Fix T64247: Crash on playback with special shader node tree

The root of the problem goes to the fact that node tree copying
uses source tree and nodes for a temporary storage.

This makes it so multiple dependency graphs can not be reliably
evaluated from different threads if they are using same original
node tree.

Solved by doing the following:

- Commonly used tree copying function (which is used by library
  manager) keeps source tree, nodes and sockets untouched.

- All the related areas (like node tree's callback) now have
  const qualifier on the input.

- Areas which needs to have those temporary pointers assigned are
  now using explicit function.

  Would be really cool to get rid of those temporary pointers
  completely, but this is a bit tricky due to hairy nature of the
  code. Can happen any time now though: is easy enough to generalize
  the new pointers mapping.

Note that this change is only intended to solve the crash.
The fact that icons shouldn't be updated on playback will be fixed
as a separate change.

Reviewers: brecht, fclem

Reviewed By: brecht, fclem

Subscribers: brecht, fclem

Differential Revision: https://developer.blender.org/D5002

10 files changed, 58 insertions, 35 deletions

diff --git a/source/blender/nodes/composite/node_composite_tree.c b/source/blender/nodes/composite/node_composite_tree.c
index 43a70a62350..89349d91f94 100644
--- a/source/blender/nodes/composite/node_composite_tree.c
+++ b/source/blender/nodes/composite/node_composite_tree.c
@@ -95,15 +95,17 @@ static void free_cache(bNodeTree *ntree)
 }
 
 /* local tree then owns all compbufs */
-static void localize(bNodeTree *UNUSED(localtree), bNodeTree *ntree)
+static void localize(bNodeTree *localtree, bNodeTree *ntree)
 {
-  bNode *node;
-  bNodeSocket *sock;
 
-  for (node = ntree->nodes.first; node; node = node->next) {
+  bNode *node = ntree->nodes.first;
+  bNode *local_node = localtree->nodes.first;
+  while (node != NULL) {
+    local_node->original = node;
+
     /* ensure new user input gets handled ok */
     node->need_exec = 0;
-    node->new_node->original = node;
+    local_node->original = node;
 
     /* move over the compbufs */
     /* right after ntreeCopyTree() oldsock pointers are valid */
@@ -111,19 +113,29 @@ static void localize(bNodeTree *UNUSED(localtree), bNodeTree *ntree)
     if (ELEM(node->type, CMP_NODE_VIEWER, CMP_NODE_SPLITVIEWER)) {
       if (node->id) {
         if (node->flag & NODE_DO_OUTPUT) {
-          node->new_node->id = (ID *)node->id;
+          local_node->id = (ID *)node->id;
         }
         else {
-          node->new_node->id = NULL;
+          local_node->id = NULL;
         }
       }
     }
 
-    for (sock = node->outputs.first; sock; sock = sock->next) {
-      sock->new_sock->cache = sock->cache;
-      sock->cache = NULL;
-      sock->new_sock->new_sock = sock;
+    bNodeSocket *output_sock = node->outputs.first;
+    bNodeSocket *local_output_sock = local_node->outputs.first;
+    while (output_sock != NULL) {
+      local_output_sock->cache = output_sock->cache;
+      output_sock->cache = NULL;
+      /* This is actually link to original: someone was just lazy enough and tried to save few
+       * bytes in the cost of readability. */
+      local_output_sock->new_sock = output_sock;
+
+      output_sock = output_sock->next;
+      local_output_sock = local_output_sock->next;
     }
+
+    node = node->next;
+    local_node = local_node->next;
   }
 }
 
diff --git a/source/blender/nodes/composite/nodes/node_composite_cryptomatte.c b/source/blender/nodes/composite/nodes/node_composite_cryptomatte.c
index 68a7e8d1589..8d05c18621f 100644
--- a/source/blender/nodes/composite/nodes/node_composite_cryptomatte.c
+++ b/source/blender/nodes/composite/nodes/node_composite_cryptomatte.c
@@ -273,7 +273,9 @@ static void node_free_cryptomatte(bNode *node)
   }
 }
 
