include/casbin/persist/watcher.h

/*
* Copyright 2020 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.
*/

#ifndef CASBIN_CPP_PERSIST_WATCHER
#define CASBIN_CPP_PERSIST_WATCHER

#include <string>

namespace casbin {

// Watcher is the interface for Casbin watchers.
class Watcher {
    public:

        // SetUpdateCallback 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().
        template <typename Func>
        void SetUpdateCallback(Func func){
            return;
        }

        // 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.
        virtual void Update() = 0;

        // Close stops and releases the watcher, the callback function will not be called any more.
        virtual void Close() = 0;
};

};  // namespace casbin

#endif