Update engine class names to better reflect there usage

Rename the single threaded engine to be the serial engine which
better matches its entrypoint, do the same for the multithreaded
engine (renaming it to the parallel engine).

Change-Id: I6174b4f1936858c13eeee416bfa3836cf20a1350

doc/source/notifications.rst

@@ -137,14 +137,14 @@ For example, this is how you can use
    >>> with printing.PrintingListener(eng):
    ...   eng.run()
    ...
-   taskflow.engines.action_engine.engine.SingleThreadedActionEngine: ... has moved flow 'cat-dog' (...) into state 'RUNNING'
-   taskflow.engines.action_engine.engine.SingleThreadedActionEngine: ... has moved task 'CatTalk' (...) into state 'RUNNING'
+   taskflow.engines.action_engine.engine.SerialActionEngine: ... has moved flow 'cat-dog' (...) into state 'RUNNING'
+   taskflow.engines.action_engine.engine.SerialActionEngine: ... has moved task 'CatTalk' (...) into state 'RUNNING'
    meow
-   taskflow.engines.action_engine.engine.SingleThreadedActionEngine: ... has moved task 'CatTalk' (...) into state 'SUCCESS' with result 'cat' (failure=False)
-   taskflow.engines.action_engine.engine.SingleThreadedActionEngine: ... has moved task 'DogTalk' (...) into state 'RUNNING'
+   taskflow.engines.action_engine.engine.SerialActionEngine: ... has moved task 'CatTalk' (...) into state 'SUCCESS' with result 'cat' (failure=False)
+   taskflow.engines.action_engine.engine.SerialActionEngine: ... has moved task 'DogTalk' (...) into state 'RUNNING'
    woof
-   taskflow.engines.action_engine.engine.SingleThreadedActionEngine: ... has moved task 'DogTalk' (...) into state 'SUCCESS' with result 'dog' (failure=False)
-   taskflow.engines.action_engine.engine.SingleThreadedActionEngine: ... has moved flow 'cat-dog' (...) into state 'SUCCESS'
+   taskflow.engines.action_engine.engine.SerialActionEngine: ... has moved task 'DogTalk' (...) into state 'SUCCESS' with result 'dog' (failure=False)
+   taskflow.engines.action_engine.engine.SerialActionEngine: ... has moved flow 'cat-dog' (...) into state 'SUCCESS'
 
 Basic listener
 --------------

setup.cfg

@@ -49,9 +49,9 @@ taskflow.persistence =
     zookeeper = taskflow.persistence.backends.impl_zookeeper:ZkBackend
 
 taskflow.engines =
-    default = taskflow.engines.action_engine.engine:SingleThreadedActionEngine
-    serial = taskflow.engines.action_engine.engine:SingleThreadedActionEngine
-    parallel = taskflow.engines.action_engine.engine:MultiThreadedActionEngine
+    default = taskflow.engines.action_engine.engine:SerialActionEngine
+    serial = taskflow.engines.action_engine.engine:SerialActionEngine
+    parallel = taskflow.engines.action_engine.engine:ParallelActionEngine
     worker-based = taskflow.engines.worker_based.engine:WorkerBasedActionEngine
 
 [nosetests]

taskflow/engines/action_engine/engine.py

@@ -225,12 +225,12 @@ class ActionEngine(base.EngineBase):
         self._compiled = True
 
 
-class SingleThreadedActionEngine(ActionEngine):
+class SerialActionEngine(ActionEngine):
     """Engine that runs tasks in serial manner."""
     _storage_factory = atom_storage.SingleThreadedStorage
 
 
-class MultiThreadedActionEngine(ActionEngine):
+class ParallelActionEngine(ActionEngine):
     """Engine that runs tasks in parallel manner."""
     _storage_factory = atom_storage.MultiThreadedStorage
 
