Function genstep

xrepo/packages/l/lua/port/lua/src/lgc.c:1415–1440

** Does a generational "step". ** Usually, this means doing a minor collection and setting the debt to ** make another collection when memory grows 'genminormul'% larger. ** ** However, there are exceptions. If memory grows 'genmajormul'% ** larger than it was at the end of the last major collection (kept ** in 'g->GCestimate'), the function does a major collection. At the ** end, it checks wheth

** in that case, do a minor collection.
*/
static void genstep (lua_State *L, global_State *g) {
  if (g->lastatomic != 0)  /* last collection was a bad one? */
    stepgenfull(L, g);  /* do a full step */
  else {
    lu_mem majorbase = g->GCestimate;  /* memory after last major collection */
    lu_mem majorinc = (majorbase / 100) * getgcparam(g->genmajormul);
    if (g->GCdebt > 0 && gettotalbytes(g) > majorbase + majorinc) {
      lu_mem numobjs = fullgen(L, g);  /* do a major collection */
      if (gettotalbytes(g) < majorbase + (majorinc / 2)) {
        /* collected at least half of memory growth since last major
           collection; keep doing minor collections */
        setminordebt(g);
      }
      else {  /* bad collection */
        g->lastatomic = numobjs;  /* signal that last collection was bad */
        setpause(g);  /* do a long wait for next (major) collection */
      }
    }
    else {  /* regular case; do a minor collection */
      youngcollection(L, g);
      setminordebt(g);
      g->GCestimate = majorbase;  /* preserve base value */
    }
  }
  lua_assert(isdecGCmodegen(g));
}

/* }====================================================== */