Cleanup: Avoid reference of RenderLayer and RenderPass in multilayer operation

This is avoids reference to data which can potentially be freed from the main
thread while the compositor job is running.

There is still some direct access to RenderResult and access to its layers
and passes in the operation implementation, but is is all internal and will
be worked on later. The purpose of this patch is to avoid unsafe pointers in
the API of the operation.

Should be no functional changes.

Ref #118337, #121761

source/blender/compositor/nodes/COM_CryptomatteNode.cc

@@ -168,12 +168,13 @@ void CryptomatteNode::input_operations_from_image_source(
       LISTBASE_FOREACH (RenderPass *, render_pass, &render_layer->passes) {
         const std::string combined_name = combined_layer_pass_name(render_layer, render_pass);
         if (combined_name != prefix && blender::StringRef(combined_name).startswith(prefix)) {
-          MultilayerColorOperation *op = new MultilayerColorOperation(render_layer, render_pass);
+          MultilayerColorOperation *op = new MultilayerColorOperation();
           iuser->layer = layer_index;
           op->set_image(image);
           op->set_image_user(*iuser);
           op->set_framenumber(context.get_framenumber());
           op->set_view_name(context.get_view_name());
+          op->set_pass_name(render_pass->name);
           r_input_operations.append(op);
         }
       }

source/blender/compositor/nodes/COM_ImageNode.cc

@@ -20,8 +20,7 @@ ImageNode::ImageNode(bNode *editor_node) : Node(editor_node)
 }
 NodeOperation *ImageNode::do_multilayer_check(NodeConverter &converter,
                                               const CompositorContext &context,
-                                              RenderLayer *render_layer,
-                                              RenderPass *render_pass,
+                                              const char *pass_name,
                                               Image *image,
                                               ImageUser *user,
                                               int framenumber,
@@ -32,13 +31,13 @@ NodeOperation *ImageNode::do_multilayer_check(NodeConverter &converter,
   MultilayerBaseOperation *operation = nullptr;
   switch (datatype) {
     case DataType::Value:
-      operation = new MultilayerValueOperation(render_layer, render_pass);
+      operation = new MultilayerValueOperation();
       break;
     case DataType::Vector:
-      operation = new MultilayerVectorOperation(render_layer, render_pass);
+      operation = new MultilayerVectorOperation();
       break;
     case DataType::Color:
-      operation = new MultilayerColorOperation(render_layer, render_pass);
+      operation = new MultilayerColorOperation();
       break;
     default:
       break;
@@ -47,6 +46,7 @@ NodeOperation *ImageNode::do_multilayer_check(NodeConverter &converter,
   operation->set_image_user(*user);
   operation->set_framenumber(framenumber);
   operation->set_view_name(context.get_view_name());
+  operation->set_pass_name(pass_name);
 
   converter.add_operation(operation);
   converter.map_output_socket(output_socket, operation->get_output_socket());
@@ -94,8 +94,7 @@ void ImageNode::convert_to_operations(NodeConverter &converter,
               case 1:
                 operation = do_multilayer_check(converter,
                                                 context,
-                                                rl,
-                                                rpass,
+                                                rpass->name,
                                                 image,
                                                 imageuser,
                                                 framenumber,
@@ -107,8 +106,7 @@ void ImageNode::convert_to_operations(NodeConverter &converter,
               case 3:
                 operation = do_multilayer_check(converter,
                                                 context,
-                                                rl,
-                                                rpass,
+                                                rpass->name,
                                                 image,
                                                 imageuser,
                                                 framenumber,
@@ -118,8 +116,7 @@ void ImageNode::convert_to_operations(NodeConverter &converter,
               case 4:
                 operation = do_multilayer_check(converter,
                                                 context,
-                                                rl,
-                                                rpass,
+                                                rpass->name,
                                                 image,
                                                 imageuser,
                                                 framenumber,

source/blender/compositor/nodes/COM_ImageNode.h

@@ -22,8 +22,7 @@ class ImageNode : public Node {
  private:
   NodeOperation *do_multilayer_check(NodeConverter &converter,
                                      const CompositorContext &context,
-                                     RenderLayer *render_layer,
-                                     RenderPass *render_pass,
+                                     const char *pass_name,
                                      Image *image,
                                      ImageUser *user,
                                      int framenumber,

source/blender/compositor/operations/COM_MultilayerImageOperation.cc

@@ -10,14 +10,6 @@
 
 namespace blender::compositor {
 
-MultilayerBaseOperation::MultilayerBaseOperation(RenderLayer *render_layer,
-                                                 RenderPass *render_pass)
-{
-  pass_id_ = BLI_findindex(&render_layer->passes, render_pass);
-  render_layer_ = render_layer;
-  render_pass_ = render_pass;
-}
-
 int MultilayerBaseOperation::get_view_index() const
 {
   if (BLI_listbase_count_at_most(&image_->rr->views, 2) <= 1) {
@@ -43,8 +35,16 @@ int MultilayerBaseOperation::get_view_index() const
 
