wait_variable.h

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*/
#ifndef ROUTER_SRC_ROUTER_INCLUDE_HELPER_WAIT_VARIABLE_H_
#define ROUTER_SRC_ROUTER_INCLUDE_HELPER_WAIT_VARIABLE_H_
 
#include <initializer_list>
 
#include "container/generic.h"
#include "mysql/harness/stdx/expected.h"
#include "mysql/harness/stdx/monitor.h"
 
template <typename ValueType>
class WaitableVariable {
 public:
  WaitableVariable() {}
  WaitableVariable(const ValueType &value) : monitor_with_value_{value} {}
 
  class DoNothing {
   public:
    void operator()() const {}
  };
 
  template <typename Container = std::initializer_list<ValueType>,
            typename Callback = DoNothing>
  bool exchange(const Container &expected, const ValueType &v,
                const Callback &after_set_callback = DoNothing()) {
    bool result{false};
    monitor_with_value_.serialize_with_cv(
        [&expected, &v, &after_set_callback, &result](auto &value, auto &cv) {
          if (helper::container::has(expected, value)) {
            value = v;
            result = true;
            after_set_callback();
            cv.notify_all();
          }
        });
 
    return result;
  }
 
  template <typename Callback = DoNothing>
  bool exchange(const ValueType &expected, const ValueType &v,
                const Callback &after_set_callback = DoNothing()) {
    bool result{false};
    monitor_with_value_.serialize_with_cv(
        [&expected, &v, &after_set_callback, &result](auto &value, auto &cv) {
          if (expected == value) {
            value = v;
            result = true;
            after_set_callback();
            cv.notify_all();
          }
        });
 
    return result;
  }
 
  template <typename Callback = DoNothing>
  ValueType get(const Callback &after_get_callback = DoNothing()) {
    ValueType result;
    monitor_with_value_.serialize_with_cv(
        [&result, &after_get_callback](auto &current_value, auto &) {
          result = current_value;
          after_get_callback();
        });
 
    return result;
  }
 
  template <typename Callback = DoNothing>
  void set(const ValueType &v,
           const Callback &after_set_callback = DoNothing()) {
    monitor_with_value_.serialize_with_cv(
        [&v, &after_set_callback](auto &value, auto &cv) {
          value = v;
          after_set_callback();
          cv.notify_all();
        });
  }
 
  template <typename Callback>
  void change(const Callback &set_callback) {
    monitor_with_value_.serialize_with_cv(
        [&set_callback](auto &value, auto &cv) {
          set_callback(value);
          cv.notify_all();
        });
  }
 
  template <typename Callback = DoNothing>
  bool is(std::initializer_list<ValueType> expected_values,
          const Callback &after_is_callback = Callback()) {
    bool result{false};
    monitor_with_value_.serialize_with_cv(
        [this, &result, &expected_values, &after_is_callback](
            auto &current_value, auto &) {
          result = helper::container::has(expected_values, current_value);
          if (result) after_is_callback();
        });
    return result;
  }
 
  template <typename Callback = DoNothing>
  bool is(const ValueType &expected_value,
          const Callback &after_is_callback = Callback()) {
    bool result{false};
    monitor_with_value_.serialize_with_cv(
        [&result, &expected_value, &after_is_callback](auto &current_value,
                                                       auto &) {
          result = (expected_value == current_value);
          if (result) after_is_callback();
        });
    return result;
  }
 
  template <typename Callback = DoNothing>
  void wait(const ValueType &expected_value,
            const Callback &callback = Callback()) {
    monitor_with_value_.wait(
        [&expected_value, &callback](const auto &current_value) {
          if (expected_value == current_value) {
            callback();
            return true;
          }
          return false;
        });
  }
 
  template <typename Callback = DoNothing>
  ValueType wait(std::initializer_list<ValueType> expected_values,
                 const Callback &callback = Callback()) {
    ValueType result;
    monitor_with_value_.wait(
        [&expected_values, &callback, &result](const auto &current_value) {
          if (helper::container::has(expected_values, current_value)) {
            result = current_value;
            callback();
            return true;
          }
          return false;
        });
 
    return result;
  }
 
  template <class Rep, class Period, typename Callback = DoNothing>
  bool wait_for(const std::chrono::duration<Rep, Period> &rel_time,
                const ValueType &expected_value,
                const Callback &callback = Callback()) {
    return monitor_with_value_.wait_for(
        rel_time, [this, expected_value, &callback](auto &current_value) {
          if (current_value == expected_value) {
            callback();
            return true;
          }
          return false;
        });
  }
 
  template <class Rep, class Period, typename Callback = DoNothing>
  stdx::expected<ValueType, bool> wait_for(
      const std::chrono::duration<Rep, Period> &rel_time,
      std::initializer_list<ValueType> expected_values,
      const Callback &callback = Callback()) {
    ValueType result;
    if (monitor_with_value_.wait_for(
            rel_time, [this, &expected_values, &result,
                       &callback](const auto &current_value) {
              if (helper::container::has(expected_values, current_value)) {
                result = current_value;
                callback();
                return true;
              }
              return false;
            })) {
      return {result};
    }
 
    return {stdx::unexpect, true};
  }
 
 private:
  WaitableMonitor<ValueType> monitor_with_value_{};
};
 
#endif  // ROUTER_SRC_ROUTER_INCLUDE_HELPER_WAIT_VARIABLE_H_