-static void node_copy_cryptomatte(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, bNode *src_node)
+static void node_copy_cryptomatte(bNodeTree *UNUSED(dest_ntree),
+                                  bNode *dest_node,
+                                  const bNode *src_node)
 {
   NodeCryptomatte *src_nc = src_node->storage;
   NodeCryptomatte *dest_nc = MEM_dupallocN(src_nc);
diff --git a/source/blender/nodes/composite/nodes/node_composite_image.c b/source/blender/nodes/composite/nodes/node_composite_image.c
index e1e23b843a1..79db436ec4e 100644
--- a/source/blender/nodes/composite/nodes/node_composite_image.c
+++ b/source/blender/nodes/composite/nodes/node_composite_image.c
@@ -432,15 +432,17 @@ static void node_composit_free_image(bNode *node)
 
 static void node_composit_copy_image(bNodeTree *UNUSED(dest_ntree),
                                      bNode *dest_node,
-                                     bNode *src_node)
+                                     const bNode *src_node)
 {
-  bNodeSocket *sock;
-
   dest_node->storage = MEM_dupallocN(src_node->storage);
 
-  /* copy extra socket info */
-  for (sock = src_node->outputs.first; sock; sock = sock->next) {
-    sock->new_sock->storage = MEM_dupallocN(sock->storage);
+  const bNodeSocket *src_output_sock = src_node->outputs.first;
+  bNodeSocket *dest_output_sock = dest_node->outputs.first;
+  while (dest_output_sock != NULL) {
+    dest_output_sock->storage = MEM_dupallocN(src_output_sock->storage);
+
+    src_output_sock = src_output_sock->next;
+    dest_output_sock = dest_output_sock->next;
   }
 }
 
@@ -556,16 +558,17 @@ static void node_composit_free_rlayers(bNode *node)
 }
 
 static void node_composit_copy_rlayers(bNodeTree *UNUSED(dest_ntree),
-                                       bNode *UNUSED(dest_node),
-                                       bNode *src_node)
+                                       bNode *dest_node,
+                                       const bNode *src_node)
 {
-  bNodeSocket *sock;
-
   /* copy extra socket info */
-  for (sock = src_node->outputs.first; sock; sock = sock->next) {
-    if (sock->storage) {
-      sock->new_sock->storage = MEM_dupallocN(sock->storage);
-    }
+  const bNodeSocket *src_output_sock = src_node->outputs.first;
+  bNodeSocket *dest_output_sock = dest_node->outputs.first;
+  while (dest_output_sock != NULL) {
+    dest_output_sock->storage = MEM_dupallocN(src_output_sock->storage);
+
+    src_output_sock = src_output_sock->next;
+    dest_output_sock = dest_output_sock->next;
   }
 }
 
diff --git a/source/blender/nodes/composite/nodes/node_composite_moviedistortion.c b/source/blender/nodes/composite/nodes/node_composite_moviedistortion.c
index d4462d937ad..dbdd65c5976 100644
--- a/source/blender/nodes/composite/nodes/node_composite_moviedistortion.c
+++ b/source/blender/nodes/composite/nodes/node_composite_moviedistortion.c
@@ -64,7 +64,7 @@ static void storage_free(bNode *node)
   node->storage = NULL;
 }
 
-static void storage_copy(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, bNode *src_node)
+static void storage_copy(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, const bNode *src_node)
 {
   if (src_node->storage) {
     dest_node->storage = BKE_tracking_distortion_copy(src_node->storage);
diff --git a/source/blender/nodes/composite/nodes/node_composite_outputFile.c b/source/blender/nodes/composite/nodes/node_composite_outputFile.c
index c700aee1bc1..faf9e20da51 100644
--- a/source/blender/nodes/composite/nodes/node_composite_outputFile.c
+++ b/source/blender/nodes/composite/nodes/node_composite_outputFile.c
@@ -228,7 +228,9 @@ static void free_output_file(bNode *node)
   MEM_freeN(node->storage);
 }
 
-static void copy_output_file(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, bNode *src_node)
+static void copy_output_file(bNodeTree *UNUSED(dest_ntree),
+                             bNode *dest_node,
+                             const bNode *src_node)
 {
   bNodeSocket *src_sock, *dest_sock;
 
diff --git a/source/blender/nodes/intern/node_util.c b/source/blender/nodes/intern/node_util.c
index 6ad1c9b6925..2ab68e2f7cf 100644
--- a/source/blender/nodes/intern/node_util.c
+++ b/source/blender/nodes/intern/node_util.c
@@ -57,12 +57,14 @@ void node_free_standard_storage(bNode *node)
   }
 }
 
