From b7bdf7d5d36825a1a750a74641f6d374dec5d67a Mon Sep 17 00:00:00 2001 From: Li Jin Date: Wed, 21 Apr 2021 09:36:25 +0800 Subject: adjust some folder levels. --- src/lua/lgc.c | 1728 --------------------------------------------------------- 1 file changed, 1728 deletions(-) delete mode 100644 src/lua/lgc.c (limited to 'src/lua/lgc.c') diff --git a/src/lua/lgc.c b/src/lua/lgc.c deleted file mode 100644 index b360eed..0000000 --- a/src/lua/lgc.c +++ /dev/null @@ -1,1728 +0,0 @@ -/* -** $Id: lgc.c $ -** Garbage Collector -** See Copyright Notice in lua.h -*/ - -#define lgc_c -#define LUA_CORE - -#include "lprefix.h" - -#include -#include - - -#include "lua.h" - -#include "ldebug.h" -#include "ldo.h" -#include "lfunc.h" -#include "lgc.h" -#include "lmem.h" -#include "lobject.h" -#include "lstate.h" -#include "lstring.h" -#include "ltable.h" -#include "ltm.h" - - -/* -** Maximum number of elements to sweep in each single step. -** (Large enough to dissipate fixed overheads but small enough -** to allow small steps for the collector.) -*/ -#define GCSWEEPMAX 100 - -/* -** Maximum number of finalizers to call in each single step. -*/ -#define GCFINMAX 10 - - -/* -** Cost of calling one finalizer. -*/ -#define GCFINALIZECOST 50 - - -/* -** The equivalent, in bytes, of one unit of "work" (visiting a slot, -** sweeping an object, etc.) -*/ -#define WORK2MEM sizeof(TValue) - - -/* -** macro to adjust 'pause': 'pause' is actually used like -** 'pause / PAUSEADJ' (value chosen by tests) -*/ -#define PAUSEADJ 100 - - -/* 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 set only the current white bit */ -#define makewhite(g,x) \ - (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) - - -/* 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))) - -#define keyiswhite(n) (keyiscollectable(n) && iswhite(gckey(n))) - - -/* -** Protected access to objects in values -*/ -#define gcvalueN(o) (iscollectable(o) ? gcvalue(o) : NULL) - - -#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)); } - -#define markobject(g,t) { if (iswhite(t)) reallymarkobject(g, obj2gco(t)); } - -/* -** mark an object that can be NULL (either because it is really optional, -** or it was stripped as debug info, or inside an uncompleted structure) -*/ -#define markobjectN(g,t) { if (t) markobject(g,t); } - -static void reallymarkobject (global_State *g, GCObject *o); -static lu_mem atomic (lua_State *L); -static void entersweep (lua_State *L); - - -/* -** {====================================================== -** Generic functions -** ======================================================= -*/ - - -/* -** one after last element in a hash array -*/ -#define gnodelast(h) gnode(h, cast_sizet(sizenode(h))) - - -static GCObject **getgclist (GCObject *o) { - switch (o->tt) { - case LUA_VTABLE: return &gco2t(o)->gclist; - case LUA_VLCL: return &gco2lcl(o)->gclist; - case LUA_VCCL: return &gco2ccl(o)->gclist; - case LUA_VTHREAD: return &gco2th(o)->gclist; - case LUA_VPROTO: return &gco2p(o)->gclist; - case LUA_VUSERDATA: { - Udata *u = gco2u(o); - lua_assert(u->nuvalue > 0); - return &u->gclist; - } - default: lua_assert(0); return 0; - } -} - - -/* -** 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) 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 the list 'p'. -*/ -#define linkobjgclist(o,p) linkgclist_(obj2gco(o), getgclist(o), &(p)) - - - -/* -** Clear keys for empty entries in tables. If entry is empty, mark its -** entry as dead. This allows the collection of the key, but keeps its -** entry in the table: its removal could break a chain and could break -** a table traversal. Other places never manipulate dead keys, because -** its associated empty value is enough to signal that the entry is -** logically empty. -*/ -static void clearkey (Node *n) { - lua_assert(isempty(gval(n))); - if (keyiscollectable(n)) - setdeadkey(n); /* unused key; remove it */ -} - - -/* -** tells whether a key or value can be cleared from a weak -** table. Non-collectable objects are never removed from weak -** tables. Strings behave as 'values', so are never removed too. for -** other objects: if really collected, cannot keep them; for objects -** being finalized, keep them in keys, but not in values -*/ -static int iscleared (global_State *g, const GCObject *o) { - if (o == NULL) return 0; /* non-collectable value */ - else if (novariant(o->tt) == LUA_TSTRING) { - markobject(g, o); /* strings are 'values', so are never weak */ - return 0; - } - else return iswhite(o); -} - - -/* -** 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); - lua_assert(isblack(o) && iswhite(v) && !isdead(g, v) && !isdead(g, o)); - if (keepinvariant(g)) { /* must keep invariant? */ - reallymarkobject(g, v); /* restore invariant */ - if (isold(o)) { - lua_assert(!isold(v)); /* white object could not be old */ - setage(v, G_OLD0); /* restore generational invariant */ - } - } - else { /* sweep phase */ - lua_assert(issweepphase(g)); - if (g->gckind == KGC_INC) /* incremental mode? */ - makewhite(g, o); /* mark 'o' as white to avoid other barriers */ - } -} - - -/* -** barrier that moves collector backward, that is, mark the black object -** pointing to a white object as gray again. -*/ -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) /* 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! */ - 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 */ - g->fixedgc = o; -} - - -/* -** create a new collectable object (with given type and size) and link -** it to 'allgc' list. -*/ -GCObject *luaC_newobj (lua_State *L, int tt, size_t sz) { - global_State *g = G(L); - GCObject *o = cast(GCObject *, luaM_newobject(L, novariant(tt), sz)); - o->marked = luaC_white(g); - o->tt = tt; - o->next = g->allgc; - g->allgc = o; - return o; -} - -/* }====================================================== */ - - - -/* -** {====================================================== -** Mark functions -** ======================================================= -*/ - - -/* -** 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) { - switch (o->tt) { - case LUA_VSHRSTR: - case LUA_VLNGSTR: { - set2black(o); /* nothing to visit */ - break; - } - case LUA_VUPVAL: { - UpVal *uv = gco2upv(o); - if (upisopen(uv)) - set2gray(uv); /* open upvalues are kept gray */ - else - set2black(uv); /* closed upvalues are visited here */ - markvalue(g, uv->v); /* mark its content */ - break; - } - case LUA_VUSERDATA: { - Udata *u = gco2u(o); - if (u->nuvalue == 0) { /* no user values? */ - markobjectN(g, u->metatable); /* mark its metatable */ - set2black(u); /* 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); /* to be visited later */ - break; - } - default: lua_assert(0); break; - } -} - - -/* -** mark metamethods for basic types -*/ -static void markmt (global_State *g) { - int i; - for (i=0; i < LUA_NUMTAGS; i++) - markobjectN(g, g->mt[i]); -} - - -/* -** mark all objects in list of being-finalized -*/ -static lu_mem markbeingfnz (global_State *g) { - GCObject *o; - lu_mem count = 0; - for (o = g->tobefnz; o != NULL; o = o->next) { - count++; - markobject(g, o); - } - return count; -} - - -/* -** 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; /* estimate of how much work was done here */ - while ((thread = *p) != NULL) { - work++; - 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? */ - lua_assert(upisopen(uv) && isgray(uv)); - markvalue(g, uv->v); /* mark its value */ - } - } - } - } - return work; -} - - -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) { - cleargraylists(g); - markobject(g, g->mainthread); - markvalue(g, &g->l_registry); - markmt(g); - markbeingfnz(g); /* mark any finalizing object left from previous cycle */ -} - -/* }====================================================== */ - - -/* -** {====================================================== -** Traverse functions -** ======================================================= -*/ - - -/* -** 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 -** atomic phase. In the atomic phase, if table has any white value, -** put it in 'weak' list, to be cleared. -*/ -static void traverseweakvalue (global_State *g, Table *h) { - Node *n, *limit = gnodelast(h); - /* if there is array part, assume it may have white values (it is not - worth traversing it now just to check) */ - int hasclears = (h->alimit > 0); - for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */ - if (isempty(gval(n))) /* entry is empty? */ - clearkey(n); /* clear its key */ - else { - lua_assert(!keyisnil(n)); - markkey(g, n); - if (!hasclears && iscleared(g, gcvalueN(gval(n)))) /* a white value? */ - hasclears = 1; /* table will have to be cleared */ - } - } - if (g->gcstate == GCSatomic && hasclears) - linkgclist(h, g->weak); /* has to be cleared later */ - else - linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */ -} - - -/* -** Traverse an ephemeron table and link it to proper list. Returns true -** iff any object was marked during this traversal (which implies that -** convergence has to continue). During propagation phase, keep table -** in 'grayagain' list, to be visited again in the atomic phase. In -** 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, 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 */ - int hasclears = 0; /* true if table has white keys */ - int hasww = 0; /* true if table has entry "white-key -> white-value" */ - unsigned int i; - unsigned int asize = luaH_realasize(h); - unsigned int nsize = sizenode(h); - /* traverse array part */ - for (i = 0; i < asize; i++) { - if (valiswhite(&h->array[i])) { - marked = 1; - reallymarkobject(g, gcvalue(&h->array[i])); - } - } - /* traverse hash part; if 'inv', traverse descending - (see 'convergeephemerons') */ - for (i = 0; i < nsize; i++) { - Node *n = inv ? gnode(h, nsize - 1 - i) : gnode(h, i); - if (isempty(gval(n))) /* entry is empty? */ - clearkey(n); /* clear its key */ - else if (iscleared(g, gckeyN(n))) { /* key is not marked (yet)? */ - hasclears = 1; /* table must be cleared */ - if (valiswhite(gval(n))) /* value not marked yet? */ - hasww = 1; /* white-white entry */ - } - else if (valiswhite(gval(n))) { /* value not marked yet? */ - marked = 1; - reallymarkobject(g, gcvalue(gval(n))); /* mark it now */ - } - } - /* link table into proper list */ - if (g->gcstate == GCSpropagate) - linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */ - else if (hasww) /* table has white->white entries? */ - 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 - genlink(g, obj2gco(h)); /* check whether collector still needs to see it */ - return marked; -} - - -static void traversestrongtable (global_State *g, Table *h) { - Node *n, *limit = gnodelast(h); - unsigned int i; - unsigned int asize = luaH_realasize(h); - for (i = 0; i < asize; i++) /* traverse array part */ - markvalue(g, &h->array[i]); - for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */ - if (isempty(gval(n))) /* entry is empty? */ - clearkey(n); /* clear its key */ - else { - lua_assert(!keyisnil(n)); - markkey(g, n); - markvalue(g, gval(n)); - } - } - genlink(g, obj2gco(h)); -} - - -static lu_mem traversetable (global_State *g, Table *h) { - const char *weakkey, *weakvalue; - const TValue *mode = gfasttm(g, h->metatable, TM_MODE); - markobjectN(g, h->metatable); - if (mode && ttisstring(mode) && /* is there a weak mode? */ - (cast_void(weakkey = strchr(svalue(mode), 'k')), - cast_void(weakvalue = strchr(svalue(mode), 'v')), - (weakkey || weakvalue))) { /* is really weak? */ - if (!weakkey) /* strong keys? */ - traverseweakvalue(g, h); - else if (!weakvalue) /* strong values? */ - traverseephemeron(g, h, 0); - else /* all weak */ - linkgclist(h, g->allweak); /* nothing to traverse now */ - } - else /* not weak */ - traversestrongtable(g, h); - return 1 + h->alimit + 2 * allocsizenode(h); -} - - -static int traverseudata (global_State *g, Udata *u) { - int i; - markobjectN(g, u->metatable); /* mark its metatable */ - for (i = 0; i < u->nuvalue; i++) - markvalue(g, &u->uv[i].uv); - genlink(g, obj2gco(u)); - return 1 + u->nuvalue; -} - - -/* -** Traverse a prototype. (While a prototype is being build, its -** arrays can be larger than needed; the extra slots are filled with -** NULL, so the use of 'markobjectN') -*/ -static int traverseproto (global_State *g, Proto *f) { - int i; - markobjectN(g, f->source); - for (i = 0; i < f->sizek; i++) /* mark literals */ - markvalue(g, &f->k[i]); - for (i = 0; i < f->sizeupvalues; i++) /* mark upvalue names */ - markobjectN(g, f->upvalues[i].name); - for (i = 0; i < f->sizep; i++) /* mark nested protos */ - markobjectN(g, f->p[i]); - for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */ - markobjectN(g, f->locvars[i].varname); - return 1 + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars; -} - - -static int traverseCclosure (global_State *g, CClosure *cl) { - int i; - for (i = 0; i < cl->nupvalues; i++) /* mark its upvalues */ - markvalue(g, &cl->upvalue[i]); - return 1 + cl->nupvalues; -} - -/* -** Traverse a Lua closure, marking its prototype and its upvalues. -** (Both can be NULL while closure is being created.) -*/ -static int traverseLclosure (global_State *g, LClosure *cl) { - int i; - markobjectN(g, cl->p); /* mark its prototype */ - for (i = 0; i < cl->nupvalues; i++) { /* visit its upvalues */ - UpVal *uv = cl->upvals[i]; - markobjectN(g, uv); /* mark upvalue */ - } - return 1 + cl->nupvalues; -} - - -/* -** 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. -** 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 || - th->openupval == NULL || isintwups(th)); - for (; o < th->top; o++) /* mark live elements in the stack */ - markvalue(g, s2v(o)); - for (uv = th->openupval; uv != NULL; uv = uv->u.open.next) - markobject(g, uv); /* open upvalues cannot be collected */ - if (g->gcstate == GCSatomic) { /* final traversal? */ - for (; o < th->stack_last + EXTRA_STACK; o++) - setnilvalue(s2v(o)); /* clear dead stack slice */ - /* 'remarkupvals' may have removed thread from 'twups' list */ - if (!isintwups(th) && th->openupval != NULL) { - th->twups = g->twups; /* link it back to the list */ - g->twups = th; - } - } - else if (!g->gcemergency) - luaD_shrinkstack(th); /* do not change stack in emergency cycle */ - return 1 + stacksize(th); -} - - -/* -** traverse one gray object, turning it to black. -*/ -static lu_mem propagatemark (global_State *g) { - GCObject *o = g->gray; - nw2black(o); - g->gray = *getgclist(o); /* remove from 'gray' list */ - switch (o->tt) { - case LUA_VTABLE: return traversetable(g, gco2t(o)); - case LUA_VUSERDATA: return traverseudata(g, gco2u(o)); - 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: return traversethread(g, gco2th(o)); - default: lua_assert(0); return 0; - } -} - - -static lu_mem propagateall (global_State *g) { - lu_mem tot = 0; - while (g->gray) - tot += propagatemark(g); - return tot; -} - - -/* -** Traverse all ephemeron tables propagating marks from keys to values. -** Repeat until it converges, that is, nothing new is marked. 