/* -*- tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 4 -*- */

#ifndef _GSM_SMOOTH_REFRESH_H

#define _GSM_SMOOTH_REFRESH_H

#include <giomm.h>

#include <glibmm.h>

#include <string>

#include "util.h"

using std::string;

class SmoothRefresh

  : private procman::NonCopyable

{

  public:

    /*

      smooth_refresh_new

      @config_interval : pointer to config_interval so we can observe

      config_interval changes.

      @return : initialized SmoothRefresh

    */

    SmoothRefresh(Glib::RefPtr<Gio::Settings> a_settings);

    ~SmoothRefresh();

    /*

      smooth_refresh_reset

      Resets state and re-read config_interval

    */

    void reset();

    /*

      smooth_refresh_get

      Computes the new refresh_interval so that CPU usage is lower than

      SMOOTH_REFRESH_PCPU.

      @new_interval : where the new refresh_interval is stored.

      @return : TRUE is refresh_interval has changed. The new refresh_interval

      is stored in @new_interval. Else FALSE;

    */

    bool get(guint &new_interval);

    static const string KEY;

    static const bool KEY_DEFAULT_VALUE;

  private:

    unsigned get_own_cpu_usage();

    void load_settings_value(Glib::ustring key);

    /*

      fuzzy logic:

      - decrease refresh interval only if current CPU% and last CPU%

      are higher than PCPU_LO

      - increase refresh interval only if current CPU% and last CPU%

      are higher than PCPU_HI

    */

    enum

    {

        PCPU_HI = 22,

        PCPU_LO = 18

    };

    /*

      -self : procman's PID (so we call getpid() only once)

      -interval : current refresh interval

      -config_interval : pointer to the configuration refresh interval.

      Used to watch configuration changes

      -interval >= -config_interval

      -last_pcpu : to avoid spikes, the last CPU%. See PCPU_{LO,HI}

      -last_total_time:

      -last_cpu_time: Save last cpu and process times to compute CPU%

    */

    Glib::RefPtr<Gio::Settings> settings;

    bool active;

    sigc::connection connection;

    guint interval;

    unsigned  last_pcpu;

    guint64 last_total_time;

    guint64 last_cpu_time;

};

#endif /* _GSM_SMOOTH_REFRESH_H */