/*
** performs a basic GC step
*/
void luaC_forcestep (lua_State *L) {
global_State *g = G(L);
int i;
if (isgenerational(g)) generationalcollection(L);
else incstep(L);
/* run a few finalizers (or all of them at the end of a collect cycle) */
for (i = 0; g->tobefnz && (i < GCFINALIZENUM || g->gcstate == GCSpause); i++)
GCTM(L, 1); /* call one finalizer */
}
/*
** call a few (up to 'g->gcfinnum') finalizers
*/
static int runafewfinalizers (lua_State *L) {
global_State *g = G(L);
unsigned int i;
lua_assert(!g->tobefnz || g->gcfinnum > 0);
for (i = 0; g->tobefnz && i < g->gcfinnum; i++)
GCTM(L, 1); /* call one finalizer */
g->gcfinnum = (!g->tobefnz) ? 0 /* nothing more to finalize? */
: g->gcfinnum * 2; /* else call a few more next time */
return i;
}
static l_mem singlestep(lua_State *L) {
global_State *g = G(L);
/*lua_checkmemory(L);*/
switch (g->gcstate) {
case GCSpause: {
markroot(L); /* start a new collection */
return 0;
}
case GCSpropagate: {
if (g->gray)
return propagatemark(g);
else { /* no more `gray' objects */
atomic(L); /* finish mark phase */
return 0;
}
}
case GCSsweepstring: {
lu_mem old = g->totalbytes;
sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
g->gcstate = GCSsweep; /* end sweep-string phase */
lua_assert(old >= g->totalbytes);
g->estimate -= old - g->totalbytes;
return GCSWEEPCOST;
}
case GCSsweep: {
lu_mem old = g->totalbytes;
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
if (*g->sweepgc == NULL) { /* nothing more to sweep? */
checkSizes(L);
g->gcstate = GCSfinalize; /* end sweep phase */
}
lua_assert(old >= g->totalbytes);
g->estimate -= old - g->totalbytes;
return GCSWEEPMAX * GCSWEEPCOST;
}
case GCSfinalize: {
if (g->tmudata) {
GCTM(L);
if (g->estimate > GCFINALIZECOST)
g->estimate -= GCFINALIZECOST;
return GCFINALIZECOST;
} else {
g->gcstate = GCSpause; /* end collection */
g->gcdept = 0;
return 0;
}
}
default:
lua_assert(0);
return 0;
}
}
// lua的gc状态机，执行顺序和下面的状态的从大到小开始一致
static l_mem singlestep (lua_State *L) {
global_State *g = G(L);
/*lua_checkmemory(L);*/
switch (g->gcstate) {
case GCSpause: {// 初始状态
markroot(L); /* start a new collection */// 主要就是标记主线程对象(也就是从白色染成灰色)
return 0;
}
case GCSpropagate: {// 这个状态也是一个标记过程，并且会被进入多次，也就是分布迭代
if (g->gray)// 如果gray对象一直存在的话，反复调用propagatemark函数，等所有的gray对象都被标记了，就会进入atomic函数处理
return propagatemark(g);
else { /* no more `gray' objects */
atomic(L); /* finish mark phase */// 原子操作
return 0;
}
}
case GCSsweepstring: {// 清理字符串的阶段
lu_mem old = g->totalbytes;
sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
if (g->sweepstrgc >= g->strt.size) /* nothing more to sweep? */
g->gcstate = GCSsweep; /* end sweep-string phase */
lua_assert(old >= g->totalbytes);
g->estimate -= old - g->totalbytes;
return GCSWEEPCOST;
}
case GCSsweep: {
lu_mem old = g->totalbytes;
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
if (*g->sweepgc == NULL) { /* nothing more to sweep? */
checkSizes(L);
g->gcstate = GCSfinalize; /* end sweep phase */
}
lua_assert(old >= g->totalbytes);
g->estimate -= old - g->totalbytes;
return GCSWEEPMAX*GCSWEEPCOST;
}
case GCSfinalize: {
if (g->tmudata) {
GCTM(L);
if (g->estimate > GCFINALIZECOST)
g->estimate -= GCFINALIZECOST;
return GCFINALIZECOST;
}
else {
g->gcstate = GCSpause; /* end collection */
g->gcdept = 0;
return 0;
}
}
default: lua_assert(0); return 0;
}
}
/*
** Call all GC tag methods
*/
void luaC_callGCTM (lua_State *L) {
while (G(L)->tmudata)
GCTM(L);
}
/*
** call all pending finalizers
*/
static void callallpendingfinalizers (lua_State *L, int propagateerrors) {
global_State *g = G(L);
while (g->tobefnz)
GCTM(L, propagateerrors);
}
/*
** call all pending finalizers
*/
static void callallpendingfinalizers (lua_State *L) {
global_State *g = G(L);
while (g->tobefnz)
GCTM(L, 0);
}