'dir' -** inverts the direction of the traversals, trying to speed up -** convergence on chains in the same table. -** -*/ -static void convergeephemerons (global_State *g) { - int changed; - int dir = 0; - do { - GCObject *w; - GCObject *next = g->ephemeron; /* get ephemeron list */ - g->ephemeron = NULL; /* tables may return to this list when traversed */ - changed = 0; - while ((w = next) != NULL) { /* for each ephemeron table */ - 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 */ - } - } - dir = !dir; /* invert direction next time */ - } while (changed); /* repeat until no more changes */ -} - -/* }====================================================== */ - - -/* -** {====================================================== -** Sweep Functions -** ======================================================= -*/ - - -/* -** clear entries with unmarked keys from all weaktables in list 'l' -*/ -static void clearbykeys (global_State *g, GCObject *l) { - for (; l; l = gco2t(l)->gclist) { - Table *h = gco2t(l); - Node *limit = gnodelast(h); - Node *n; - for (n = gnode(h, 0); n < limit; n++) { - if (iscleared(g, gckeyN(n))) /* unmarked key? */ - setempty(gval(n)); /* remove entry */ - if (isempty(gval(n))) /* is entry empty? */ - clearkey(n); /* clear its key */ - } - } -} - - -/* -** clear entries with unmarked values from all weaktables in list 'l' up -** to element 'f' -*/ -static void clearbyvalues (global_State *g, GCObject *l, GCObject *f) { - for (; l != f; l = gco2t(l)->gclist) { - Table *h = gco2t(l); - Node *n, *limit = gnodelast(h); - unsigned int i; - unsigned int asize = luaH_realasize(h); - for (i = 0; i < asize; i++) { - TValue *o = &h->array[i]; - if (iscleared(g, gcvalueN(o))) /* value was collected? */ - setempty(o); /* remove entry */ - } - for (n = gnode(h, 0); n < limit; n++) { - if (iscleared(g, gcvalueN(gval(n)))) /* unmarked value? */ - setempty(gval(n)); /* remove entry */ - if (isempty(gval(n))) /* is entry empty? */ - clearkey(n); /* clear its key */ - } - } -} - - -static void freeupval (lua_State *L, UpVal *uv) { - if (upisopen(uv)) - luaF_unlinkupval(uv); - luaM_free(L, uv); -} - - -static void freeobj (lua_State *L, GCObject *o) { - switch (o->tt) { - case LUA_VPROTO: - luaF_freeproto(L, gco2p(o)); - break; - case LUA_VUPVAL: - freeupval(L, gco2upv(o)); - break; - case LUA_VLCL: { - LClosure *cl = gco2lcl(o); - luaM_freemem(L, cl, sizeLclosure(cl->nupvalues)); - break; - } - case LUA_VCCL: { - CClosure *cl = gco2ccl(o); - luaM_freemem(L, cl, sizeCclosure(cl->nupvalues)); - break; - } - case LUA_VTABLE: - luaH_free(L, gco2t(o)); - break; - case LUA_VTHREAD: - luaE_freethread(L, gco2th(o)); - break; - case LUA_VUSERDATA: { - Udata *u = gco2u(o); - luaM_freemem(L, o, sizeudata(u->nuvalue, u->len)); - break; - } - case LUA_VSHRSTR: { - TString *ts = gco2ts(o); - luaS_remove(L, ts); /* remove it from hash table */ - luaM_freemem(L, ts, sizelstring(ts->shrlen)); - break; - } - case LUA_VLNGSTR: { - TString *ts = gco2ts(o); - luaM_freemem(L, ts, sizelstring(ts->u.lnglen)); - break; - } - default: lua_assert(0); - } -} - - -/* -** sweep at most 'countin' elements from a list of GCObjects erasing dead -** objects, where a dead object is one marked with the old (non current) -** white; change all non-dead objects back to white, preparing for next -** collection cycle. Return where to continue the traversal or NULL if -** list is finished. ('*countout' gets the number of elements traversed.) -*/ -static GCObject **sweeplist (lua_State *L, GCObject **p, int countin, - int *countout) { - global_State *g = G(L); - int ow = otherwhite(g); - int i; - int white = luaC_white(g); /* current white */ - for (i = 0; *p != NULL && i < countin; i++) { - GCObject *curr = *p; - int marked = curr->marked; - if (isdeadm(ow, marked)) { /* is 'curr' dead? */ - *p = curr->next; /* remove 'curr' from list */ - freeobj(L, curr); /* erase 'curr' */ - } - else { /* change mark to 'white' */ - curr->marked = cast_byte((marked & ~maskgcbits) | white); - p = &curr->next; /* go to next element */ - } - } - if (countout) - *countout = i; /* number of elements traversed */ - return (*p == NULL) ? NULL : p; -} - - -/* -** sweep a list until a live object (or end of list) -*/ -static GCObject **sweeptolive (lua_State *L, GCObject **p) { - GCObject **old = p; - do { - p = sweeplist(L, p, 1, NULL); - } while (p == old); - return p; -} - -/* }====================================================== */ - - -/* -** {====================================================== -** Finalization -** ======================================================= -*/ - -/* -** If possible, shrink string table. -*/ -static void checkSizes (lua_State *L, global_State *g) { - if (!g->gcemergency) { - if (g->strt.nuse < g->strt.size / 4) { /* string table too big? */ - l_mem olddebt = g->GCdebt; - luaS_resize(L, g->strt.size / 2); - g->GCestimate += g->GCdebt - olddebt; /* correct estimate */ - } - } -} - - -/* -** Get the next udata to be finalized from the 'tobefnz' list, and -** link it back into the 'allgc' list. -*/ -static GCObject *udata2finalize (global_State *g) { - GCObject *o = g->tobefnz; /* get first element */ - lua_assert(tofinalize(o)); - g->tobefnz = o->next; /* remove it from 'tobefnz' list */ - o->next = g->allgc; /* return it to 'allgc' list */ - g->allgc = o; - 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; -} - - -static void dothecall (lua_State *L, void *ud) { - UNUSED(ud); - luaD_callnoyield(L, L->top - 2, 0); -} - - -static void GCTM (lua_State *L) { - global_State *g = G(L); - const TValue *tm; - TValue v; - lua_assert(!g->gcemergency); - setgcovalue(L, &v, udata2finalize(g)); - tm = luaT_gettmbyobj(L, &v, TM_GC); - if (!notm(tm)) { /* is there a finalizer? */ - int status; - lu_byte oldah = L->allowhook; - int running = g->gcrunning; - L->allowhook = 0; /* stop debug hooks during GC metamethod */ - g->gcrunning = 0; /* avoid GC steps */ - setobj2s(L, L->top++, tm); /* push finalizer... */ - setobj2s(L, L->top++, &v); /* ... and its argument */ - L->ci->callstatus |= CIST_FIN; /* will run a finalizer */ - status = luaD_pcall(L, dothecall, NULL, savestack(L, L->top - 2), 0); - L->ci->callstatus &= ~CIST_FIN; /* not running a finalizer anymore */ - L->allowhook = oldah; /* restore hooks */ - g->gcrunning = running; /* restore state */ - if (l_unlikely(status != LUA_OK)) { /* error while running __gc? */ - luaE_warnerror(L, "__gc metamethod"); - L->top--; /* pops error object */ - } - } -} - - -/* -** Call a few finalizers -*/ -static int runafewfinalizers (lua_State *L, int n) { - global_State *g = G(L); - int i; - for (i = 0; i < n && g->tobefnz; i++) - GCTM(L); /* call one finalizer */ - return i; -} - - -/* -** call all pending finalizers -*/ -static void callallpendingfinalizers (lua_State *L) { - global_State *g = G(L); - while (g->tobefnz) - GCTM(L); -} - - -/* -** find last 'next' field in list 'p' list (to add elements in its end) -*/ -static GCObject **findlast (GCObject **p) { - while (*p != NULL) - p = &(*p)->next; - return p; -} - - -/* -** Move all unreachable objects (or 'all' objects) that need -** finalization from list 'finobj' to list 'tobefnz' (to be finalized). -** (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->finobjold1) { /* traverse all finalizable objects */ - lua_assert(tofinalize(curr)); - if (!(iswhite(curr) || all)) /* not being collected? */ - p = &curr->next; /* don't bother with it */ - else { - if (curr == g->finobjsur) /* removing 'finobjsur'? */ - g->finobjsur = curr->next; /* correct it */ - *p = curr->next; /* remove 'curr' from 'finobj' list */ - curr->next = *lastnext; /* link at the end of 'tobefnz' list */ - *lastnext = curr; - lastnext = &curr->next; - } - } -} - - -/* -** 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. -*/ -void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) { - global_State *g = G(L); - if (tofinalize(o) || /* obj. is already marked... */ - gfasttm(g, mt, TM_GC) == NULL) /* or has no finalizer? */ - return; /* nothing to be done */ - else { /* move 'o' to 'finobj' list */ - GCObject **p; - if (issweepphase(g)) { - makewhite(g, o); /* "sweep" object 'o' */ - if (g->sweepgc == &o->next) /* should not remove 'sweepgc' object */ - g->sweepgc = sweeptolive(L, g->sweepgc); /* change 'sweepgc' */ - } - 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 */ - o->next = g->finobj; /* link it in 'finobj' list */ - g->finobj = o; - l_setbit(o->marked, FINALIZEDBIT); /* mark it as such */ - } -} - -/* }====================================================== */ - - -/* -** {====================================================== -** Generational Collector -** ======================================================= -*/ - -static void setpause (global_State *g); - - -/* -** 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, 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 */ - } - } -} - - -/* -** Sweep for generational mode. Delete dead objects. (Because the -** collection is not incremental, there are no "new white" objects -** 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 **pfirstold1) { - static const lu_byte nextage[] = { - G_SURVIVAL, /* from G_NEW */ - G_OLD1, /* from G_SURVIVAL */ - G_OLD1, /* from G_OLD0 */ - G_OLD, /* from G_OLD1 */ - G_OLD, /* from G_OLD (do not change) */ - G_TOUCHED1, /* from G_TOUCHED1 (do not change) */ - G_TOUCHED2 /* from G_TOUCHED2 (do not change) */ - }; - int white = luaC_white(g); - GCObject *curr; - while ((curr = *p) != limit) { - if (iswhite(curr)) { /* is 'curr' dead? */ - lua_assert(!isold(curr) && isdead(g, curr)); - *p = curr->next; /* remove 'curr' from list */ - freeobj(L, curr); /* erase 'curr' */ - } - else { /* correct mark and age */ - 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 */ - } - } - return p; -} - - -/* -** Traverse a list making all its elements white and clearing their -** 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 & ~maskgcbits) | white); -} - - -/* -** 