Nodes: efficient node tree queries and inlining

This adds two data structures that wrap a node tree. However, they work
on different abstraction levels.

`NodeTreeRef` is an immutable structure that makes working with a node
tree in C++ much more efficient and convenient. It supports various
queries efficiently, that are not easily possible using just `bNodeTree`.

`DerivedNodeTree` builds on top of `NodeTreeRef`. It contains a flattened
view on the node tree, i.e. with node groups being inlined. Every inlined
node still knows its "call stack". It supports pretty much the same queries
as `NodeTreeRef`.

Both data structures come with a dot graph exporter for debugging purposes.

Reviewers: brecht

Differential Revision: https://developer.blender.org/D7628

1 files changed, 442 insertions, 0 deletions

diff --git a/source/blender/blenkernel/intern/derived_node_tree.cc b/source/blender/blenkernel/intern/derived_node_tree.cc
new file mode 100644
index 00000000000..80ae521642e
--- /dev/null
+++ b/source/blender/blenkernel/intern/derived_node_tree.cc
@@ -0,0 +1,442 @@
+/*
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ */
+
+#include "BKE_derived_node_tree.hh"
+
+#include "BLI_dot_export.hh"
+
+#define UNINITIALIZED_ID UINT32_MAX
+
+namespace BKE {
+
+static const NodeTreeRef &get_tree_ref(NodeTreeRefMap &node_tree_refs, bNodeTree *btree)
+{
+  return *node_tree_refs.lookup_or_add(btree,
+                                       [&]() { return blender::make_unique<NodeTreeRef>(btree); });
+}
+
+DerivedNodeTree::DerivedNodeTree(bNodeTree *btree, NodeTreeRefMap &node_tree_refs) : m_btree(btree)
+{
+  const NodeTreeRef &main_tree_ref = get_tree_ref(node_tree_refs, btree);
+
+  Vector<DNode *> all_nodes;
+  Vector<DGroupInput *> all_group_inputs;
+  Vector<DParentNode *> all_parent_nodes;
+
+  this->insert_nodes_and_links_in_id_order(main_tree_ref, nullptr, all_nodes);
+  this->expand_groups(all_nodes, all_group_inputs, all_parent_nodes, node_tree_refs);
+  this->remove_expanded_group_interfaces(all_nodes);
+  this->remove_unused_group_inputs(all_group_inputs);
+  this->store_in_this_and_init_ids(
+      std::move(all_nodes), std::move(all_group_inputs), std::move(all_parent_nodes));
+}
+
+BLI_NOINLINE void DerivedNodeTree::insert_nodes_and_links_in_id_order(const NodeTreeRef &tree_ref,
+                                                                      DParentNode *parent,
+                                                                      Vector<DNode *> &all_nodes)
+{
+  Array<DSocket *, 64> sockets_map(tree_ref.sockets().size());
+
+  /* Insert nodes. */
+  for (const NodeRef *node_ref : tree_ref.nodes()) {
+    DNode &node = this->create_node(*node_ref, parent, sockets_map);
+    all_nodes.append(&node);
+  }
+
+  /* Insert links. */
+  for (const NodeRef *node_ref : tree_ref.nodes()) {
+    for (const InputSocketRef *to_socket_ref : node_ref->inputs()) {
+      DInputSocket *to_socket = (DInputSocket *)sockets_map[to_socket_ref->id()];
+      for (const OutputSocketRef *from_socket_ref : to_socket_ref->linked_sockets()) {
+        DOutputSocket *from_socket = (DOutputSocket *)sockets_map[from_socket_ref->id()];
+        to_socket->m_linked_sockets.append(from_socket);
+        from_socket->m_linked_sockets.append(to_socket);
+      }
+    }
+  }
+}
+
+DNode &DerivedNodeTree::create_node(const NodeRef &node_ref,
+                                    DParentNode *parent,
