heron/common/src/cpp/config/yaml-file-reader.h

/*
 * Copyright 2015 Twitter, Inc.
 *
 * 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.
 */

////////////////////////////////////////////////////////////////
//
// yaml-file-reader.h
//
// This file deals with reading yaml config file.
// It also does auto reloads if the file changes
//
///////////////////////////////////////////////////////////////
#ifndef YAML_FILE_READER_H_
#define YAML_FILE_READER_H_

#include "yaml-cpp/yaml.h"
#include "basics/callback.h"
#include "basics/sptypes.h"
#include "network/event_loop.h"

namespace heron {
namespace config {

class YamlFileReader {
 public:
  YamlFileReader(EventLoop* eventLoop, const sp_string& _config_file);
  virtual ~YamlFileReader();

 protected:
  virtual void OnConfigFileLoad() = 0;
  void LoadConfig();
  void AddIfMissing(const sp_string& _var, const sp_string& _default);

  YAML::Node config_;

 private:
  void CheckForChange(EventLoop::Status);

  VCallback<EventLoop::Status> reload_cb_;
  sp_string config_file_;
  time_t last_reload_;
};
}  // namespace config
}  // namespace heron

#endif