diff options
Diffstat (limited to 'libs/liblua/src/lgc.c')
| -rw-r--r-- | libs/liblua/src/lgc.c | 424 |
1 files changed, 259 insertions, 165 deletions
diff --git a/libs/liblua/src/lgc.c b/libs/liblua/src/lgc.c index f26c921a96..4a7bcaed37 100644 --- a/libs/liblua/src/lgc.c +++ b/libs/liblua/src/lgc.c @@ -60,16 +60,24 @@ #define PAUSEADJ 100 -/* mask to erase all color bits (plus gen. related stuff) */ -#define maskcolors (~(bitmask(BLACKBIT) | WHITEBITS | AGEBITS)) +/* mask with all color bits */ +#define maskcolors (bitmask(BLACKBIT) | WHITEBITS) +/* mask with all GC bits */ +#define maskgcbits (maskcolors | AGEBITS) -/* macro to erase all color bits then sets only the current white bit */ + +/* macro to erase all color bits then set only the current white bit */ #define makewhite(g,x) \ - (x->marked = cast_byte((x->marked & maskcolors) | luaC_white(g))) + (x->marked = cast_byte((x->marked & ~maskcolors) | luaC_white(g))) + +/* make an object gray (neither white nor black) */ +#define set2gray(x) resetbits(x->marked, maskcolors) -#define white2gray(x) resetbits(x->marked, WHITEBITS) -#define black2gray(x) resetbit(x->marked, BLACKBIT) + +/* make an object black (coming from any color) */ +#define set2black(x) \ + (x->marked = cast_byte((x->marked & ~WHITEBITS) | bitmask(BLACKBIT))) #define valiswhite(x) (iscollectable(x) && iswhite(gcvalue(x))) @@ -77,16 +85,13 @@ #define keyiswhite(n) (keyiscollectable(n) && iswhite(gckey(n))) -#define checkconsistency(obj) \ - lua_longassert(!iscollectable(obj) || righttt(obj)) - /* ** Protected access to objects in values */ #define gcvalueN(o) (iscollectable(o) ? gcvalue(o) : NULL) -#define markvalue(g,o) { checkconsistency(o); \ +#define markvalue(g,o) { checkliveness(g->mainthread,o); \ if (valiswhite(o)) reallymarkobject(g,gcvalue(o)); } #define markkey(g, n) { if keyiswhite(n) reallymarkobject(g,gckey(n)); } @@ -135,15 +140,23 @@ static GCObject **getgclist (GCObject *o) { /* -** Link a collectable object 'o' with a known type into list pointed by 'p'. +** Link a collectable object 'o' with a known type into the list 'p'. +** (Must be a macro to access the 'gclist' field in different types.) */ -#define linkgclist(o,p) ((o)->gclist = (p), (p) = obj2gco(o)) +#define linkgclist(o,p) linkgclist_(obj2gco(o), &(o)->gclist, &(p)) + +static void linkgclist_ (GCObject *o, GCObject **pnext, GCObject **list) { + lua_assert(!isgray(o)); /* cannot be in a gray list */ + *pnext = *list; + *list = o; + set2gray(o); /* now it is */ +} /* -** Link a generic collectable object 'o' into list pointed by 'p'. +** Link a generic collectable object 'o' into the list 'p'. */ -#define linkobjgclist(o,p) (*getgclist(o) = (p), (p) = obj2gco(o)) +#define linkobjgclist(o,p) linkgclist_(obj2gco(o), getgclist(o), &(p)) @@ -181,14 +194,17 @@ static int iscleared (global_State *g, const GCObject *o) { /* -** barrier that moves collector forward, that is, mark the white object -** 'v' being pointed by the black object 'o'. (If in sweep phase, clear -** the black object to white [sweep it] to avoid other barrier calls for -** this same object.) In the generational mode, 'v' must also become -** old, if 'o' is old; however, it cannot be changed directly to OLD, -** because it may still point to non-old objects. So, it is marked as -** OLD0. In the next cycle it will become OLD1, and in the next it -** will finally become OLD (regular old). +** Barrier that moves collector forward, that is, marks the white object +** 'v' being pointed by the black object 'o'. In the generational +** mode, 'v' must also become old, if 'o' is old; however, it cannot +** be changed directly to OLD, because it may still point to non-old +** objects. So, it is marked as OLD0. In the next cycle it will become +** OLD1, and in the next it will finally become OLD (regular