+                                    MutableSpan<DSocket *> r_sockets_map)
+{
+  DNode &node = *m_allocator.construct<DNode>();
+  node.m_node_ref = &node_ref;
+  node.m_parent = parent;
+  node.m_id = UNINITIALIZED_ID;
+
+  node.m_inputs = m_allocator.construct_elements_and_pointer_array<DInputSocket>(
+      node_ref.inputs().size());
+  node.m_outputs = m_allocator.construct_elements_and_pointer_array<DOutputSocket>(
+      node_ref.outputs().size());
+
+  for (uint i : node.m_inputs.index_range()) {
+    const InputSocketRef &socket_ref = node_ref.input(i);
+    DInputSocket &socket = *node.m_inputs[i];
+
+    socket.m_id = UNINITIALIZED_ID;
+    socket.m_node = &node;
+    socket.m_socket_ref = &socket_ref;
+
+    r_sockets_map[socket_ref.id()] = &socket;
+  }
+
+  for (uint i : node.m_outputs.index_range()) {
+    const OutputSocketRef &socket_ref = node_ref.output(i);
+    DOutputSocket &socket = *node.m_outputs[i];
+
+    socket.m_id = UNINITIALIZED_ID;
+    socket.m_node = &node;
+    socket.m_socket_ref = &socket_ref;
+
+    r_sockets_map[socket_ref.id()] = &socket;
+  }
+
+  return node;
+}
+
+BLI_NOINLINE void DerivedNodeTree::expand_groups(Vector<DNode *> &all_nodes,
+                                                 Vector<DGroupInput *> &all_group_inputs,
+                                                 Vector<DParentNode *> &all_parent_nodes,
+                                                 NodeTreeRefMap &node_tree_refs)
+{
+  for (uint i = 0; i < all_nodes.size(); i++) {
+    DNode &node = *all_nodes[i];
+    if (node.m_node_ref->is_group_node()) {
+      this->expand_group_node(node, all_nodes, all_group_inputs, all_parent_nodes, node_tree_refs);
+    }
+  }
+}
+
+BLI_NOINLINE void DerivedNodeTree::expand_group_node(DNode &group_node,
+                                                     Vector<DNode *> &all_nodes,
+                                                     Vector<DGroupInput *> &all_group_inputs,
+                                                     Vector<DParentNode *> &all_parent_nodes,
+                                                     NodeTreeRefMap &node_tree_refs)
+{
+  const NodeRef &group_node_ref = *group_node.m_node_ref;
+  BLI_assert(group_node_ref.is_group_node());
+
+  bNodeTree *btree = (bNodeTree *)group_node_ref.bnode()->id;
+  if (btree == nullptr) {
+    return;
+  }
+
+  const NodeTreeRef &group_ref = get_tree_ref(node_tree_refs, btree);
+
+  DParentNode &parent = *m_allocator.construct<DParentNode>();
+  parent.m_id = all_parent_nodes.append_and_get_index(&parent);
+  parent.m_parent = group_node.m_parent;
+  parent.m_node_ref = &group_node_ref;
+
+  this->insert_nodes_and_links_in_id_order(group_ref, &parent, all_nodes);
+  Span<DNode *> new_nodes_by_id = all_nodes.as_span().take_back(group_ref.nodes().size());
+
+  this->create_group_inputs_for_unlinked_inputs(group_node, all_group_inputs);
+  this->relink_group_inputs(group_ref, new_nodes_by_id, group_node);
+  this->relink_group_outputs(group_ref, new_nodes_by_id, group_node);
+}
+
+BLI_NOINLINE void DerivedNodeTree::create_group_inputs_for_unlinked_inputs(
+    DNode &node, Vector<DGroupInput *> &all_group_inputs)
+{
+  for (DInputSocket *input_socket : node.m_inputs) {
+    if (input_socket->is_linked()) {
+      continue;
+    }
+
+    DGroupInput &group_input = *m_allocator.construct<DGroupInput>();
+    group_input.m_id = UNINITIALIZED_ID;
