From 2c3a1299709f2612e96c37e4e121c83ad4df7a56 Mon Sep 17 00:00:00 2001
From: Andrew Godwin
Date: Wed, 9 Nov 2022 23:48:31 -0700
Subject: Profile fetching now working on state machine

---
 stator/models.py | 65 +++++++++++++++++++++++---------------------------------
 1 file changed, 26 insertions(+), 39 deletions(-)

(limited to 'stator/models.py')

diff --git a/stator/models.py b/stator/models.py
index 235b18c..50ee622 100644
--- a/stator/models.py
+++ b/stator/models.py
@@ -1,13 +1,13 @@
 import datetime
 import traceback
-from typing import ClassVar, List, Optional, Type, cast
+from typing import ClassVar, List, Optional, Type, Union, cast
 
 from asgiref.sync import sync_to_async
 from django.db import models, transaction
 from django.utils import timezone
 from django.utils.functional import classproperty
 
-from stator.graph import State, StateGraph, Transition
+from stator.graph import State, StateGraph
 
 
 class StateField(models.CharField):
@@ -29,16 +29,6 @@ class StateField(models.CharField):
         kwargs["graph"] = self.graph
         return name, path, args, kwargs
 
-    def from_db_value(self, value, expression, connection):
-        if value is None:
-            return value
-        return self.graph.states[value]
-
-    def to_python(self, value):
-        if isinstance(value, State) or value is None:
-            return value
-        return self.graph.states[value]
-
     def get_prep_value(self, value):
         if isinstance(value, State):
             return value.name
@@ -95,7 +85,9 @@ class StatorModel(models.Model):
                     (
                         models.Q(
                             state_attempted__lte=timezone.now()
-                            - datetime.timedelta(seconds=state.try_interval)
+                            - datetime.timedelta(
+                                seconds=cast(float, state.try_interval)
+                            )
                         )
                         | models.Q(state_attempted__isnull=True)
                     ),
@@ -117,7 +109,7 @@ class StatorModel(models.Model):
                 ].select_for_update()
             )
             cls.objects.filter(pk__in=[i.pk for i in selected]).update(
-                state_locked_until=timezone.now()
+                state_locked_until=lock_expiry
             )
         return selected
 
@@ -143,36 +135,36 @@ class StatorModel(models.Model):
         self.state_ready = True
         self.save()
 
-    async def atransition_attempt(self) -> bool:
+    async def atransition_attempt(self) -> Optional[str]:
         """
         Attempts to transition the current state by running its handler(s).
         """
-        # Try each transition in priority order
-        for transition in self.state.transitions(automatic_only=True):
-            try:
-                success = await transition.get_handler()(self)
-            except BaseException as e:
-                await StatorError.acreate_from_instance(self, transition, e)
-                traceback.print_exc()
-                continue
-            if success:
-                await self.atransition_perform(transition.to_state.name)
-                return True
+        try:
+            next_state = await self.state_graph.states[self.state].handler(self)
+        except BaseException as e:
+            await StatorError.acreate_from_instance(self, e)
+            traceback.print_exc()
+        else:
+            if next_state:
+                await self.atransition_perform(next_state)
+                return next_state
         await self.__class__.objects.filter(pk=self.pk).aupdate(
             state_attempted=timezone.now(),
             state_locked_until=None,
             state_ready=False,
         )
-        return False
+        return None
 
-    def transition_perform(self, state_name):
+    def transition_perform(self, state: Union[State, str]):
         """
         Transitions the instance to the given state name, forcibly.
         """
-        if state_name not in self.state_graph.states:
-            raise ValueError(f"Invalid state {state_name}")
+        if isinstance(state, State):
+            state = state.name
+        if state not in self.state_graph.states:
+            raise ValueError(f"Invalid state {state}")
         self.__class__.objects.filter(pk=self.pk).update(
-            state=state_name,
+            state=state,
             state_changed=timezone.now(),
             state_attempted=None,
             state_locked_until=None,
@@ -194,11 +186,8 @@ class StatorError(models.Model):
     # The primary key of that model (probably int or str)
     instance_pk = models.CharField(max_length=200)
 
-    # The state we moved from
-    from_state = models.CharField(max_length=200)
-
-    # The state we moved to (or tried to)
-    to_state = models.CharField(max_length=200)
+    # The state we were on
+    state = models.CharField(max_length=200)
 
     # When it happened
     date = models.DateTimeField(auto_now_add=True)
@@ -213,14 +202,12 @@ class StatorError(models.Model):
     async def acreate_from_instance(
         cls,
         instance: StatorModel,
-        transition: Transition,
         exception: Optional[BaseException] = None,
     ):
         return await cls.objects.acreate(
             model_label=instance._meta.label_lower,
             instance_pk=str(instance.pk),
-            from_state=transition.from_state,
-            to_state=transition.to_state,
+            state=instance.state,
             error=str(exception),
             error_details=traceback.format_exc(),
         )
-- 
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