old). By +** then, any object it points to will also be old. If called in the +** incremental sweep phase, it clears the black object to white (sweep +** it) to avoid other barrier calls for this same object. (That cannot +** be done is generational mode, as its sweep does not distinguish +** whites from deads.) */ void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) { global_State *g = G(L); @@ -202,7 +218,8 @@ void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) { } else { /* sweep phase */ lua_assert(issweepphase(g)); - makewhite(g, o); /* mark main obj. as white to avoid other barriers */ + if (g->gckind == KGC_INC) /* incremental mode? */ + makewhite(g, o); /* mark 'o' as white to avoid other barriers */ } } @@ -214,18 +231,20 @@ void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) { void luaC_barrierback_ (lua_State *L, GCObject *o) { global_State *g = G(L); lua_assert(isblack(o) && !isdead(g, o)); - lua_assert(g->gckind != KGC_GEN || (isold(o) && getage(o) != G_TOUCHED1)); - if (getage(o) != G_TOUCHED2) /* not already in gray list? */ - linkobjgclist(o, g->grayagain); /* link it in 'grayagain' */ - black2gray(o); /* make object gray (again) */ - setage(o, G_TOUCHED1); /* touched in current cycle */ + lua_assert((g->gckind == KGC_GEN) == (isold(o) && getage(o) != G_TOUCHED1)); + if (getage(o) == G_TOUCHED2) /* already in gray list? */ + set2gray(o); /* make it gray to become touched1 */ + else /* link it in 'grayagain' and paint it gray */ + linkobjgclist(o, g->grayagain); + if (isold(o)) /* generational mode? */ + setage(o, G_TOUCHED1); /* touched in current cycle */ } void luaC_fix (lua_State *L, GCObject *o) { global_State *g = G(L); lua_assert(g->allgc == o); /* object must be 1st in 'allgc' list! */ - white2gray(o); /* they will be gray forever */ + set2gray(o); /* they will be gray forever */ setage(o, G_OLD); /* and old forever */ g->allgc = o->next; /* remove object from 'allgc' list */ o->next = g->fixedgc; /* link it to 'fixedgc' list */ @@ -259,24 +278,30 @@ GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) { /* -** Mark an object. Userdata, strings, and closed upvalues are visited -** and turned black here. Other objects are marked gray and added -** to appropriate list to be visited (and turned black) later. (Open -** upvalues are already linked in 'headuv' list. They are kept gray -** to avoid barriers, as their values will be revisited by the thread.) +** Mark an object. Userdata with no user values, strings, and closed +** upvalues are visited and turned black here. Open upvalues are +** already indirectly linked through their respective threads in the +** 'twups' list, so they don't go to the gray list; nevertheless, they +** are kept gray to avoid barriers, as their values will be revisited +** by the thread or by 'remarkupvals'. Other objects are added to the +** gray list to be visited (and turned black) later. Both userdata and +** upvalues can call this function recursively, but this recursion goes +** for at most two levels: An upvalue cannot refer to another upvalue +** (only closures can), and a userdata's metatable must be a table. */ static void reallymarkobject (global_State *g, GCObject *o) { - white2gray(o); switch (o->tt) { case LUA_VSHRSTR: case LUA_VLNGSTR: { - gray2black(o); + set2black(o); /* nothing to visit */ break; } case LUA_VUPVAL: { UpVal *uv = gco2upv(o); - if (!upisopen(uv)) /* open upvalues are kept gray */ - gray2black(o); + if (upisopen(uv)) + set2gray(uv); /* open upvalues are kept gray */ + else + set2black(o); /* closed upvalues are visited here */ markvalue(g, uv->v); /* mark its content */ break; } @@ -284,14 +309,14 @@ static void reallymarkobject (global_State *g, GCObject *o) { Udata *u = gco2u(o); if (u->nuvalue == 0) { /* no user values? */ markobjectN(g, u->metatable); /* mark