[vlc-devel] [PATCH v2 09/13] vout/control: move the lock outside of the control API

Thomas Guillem thomas at gllm.fr
Mon Aug 17 16:33:13 CEST 2020


On Mon, Aug 17, 2020, at 15:15, Steve Lhomme wrote:
> The lock is still need to wait for incoming controls before the deadline.

*is still needed*

> 
> The picture_fifo is always called under the control_lock for consistency with
> the conditional variable state.
> ---
>  src/video_output/control.c      | 24 ++----------------------
>  src/video_output/control.h      |  5 +----
>  src/video_output/video_output.c | 33 ++++++++++++++++++++++-----------
>  3 files changed, 25 insertions(+), 37 deletions(-)
> 
> diff --git a/src/video_output/control.c b/src/video_output/control.c
> index 6454461b068..cf974f4e29c 100644
> --- a/src/video_output/control.c
> +++ b/src/video_output/control.c
> @@ -38,7 +38,6 @@ void vout_control_cmd_Init(vout_control_cmd_t *cmd, int type)
>  /* */
>  void vout_control_Init(vout_control_t *ctrl)
>  {
> -    vlc_mutex_init(&ctrl->lock);
>      vlc_cond_init(&ctrl->wait_request);
>  
>      ctrl->is_dead = false;
> @@ -54,27 +53,21 @@ void vout_control_Clean(vout_control_t *ctrl)
>  
>  void vout_control_Dead(vout_control_t *ctrl)
>  {
> -    vlc_mutex_lock(&ctrl->lock);
>      ctrl->is_dead = true;
> -    vlc_mutex_unlock(&ctrl->lock);
>  }
>  
>  void vout_control_Push(vout_control_t *ctrl, vout_control_cmd_t *cmd)
>  {
> -    vlc_mutex_lock(&ctrl->lock);
>      if (!ctrl->is_dead) {
>          ARRAY_APPEND(ctrl->cmd, *cmd);
>          vlc_cond_signal(&ctrl->wait_request);
>      }
> -    vlc_mutex_unlock(&ctrl->lock);
>  }
>  
>  void vout_control_Wake(vout_control_t *ctrl)
>  {
> -    vlc_mutex_lock(&ctrl->lock);
>      ctrl->can_sleep = false;
>      vlc_cond_signal(&ctrl->wait_request);
> -    vlc_mutex_unlock(&ctrl->lock);
>  }
>  
>  void vout_control_PushVoid(vout_control_t *ctrl, int type)
> @@ -85,25 +78,13 @@ void vout_control_PushVoid(vout_control_t *ctrl, int type)
>      vout_control_Push(ctrl, &cmd);
>  }
>  
> -void vout_control_Hold(vout_control_t *ctrl)
> -{
> -    vlc_mutex_lock(&ctrl->lock);
> -}
> -
> -void vout_control_Release(vout_control_t *ctrl)
> -{
> -    vlc_mutex_unlock(&ctrl->lock);
> -}
> -
>  int vout_control_Pop(vout_control_t *ctrl, vout_control_cmd_t *cmd,
> -                     vlc_tick_t deadline)
> +                     vlc_tick_t deadline, vlc_mutex_t *lock)
>  {
> -    vlc_mutex_lock(&ctrl->lock);
> -
>      if (ctrl->cmd.i_size <= 0) {
>          /* Spurious wakeups are perfectly fine */
>          if (deadline != INVALID_DEADLINE && ctrl->can_sleep) {
> -            vlc_cond_timedwait(&ctrl->wait_request, &ctrl->lock, deadline);
> +            vlc_cond_timedwait(&ctrl->wait_request, lock, deadline);
>          }
>      }
>  
> @@ -116,7 +97,6 @@ int vout_control_Pop(vout_control_t *ctrl, 
> vout_control_cmd_t *cmd,
>          has_cmd = false;
>          ctrl->can_sleep = true;
>      }
> -    vlc_mutex_unlock(&ctrl->lock);
>  
>      return has_cmd ? VLC_SUCCESS : VLC_EGENERIC;
>  }
> diff --git a/src/video_output/control.h b/src/video_output/control.h
> index d7b5f1f4aac..5e73d2fc3ab 100644
> --- a/src/video_output/control.h