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. -** '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) { - 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; -} - - -/* -** Correct all gray lists, coalescing them into 'grayagain'. -*/ -static void correctgraylists (global_State *g) { - GCObject **list = correctgraylist(&g->grayagain); - *list = g->weak; g->weak = NULL; - list = correctgraylist(list); - *list = g->allweak; g->allweak = NULL; - list = correctgraylist(list); - *list = g->ephemeron; g->ephemeron = NULL; - correctgraylist(list); -} - - -/* -** 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. -*/ -static void markold (global_State *g, GCObject *from, GCObject *to) { - GCObject *p; - for (p = from; p != to; p = p->next) { - if (getage(p) == G_OLD1) { - lua_assert(!iswhite(p)); - changeage(p, G_OLD1, G_OLD); /* now they are old */ - if (isblack(p)) - reallymarkobject(g, p); - } - } -} - - -/* -** Finish a young-generation collection. -*/ -static void finishgencycle (lua_State *L, global_State *g) { - correctgraylists(g); - checkSizes(L, g); - g->gcstate = GCSpropagate; /* skip restart */ - if (!g->gcemergency) - callallpendingfinalizers(L); -} - - -/* -** 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); - 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 */ - 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 */ - 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, &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->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->finobjold1 = g->finobjsur = g->finobj; - - sweep2old(L, &g->tobefnz); - - g->gckind = KGC_GEN; - g->lastatomic = 0; - g->GCestimate = gettotalbytes(g); /* base for memory control */ - finishgencycle(L, g); -} - - -/* -** Enter generational mode. Must go until the end of an atomic cycle -** 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; - luaC_runtilstate(L, bitmask(GCSpause)); /* prepare to start a new cycle */ - luaC_runtilstate(L, bitmask(GCSpropagate)); /* start new cycle */ - numobjs = atomic(L); /* propagates all and then do the atomic stuff */ - atomic2gen(L, g); - return numobjs; -} - - -/* -** Enter incremental mode. Turn all objects white, make all -** intermediate lists point to NULL (to avoid invalid pointers), -** and go to the pause state. -*/ -static void enterinc (global_State *g) { - whitelist(g, g->allgc); - g->reallyold = g->old1 = g->survival = NULL; - whitelist(g, g->finobj); - whitelist(g, g->tobefnz); - g->finobjrold = g->finobjold1 = g->finobjsur = NULL; - g->gcstate = GCSpause; - g->gckind = KGC_INC; - g->lastatomic = 0; -} - - -/* -** Change collector mode to 'newmode'. -*/ -void luaC_changemode (lua_State *L, int newmode) { - global_State *g = G(L); - if (newmode != g->gckind) { - if (newmode == KGC_GEN) /* entering generational mode? */ - entergen(L, g); - else - enterinc(g); /* entering incremental mode */ - } - g->lastatomic = 0; -} - - -/* -** Does a full collection in generational mode. -*/ -static lu_mem fullgen (lua_State *L, global_State *g) { - enterinc(g); - return entergen(L, g); -} - - -/* -** Set debt for the next minor collection, which will happen when -** memory grows 'genminormul'%. -*/ -static void setminordebt (global_State *g) { - luaE_setdebt(g, -(cast(l_mem, (gettotalbytes(g) / 100)) * g->genminormul)); -} - - -/* -** Does a major collection after last collection was a "bad collection". -** -** When the program is building a big structure, it allocates lots of -** memory but generates very little garbage. In those scenarios, -** the generational mode just wastes time doing small collections, and -** major collections are frequently what we call a "bad collection", a -** collection that frees too few objects. To avoid the cost of switching -** between generational mode and the incremental mode needed for full -** (major) collections, the collector tries to stay in incremental mode -** after a bad collection, and to switch back to generational mode only -** after a "good" collection (one that traverses less than 9/8 objects -** of the previous one). -** The collector must choose whether to stay in incremental mode or to -** switch back to generational mode before sweeping. At this point, it -** does not know the real memory in use, so it cannot use memory to -** decide whether to return to generational mode. Instead, it uses the -** number of objects traversed (returned by 'atomic') as a proxy. The -** field 'g->lastatomic' keeps this count from the last collection. -** ('g->lastatomic != 0' also means that the last collection was bad.) -*/ -static void stepgenfull (lua_State *L, global_State *g) { - lu_mem newatomic; /* count of traversed objects */ - lu_mem lastatomic = g->lastatomic; /* count from last collection */ - if (g->gckind == KGC_GEN) /* still in generational mode? */ - enterinc(g); /* enter incremental mode */ - luaC_runtilstate(L, bitmask(GCSpropagate)); /* start new cycle */ - newatomic = atomic(L); /* mark everybody */ - if (newatomic < lastatomic + (lastatomic >> 3)) { /* good