static lu_mem singlestep (lua_State *L) {
global_State *g = G(L);
switch (g->gcstate) {
case GCSpause: {
g->GCmemtrav = g->strt.size * sizeof(GCObject*);
restartcollection(g);
g->gcstate = GCSpropagate;
return g->GCmemtrav;
}
case GCSpropagate: {
g->GCmemtrav = 0;
lua_assert(g->gray);
propagatemark(g);
if (g->gray == NULL) /* no more gray objects? */
g->gcstate = GCSatomic; /* finish propagate phase */
return g->GCmemtrav; /* memory traversed in this step */
}
case GCSatomic: {
lu_mem work;
int sw;
propagateall(g); /* make sure gray list is empty */
work = atomic(L); /* work is what was traversed by 'atomic' */
sw = entersweep(L);
g->GCestimate = gettotalbytes(g); /* first estimate */;
return work + sw * GCSWEEPCOST;
}
case GCSswpallgc: { /* sweep "regular" objects */
return sweepstep(L, g, GCSswpfinobj, &g->finobj);
}
case GCSswpfinobj: { /* sweep objects with finalizers */
return sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
}
case GCSswptobefnz: { /* sweep objects to be finalized */
return sweepstep(L, g, GCSswpend, NULL);
}
case GCSswpend: { /* finish sweeps */
makewhite(g, g->mainthread); /* sweep main thread */
checkSizes(L, g);
g->gcstate = GCScallfin;
return 0;
}
case GCScallfin: { /* call remaining finalizers */
if (g->tobefnz && g->gckind != KGC_EMERGENCY) {
int n = runafewfinalizers(L);
return (n * GCFINALIZECOST);
}
else { /* emergency mode or no more finalizers */
g->gcstate = GCSpause; /* finish collection */
return 0;
}
}
default:
lua_assert(0);
return 0;
}
}
/*
** performs a basic GC step when collector is running
*/
void luaC_step (lua_State *L) {
global_State *g = G(L);
l_mem debt = getdebt(g); /* GC deficit (be paid now) */
if (!g->gcrunning) { /* not running? */
luaE_setdebt(g, -GCSTEPSIZE * 10); /* avoid being called too often */
return;
}
do { /* repeat until pause or enough "credit" (negative debt) */
lu_mem work = singlestep(L); /* perform one single step */
debt -= work;
} while (debt > -GCSTEPSIZE && g->gcstate != GCSpause);
if (g->gcstate == GCSpause)
setpause(g); /* pause until next cycle */
else {
debt = (debt / g->gcstepmul) * STEPMULADJ; /* convert 'work units' to Kb */
luaE_setdebt(g, debt);
runafewfinalizers(L);
}
}