its metatable */ - gray2black(o); /* nothing else to mark */ + set2black(o); /* nothing else to mark */ break; } /* else... */ } /* FALLTHROUGH */ case LUA_VLCL: case LUA_VCCL: case LUA_VTABLE: case LUA_VTHREAD: case LUA_VPROTO: { - linkobjgclist(o, g->gray); + linkobjgclist(o, g->gray); /* to be visited later */ break; } default: lua_assert(0); break; @@ -324,28 +349,36 @@ static lu_mem markbeingfnz (global_State *g) { /* -** Mark all values stored in marked open upvalues from non-marked threads. -** (Values from marked threads were already marked when traversing the -** thread.) Remove from the list threads that no longer have upvalues and -** not-marked threads. +** For each non-marked thread, simulates a barrier between each open +** upvalue and its value. (If the thread is collected, the value will be +** assigned to the upvalue, but then it can be too late for the barrier +** to act. The "barrier" does not need to check colors: A non-marked +** thread must be young; upvalues cannot be older than their threads; so +** any visited upvalue must be young too.) Also removes the thread from +** the list, as it was already visited. Removes also threads with no +** upvalues, as they have nothing to be checked. (If the thread gets an +** upvalue later, it will be linked in the list again.) */ static int remarkupvals (global_State *g) { lua_State *thread; lua_State **p = &g->twups; - int work = 0; + int work = 0; /* estimate of how much work was done here */ while ((thread = *p) != NULL) { work++; - lua_assert(!isblack(thread)); /* threads are never black */ - if (isgray(thread) && thread->openupval != NULL) + if (!iswhite(thread) && thread->openupval != NULL) p = &thread->twups; /* keep marked thread with upvalues in the list */ else { /* thread is not marked or without upvalues */ UpVal *uv; + lua_assert(!isold(thread) || thread->openupval == NULL); *p = thread->twups; /* remove thread from the list */ thread->twups = thread; /* mark that it is out of list */ for (uv = thread->openupval; uv != NULL; uv = uv->u.open.next) { + lua_assert(getage(uv) <= getage(thread)); work++; - if (!iswhite(uv)) /* upvalue already visited? */ + if (!iswhite(uv)) { /* upvalue already visited? */ + lua_assert(upisopen(uv) && isgray(uv)); markvalue(g, uv->v); /* mark its value */ + } } } } @@ -353,12 +386,17 @@ static int remarkupvals (global_State *g) { } +static void cleargraylists (global_State *g) { + g->gray = g->grayagain = NULL; + g->weak = g->allweak = g->ephemeron = NULL; +} + + /* ** mark root set and reset all gray lists, to start a new collection */ static void restartcollection (global_State *g) { - g->gray = g->grayagain = NULL; - g->weak = g->allweak = g->ephemeron = NULL; + cleargraylists(g); markobject(g, g->mainthread); markvalue(g, &g->l_registry); markmt(g); @@ -374,6 +412,26 @@ static void restartcollection (global_State *g) { ** ======================================================= */ + +/* +** Check whether object 'o' should be kept in the 'grayagain' list for +** post-processing by 'correctgraylist'. (It could put all old objects +** in the list and leave all the work to 'correctgraylist', but it is +** more efficient to avoid adding elements that will be removed.) Only +** TOUCHED1 objects need to be in the list. TOUCHED2 doesn't need to go +** back to a gray list, but then it must become OLD. (That is what +** 'correctgraylist' does when it finds a TOUCHED2 object.) +*/ +static void genlink (global_State *g, GCObject *o) { + lua_assert(isblack(o)); + if (getage(o) == G_TOUCHED1) { /* touched in this cycle? */ + linkobjgclist(o, g->grayagain); /* link it back in 'grayagain' */ + } /* everything else do not need to be linked back */ + else if (getage(o) == G_TOUCHED2) + changeage(o, G_TOUCHED2, G_OLD); /* advance age */ +} + + /* ** Traverse a table with