ActivityRuntimeEnvironment: Become a context manager.

Avoids logic duplication on how to store the environment.
Avoids relying on ERP5 products (for whatever it's worth anyway).

product/CMFActivity/Activity/SQLBase.py

@@ -36,7 +36,7 @@ from ZODB.POSException import ConflictError
 from Products.CMFActivity.ActivityTool import (
   Message, MESSAGE_NOT_EXECUTED, MESSAGE_EXECUTED, SkippedMessage)
 from Products.CMFActivity.ActivityRuntimeEnvironment import (
-  DEFAULT_MAX_RETRY, ActivityRuntimeEnvironment, getTransactionalVariable)
+  DEFAULT_MAX_RETRY, ActivityRuntimeEnvironment)
 from Queue import Queue, VALIDATION_ERROR_DELAY, VALID, INVALID_PATH
 from Products.CMFActivity.Errors import ActivityFlushError
 
@@ -508,10 +508,9 @@ class SQLBase(Queue):
       # everything needed from MySQL to get a fresh view of ZODB objects.
       transaction.commit()
       transaction.begin()
-      tv = getTransactionalVariable()
-      tv['activity_runtime_environment'] = activity_runtime_environment
       # Try to invoke
       try:
+        with activity_runtime_environment:
           method(*args)
         # Abort if at least 1 message failed. On next tic, only those that
         # succeeded will be selected because their at_date won't have been
@@ -533,7 +532,7 @@ class SQLBase(Queue):
         if exc_info:
           try:
             # Register it again.
-            tv['activity_runtime_environment'] = activity_runtime_environment
+            with activity_runtime_environment:
               cancel = message.on_error_callback(*exc_info)
             del exc_info, message.exc_info
             transaction.commit()

product/CMFActivity/ActivityRuntimeEnvironment.py

-from Products.ERP5Type.TransactionalVariable import getTransactionalVariable
+from threading import local
 from AccessControl import ClassSecurityInfo
 from Products.ERP5Type.Globals import InitializeClass
 
 DEFAULT_MAX_RETRY = 3
+_activity_runtime_environment = local()
 
 def getActivityRuntimeEnvironment():
   """
     Raises KeyError if called outside activity.
   """
-  return getTransactionalVariable()['activity_runtime_environment']
+  try:
+    return _activity_runtime_environment.value
+  except AttributeError:
+    raise KeyError
 
 def _getActivityRuntimeEnvironment():
-  try:
-    return getActivityRuntimeEnvironment()
-  except KeyError:
-    return
+  return getattr(_activity_runtime_environment, 'value', None)
 
 
 class BaseMessage:
@@ -43,6 +44,14 @@ class ActivityRuntimeEnvironment(object):
   def __init__(self, message):
     self._message = message
 
+  def __enter__(self):
+    assert not hasattr(_activity_runtime_environment, 'value')
+    _activity_runtime_environment.value = self
+
+  def __exit__(self, exc_type, exc_val, exc_tb):
+    assert _activity_runtime_environment.value is self
+    del _activity_runtime_environment.value
+
   security.declarePublic('getTag')
   def getTag(self, default=None):
     return self._message.activity_kw.get('tag', default)