static l_mem singlestep (lua_State *L) {
global_State *g = G(L);
switch (g->gcstate) {
case GCSpause: {
if (!isgenerational(g))
markroot(g); /* start a new collection */
/* in any case, root must be marked */
lua_assert(!iswhite(obj2gco(g->mainthread))
&& !iswhite(gcvalue(&g->l_registry)));
g->gcstate = GCSpropagate;
return GCROOTCOST;
}
case GCSpropagate: {
if (g->gray)
return propagatemark(g);
else { /* no more `gray' objects */
g->gcstate = GCSatomic; /* finish mark phase */
atomic(L);
return GCATOMICCOST;
}
}
case GCSsweepstring: {
if (g->sweepstrgc < g->strt.size) {
sweepwholelist(L, &g->strt.hash[g->sweepstrgc++]);
return GCSWEEPCOST;
}
else { /* no more strings to sweep */
g->sweepgc = &g->finobj; /* prepare to sweep finalizable objects */
g->gcstate = GCSsweepudata;
return 0;
}
}
case GCSsweepudata: {
if (*g->sweepgc) {
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
return GCSWEEPMAX*GCSWEEPCOST;
}
else {
g->sweepgc = &g->allgc; /* go to next phase */
g->gcstate = GCSsweep;
return GCSWEEPCOST;
}
}
case GCSsweep: {
if (*g->sweepgc) {
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
return GCSWEEPMAX*GCSWEEPCOST;
}
else {
/* sweep main thread */
GCObject *mt = obj2gco(g->mainthread);
sweeplist(L, &mt, 1);
checkSizes(L);
g->gcstate = GCSpause; /* finish collection */
return GCSWEEPCOST;
}
}
default: lua_assert(0); return 0;
}
}
static size_t mark (lua_State *L) {
size_t deadmem;
GCState st;
GCObject *wkv;
st.L = L;
st.g = G(L);
st.tmark = NULL;
st.wkv = st.wk = st.wv = NULL;
markroot(&st, L);
propagatemarks(&st); /* mark all reachable objects */
cleartablevalues(L, st.wkv);
cleartablevalues(L, st.wv);
wkv = st.wkv; /* keys must be cleared after preserving udata */
st.wkv = NULL;
st.wv = NULL;
deadmem = luaC_separateudata(L); /* separate userdata to be preserved */
marktmu(&st); /* mark `preserved' userdata */
propagatemarks(&st); /* remark, to propagate `preserveness' */
cleartablekeys(L, wkv);
/* `propagatemarks' may resuscitate some weak tables; clear them too */
cleartablekeys(L, st.wk);
cleartablevalues(L, st.wv);
cleartablekeys(L, st.wkv);
cleartablevalues(L, st.wkv);
return deadmem;
}
void luaC_fullgc (lua_State *L) {
global_State *g = G(L);
if(is_block_gc(L)) return;
set_block_gc(L);
if (g->gcstate <= GCSpropagate) {
/* reset sweep marks to sweep all elements (returning them to white) */
g->sweepstrgc = 0;
g->sweepgc = &g->rootgc;
/* reset other collector lists */
g->gray = NULL;
g->grayagain = NULL;
g->weak = NULL;
g->gcstate = GCSsweepstring;
}
lua_assert(g->gcstate != GCSpause && g->gcstate != GCSpropagate);
/* finish any pending sweep phase */
while (g->gcstate != GCSfinalize) {
lua_assert(g->gcstate == GCSsweepstring || g->gcstate == GCSsweep);
singlestep(L);
}
markroot(L);
while (g->gcstate != GCSpause) {
singlestep(L);
}
setthreshold(g);
unset_block_gc(L);
}
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;
}
}
static lu_mem singlestep (lua_State *L) {
global_State *g = G(L);
switch (g->gcstate) {
case GCSpause: {
g->GCmemtrav = 0; /* start to count memory traversed */
if (!isgenerational(g))
markroot(g); /* start a new collection */
/* in any case, root must be marked at this point */
lua_assert(!iswhite(obj2gco(g->mainthread))
&& !iswhite(gcvalue(&g->l_registry)));
g->gcstate = GCSpropagate;
return g->GCmemtrav;
}
case GCSpropagate: {
if (g->gray) {
lu_mem oldtrav = g->GCmemtrav;
propagatemark(g);
return g->GCmemtrav - oldtrav; /* memory traversed in this step */
}
else { /* no more `gray' objects */
lu_mem work;
int sw;
g->gcstate = GCSatomic; /* finish mark phase */
g->GCestimate = g->GCmemtrav; /* save what was counted */;
work = atomic(L); /* add what was traversed by 'atomic' */
g->GCestimate += work; /* estimate of total memory traversed */
sw = entersweep(L);
return work + sw * GCSWEEPCOST;
}
}
case GCSsweepstring: {
int i;
for (i = 0; i < GCSWEEPMAX && g->sweepstrgc + i < g->strt.size; i++)
sweepwholelist(L, &g->strt.hash[g->sweepstrgc + i]);
g->sweepstrgc += i;
if (g->sweepstrgc >= g->strt.size) /* no more strings to sweep? */
g->gcstate = GCSsweepudata;
return i * GCSWEEPCOST;
}
case GCSsweepudata: {
if (g->sweepfin) {
g->sweepfin = sweeplist(L, g->sweepfin, GCSWEEPMAX);
return GCSWEEPMAX*GCSWEEPCOST;
}
else {
g->gcstate = GCSsweep;
return 0;
}
}
case GCSsweep: {
if (g->sweepgc) {
g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
return GCSWEEPMAX*GCSWEEPCOST;
}
else {
/* sweep main thread */
GCObject *mt = obj2gco(g->mainthread);
sweeplist(L, &mt, 1);
checkSizes(L);
g->gcstate = GCSpause; /* finish collection */
return GCSWEEPCOST;
}
}
default: lua_assert(0); return 0;
}
}