weak values and link it to proper list. During ** propagate phase, keep it in 'grayagain' list, to be revisited in the @@ -410,8 +468,9 @@ static void traverseweakvalue (global_State *g, Table *h) { ** the atomic phase, if table has any white->white entry, it has to ** be revisited during ephemeron convergence (as that key may turn ** black). Otherwise, if it has any white key, table has to be cleared -** (in the atomic phase). In generational mode, it (like all visited -** tables) must be kept in some gray list for post-processing. +** (in the atomic phase). In generational mode, some tables +** must be kept in some gray list for post-processing; this is done +** by 'genlink'. */ static int traverseephemeron (global_State *g, Table *h, int inv) { int marked = 0; /* true if an object is marked in this traversal */ @@ -450,10 +509,8 @@ static int traverseephemeron (global_State *g, Table *h, int inv) { linkgclist(h, g->ephemeron); /* have to propagate again */ else if (hasclears) /* table has white keys? */ linkgclist(h, g->allweak); /* may have to clean white keys */ - else if (g->gckind == KGC_GEN) - linkgclist(h, g->grayagain); /* keep it in some list */ else - gray2black(h); + genlink(g, obj2gco(h)); /* check whether collector still needs to see it */ return marked; } @@ -473,10 +530,7 @@ static void traversestrongtable (global_State *g, Table *h) { markvalue(g, gval(n)); } } - if (g->gckind == KGC_GEN) { - linkgclist(h, g->grayagain); /* keep it in some gray list */ - black2gray(h); - } + genlink(g, obj2gco(h)); } @@ -488,7 +542,6 @@ static lu_mem traversetable (global_State *g, Table *h) { (cast_void(weakkey = strchr(svalue(mode), 'k')), cast_void(weakvalue = strchr(svalue(mode), 'v')), (weakkey || weakvalue))) { /* is really weak? */ - black2gray(h); /* keep table gray */ if (!weakkey) /* strong keys? */ traverseweakvalue(g, h); else if (!weakvalue) /* strong values? */ @@ -507,10 +560,7 @@ static int traverseudata (global_State *g, Udata *u) { markobjectN(g, u->metatable); /* mark its metatable */ for (i = 0; i < u->nuvalue; i++) markvalue(g, &u->uv[i].uv); - if (g->gckind == KGC_GEN) { - linkgclist(u, g->grayagain); /* keep it in some gray list */ - black2gray(u); - } + genlink(g, obj2gco(u)); return 1 + u->nuvalue; } @@ -559,12 +609,21 @@ static int traverseLclosure (global_State *g, LClosure *cl) { /* ** Traverse a thread, marking the elements in the stack up to its top -** and cleaning the rest of the stack in the final traversal. -** That ensures that the entire stack have valid (non-dead) objects. +** and cleaning the rest of the stack in the final traversal. That +** ensures that the entire stack have valid (non-dead) objects. +** Threads have no barriers. In gen. mode, old threads must be visited +** at every cycle, because they might point to young objects. In inc. +** mode, the thread can still be modified before the end of the cycle, +** and therefore it must be visited again in the atomic phase. To ensure +** these visits, threads must return to a gray list if they are not new +** (which can only happen in generational mode) or if the traverse is in +** the propagate phase (which can only happen in incremental mode). */ static int traversethread (global_State *g, lua_State *th) { UpVal *uv; StkId o = th->stack; + if (isold(th) || g->gcstate == GCSpropagate) + linkgclist(th, g->grayagain); /* insert into 'grayagain' list */ if (o == NULL) return 1; /* stack not completely built yet */ lua_assert(g->gcstate == GCSatomic || @@ -590,12 +649,11 @@ static int traversethread (global_State *g, lua_State *th) { /* -** traverse one gray object, turning it to black (except for threads, -** which are always gray). +** traverse one gray object, turning it to black. */ static lu_mem propagatemark (global_State *g) { GCObject *o = g->gray; - gray2black(o); + nw2black(o); g->gray = *getgclist(o); /* remove from 'gray' list */ switch (o->tt) { case LUA_VTABLE: return traversetable(g, gco2t(o)); @@ -603,12 +661,7 @@ static lu_mem propagatemark (global_State *g) { case LUA_VLCL: return traverseLclosure(g, gco2lcl(o)); case LUA_VCCL: return traverseCclosure(g, gco2ccl(o)); case LUA_VPROTO: return traverseproto(g, gco2p(o)); - case LUA_VTHREAD: { - lua_State *th = gco2th(o); - linkgclist(th, g->grayagain); /* insert into 'grayagain' list */ - black2gray(o); - return traversethread(g, th); - } + case LUA_VTHREAD: return traversethread(g, gco2th(o)); default: lua_assert(0); return 0; } } @@ -638,8 +691,10 @@ static void convergeephemerons (global_State *g) { g->ephemeron = NULL; /* tables may return to this list when traversed */ changed = 0; while ((w = next) != NULL) { /* for each ephemeron table */ - next = gco2t(w)->gclist; /* list is rebuilt during loop */ - if (traverseephemeron(g, gco2t(w), dir)) { /* marked some value? */ + Table *h = gco2t(w); + next = h->gclist; /* list is rebuilt during loop */ + nw2black(h); /* out of the list (for now) */ + if (traverseephemeron(g, h, dir)) { /* marked some value? */ propagateall(g); /* propagate changes */ changed = 1; /* will have to revisit all ephemeron tables */ } @@ -766,7 +821,7 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, int countin, freeobj(L, curr); /* erase 'curr' */ } else { /* change mark to 'white' */ - curr->marked = cast_byte((marked & maskcolors) | white); + curr->marked = cast_byte((marked & ~maskgcbits) | white); p = &curr->next; /* go to next element */ } } @@ -823,6 +878,8 @@ static GCObject *udata2finalize (global_State *g) { resetbit(o->marked, FINALIZEDBIT); /* object is "normal" again */ if (issweepphase(g)) makewhite(g, o); /* "sweep" object */ + else if (getage(o) == G_OLD1) + g->firstold1 = o; /* it is the first OLD1 object in the list */ return o; } @@ -896,15 +953,15 @@ static GCObject **findlast (GCObject **p) { /* ** Move all unreachable objects (or 'all' objects) that need ** finalization from list 'finobj' to list 'tobefnz' (to be finalized). -** (Note that objects after 'finobjold' cannot be white, so they -** don't need to be traversed. In incremental mode, 'finobjold' is NULL, +** (Note that objects after 'finobjold1' cannot be white, so they +** don't need to be traversed. In incremental mode, 'finobjold1' is NULL, ** so the whole list is traversed.) */ static void separatetobefnz (global_State *g, int all) { GCObject *curr; GCObject **p = &g->finobj; GCObject **lastnext = findlast(&g->tobefnz); - while ((curr = *p) != g->finobjold) { /* traverse all finalizable objects */ + while ((curr = *p) != g->finobjold1) { /* traverse all finalizable objects */ lua_assert(tofinalize(curr)); if (!(iswhite(curr) || all)) /* not being collected? */ p = &curr->next; /* don't bother with it */ @@ -921,6 +978,27 @@ static void separatetobefnz (global_State *g, int all) { /* +** If pointer 'p' points to 'o', move it to the next element. +*/ +static void checkpointer (GCObject **p, GCObject *o) { + if (o == *p) + *p = o->next; +} + + +/* +** Correct pointers to objects inside 'allgc' list when +** object 'o' is being removed from the list. +*/ +static void correctpointers (global_State *g, GCObject *o) { + checkpointer(&g->survival, o); + checkpointer(&g->old1, o); + checkpointer(&g->reallyold, o); + checkpointer(&g->firstold1, o); +} + + +/* ** if object 'o' has a finalizer, remove it from 'allgc' list (must ** search the list to find it) and link it in 'finobj' list. */ @@ -936,14 +1014,8 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { if (g->sweepgc == &o->next) /* should not remove 'sweepgc' object */ g->sweepgc = sweeptolive(L, g->sweepgc); /* change 'sweepgc' */ } - else { /* correct pointers into 'allgc' list, if needed */ - if (o == g->survival) - g->survival = o->next; - if (o == g->old) - g->old = o->next; - if (o == g->reallyold) - g->reallyold = o->next; - } + else + correctpointers(g, o); /* search for pointer pointing to 'o' */ for (p = &g->allgc; *p != o; p = &(*p)->next) { /* empty */ } *p = o->next; /* remove 'o' from 'allgc' list */ @@ -965,24 +1037,31 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { static void setpause (global_State *g); -/* mask to erase all color bits, not changing gen-related stuff */ -#define maskgencolors (~(bitmask(BLACKBIT) | WHITEBITS)) - - /* -** Sweep a list of objects, deleting dead ones and turning -** the non dead to old (without changing their colors). +** Sweep a list of objects to enter generational mode. Deletes dead +** objects and turns the non dead to old. All non-dead threads---which +** are now old---must be in a gray list. Everything else is not in a +** gray list. Open upvalues are also kept gray. */ static void sweep2old (lua_State *L, GCObject **p) { GCObject *curr; + global_State *g = G(L); while ((curr = *p) != NULL) { if (iswhite(curr)) { /* is 'curr' dead? */ - lua_assert(isdead(G(L), curr)); + lua_assert(isdead(g, curr)); *p = curr->next; /* remove 'curr' from list */ freeobj(L, curr); /* erase 'curr' */ } else { /* all surviving objects become old */ setage(curr, G_OLD); + if (curr->tt == LUA_VTHREAD) { /* threads must be watched */ + lua_State *th = gco2th(curr); + linkgclist(th, g->grayagain); /* insert into 'grayagain' list */ + } + else if (curr->tt == LUA_VUPVAL && upisopen(gco2upv(curr))) + set2gray(curr); /* open upvalues are always gray */ + else /* everything else is black */ + nw2black(curr); p = &curr->next; /* go to next element */ } } @@ -995,9 +1074,13 @@ static void sweep2old (lua_State *L, GCObject **p) { ** during the sweep. So, any white object must be dead.) For ** non-dead objects, advance their ages and clear the color of ** new objects. (Old objects keep their colors.) +** The ages of G_TOUCHED1 and G_TOUCHED2 objects cannot be advanced +** here, because these old-generation objects are usually not swept +** here. They will all be advanced in 'correctgraylist'. That function +** will also remove objects turned white here from any gray list. */ static GCObject **sweepgen (lua_State *L, global_State *g, GCObject **p, - GCObject *limit) { + GCObject *limit, GCObject **pfirstold1) { static const lu_byte nextage[] = { G_SURVIVAL, /* from G_NEW */ G_OLD1, /* from G_SURVIVAL */ @@ -1016,9 +1099,15 @@ static GCObject **sweepgen (lua_State *L, global_State *g, GCObject **p, freeobj(L, curr); /* erase 'curr' */ } else { /* correct mark and age */ - if (getage(curr) == G_NEW) - curr->marked = cast_byte((curr->marked & maskgencolors) | white); - setage(curr, nextage[getage(curr)]); + if (getage(curr) == G_NEW) { /* new objects go back to white */ + int marked = curr->marked & ~maskgcbits; /* erase GC bits */ + curr->marked = cast_byte(marked | G_SURVIVAL | white); + } + else { /* all other objects will be old, and so keep their color */ + setage(curr, nextage[getage(curr)]); + if (getage(curr) == G_OLD1 && *pfirstold1 == NULL) + *pfirstold1 = curr; /* first OLD1 object in the list */ + } p = &curr->next; /* go to next element */ } } @@ -1028,58 +1117,50 @@ static GCObject **sweepgen (lua_State *L, global_State *g, GCObject **p, /* ** Traverse a list making all its elements white and clearing their -** age. +** age. In incremental mode, all objects are 'new' all the time, +** except for fixed strings (which are always old). */ static void whitelist (global_State *g, GCObject *p) { int white = luaC_white(g); for (; p != NULL; p = p->next) - p->marked = cast_byte((p->marked & maskcolors) | white); + p->marked = cast_byte((p->marked & ~maskgcbits) | white); } /* -** Correct a list of gray objects. +** Correct