commit_order_clock.h

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#ifndef MYSQL_SCHEDULER_COMMIT_ORDER_CLOCK_H
#define MYSQL_SCHEDULER_COMMIT_ORDER_CLOCK_H
 
#include <atomic>
#include <cstdint>
#include <functional>
#include <limits>
#include <ostream>
 
#include "mysql/concurrency/condition_variable.h"
#include "mysql/scheduler/scheduler_clock.h"
 
namespace mysql::scheduler {
 
class Commit_order_clock : public Scheduler_clock {
 public:
  using Time_point_t = uint64_t;
 
  /// Constructor
  /// @param start_point Clock start point (set as now time)
  Commit_order_clock(Time_point_t start_point = 0);
 
  /// @brief Gets clock start time
  /// @return Start time
  Time_point_t start_time() const override;
 
  /// @brief Gets current time, i.e. current processing window value
  /// @return Current time, i.e. current processing window value
  Time_point_t now() const override;
 
  /// @brief Subscribes a task to \a time processing window
  /// @param task_id Unused task ID
  /// @param time Time window to which a task will be subscribed
  /// @return True if task has been subscribed, false otherwise
  bool add_time(Task_id task_id, Time_point_t time) override;
 
  /// @brief Notify that task finished execution. Called by asynchronous workers
  /// executing task. When specific conditions are met, tick will advance the
  /// internal clock value.
  /// @param task_id Unused task ID
  /// @param time Delay value the task was subscribed to
  /// @return True if time advanced, false otherwise
  bool tick(Task_id task_id, Time_point_t time) override;
 
  /// @brief This clock dependency type is start-to-start
  Scheduler_dependency_type get_type() const override {
    return Scheduler_dependency_type::start_to_start;
  }
 
 private:
  /// Current clock value (now / delay from the start point)
  std::atomic<Time_point_t> m_clock{0};
  /// Used to track stalled clock unblocking (clock was twicked by this count)
  std::atomic<std::size_t> m_twicked_count{0};
};
 
}  // namespace mysql::scheduler
 
#endif  // MYSQL_SCHEDULER_COMMIT_ORDER_CLOCK_H