1 files changed, 177 insertions, 0 deletions
diff --git a/vicn/core/state.py b/vicn/core/state.py
new file mode 100644
index 00000000..d5069b24
--- /dev/null
+++ b/vicn/core/state.py
@@ -0,0 +1,177 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2017 Cisco and/or its affiliates.
+#
+# 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.
+#
+
+import asyncio
+import random
+import string
+
+class NEVER_SET:
+    pass
+
+# Separator for components of the UUID
+UUID_SEP = '-'
+
+# Length of the random component of the UUID
+UUID_LEN = 5
+
+class ResourceState:
+    UNINITIALIZED       = 'UNINITIALIZED'
+    PENDING_DEPS        = 'PENDING_DEPS'
+    DEPS_OK             = 'DEPS_OK'
+    PENDING_INIT        = 'PENDING_INIT'
+    INITIALIZED         = 'INITIALIZED'
+    PENDING_GET         = 'PENDING_GET'
+    GET_DONE            = 'GET_DONE'
+    PENDING_KEYS        = 'PENDING_KEYS'
+    KEYS_OK             = 'KEYS_OK'
+    PENDING_CREATE      = 'PENDING_CREATE'
+    CREATED             = 'CREATED'
+    DIRTY               = 'DIRTY'
+    CLEAN               = 'CLEAN'
+    PENDING_UPDATE      = 'PENDING_UPDATE'
+    PENDING_DELETE      = 'PENDING_DELETE'
+    DELETED             = 'DELETED'
+
+class AttributeState:
+    UNINITIALIZED       = 'UNINITIALIZED'
+    INITIALIZED         = 'INITIALIZED'
+    DIRTY               = 'DIRTY'
+    PENDING_INIT        = 'PENDING_INIT'
+    PENDING_UPDATE      = 'PENDING_UPDATE'
+    CLEAN               = 'CLEAN'
+
+class Operations:
+    SET = 'set'
+    LIST_ADD = 'add'
+    LIST_REMOVE = 'remove'
+    LIST_CLEAR = 'clear'
+
+class UUID:
+    def __init__(self, name, cls):
+        self._uuid = self._make_uuid(name, cls)
+
+    def _make_uuid(self, name, cls):
+        """Generate a unique resource identifier
+
+        The UUID consists in the type of the resource, to which is added a
+        random identifier of length UUID_LEN. Components of the UUID are
+        separated by UUID_SEP.
+        """
+        uuid = ''.join(random.choice(string.ascii_uppercase + string.digits) 
+                for _ in range(UUID_LEN))
+        if name:
+            uuid = name # + UUID_SEP + uuid
+        return UUID_SEP.join([cls.__name__, uuid])
+
+    def __repr__(self):
+        return '<UUID {}>'.format(self._uuid)
+
+    def __lt__(self, other):
+        return self._uuid < other._uuid
+
+    __str__ = __repr__
+
+class PendingValue:
+    def __init__(self, value = None):
+        self.clear(value)
+
+    def clear(self, value=NEVER_SET):
+        self.value = NEVER_SET
+        self.operations = list()
+
+    def trigger(self, action, value, cur_value = None):
+
+        if self.value is NEVER_SET:
+            if cur_value is not None:
+                self.value = cur_value
+
+        if action == Operations.SET:
+            self.value = value
+            self.operations = [(Operations.SET, value)] 
+        elif action == Operations.LIST_CLEAR:
+            self.value = list()
+            self.operations = [(Operations.LIST_CLEAR, None)]
+        else:
+            if action == Operations.LIST_ADD:
+                self.value.append(value)
+            elif action == Operations.LIST_REMOVE:
+                self.value.remove(value)
+            else:
+                raise RuntimeError
+            self.operations.append((action, value))
+
+class InstanceState:
+    def __init__(self, manager, instance, name = None):
+
+        # Unique identifier for the instance. This is useful for relation
+        # between resources
+        self.uuid = UUID(name, instance.__class__)
+        self.instance       = instance
+
+        # Instance manager
+        self.manager        = manager
+
+        # Events
+        self.events         = dict()
+
+        # Stores the requested value : attribute_name -> requested operations =
+        # LIST set add remove clear
+        self.dirty          = dict()
+
+
+        # Initialize resource state
+        self.lock = asyncio.Lock() 
+        self.write_lock = asyncio.Lock()
+        self.state          = ResourceState.UNINITIALIZED
+        self.clean = asyncio.Event()
+        self.clean.clear()
+        self.init  = asyncio.Event()
+        self.init.clear()
+        self.change_event = asyncio.Event()
+        self.change_event.clear()
+        self.change_success = None
+        self.change_value = None
+        self.log = list()
+
+        self.attr_lock = dict()
+        self.attr_init = dict()
+        self.attr_clean = dict()
+        self.attr_state = dict()
+        self.attr_change_event = dict()
+        self.attr_change_success = dict()
+        self.attr_change_value= dict()
+        self.attr_log = dict()
+        # Initialize attribute state
+        for attribute in instance.iter_attributes():
+            self.attr_lock[attribute.name] = asyncio.Lock() 
+            self.attr_init[attribute.name] = asyncio.Event()
+            self.attr_clean[attribute.name] = asyncio.Event()
+            self.attr_state[attribute.name] = AttributeState.UNINITIALIZED
+            self.attr_change_event[attribute.name] = asyncio.Event()
+            self.attr_change_event[attribute.name].clear()
+            self.attr_change_success[attribute.name] = None
+            self.attr_change_value[attribute.name] = None
+            self.dirty[attribute.name] = PendingValue(NEVER_SET)
+            self.attr_log[attribute.name] = list()
+
+    def set_dirty(self, attr_name):
+        self.attr_dirty.add(attr_name)
+        self.manager.set_dirty(self.uuid)
+
+    def trigger(self, attribute_name, action, value):
+        self.dirty[attribute_name].trigger(action, value)