@@ -240,7 +240,7 @@ class MultiThreadedActionEngine(ActionEngine):
 
     def __init__(self, flow, flow_detail, backend, conf,
                  executor=None, max_workers=None):
-        super(MultiThreadedActionEngine, self).__init__(
-            flow, flow_detail, backend, conf)
+        super(ParallelActionEngine, self).__init__(flow, flow_detail,
+                                                   backend, conf)
         self._executor = executor
         self._max_workers = max_workers

taskflow/examples/run_by_iter.py

@@ -30,9 +30,9 @@ sys.path.insert(0, top_dir)
 sys.path.insert(0, self_dir)
 
 
-from taskflow.engines.action_engine import engine
+from taskflow import engines
 from taskflow.patterns import linear_flow as lf
-from taskflow.persistence.backends import impl_memory
+from taskflow.persistence import backends as persistence_backends
 from taskflow import task
 from taskflow.utils import persistence_utils
 
@@ -73,18 +73,15 @@ flows = []
 for i in range(0, flow_count):
     f = make_alphabet_flow(i + 1)
     flows.append(make_alphabet_flow(i + 1))
-be = impl_memory.MemoryBackend({})
+be = persistence_backends.fetch(conf={'connection': 'memory'})
 book = persistence_utils.temporary_log_book(be)
-engines = []
+engine_iters = []
 for f in flows:
     fd = persistence_utils.create_flow_detail(f, book, be)
-    e = engine.SingleThreadedActionEngine(f, fd, be, {})
+    e = engines.load(f, flow_detail=fd, backend=be, book=book)
     e.compile()
     e.storage.inject({'A': 'A'})
     e.prepare()
-    engines.append(e)
-engine_iters = []
-for e in engines:
     engine_iters.append(e.run_iter())
 while engine_iters:
     for it in list(engine_iters):

taskflow/examples/run_by_iter_enumerate.py

@@ -27,9 +27,9 @@ top_dir = os.path.abspath(os.path.join(os.path.dirname(__file__),
 sys.path.insert(0, top_dir)
 sys.path.insert(0, self_dir)
 
-from taskflow.engines.action_engine import engine
+from taskflow import engines
 from taskflow.patterns import linear_flow as lf
-from taskflow.persistence.backends import impl_memory
+from taskflow.persistence import backends as persistence_backends
 from taskflow import task
 from taskflow.utils import persistence_utils
 
@@ -48,10 +48,10 @@ f = lf.Flow("counter")
 for i in range(0, 10):
     f.add(EchoNameTask("echo_%s" % (i + 1)))
 
-be = impl_memory.MemoryBackend()
+be = persistence_backends.fetch(conf={'connection': 'memory'})
 book = persistence_utils.temporary_log_book(be)
 fd = persistence_utils.create_flow_detail(f, book, be)
-e = engine.SingleThreadedActionEngine(f, fd, be, {})
+e = engines.load(f, flow_detail=fd, backend=be, book=book)
 e.compile()
 e.prepare()
 

taskflow/tests/unit/test_engines.py

@@ -555,11 +555,11 @@ class SingleThreadedEngineTest(EngineTaskTest,
 
     def test_correct_load(self):
         engine = self._make_engine(utils.TaskNoRequiresNoReturns)
-        self.assertIsInstance(engine, eng.SingleThreadedActionEngine)
+        self.assertIsInstance(engine, eng.SerialActionEngine)
 
     def test_singlethreaded_is_the_default(self):
         engine = taskflow.engines.load(utils.TaskNoRequiresNoReturns)
-        self.assertIsInstance(engine, eng.SingleThreadedActionEngine)
+        self.assertIsInstance(engine, eng.SerialActionEngine)
 
 
 class MultiThreadedEngineTest(EngineTaskTest,
@@ -578,7 +578,7 @@ class MultiThreadedEngineTest(EngineTaskTest,
 
     def test_correct_load(self):
         engine = self._make_engine(utils.TaskNoRequiresNoReturns)
-        self.assertIsInstance(engine, eng.MultiThreadedActionEngine)
+        self.assertIsInstance(engine, eng.ParallelActionEngine)
         self.assertIs(engine._executor, None)
 
     def test_using_common_executor(self):