+    group_input.m_socket_ref = &input_socket->socket_ref();
+    group_input.m_parent = node.m_parent;
+
+    group_input.m_linked_sockets.append(input_socket);
+    input_socket->m_linked_group_inputs.append(&group_input);
+    all_group_inputs.append(&group_input);
+  }
+}
+
+BLI_NOINLINE void DerivedNodeTree::relink_group_inputs(const NodeTreeRef &group_ref,
+                                                       Span<DNode *> nodes_by_id,
+                                                       DNode &group_node)
+{
+  Span<const NodeRef *> node_refs = group_ref.nodes_with_idname("NodeGroupInput");
+  if (node_refs.size() == 0) {
+    return;
+  }
+  /* TODO: Pick correct group input node if there are more than one. */
+  const NodeRef &input_node_ref = *node_refs[0];
+  DNode &input_node = *nodes_by_id[input_node_ref.id()];
+
+  uint input_amount = group_node.inputs().size();
+  BLI_assert(input_amount == input_node_ref.outputs().size() - 1);
+
+  for (uint input_index : IndexRange(input_amount)) {
+    DInputSocket *outside_group = group_node.m_inputs[input_index];
+    DOutputSocket *inside_group = input_node.m_outputs[input_index];
+
+    for (DOutputSocket *outside_connected : outside_group->m_linked_sockets) {
+      outside_connected->m_linked_sockets.remove_first_occurrence_and_reorder(outside_group);
+    }
+
+    for (DGroupInput *outside_connected : outside_group->m_linked_group_inputs) {
+      outside_connected->m_linked_sockets.remove_first_occurrence_and_reorder(outside_group);
+    }
+
+    for (DInputSocket *inside_connected : inside_group->m_linked_sockets) {
+      inside_connected->m_linked_sockets.remove_first_occurrence_and_reorder(inside_group);
+
+      for (DOutputSocket *outside_connected : outside_group->m_linked_sockets) {
+        inside_connected->m_linked_sockets.append(outside_connected);
+        outside_connected->m_linked_sockets.append(inside_connected);
+      }
+
+      for (DGroupInput *outside_connected : outside_group->m_linked_group_inputs) {
+        inside_connected->m_linked_group_inputs.append(outside_connected);
+        outside_connected->m_linked_sockets.append(inside_connected);
+      }
+    }
+
+    inside_group->m_linked_sockets.clear();
+    outside_group->m_linked_sockets.clear();
+    outside_group->m_linked_group_inputs.clear();
+  }
+}
+
+BLI_NOINLINE void DerivedNodeTree::relink_group_outputs(const NodeTreeRef &group_ref,
+                                                        Span<DNode *> nodes_by_id,
+                                                        DNode &group_node)
+{
+  Span<const NodeRef *> node_refs = group_ref.nodes_with_idname("NodeGroupOutput");
+  if (node_refs.size() == 0) {
+    return;
+  }
+  /* TODO: Pick correct group output node if there are more than one. */
+  const NodeRef &output_node_ref = *node_refs[0];
+  DNode &output_node = *nodes_by_id[output_node_ref.id()];
+
+  uint output_amount = group_node.outputs().size();
+  BLI_assert(output_amount == output_node_ref.inputs().size() - 1);
+
+  for (uint output_index : IndexRange(output_amount)) {
+    DOutputSocket *outside_group = group_node.m_outputs[output_index];
+    DInputSocket *inside_group = output_node.m_inputs[output_index];
+
+    for (DInputSocket *outside_connected : outside_group->m_linked_sockets) {
+      outside_connected->m_linked_sockets.remove_first_occurrence_and_reorder(outside_group);