a list of gray objects. Return pointer to where rest of the +** list should be linked. ** Because this correction is done after sweeping, young objects might ** be turned white and still be in the list. They are only removed. -** For tables and userdata, advance 'touched1' to 'touched2'; 'touched2' -** objects become regular old and are removed from the list. -** For threads, just remove white ones from the list. +** 'TOUCHED1' objects are advanced to 'TOUCHED2' and remain on the list; +** Non-white threads also remain on the list; 'TOUCHED2' objects become +** regular old; they and anything else are removed from the list. */ static GCObject **correctgraylist (GCObject **p) { GCObject *curr; while ((curr = *p) != NULL) { - switch (curr->tt) { - case LUA_VTABLE: case LUA_VUSERDATA: { - GCObject **next = getgclist(curr); - if (getage(curr) == G_TOUCHED1) { /* touched in this cycle? */ - lua_assert(isgray(curr)); - gray2black(curr); /* make it black, for next barrier */ - changeage(curr, G_TOUCHED1, G_TOUCHED2); - p = next; /* go to next element */ - } - else { /* not touched in this cycle */ - if (!iswhite(curr)) { /* not white? */ - lua_assert(isold(curr)); - if (getage(curr) == G_TOUCHED2) /* advance from G_TOUCHED2... */ - changeage(curr, G_TOUCHED2, G_OLD); /* ... to G_OLD */ - gray2black(curr); /* make it black */ - } - /* else, object is white: just remove it from this list */ - *p = *next; /* remove 'curr' from gray list */ - } - break; - } - case LUA_VTHREAD: { - lua_State *th = gco2th(curr); - lua_assert(!isblack(th)); - if (iswhite(th)) /* new object? */ - *p = th->gclist; /* remove from gray list */ - else /* old threads remain gray */ - p = &th->gclist; /* go to next element */ - break; - } - default: lua_assert(0); /* nothing more could be gray here */ + GCObject **next = getgclist(curr); + if (iswhite(curr)) + goto remove; /* remove all white objects */ + else if (getage(curr) == G_TOUCHED1) { /* touched in this cycle? */ + lua_assert(isgray(curr)); + nw2black(curr); /* make it black, for next barrier */ + changeage(curr, G_TOUCHED1, G_TOUCHED2); + goto remain; /* keep it in the list and go to next element */ + } + else if (curr->tt == LUA_VTHREAD) { + lua_assert(isgray(curr)); + goto remain; /* keep non-white threads on the list */ + } + else { /* everything else is removed */ + lua_assert(isold(curr)); /* young objects should be white here */ + if (getage(curr) == G_TOUCHED2) /* advance from TOUCHED2... */ + changeage(curr, G_TOUCHED2, G_OLD); /* ... to OLD */ + nw2black(curr); /* make object black (to be removed) */ + goto remove; } + remove: *p = *next; continue; + remain: p = next; continue; } return p; } @@ -1100,7 +1181,7 @@ static void correctgraylists (global_State *g) { /* -** Mark 'OLD1' objects when starting a new young collection. +** Mark black 'OLD1' objects when starting a new young collection. ** Gray objects are already in some gray list, and so will be visited ** in the atomic step. */ @@ -1109,10 +1190,9 @@ static void markold (global_State *g, GCObject *from, GCObject *to) { for (p = from; p != to; p = p->next) { if (getage(p) == G_OLD1) { lua_assert(!iswhite(p)); - if (isblack(p)) { - black2gray(p); /* should be '2white', but gray works too */ + changeage(p, G_OLD1, G_OLD); /* now they are old */ + if (isblack(p)) reallymarkobject(g, p); - } } } } @@ -1131,50 +1211,63 @@ static void finishgencycle (lua_State *L, global_State *g) { /* -** Does a young collection. First, mark 'OLD1' objects. (Only survival -** and "recent old" lists can contain 'OLD1' objects. New lists cannot -** contain 'OLD1' objects, at most 'OLD0' objects that were already -** visited when marked old.) Then does the atomic step. Then, -** sweep all lists and advance pointers. Finally, finish the collection. +** Does a young collection. First, mark 