 ImBuf *MultilayerBaseOperation::get_im_buf()
 {
+  if (image_ == nullptr) {
+    return nullptr;
+  }
+
+  const RenderLayer *render_layer = static_cast<const RenderLayer *>(
+      BLI_findlink(&image_->rr->layers, image_user_.layer));
+
   image_user_.view = get_view_index();
-  image_user_.pass = pass_id_;
+  image_user_.pass = BLI_findstringindex(
+      &render_layer->passes, pass_name_.c_str(), offsetof(RenderPass, name));
 
   if (BKE_image_multilayer_index(image_->rr, &image_user_)) {
     return BaseImageOperation::get_im_buf();
@@ -69,15 +69,12 @@ std::unique_ptr<MetaData> MultilayerColorOperation::get_meta_data()
 {
   BLI_assert(buffer_);
   MetaDataExtractCallbackData callback_data = {nullptr};
+  /* TODO: Make access to the render result thread-safe. */
   RenderResult *render_result = image_->rr;
   if (render_result && render_result->stamp_data) {
-    RenderLayer *render_layer = render_layer_;
-    RenderPass *render_pass = render_pass_;
-    std::string full_layer_name =
-        std::string(render_layer->name,
-                    BLI_strnlen(render_layer->name, sizeof(render_layer->name))) +
-        "." +
-        std::string(render_pass->name, BLI_strnlen(render_pass->name, sizeof(render_pass->name)));
+    const RenderLayer *render_layer = static_cast<const RenderLayer *>(
+        BLI_findlink(&image_->rr->layers, image_user_.layer));
+    std::string full_layer_name = std::string(render_layer->name) + "." + pass_name_;
     blender::StringRef cryptomatte_layer_name =
         blender::bke::cryptomatte::BKE_cryptomatte_extract_layer_name(full_layer_name);
     callback_data.set_cryptomatte_keys(cryptomatte_layer_name);

source/blender/compositor/operations/COM_MultilayerImageOperation.h

@@ -4,17 +4,15 @@
 
 #pragma once
 
+#include <string>
+
 #include "COM_ImageOperation.h"
 
 namespace blender::compositor {
 
 class MultilayerBaseOperation : public BaseImageOperation {
- private:
-  int pass_id_;
-
  protected:
-  RenderLayer *render_layer_;
-  RenderPass *render_pass_;
+  std::string pass_name_;
 
   /* Returns the image view to use for the current active view. */
   int get_view_index() const;
@@ -22,10 +20,12 @@ class MultilayerBaseOperation : public BaseImageOperation {
   ImBuf *get_im_buf() override;
 
  public:
-  /**
-   * Constructor
-   */
-  MultilayerBaseOperation(RenderLayer *render_layer, RenderPass *render_pass);
+  MultilayerBaseOperation() = default;
+
+  void set_pass_name(std::string pass_name)
+  {
+    pass_name_ = std::move(pass_name);
+  }
 
   void update_memory_buffer_partial(MemoryBuffer *output,
                                     const rcti &area,
@@ -34,8 +34,7 @@ class MultilayerBaseOperation : public BaseImageOperation {
 
 class MultilayerColorOperation : public MultilayerBaseOperation {
  public:
-  MultilayerColorOperation(RenderLayer *render_layer, RenderPass *render_pass)
-      : MultilayerBaseOperation(render_layer, render_pass)
+  MultilayerColorOperation()
   {
     this->add_output_socket(DataType::Color);
   }
@@ -44,8 +43,7 @@ class MultilayerColorOperation : public MultilayerBaseOperation {
 
 class MultilayerValueOperation : public MultilayerBaseOperation {
  public:
-  MultilayerValueOperation(RenderLayer *render_layer, RenderPass *render_pass)
-      : MultilayerBaseOperation(render_layer, render_pass)
+  MultilayerValueOperation()
   {
     this->add_output_socket(DataType::Value);
   }
@@ -53,8 +51,7 @@ class MultilayerValueOperation : public MultilayerBaseOperation {
 
 class MultilayerVectorOperation : public MultilayerBaseOperation {
  public:
-  MultilayerVectorOperation(RenderLayer *render_layer, RenderPass *render_pass)
-      : MultilayerBaseOperation(render_layer, render_pass)
+  MultilayerVectorOperation()
   {
     this->add_output_socket(DataType::Vector);
   }