+    }
+
+    for (DOutputSocket *inside_connected : inside_group->m_linked_sockets) {
+      inside_connected->m_linked_sockets.remove_first_occurrence_and_reorder(inside_group);
+
+      for (DInputSocket *outside_connected : outside_group->m_linked_sockets) {
+        inside_connected->m_linked_sockets.append(outside_connected);
+        outside_connected->m_linked_sockets.append(inside_connected);
+      }
+    }
+
+    for (DGroupInput *inside_connected : inside_group->m_linked_group_inputs) {
+      inside_connected->m_linked_sockets.remove_first_occurrence_and_reorder(inside_group);
+
+      for (DInputSocket *outside_connected : outside_group->m_linked_sockets) {
+        inside_connected->m_linked_sockets.append(outside_connected);
+        outside_connected->m_linked_group_inputs.append(inside_connected);
+      }
+    }
+
+    outside_group->m_linked_sockets.clear();
+    inside_group->m_linked_sockets.clear();
+  }
+}
+
+BLI_NOINLINE void DerivedNodeTree::remove_expanded_group_interfaces(Vector<DNode *> &all_nodes)
+{
+  int index = 0;
+  while (index < all_nodes.size()) {
+    DNode &node = *all_nodes[index];
+    const NodeRef &node_ref = *node.m_node_ref;
+    if (node_ref.is_group_node() ||
+        (node.m_parent != nullptr &&
+         (node_ref.is_group_input_node() || node_ref.is_group_output_node()))) {
+      all_nodes.remove_and_reorder(index);
+      node.destruct_with_sockets();
+    }
+    else {
+      index++;
+    }
+  }
+}
+
+BLI_NOINLINE void DerivedNodeTree::remove_unused_group_inputs(
+    Vector<DGroupInput *> &all_group_inputs)
+{
+  int index = 0;
+  while (index < all_group_inputs.size()) {
+    DGroupInput &group_input = *all_group_inputs[index];
+    if (group_input.m_linked_sockets.is_empty()) {
+      all_group_inputs.remove_and_reorder(index);
+      group_input.~DGroupInput();
+    }
+    else {
+      index++;
+    }
+  }
+}
+
+void DNode::destruct_with_sockets()
+{
+  for (DInputSocket *socket : m_inputs) {
+    socket->~DInputSocket();
+  }
+  for (DOutputSocket *socket : m_outputs) {
+    socket->~DOutputSocket();
+  }
+  this->~DNode();
+}
+
+BLI_NOINLINE void DerivedNodeTree::store_in_this_and_init_ids(
+    Vector<DNode *> &&all_nodes,
+    Vector<DGroupInput *> &&all_group_inputs,
+    Vector<DParentNode *> &&all_parent_nodes)
+{
+  m_nodes_by_id = std::move(all_nodes);
+  m_group_inputs = std::move(all_group_inputs);
+  m_parent_nodes = std::move(all_parent_nodes);
+
+  for (uint node_index : m_nodes_by_id.index_range()) {
+    DNode *node = m_nodes_by_id[node_index];
+    node->m_id = node_index;
+
+    m_nodes_by_idname.lookup_or_add_default(node->idname()).append(node);
+
+    for (DInputSocket *socket : node->m_inputs) {
+      socket->m_id = m_sockets_by_id.append_and_get_index(socket);
+      m_input_sockets.append(socket);
+    }
+    for (DOutputSocket *socket : node->m_outputs) {
+      socket->m_id = m_sockets_by_id.append_and_get_index(socket);
+      m_output_sockets.append(socket);
+    }
+  }
+
+  for (uint i : m_group_inputs.index_range()) {
+    m_group_inputs[i]->m_id = i;
+  }
+}
+
+DerivedNodeTree::~DerivedNodeTree()
+{
+  for (DInputSocket *socket : m_input_sockets) {
+    socket->~DInputSocket();
+  }
+  for (DOutputSocket *socket : m_output_sockets) {
+    socket->~DOutputSocket();
+  }
+  for (DNode *node : m_nodes_by_id) {
+    node->~DNode();
+  }
+  for (DGroupInput *group_input : m_group_inputs) {
