Cache island topology data

Store island topology in `mjData` so repeated island solves can reuse stable connect/weld equality partitions. Add cache invalidation checks for active equality changes and cover the fast path with an island regression test. Signed-off-by: teerthsharma <teerths57@gmail.com>
2026-07-11 19:08:15 +05:30
parent 03203e2f32
commit bc32db7f25
5 changed files with 319 additions and 2 deletions
@@ -198,6 +198,11 @@ typedef struct mjData_ {
  // sleep state
  int*    tree_asleep;       // <0: awake; >=0: index cycle of sleeping trees    (ntree x 1)

+  // opaque internal island topology cache; users must not modify
+  int* island_cache_tree;    // tree and island topology                         (ntree x 28)
+  int* island_cache_dof;     // DOF topology                                     (nv x 8)
+  int* island_cache_eq;      // equality topology                                (neq x 40)
+
  // plugins
  int*       plugin;         // copy of m->plugin, required for deletion         (nplugin x 1)
  uintptr_t* plugin_data;    // pointer to plugin-managed data structure         (nplugin x 1)