collection? */ - atomic2gen(L, g); /* return to generational mode */ - setminordebt(g); - } - else { /* another bad collection; stay in incremental mode */ - g->GCestimate = gettotalbytes(g); /* first estimate */; - entersweep(L); - luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */ - setpause(g); - g->lastatomic = newatomic; - } -} - - -/* -** 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 whether the major collection was able to free a -** decent amount of memory (at least half the growth in memory since -** previous major collection). If so, the collector keeps its state, -** and the next collection will probably be minor again. Otherwise, -** we have what we call a "bad collection". In that case, set the field -** 'g->lastatomic' to signal that fact, so that the next collection will -** go to 'stepgenfull'. -** -** 'GCdebt <= 0' means an explicit call to GC step with "size" zero; -** 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)); -} - -/* }====================================================== */ - - -/* -** {====================================================== -** GC control -** ======================================================= -*/ - - -/* -** Set the "time" to wait before starting a new GC cycle; cycle will -** start when memory use hits the threshold of ('estimate' * pause / -** PAUSEADJ). (Division by 'estimate' should be OK: it cannot be zero, -** because Lua cannot even start with less than PAUSEADJ bytes). -*/ -static void setpause (global_State *g) { - l_mem threshold, debt; - int pause = getgcparam(g->gcpause); - l_mem estimate = g->GCestimate / PAUSEADJ; /* adjust 'estimate' */ - lua_assert(estimate > 0); - threshold = (pause < MAX_LMEM / estimate) /* overflow? */ - ? estimate * pause /* no overflow */ - : MAX_LMEM; /* overflow; truncate to maximum */ - debt = gettotalbytes(g) - threshold; - if (debt > 0) debt = 0; - luaE_setdebt(g, debt); -} - - -/* -** Enter first sweep phase. -** The call to 'sweeptolive' makes the pointer point to an object -** inside the list (instead of to the header), so that the real sweep do -** not need to skip objects created between "now" and the start of the -** real sweep. -*/ -static void entersweep (lua_State *L) { - global_State *g = G(L); - g->gcstate = GCSswpallgc; - lua_assert(g->sweepgc == NULL); - g->sweepgc = sweeptolive(L, &g->allgc); -} - - -/* -** Delete all objects in list 'p' until (but not including) object -** 'limit'. -*/ -static void deletelist (lua_State *L, GCObject *p, GCObject *limit) { - while (p != limit) { - GCObject *next = p->next; - freeobj(L, p); - p = next; - } -} - - -/* -** Call all finalizers of the objects in the given Lua state, and -** then free all objects, except for the main thread. -*/ -void luaC_freeallobjects (lua_State *L) { - global_State *g = G(L); - luaC_changemode(L, KGC_INC); - separatetobefnz(g, 1); /* separate all objects with finalizers */ - lua_assert(g->finobj == NULL); - callallpendingfinalizers(L); - deletelist(L, g->allgc, obj2gco(g->mainthread)); - deletelist(L, g->finobj, NULL); - deletelist(L, g->fixedgc, NULL); /* collect fixed objects */ - lua_assert(g->strt.nuse == 0); -} - - -static lu_mem atomic (lua_State *L) { - global_State *g = G(L); - lu_mem work = 0; - GCObject *origweak, *origall; - GCObject *grayagain = g->grayagain; /* save original list */ - g->grayagain = NULL; - lua_assert(g->ephemeron == NULL && g->weak == NULL); - lua_assert(!iswhite(g->mainthread)); - g->gcstate = GCSatomic; - markobject(g, L); /* mark running thread */ - /* registry and global metatables may be changed by API */ - markvalue(g, &g->l_registry); - markmt(g); /* mark global metatables */ - work += propagateall(g); /* empties 'gray' list */ - /* remark occasional upvalues of (maybe) dead threads */ - work += remarkupvals(g); - work += propagateall(g); /* propagate changes */ - g->gray = grayagain; - work += propagateall(g); /* traverse 'grayagain' list */ - convergeephemerons(g); - /* at this point, all strongly accessible objects are marked. */ - /* Clear values from weak tables, before checking finalizers */ - clearbyvalues(g, g->weak, NULL); - clearbyvalues(g, g->allweak, NULL); - origweak = g->weak; origall = g->allweak; - separatetobefnz(g, 0); /* separate objects to be finalized */ - work += markbeingfnz(g); /* mark objects that will be finalized */ - work += propagateall(g); /* remark, to propagate 'resurrection' */ - convergeephemerons(g); - /* at this point, all resurrected objects are marked. */ - /* remove dead objects from weak tables */ - clearbykeys(g, g->ephemeron); /* clear keys from all ephemeron tables */ - clearbykeys(g, g->allweak); /* clear keys from all 'allweak' tables */ - /* clear values from resurrected weak tables */ - clearbyvalues(g, g->weak, origweak); - clearbyvalues(g, g->allweak, origall); - luaS_clearcache(g); - g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */ - lua_assert(g->gray == NULL); - return work; /* estimate of slots marked by 'atomic' */ -} - - -static int