+    group_input->~DGroupInput();
+  }
+  for (DParentNode *parent : m_parent_nodes) {
+    parent->~DParentNode();
+  }
+}
+
+namespace Dot = blender::DotExport;
+
+static Dot::Cluster *get_cluster_for_parent(Dot::DirectedGraph &graph,
+                                            Map<const DParentNode *, Dot::Cluster *> &clusters,
+                                            const DParentNode *parent)
+{
+  if (parent == nullptr) {
+    return nullptr;
+  }
+  return clusters.lookup_or_add(parent, [&]() {
+    Dot::Cluster *parent_cluster = get_cluster_for_parent(graph, clusters, parent->parent());
+    bNodeTree *btree = (bNodeTree *)parent->node_ref().bnode()->id;
+    Dot::Cluster *new_cluster = &graph.new_cluster(parent->node_ref().name() + " / " +
+                                                   StringRef(btree->id.name + 2));
+    new_cluster->set_parent_cluster(parent_cluster);
+    return new_cluster;
+  });
+}
+
+std::string DerivedNodeTree::to_dot() const
+{
+  Dot::DirectedGraph digraph;
+  digraph.set_rankdir(Dot::Attr_rankdir::LeftToRight);
+
+  Map<const DNode *, Dot::NodeWithSocketsRef> dot_nodes;
+  Map<const DGroupInput *, Dot::NodeWithSocketsRef> dot_group_inputs;
+  Map<const DParentNode *, Dot::Cluster *> dot_clusters;
+
+  for (const DNode *node : m_nodes_by_id) {
+    Dot::Node &dot_node = digraph.new_node("");
+    dot_node.set_background_color("white");
+
+    Vector<std::string> input_names;
+    for (const DInputSocket *socket : node->inputs()) {
+      input_names.append(socket->name());
+    }
+    Vector<std::string> output_names;
+    for (const DOutputSocket *socket : node->outputs()) {
+      output_names.append(socket->name());
+    }
+
+    dot_nodes.add_new(node,
+                      Dot::NodeWithSocketsRef(dot_node, node->name(), input_names, output_names));
+
+    Dot::Cluster *cluster = get_cluster_for_parent(digraph, dot_clusters, node->parent());
+    dot_node.set_parent_cluster(cluster);
+  }
+
+  for (const DGroupInput *group_input : m_group_inputs) {
+    Dot::Node &dot_node = digraph.new_node("");
+    dot_node.set_background_color("white");
+
+    std::string group_input_name = group_input->name();
+    dot_group_inputs.add_new(
+        group_input, Dot::NodeWithSocketsRef(dot_node, "Group Input", {}, {group_input_name}));
+
+    Dot::Cluster *cluster = get_cluster_for_parent(digraph, dot_clusters, group_input->parent());
+    dot_node.set_parent_cluster(cluster);
+  }
+
+  for (const DNode *to_node : m_nodes_by_id) {
+    Dot::NodeWithSocketsRef &to_dot_node = dot_nodes.lookup(to_node);
+
+    for (const DInputSocket *to_socket : to_node->inputs()) {
+      for (const DOutputSocket *from_socket : to_socket->linked_sockets()) {
+        const DNode *from_node = &from_socket->node();
+        Dot::NodeWithSocketsRef &from_dot_node = dot_nodes.lookup(from_node);
+
+        digraph.new_edge(from_dot_node.output(from_socket->index()),
+                         to_dot_node.input(to_socket->index()));
+      }
+      for (const DGroupInput *group_input : to_socket->linked_group_inputs()) {
+        Dot::NodeWithSocketsRef &from_dot_node = dot_group_inputs.lookup(group_input);
+
+        digraph.new_edge(from_dot_node.output(0), to_dot_node.input(to_socket->index()));
+      }
+    }
+  }
+
+  digraph.set_random_cluster_bgcolors();
+  return digraph.to_dot_string();
+}
+
+}  // namespace BKE