-void node_copy_curves(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, bNode *src_node)
+void node_copy_curves(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, const bNode *src_node)
 {
   dest_node->storage = curvemapping_copy(src_node->storage);
 }
 
-void node_copy_standard_storage(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, bNode *src_node)
+void node_copy_standard_storage(bNodeTree *UNUSED(dest_ntree),
+                                bNode *dest_node,
+                                const bNode *src_node)
 {
   dest_node->storage = MEM_dupallocN(src_node->storage);
 }
diff --git a/source/blender/nodes/intern/node_util.h b/source/blender/nodes/intern/node_util.h
index ec5cd074922..7eef70db498 100644
--- a/source/blender/nodes/intern/node_util.h
+++ b/source/blender/nodes/intern/node_util.h
@@ -58,10 +58,10 @@ extern void node_free_standard_storage(struct bNode *node);
 
 extern void node_copy_curves(struct bNodeTree *dest_ntree,
                              struct bNode *dest_node,
-                             struct bNode *src_node);
+                             const struct bNode *src_node);
 extern void node_copy_standard_storage(struct bNodeTree *dest_ntree,
                                        struct bNode *dest_node,
-                                       struct bNode *src_node);
+                                       const struct bNode *src_node);
 extern void *node_initexec_curves(struct bNodeExecContext *context,
                                   struct bNode *node,
                                   bNodeInstanceKey key);
diff --git a/source/blender/nodes/shader/nodes/node_shader_script.c b/source/blender/nodes/shader/nodes/node_shader_script.c
index 29d3fd3ba67..42ab272de0e 100644
--- a/source/blender/nodes/shader/nodes/node_shader_script.c
+++ b/source/blender/nodes/shader/nodes/node_shader_script.c
@@ -44,7 +44,9 @@ static void node_free_script(bNode *node)
   }
 }
 
-static void node_copy_script(bNodeTree *UNUSED(dest_ntree), bNode *dest_node, bNode *src_node)
+static void node_copy_script(bNodeTree *UNUSED(dest_ntree),
+                             bNode *dest_node,
+                             const bNode *src_node)
 {
   NodeShaderScript *src_nss = src_node->storage;
   NodeShaderScript *dest_nss = MEM_dupallocN(src_nss);
diff --git a/source/blender/nodes/shader/nodes/node_shader_tex_pointdensity.c b/source/blender/nodes/shader/nodes/node_shader_tex_pointdensity.c
index 561f39716b9..dbf79ec1f1d 100644
--- a/source/blender/nodes/shader/nodes/node_shader_tex_pointdensity.c
+++ b/source/blender/nodes/shader/nodes/node_shader_tex_pointdensity.c
@@ -57,7 +57,7 @@ static void node_shader_free_tex_pointdensity(bNode *node)
 
 static void node_shader_copy_tex_pointdensity(bNodeTree *UNUSED(dest_ntree),
                                               bNode *dest_node,
-                                              bNode *src_node)
+                                              const bNode *src_node)
 {
   dest_node->storage = MEM_dupallocN(src_node->storage);
   NodeShaderTexPointDensity *point_density = dest_node->storage;
diff --git a/source/blender/nodes/texture/nodes/node_texture_output.c b/source/blender/nodes/texture/nodes/node_texture_output.c
index f9f91e65912..cdacb05153d 100644
--- a/source/blender/nodes/texture/nodes/node_texture_output.c
+++ b/source/blender/nodes/texture/nodes/node_texture_output.c
@@ -154,7 +154,7 @@ static void init(bNodeTree *UNUSED(ntree), bNode *node)
   assign_index(node);
 }
 
-static void copy(bNodeTree *dest_ntree, bNode *dest_node, bNode *src_node)
+static void copy(bNodeTree *dest_ntree, bNode *dest_node, const bNode *src_node)
 {
   node_copy_standard_storage(dest_ntree, dest_node, src_node);
   unique_name(dest_node);