> +++ b/src/video_output/control.h
> @@ -37,7 +37,6 @@ typedef struct {
>  void vout_control_cmd_Init(vout_control_cmd_t *, int type);
>  
>  typedef struct {
> -    vlc_mutex_t lock;
>      vlc_cond_t  wait_request;
>  
>      /* */
> @@ -56,13 +55,11 @@ void vout_control_WaitEmpty(vout_control_t *);
>  void vout_control_Push(vout_control_t *, vout_control_cmd_t *);
>  void vout_control_PushVoid(vout_control_t *, int type);
>  void vout_control_Wake(vout_control_t *);
> -void vout_control_Hold(vout_control_t *);
> -void vout_control_Release(vout_control_t *);
>  
>  /* control inside of the vout thread */
>  #define INVALID_DEADLINE   ((vlc_tick_t) INT64_MAX)
>  
> -int vout_control_Pop(vout_control_t *, vout_control_cmd_t *, 
> vlc_tick_t deadline);
> +int vout_control_Pop(vout_control_t *, vout_control_cmd_t *, 
> vlc_tick_t deadline, vlc_mutex_t *lock);
>  void vout_control_Dead(vout_control_t *);
>  
>  #endif
> diff --git a/src/video_output/video_output.c b/src/video_output/video_output.c
> index be7b2185fe8..3cdc849e507 100644
> --- a/src/video_output/video_output.c
> +++ b/src/video_output/video_output.c
> @@ -120,6 +120,7 @@ typedef struct vout_thread_sys_t
>      vlc_blender_t   *spu_blend;
>  
>      /* Thread & synchronization */
> +    vlc_mutex_t     control_lock;
>      vout_control_t  control;
>      vlc_thread_t    thread;
>  
> @@ -497,8 +498,10 @@ void vout_PutPicture(vout_thread_t *vout, 
> picture_t *picture)
>      vout_thread_sys_t *sys = VOUT_THREAD_TO_SYS(vout);
>      assert(!sys->dummy);
>      picture->p_next = NULL;
> +    vlc_mutex_lock(&sys->control_lock);
>      picture_fifo_Push(sys->decoder_fifo, picture);
>      vout_control_Wake(&sys->control);
> +    vlc_mutex_unlock(&sys->control_lock);
>  }
>  
>  /* */
> @@ -1558,7 +1561,7 @@ void vout_ChangePause(vout_thread_t *vout, bool 
> is_paused, vlc_tick_t date)
>      vout_thread_sys_t *sys = VOUT_THREAD_TO_SYS(vout);
>      assert(!sys->dummy);
>  
> -    vout_control_Hold(&sys->control);
> +    vlc_mutex_lock(&sys->control_lock);
>      assert(!sys->pause.is_on || !is_paused);
>  
>      if (sys->pause.is_on)
> @@ -1569,7 +1572,7 @@ void vout_ChangePause(vout_thread_t *vout, bool 
> is_paused, vlc_tick_t date)
>      }
>      sys->pause.is_on = is_paused;
>      sys->pause.date  = date;
> -    vout_control_Release(&sys->control);
> +    vlc_mutex_unlock(&sys->control_lock);
>  
>      vlc_mutex_lock(&sys->window_lock);
>      vout_window_SetInhibition(sys->display_cfg.window, !is_paused);
> @@ -1618,9 +1621,9 @@ void vout_Flush(vout_thread_t *vout, vlc_tick_t date)
>      vout_thread_sys_t *sys = VOUT_THREAD_TO_SYS(vout);
>      assert(!sys->dummy);
>  
> -    vout_control_Hold(&sys->control);
> +    vlc_mutex_lock(&sys->control_lock);
>      vout_FlushUnlocked(sys, false, date);
> -    vout_control_Release(&sys->control);
> +    vlc_mutex_unlock(&sys->control_lock);
>  }
>  
>  void vout_NextPicture(vout_thread_t *vout, vlc_tick_t *duration)
> @@ -1629,7 +1632,7 @@ void vout_NextPicture(vout_thread_t *vout, 
> vlc_tick_t *duration)
>      assert(!sys->dummy);
>      *duration = 0;
>  
> -    vout_control_Hold(&sys->control);
> +    vlc_mutex_lock(&sys->control_lock);
>      if (sys->step.last == VLC_TICK_INVALID)
>          sys->step.last = sys->displayed.timestamp;
>  
> @@ -1643,7 +1646,7 @@ void vout_NextPicture(vout_thread_t *vout, 
> vlc_tick_t *duration)
>              /* TODO advance subpicture by the duration ... */
>          }
>      }
> -    vout_control_Release(&sys->control);
> +    vlc_mutex_unlock(&sys->control_lock);
>  }
>  
>  void vout_ChangeDelay(vout_thread_t *vout, vlc_tick_t delay)
> @@ -1652,10 +1655,10 @@ void vout_ChangeDelay(vout_thread_t *vout, 
> vlc_tick_t delay)
>      assert(!sys->dummy);
>      assert(sys->display);
>  
> -    vout_control_Hold(&sys->control);
> +    vlc_mutex_lock(&sys->control_lock);
>      vlc_clock_SetDelay(sys->clock, delay);
>      sys->delay = delay;
> -    vout_control_Release(&sys->control);
> +    vlc_mutex_unlock(&sys->control_lock);
>  }
>  
>  void vout_ChangeRate(vout_thread_t *vout, float rate)
> @@ -1663,9 +1666,9 @@ void vout_ChangeRate(vout_thread_t *vout, float rate)
>      vout_thread_sys_t *sys = VOUT_THREAD_TO_SYS(vout);
>      assert(!sys->dummy);
>  
> -    vout_control_Hold(&sys->control);
> +    vlc_mutex_lock(&sys->control_lock);
>      sys->rate = rate;
> -    vout_control_Release(&sys->control);
> +    vlc_mutex_unlock(&sys->control_lock);
>  }
>  
>  void vout_ChangeSpuDelay(vout_thread_t *vout, size_t channel_id,
> @@ -1895,12 +1898,15 @@ static void *Thread(void *object)
>              deadline = INVALID_DEADLINE;
>          }
>  
> -        while (!vout_control_Pop(&sys->control, &cmd, deadline)) {
> +        vlc_mutex_lock(&sys->control_lock);
> +        while (!vout_control_Pop(&sys->control, &cmd, deadline, 
> &sys->control_lock)) {
>              switch(cmd.type) {
>                  case VOUT_CONTROL_TERMINATE:
> +                    vlc_mutex_unlock(&sys->control_lock);
>                      return NULL; /* no need to clean &cmd */
>              }
>          }
> +        vlc_mutex_unlock(&sys->control_lock);
>  
>          wait = ThreadDisplayPicture(vout, &deadline) != VLC_SUCCESS;
>  
> @@ -1961,7 +1967,9 @@ void vout_StopDisplay(vout_thread_t *vout)
>  {
>      vout_thread_sys_t *sys = VOUT_THREAD_TO_SYS(vout);
>  
> +    vlc_mutex_lock(&sys->control_lock);
>      vout_control_PushVoid(&sys->control, VOUT_CONTROL_TERMINATE);
> +    vlc_mutex_unlock(&sys->control_lock);
>      vlc_join(sys->thread, NULL);
>  
>      vout_ReleaseDisplay(sys);
> @@ -2000,7 +2008,9 @@ void vout_Close(vout_thread_t *vout)
>  
>      vout_IntfDeinit(VLC_OBJECT(vout));
>      vout_snapshot_End(sys->snapshot);
> +    vlc_mutex_lock(&sys->control_lock);
>      vout_control_Dead(&sys->control);
> +    vlc_mutex_unlock(&sys->control_lock);
>      vout_chrono_Clean(&sys->render);
>  
>      if (sys->spu)
> @@ -2106,6 +2116,7 @@ vout_thread_t *vout_Create(vlc_object_t *object)
>      sys->spu = var_InheritBool(vout, "spu") || var_InheritBool(vout, "osd") ?
>                 spu_Create(vout, vout) : NULL;
>  
> +    vlc_mutex_init(&sys->control_lock);
>      vout_control_Init(&sys->control);
>  
>      sys->title.show     = var_InheritBool(vout, "video-title-show");
> -- 
> 2.26.2
> 
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