Implement pending jobs counter

While running the job dispatchers we keep track on jobs being inserted and executed so we
at least know about the number of unprocessed jobs via dt_control_jobs_pending()

Also show pending jobs in the log if closing dt.

src/control/control.c

@@ -201,6 +201,7 @@ void dt_control_init(dt_control_t *s)
   s->widget_definitions = g_ptr_array_new ();
   s->input_drivers = NULL;
   dt_atomic_set_int(&s->running, DT_CONTROL_STATE_DISABLED);
+  dt_atomic_set_int(&s->pending_jobs, 0);
   s->cups_started = FALSE;
 
   dt_action_define_fallback(DT_ACTION_TYPE_IOP, &dt_action_def_iop);
@@ -328,8 +329,9 @@ void dt_control_shutdown(dt_control_t *control)
   pthread_cond_broadcast(&control->cond);
   dt_pthread_mutex_unlock(&control->cond_mutex);
 
-  dt_print(DT_DEBUG_CONTROL, "[dt_control_shutdown] closing control threads%s",
-    cleanup ? " in cleanup mode" : "");
+  dt_print(DT_DEBUG_CONTROL, "[dt_control_shutdown] closing control threads%s, %d pending jobs",
+    cleanup ? "in cleanup mode" : "",
+    dt_control_jobs_pending(control));
 
   if(!cleanup)
     return;   // if not running there are no threads to join

src/control/control.h

@@ -187,6 +187,7 @@ typedef struct dt_control_t
 
   // job management
   dt_atomic_int running;
+  dt_atomic_int pending_jobs;
   gboolean cups_started;
   gboolean export_scheduled;
   dt_pthread_mutex_t queue_mutex, cond_mutex;

src/control/jobs.c

@@ -314,6 +314,7 @@ static void _control_job_execute(_dt_job_t *job)
 
   _control_job_set_state(job, DT_JOB_STATE_FINISHED);
   _control_job_print(job, "run_job-", "", DT_CTL_WORKER_RESERVED + _control_get_threadid());
+  dt_atomic_add_int(&darktable.control->pending_jobs, -1);
 }
 
 static gboolean _control_run_job(dt_control_t *control)
@@ -432,6 +433,7 @@ gboolean dt_control_add_job(dt_control_t *control,
       }
     }
 
+    dt_atomic_add_int(&darktable.control->pending_jobs, 1);
     // if the job is already in the queue -> move it to the top
     for(GList *iter = *queue; iter; iter = g_list_next(iter))
     {
@@ -446,6 +448,7 @@ gboolean dt_control_add_job(dt_control_t *control,
         job_for_disposal = job;
 
         job = other_job;
+        dt_atomic_add_int(&darktable.control->pending_jobs, -1);
         break; // there can't be any further copy in the list
       }
     }
@@ -462,6 +465,7 @@ gboolean dt_control_add_job(dt_control_t *control,
       dt_control_job_dispose(last->data);
       *queue = g_list_delete_link(*queue, last);
       length--;
+      dt_atomic_add_int(&darktable.control->pending_jobs, -1);
     }
 
     control->queue_length[queue_id] = length;
@@ -477,6 +481,7 @@ gboolean dt_control_add_job(dt_control_t *control,
       job->priority = DT_CONTROL_FG_PRIORITY;
     *queue = g_list_append(*queue, job);
     control->queue_length[queue_id]++;
+    dt_atomic_add_int(&darktable.control->pending_jobs, 1);
   }
   _control_job_set_state(job, DT_JOB_STATE_QUEUED);
   dt_pthread_mutex_unlock(&control->queue_mutex);
@@ -636,6 +641,11 @@ void dt_control_jobs_cleanup(dt_control_t *control)
   control->thread = NULL;
 }
 
+int dt_control_jobs_pending(dt_control_t *control)
+{
+  return control ? dt_atomic_get_int(&control->pending_jobs) : 0;
+}
+
 // clang-format off
 // modelines: These editor modelines have been set for all relevant files by tools/update_modelines.py
 // vim: shiftwidth=2 expandtab tabstop=2 cindent

src/control/jobs.h

@@ -82,6 +82,7 @@ double dt_control_job_get_progress(dt_job_t *job);
 struct dt_control_t;
 void dt_control_jobs_init(struct dt_control_t *control);
 void dt_control_jobs_cleanup(struct dt_control_t *control);
+int dt_control_jobs_pending(struct dt_control_t *control);
 
 gboolean dt_control_add_job(struct dt_control_t *control, dt_job_queue_t queue_id, dt_job_t *job);
 gboolean dt_control_add_job_res(struct dt_control_t *s, dt_job_t *job, int32_t res);