self.debug:                              # pragma: nocover
+            print('[{:02d}] -> {}'.format(self._count, name), file=sys.stderr)
+        return name, step
 
-        :param stop_after: Name of method, sans prefix to run the
-            state machine through.  In other words, the state machine runs
-            until the named method completes.
-        """
+    def run_thru(self, stop_after):
+        """See `IWorkflow`."""
         results = []
         while True:
             try:
@@ -93,12 +92,7 @@ class Workflow:
         return results
 
     def run_until(self, stop_before):
-        """Trun the state machine until (not including) the given step.
-
-        :param stop_before: Name of method, sans prefix that the
-            state machine is run until the method is reached.  Unlike
-            `run_thru()` the named method is not run.
-        """
+        """See `IWorkflow`."""
         results = []
         while True:
             try:
@@ -116,35 +110,29 @@ class Workflow:
         return results
 
     def save(self):
+        """See `IWorkflow`."""
         assert self.token, 'Workflow token must be set'
         state_manager = getUtility(IWorkflowStateManager)
-        data = {attr: getattr(self, attr) for attr in self.SAVE_ATTRIBUTES}
-        # Note: only the next step is saved, not the whole stack.  This is not
-        # an issue in practice, since there's never more than a single step in
-        # the queue anyway.  If we want to support more than a single step in
-        # the queue *and* want to support state saving/restoring, change this
-        # method and the restore() method.
+        data = {attr: getattr(self, attr) for attr in self.save_attributes}
+        # Save the workflow stack.
         if len(self._next) == 0:
-            step = None
-        elif len(self._next) == 1:
-            step = self._next[0]
+            steps = '[]'
         else:
-            raise AssertionError(
-                "Can't save a workflow state with more than one step "
-                "in the queue")
-        state_manager.save(self.token, step, json.dumps(data))
+            steps = json.dumps(list(self._next))
+        state_manager.save(self.token, steps, json.dumps(data))
 
     def restore(self):
+        """See `IWorkflow`."""
         state_manager = getUtility(IWorkflowStateManager)
         state = state_manager.restore(self.token)
         if state is None:
             # The token doesn't exist in the database.
             raise LookupError(self.token)
         self._next.clear()
-        if state.step:
-            self._next.append(state.step)
+        if state.steps:
+            self._next.extend(json.loads(state.steps))
         data = json.loads(state.data)
-        for attr in self.SAVE_ATTRIBUTES:
+        for attr in self.save_attributes:
             try:
                 setattr(self, attr, data[attr])
             except KeyError: