/**
 * Copyright (c) 2021 OceanBase
 * OceanBase CE is licensed under Mulan PubL v2.
 * You can use this software according to the terms and conditions of the Mulan PubL v2.
 * You may obtain a copy of Mulan PubL v2 at:
 *          http://license.coscl.org.cn/MulanPubL-2.0
 * THIS SOFTWARE IS PROVIDED ON AN "AS IS" BASIS, WITHOUT WARRANTIES OF ANY KIND,
 * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
 * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
 * See the Mulan PubL v2 for more details.
 */

#ifndef OB_TASK_DEFINE_H
#define OB_TASK_DEFINE_H

#include <type_traits>
#include "lib/utility/ob_rate_limiter.h"

namespace oceanbase {
namespace share {
enum class ObTaskType { GENERIC, USER_REQUEST, DATA_MAINTAIN, ROOT_SERVICE, SCHEMA, MAX };

template <typename E>
constexpr typename std::underlying_type<E>::type toUType(E enumerator) noexcept
{
  return static_cast<typename std::underlying_type<E>::type>(enumerator);
}

// Not support change log rate percentage of each task dynamically.
class ObTaskController {
  using RateLimiter = lib::ObRateLimiter;
  static constexpr auto MAX_TASK_ID = toUType(ObTaskType::MAX);
  static constexpr int64_t LOG_RATE_LIMIT = 10 << 20;

public:
  ObTaskController();
  virtual ~ObTaskController();

  int init();
  void destroy();
  void switch_task(ObTaskType task_id);
  void allow_next_syslog(int64_t count = 1);

  void set_log_rate_limit(int64_t limit);

  static ObTaskController& get();

private:
  template <ObTaskType id>
  void set_log_rate(int64_t rate)
  {
    if (id != ObTaskType::MAX) {
      get_limiter(id)->set_rate(rate);
    }
  }

  template <ObTaskType id>
  void set_log_rate_pctg(double pctg)
  {
    if (id != ObTaskType::MAX) {
      rate_pctgs_[toUType(id)] = pctg;
    }
  }

  void calc_log_rate();

  RateLimiter* get_limiter(ObTaskType id)
  {
    return limiters_[toUType(id)];
  };

private:
  RateLimiter* limiters_[MAX_TASK_ID];
  double rate_pctgs_[MAX_TASK_ID];
  int64_t log_rate_limit_;

  static ObTaskController instance_;
};

}  // namespace share
}  // namespace oceanbase

#endif /* OB_TASK_DEFINE_H */