sweepstep (lua_State *L, global_State *g, - int nextstate, GCObject **nextlist) { - if (g->sweepgc) { - l_mem olddebt = g->GCdebt; - int count; - g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX, &count); - g->GCestimate += g->GCdebt - olddebt; /* update estimate */ - return count; - } - else { /* enter next state */ - g->gcstate = nextstate; - g->sweepgc = nextlist; - return 0; /* no work done */ - } -} - - -static lu_mem singlestep (lua_State *L) { - global_State *g = G(L); - lu_mem work; - lua_assert(!g->gcstopem); /* collector is not reentrant */ - g->gcstopem = 1; /* no emergency collections while collecting */ - switch (g->gcstate) { - case GCSpause: { - restartcollection(g); - g->gcstate = GCSpropagate; - work = 1; - break; - } - case GCSpropagate: { - if (g->gray == NULL) { /* no more gray objects? */ - g->gcstate = GCSenteratomic; /* finish propagate phase */ - work = 0; - } - else - work = propagatemark(g); /* traverse one gray object */ - break; - } - case GCSenteratomic: { - work = atomic(L); /* work is what was traversed by 'atomic' */ - entersweep(L); - g->GCestimate = gettotalbytes(g); /* first estimate */; - break; - } - case GCSswpallgc: { /* sweep "regular" objects */ - work = sweepstep(L, g, GCSswpfinobj, &g->finobj); - break; - } - case GCSswpfinobj: { /* sweep objects with finalizers */ - work = sweepstep(L, g, GCSswptobefnz, &g->tobefnz); - break; - } - case GCSswptobefnz: { /* sweep objects to be finalized */ - work = sweepstep(L, g, GCSswpend, NULL); - break; - } - case GCSswpend: { /* finish sweeps */ - checkSizes(L, g); - g->gcstate = GCScallfin; - work = 0; - break; - } - case GCScallfin: { /* call remaining finalizers */ - if (g->tobefnz && !g->gcemergency) { - g->gcstopem = 0; /* ok collections during finalizers */ - work = runafewfinalizers(L, GCFINMAX) * GCFINALIZECOST; - } - else { /* emergency mode or no more finalizers */ - g->gcstate = GCSpause; /* finish collection */ - work = 0; - } - break; - } - default: lua_assert(0); return 0; - } - g->gcstopem = 0; - return work; -} - - -/* -** advances the garbage collector until it reaches a state allowed -** by 'statemask' -*/ -void luaC_runtilstate (lua_State *L, int statesmask) { - global_State *g = G(L); - while (!testbit(statesmask, g->gcstate)) - singlestep(L); -} - - -/* -** Performs a basic incremental step. The debt and step size are -** converted from bytes to "units of work"; then the function loops -** running single steps until adding that many units of work or -** finishing a cycle (pause state). Finally, it sets the debt that -** controls when next step will be performed. -*/ -static void incstep (lua_State *L, global_State *g) { - int stepmul = (getgcparam(g->gcstepmul) | 1); /* avoid division by 0 */ - l_mem debt = (g->GCdebt / WORK2MEM) * stepmul; - l_mem stepsize = (g->gcstepsize <= log2maxs(l_mem)) - ? ((cast(l_mem, 1) << g->gcstepsize) / WORK2MEM) * stepmul - : MAX_LMEM; /* overflow; keep maximum value */ - do { /* repeat until pause or enough "credit" (negative debt) */ - lu_mem work = singlestep(L); /* perform one single step */ - debt -= work; - } while (debt > -stepsize && g->gcstate != GCSpause); - if (g->gcstate == GCSpause) - setpause(g); /* pause until next cycle */ - else { - debt = (debt / stepmul) * WORK2MEM; /* convert 'work units' to bytes */ - luaE_setdebt(g, debt); - } -} - -/* -** performs a basic GC step if collector is running -*/ -void luaC_step (lua_State *L) { - global_State *g = G(L); - lua_assert(!g->gcemergency); - if (g->gcrunning) { /* running? */ - if(isdecGCmodegen(g)) - genstep(L, g); - else - incstep(L, g); - } -} - - -/* -** Perform a full collection in incremental mode. -** Before running the collection, check 'keepinvariant'; if it is true, -** there may be some objects marked as black, so the collector has -** to sweep all objects to turn them back to white (as white has not -** changed, nothing will be collected). -*/ -static void fullinc (lua_State *L, global_State *g) { - if (keepinvariant(g)) /* black objects? */ - entersweep(L); /* sweep everything to turn them back to white */ - /* finish any pending sweep phase to start a new cycle */ - luaC_runtilstate(L, bitmask(GCSpause)); - luaC_runtilstate(L, bitmask(GCScallfin)); /* run up to finalizers */ - /* estimate must be correct after a full GC cycle */ - lua_assert(g->GCestimate == gettotalbytes(g)); - luaC_runtilstate(L, bitmask(GCSpause)); /* finish collection */ - setpause(g); -} - - -/* -** Performs a full GC cycle; if 'isemergency', set a flag to avoid -** some operations which could change the interpreter state in some -** unexpected ways (running finalizers and shrinking some structures). -*/ -void luaC_fullgc (lua_State *L, int isemergency) { - global_State *g = G(L); - lua_assert(!g->gcemergency); - g->gcemergency = isemergency; /* set flag */ - if (g->gckind == KGC_INC) - fullinc(L, g); - else - fullgen(L, g); - g->gcemergency = 0; -} - -/* }====================================================== */ - - -- cgit v1.2.3-55-g6feb