[libcamera-devel] [PATCH v7 1/2] cam: event_loop: Add timer events to event loop

[Eric Curtin]

Hi Guys,

I know holidays are coming up. Just a friendly reminder if you get a
chance to review.

Is mise le meas/Regards,

Eric Curtin


On Fri, 8 Apr 2022 at 17:00, Eric Curtin <ecurtin at redhat.com> wrote:
>
> Extend the EventLoop class to support periodic timer events. This can be
> used to run tasks periodically, such as handling the event loop of SDL.
>
> Signed-off-by: Eric Curtin <ecurtin at redhat.com>
> ---
>  src/cam/event_loop.cpp | 37 +++++++++++++++++++++++++++++++++----
>  src/cam/event_loop.h   |  3 +++
>  2 files changed, 36 insertions(+), 4 deletions(-)
>
> diff --git a/src/cam/event_loop.cpp b/src/cam/event_loop.cpp
> index e25784c0..1e1a4269 100644
> --- a/src/cam/event_loop.cpp
> +++ b/src/cam/event_loop.cpp
> @@ -60,6 +60,17 @@ void EventLoop::callLater(const std::function<void()> &func)
>         event_base_once(base_, -1, EV_TIMEOUT, dispatchCallback, this, nullptr);
>  }
>
> +int EventLoop::eventNew(const std::unique_ptr<Event> &event, const int fd, const short events)
> +{
> +       event->event_ = event_new(base_, fd, events, &EventLoop::Event::dispatch, event.get());
> +       if (!event->event_) {
> +               std::cerr << "Failed to create event for fd " << fd << std::endl;
> +               return -EINVAL;
> +       }
> +
> +       return 0;
> +}
> +
>  void EventLoop::addEvent(int fd, EventType type,
>                          const std::function<void()> &callback)
>  {
> @@ -68,10 +79,7 @@ void EventLoop::addEvent(int fd, EventType type,
>                      | (type & Write ? EV_WRITE : 0)
>                      | EV_PERSIST;
>
> -       event->event_ = event_new(base_, fd, events, &EventLoop::Event::dispatch,
> -                                 event.get());
> -       if (!event->event_) {
> -               std::cerr << "Failed to create event for fd " << fd << std::endl;
> +       if (eventNew(event, fd, events)) {
>                 return;
>         }
>
> @@ -84,6 +92,27 @@ void EventLoop::addEvent(int fd, EventType type,
>         events_.push_back(std::move(event));
>  }
>
> +void EventLoop::addTimerEvent(const suseconds_t period,
> +                             const std::function<void()> &callback)
> +{
> +       std::unique_ptr<Event> event = std::make_unique<Event>(callback);
> +       if (eventNew(event, -1, EV_PERSIST)) {
> +               return;
> +       }
> +
> +       struct timeval tv;
> +       tv.tv_sec = 0;
> +       tv.tv_usec = period;
> +
> +       int ret = event_add(event->event_, &tv);
> +       if (ret < 0) {
> +               std::cerr << "Failed to add timer event" << std::endl;
> +               return;
> +       }
> +
> +       events_.push_back(std::move(event));
> +}
> +
>  void EventLoop::dispatchCallback([[maybe_unused]] evutil_socket_t fd,
>                                  [[maybe_unused]] short flags, void *param)
>  {
> diff --git a/src/cam/event_loop.h b/src/cam/event_loop.h
> index a4613eb2..3d3561e5 100644
> --- a/src/cam/event_loop.h
> +++ b/src/cam/event_loop.h
> @@ -36,6 +36,8 @@ public:
>
>         void addEvent(int fd, EventType type,
>                       const std::function<void()> &handler);
> +       void addTimerEvent(const suseconds_t period,
> +                          const std::function<void()> &handler);
>
>  private:
>         struct Event {
> @@ -60,4 +62,5 @@ private:
>         static void dispatchCallback(evutil_socket_t fd, short flags,
>                                      void *param);
>         void dispatchCall();
> +       int eventNew(const std::unique_ptr<Event> &event, const int fd, const short events);
>  };
> --
> 2.35.1
>