'OLD1' objects. Then does the +** atomic step. Then, sweep all lists and advance pointers. Finally, +** finish the collection. */ static void youngcollection (lua_State *L, global_State *g) { GCObject **psurvival; /* to point to first non-dead survival object */ + GCObject *dummy; /* dummy out parameter to 'sweepgen' */ lua_assert(g->gcstate == GCSpropagate); - markold(g, g->survival, g->reallyold); + if (g->firstold1) { /* are there regular OLD1 objects? */ + markold(g, g->firstold1, g->reallyold); /* mark them */ + g->firstold1 = NULL; /* no more OLD1 objects (for now) */ + } markold(g, g->finobj, g->finobjrold); + markold(g, g->tobefnz, NULL); atomic(L); /* sweep nursery and get a pointer to its last live element */ - psurvival = sweepgen(L, g, &g->allgc, g->survival); - /* sweep 'survival' and 'old' */ - sweepgen(L, g, psurvival, g->reallyold); - g->reallyold = g->old; - g->old = *psurvival; /* 'survival' survivals are old now */ + g->gcstate = GCSswpallgc; + psurvival = sweepgen(L, g, &g->allgc, g->survival, &g->firstold1); + /* sweep 'survival' */ + sweepgen(L, g, psurvival, g->old1, &g->firstold1); + g->reallyold = g->old1; + g->old1 = *psurvival; /* 'survival' survivals are old now */ g->survival = g->allgc; /* all news are survivals */ /* repeat for 'finobj' lists */ - psurvival = sweepgen(L, g, &g->finobj, g->finobjsur); - /* sweep 'survival' and 'old' */ - sweepgen(L, g, psurvival, g->finobjrold); - g->finobjrold = g->finobjold; - g->finobjold = *psurvival; /* 'survival' survivals are old now */ + dummy = NULL; /* no 'firstold1' optimization for 'finobj' lists */ + psurvival = sweepgen(L, g, &g->finobj, g->finobjsur, &dummy); + /* sweep 'survival' */ + sweepgen(L, g, psurvival, g->finobjold1, &dummy); + g->finobjrold = g->finobjold1; + g->finobjold1 = *psurvival; /* 'survival' survivals are old now */ g->finobjsur = g->finobj; /* all news are survivals */ - sweepgen(L, g, &g->tobefnz, NULL); - + sweepgen(L, g, &g->tobefnz, NULL, &dummy); finishgencycle(L, g); } +/* +** Clears all gray lists, sweeps objects, and prepare sublists to enter +** generational mode. The sweeps remove dead objects and turn all +** surviving objects to old. Threads go back to 'grayagain'; everything +** else is turned black (not in any gray list). +*/ static void atomic2gen (lua_State *L, global_State *g) { + cleargraylists(g); /* sweep all elements making them old */ + g->gcstate = GCSswpallgc; sweep2old(L, &g->allgc); /* everything alive now is old */ - g->reallyold = g->old = g->survival = g->allgc; + g->reallyold = g->old1 = g->survival = g->allgc; + g->firstold1 = NULL; /* there are no OLD1 objects anywhere */ /* repeat for 'finobj' lists */ sweep2old(L, &g->finobj); - g->finobjrold = g->finobjold = g->finobjsur = g->finobj; + g->finobjrold = g->finobjold1 = g->finobjsur = g->finobj; sweep2old(L, &g->tobefnz); @@ -1187,8 +1280,9 @@ static void atomic2gen (lua_State *L, global_State *g) { /* ** Enter generational mode. Must go until the end of an atomic cycle -** to ensure that all threads and weak tables are in the gray lists. -** Then, turn all objects into old and finishes the collection. +** to ensure that all objects are correctly marked and weak tables +** are cleared. Then, turn all objects into old and finishes the +** collection. */ static lu_mem entergen (lua_State *L, global_State *g) { lu_mem numobjs; @@ -1207,10 +1301,10 @@ static lu_mem entergen (lua_State *L, global_State *g) { */ static void enterinc (global_State *g) { whitelist(g, g->allgc); - g->reallyold = g->old = g->survival = NULL; + g->reallyold = g->old1 = g->survival = NULL; whitelist(g, g->finobj); whitelist(g, g->tobefnz); - g->finobjrold = g->finobjold = g->finobjsur = NULL; + g->finobjrold = g->finobjold1 = g->finobjsur = NULL; g->gcstate = GCSpause; g->gckind = KGC_INC; g->lastatomic = 0; |