Added suspended audit state

New audit state SUSPENDED is added in this patch set. If audit
state with continuous mode is changed from ONGOING to SUSPENDED,
audit's job is removed and the audit is not executed.
If audit state changed from SUSPENDED to ONGOING in reverse,
audit is executed again periodically.

Change-Id: I32257f56a40c0352a7c24f3fb80ad95ec28dc614
Implements: blueprint suspended-audit-state

watcher/objects/audit.py

@@ -46,6 +46,9 @@ be one of the following:
 -  **CANCELLED** : the :ref:`Audit <audit_definition>` was in **PENDING** or
    **ONGOING** state and was cancelled by the
    :ref:`Administrator <administrator_definition>`
+-  **SUSPENDED** : the :ref:`Audit <audit_definition>` was in **ONGOING**
+   state and was suspended by the
+   :ref:`Administrator <administrator_definition>`
 """
 
 import enum
@@ -66,6 +69,7 @@ class State(object):
     CANCELLED = 'CANCELLED'
     DELETED = 'DELETED'
     PENDING = 'PENDING'
+    SUSPENDED = 'SUSPENDED'
 
 
 class AuditType(enum.Enum):
@@ -296,3 +300,25 @@ class Audit(base.WatcherPersistentObject, base.WatcherObject,
             notifications.audit.send_delete(self._context, self)
 
         _notify()
+
+
+class AuditStateTransitionManager(object):
+
+    TRANSITIONS = {
+        State.PENDING: [State.ONGOING, State.CANCELLED],
+        State.ONGOING: [State.FAILED, State.SUCCEEDED,
+                        State.CANCELLED, State.SUSPENDED],
+        State.FAILED: [State.DELETED],
+        State.SUCCEEDED: [State.DELETED],
+        State.CANCELLED: [State.DELETED],
+        State.SUSPENDED: [State.ONGOING, State.DELETED],
+    }
+
+    INACTIVE_STATES = (State.CANCELLED, State.DELETED,
+                       State.FAILED, State.SUSPENDED)
+
+    def check_transition(self, initial, new):
+        return new in self.TRANSITIONS.get(initial, [])
+
+    def is_inactive(self, audit):
+        return audit.state in self.INACTIVE_STATES