feat: PyCasbin Watcher interfaces added

Signed-off-by: ffyuanda <46557895+ffyuanda@users.noreply.github.com>

casbin/persist/watcher.py

@@ -0,0 +1,38 @@
+# Copyright 2021 The Casbin Authors. All Rights Reserved.
+#
+# 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.
+
+class Watcher:
+    """Watcher is the interface for PyCasbin watchers."""
+
+    def set_update_callback(self, func: callable):
+        """
+        set_update_callback sets the callback function that the watcher will call
+        when the policy in DB has been changed by other instances.
+        A classic callback is Enforcer.LoadPolicy().
+        """
+        pass
+
+    def update(self):
+        """
+        update calls the update callback of other instances to synchronize their policy.
+        It is usually called after changing the policy in DB, like Enforcer.SavePolicy(),
+        Enforcer.AddPolicy(), Enforcer.RemovePolicy(), etc.
+        """
+        pass
+
+    def close(self):
+        """
+        close stops and releases the watcher, the callback function will not be called any more.
+        """
+        pass

casbin/persist/watcher_ex.py

@@ -0,0 +1,63 @@
+# Copyright 2021 The Casbin Authors. All Rights Reserved.
+#
+# 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.
+
+from casbin.model import Model
+
+
+class WatcherEx:
+    """
+    WatcherEx is the strengthened version of PyCasbin Watcher.
+    """
+
+    def update_for_add_policy(self, sec: str, ptype: str, *params: str):
+        """
+        update_for_add_policy calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.AddPolicy()
+        """
+        pass
+
+    def update_for_remove_policy(self, sec: str, ptype: str, *params: str):
+        """
+        update_for_remove_policy calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.RemovePolicy()
+        """
+        pass
+
+    def update_for_remove_filtered_policy(self, sec: str, ptype: str, field_index: int, *field_values: str):
+        """
+        update_for_remove_filtered_policy calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.RemoveFilteredNamedGroupingPolicy()
+        """
+        pass
+
+    def update_for_save_policy(self, model: Model):
+        """
+        update_for_save_policy calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.RemoveFilteredNamedGroupingPolicy()
+        """
+        pass
+
+    def update_for_add_policies(self, sec: str, ptype: str, *rules: [str]):
+        """
+        update_for_add_policies calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.AddPolicies()
+        """
+        pass
+
+    def update_for_remove_policies(self, sec: str, ptype: str, *rules: [str]):
+        """
+        update_for_remove_policies calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.RemovePolicies()
+        """
+        pass

casbin/persist/watcher_update.py

@@ -0,0 +1,32 @@
+# Copyright 2021 The Casbin Authors. All Rights Reserved.
+#
+# 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.
+
+class WatcherUpdatable:
+    """
+    WatcherUpdatable is the strengthened version of PyCasbin Watcher.
+    """
+
+    def update_for_update_policy(self, old_rule: [str], new_rule: [str]):
+        """
+        update_for_update_policy calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.UpdatePolicy()
+        """
+        pass
+
+    def update_for_update_policies(self, old_rules: [str], new_rules: [str]):
+        """
+        update_for_update_policies calls the update callback of other instances to synchronize their policy.
+        It is called after Enforcer.UpdatePolicies()
+        """
+        pass