Create a scheduler interface and move the current scheduler into the scheduler package

zoe_master/execution_manager.py

@@ -59,8 +59,7 @@ def restart_resubmit_scheduler(state: SQLManager, scheduler: ZoeScheduler):
         scheduler.incoming(e)
 
 
-def execution_delete(scheduler: ZoeScheduler, execution: Execution):
-    """Remove an execution from the scheduler, must only be called if the execution is NOT running."""
+def execution_delete(execution: Execution):
+    """Remove an execution, must only be called if the execution is NOT running."""
     assert not execution.is_active()
     exec_logs.delete(execution)
-    scheduler.remove_execution(execution)

zoe_master/scheduler/base_scheduler.py

+# Copyright (c) 2017, Daniele Venzano
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or
+# implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+"""The base class for Zoe schedulers"""
+
+import zoe_lib.sql_manager
+
+
+class ZoeBaseScheduler:
+    """The base class for Zoe schedulers"""
+
+    def __init__(self, state: zoe_lib.sql_manager.SQLManager):
+        self.state = state
+
+    def trigger(self):
+        """Trigger a scheduler run."""
+        raise NotImplementedError
+
+    def incoming(self, execution: zoe_lib.sql_manager.Execution):
+        """
+        This method adds the execution to the end of the FIFO queue and triggers the scheduler.
+        :param execution: The execution
+        :return:
+        """
+        raise NotImplementedError
+
+    def terminate(self, execution: zoe_lib.sql_manager.Execution) -> None:
+        """
+        Inform the master that an execution has been terminated. This can be done asynchronously.
+        :param execution: the terminated execution
+        :return: None
+        """
+        raise NotImplementedError
+
+    def quit(self):
+        """Stop the scheduler."""
+        raise NotImplementedError
+
+    def stats(self):
+        """Scheduler statistics."""
+        raise NotImplementedError

zoe_master/scheduler.py → zoe_master/scheduler/scheduler.py

@@ -22,13 +22,15 @@ from zoe_lib.sql_manager import Execution
 
 from zoe_master.exceptions import ZoeStartExecutionFatalException, ZoeStartExecutionRetryException
 from zoe_master.zapp_to_docker import execution_to_containers, terminate_execution
+from zoe_master.scheduler.base_scheduler import ZoeBaseScheduler
 
 log = logging.getLogger(__name__)
 
 
-class ZoeScheduler:
+class ZoeSimpleScheduler(ZoeBaseScheduler):
     """The Scheduler class."""
-    def __init__(self):
+    def __init__(self, state):
+        super().__init__(state)
         self.fifo_queue = []
         self.trigger_semaphore = threading.Semaphore(0)
         self.async_threads = []
@@ -68,13 +70,6 @@ class ZoeScheduler:
         th.start()
         self.async_threads.append(th)
 
-    def remove_execution(self, execution: Execution):
-        """Removes the execution form the queue."""
-        try:
-            self.fifo_queue.remove(execution)
-        except ValueError:
-            pass
-
     def loop_start_th(self):
         """The Scheduler thread loop."""
         auto_trigger_base = 60  # seconds