Re-introduce previously reverted raster mask release fix

src/develop/pixelpipe_hb.c

@@ -640,6 +640,81 @@ static void _dev_pixelpipe_synch(dt_dev_pixelpipe_t *pipe,
   }
 }
 
+/** remove stale entries (deleted, disabled or de-synced consumers) from a
+    raster mask source's users table, so it doesn't keep
+    publishing/invalidating forever */
+static void _iop_prune_stale_raster_users(dt_dev_pixelpipe_t *pipe, dt_iop_module_t *module)
+{
+  GHashTable *users = module->raster_mask.source.users;
+  if(!module->dev || !users || g_hash_table_size(users) == 0)
+    return;
+
+  /* Phantom users (deleted or de-synced consumers) keep the source republishing
+     -- and invalidating downstream -- every run. Judge each consumer from its
+     node in THIS pipe, never from module->enabled/blend_params: those track the
+     darkroom UI and are stale in the export pipe, where the piece is authoritative
+     (dropped a live export consumer's mask, regression 0167-raster-mask). We only
+     compare the consumer pointer, so a freed module is never dereferenced. */
+  GHashTableIter iter;
+  gpointer key, value;
+  g_hash_table_iter_init(&iter, users);
+  while(g_hash_table_iter_next(&iter, &key, &value))
+  {
+    dt_iop_module_t *sink = key;
+
+    // locate the consumer's node in this pipe (pointer-only match)
+    dt_dev_pixelpipe_iop_t *sink_piece = NULL;
+    for(GList *nodes = pipe->nodes; nodes; nodes = g_list_next(nodes))
+    {
+      dt_dev_pixelpipe_iop_t *p = nodes->data;
+      if(p->module == sink)
+      {
+        sink_piece = p;
+        break;
+      }
+    }
+    if(!sink_piece)
+    {
+      g_hash_table_iter_remove(&iter);
+      dt_print_pipe(DT_DEBUG_PIPE | DT_DEBUG_MASKS,
+                    "prune stale raster user",
+                    pipe,
+                    module,
+                    DT_DEVICE_NONE,
+                    NULL,
+                    NULL,
+                    "dropped deleted consumer");
+      continue;
+    }
+
+    // a real consumer must still point back at us, have its node enabled in
+    // this pipe, and actually have its blending in raster-mask mode. A module
+    // that named us as raster source but is then disabled (or switched its mask
+    // to drawn/parametric) leaves a phantom entry that would otherwise keep us
+    // publishing -- and invalidating every downstream cacheline -- on every run.
+    const dt_develop_blend_params_t *bp = sink_piece->blendop_data;
+    const gboolean consumes = sink->raster_mask.sink.source == module && sink_piece->enabled &&
+                              bp && (bp->mask_mode & DEVELOP_MASK_RASTER);
+    if(!consumes)
+    {
+      g_hash_table_iter_remove(&iter);
+      dt_print_pipe(DT_DEBUG_PIPE | DT_DEBUG_MASKS,
+                    "prune stale raster user",
+                    pipe,
+                    module,
+                    DT_DEVICE_NONE,
+                    NULL,
+                    NULL,
+                    "dropped '%s%s' (%s)",
+                    sink->op,
+                    dt_iop_get_instance_id(sink),
+                    sink->raster_mask.sink.source != module ? "de-synced"
+                    : !sink_piece->enabled                  ? "disabled"
+                                                            : "not in raster mode");
+    }
+  }
+}
+
 void dt_dev_pixelpipe_synch_all(dt_dev_pixelpipe_t *pipe, dt_develop_t *dev)
 {
   dt_pthread_mutex_lock(&pipe->busy_mutex);
@@ -675,6 +750,12 @@ void dt_dev_pixelpipe_synch_all(dt_dev_pixelpipe_t *pipe, dt_develop_t *dev)
     _dev_pixelpipe_synch(pipe, dev, history);
     history = g_list_next(history);
   }
+
+  // history has been (re)applied, so real raster consumers have re-registered;
+  // drop any phantom users left behind by deleted or de-synced consumers
+  for(GList *nodes = pipe->nodes; nodes; nodes = g_list_next(nodes))
+    _iop_prune_stale_raster_users(pipe, ((dt_dev_pixelpipe_iop_t *)nodes->data)->module);
+
   dt_print_pipe(DT_DEBUG_PARAMS,
            "synch all modules done",
            pipe, NULL, DT_DEVICE_NONE, NULL, NULL,
@@ -699,6 +780,12 @@ void dt_dev_pixelpipe_synch_top(dt_dev_pixelpipe_t *pipe, dt_develop_t *dev)
     dt_print_pipe(DT_DEBUG_PARAMS, "synch top history module missing!",
       pipe, NULL, DT_DEVICE_NONE, NULL, NULL);
   }
+
+  // clear any phantom raster users (deleted/de-synced consumers) so a source
+  // doesn't keep republishing its mask and invalidating downstream every run
+  for(GList *nodes = pipe->nodes; nodes; nodes = g_list_next(nodes))
+    _iop_prune_stale_raster_users(pipe, ((dt_dev_pixelpipe_iop_t *)nodes->data)->module);
+
   dt_pthread_mutex_unlock(&pipe->busy_mutex);
 }