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-rw-r--r--3rdparty/lua/src/lgc.c1419
1 files changed, 986 insertions, 433 deletions
diff --git a/3rdparty/lua/src/lgc.c b/3rdparty/lua/src/lgc.c
index ba2c19e14e9..42a73d813ac 100644
--- a/3rdparty/lua/src/lgc.c
+++ b/3rdparty/lua/src/lgc.c
@@ -1,5 +1,5 @@
/*
-** $Id: lgc.c,v 2.215 2016/12/22 13:08:50 roberto Exp $
+** $Id: lgc.c $
** Garbage Collector
** See Copyright Notice in lua.h
*/
@@ -9,9 +9,10 @@
#include "lprefix.h"
-
+#include <stdio.h>
#include <string.h>
+
#include "lua.h"
#include "ldebug.h"
@@ -27,29 +28,29 @@
/*
-** internal state for collector while inside the atomic phase. The
-** collector should never be in this state while running regular code.
+** 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 GCSinsideatomic (GCSpause + 1)
+#define GCSWEEPMAX 100
/*
-** cost of sweeping one element (the size of a small object divided
-** by some adjust for the sweep speed)
+** Maximum number of finalizers to call in each single step.
*/
-#define GCSWEEPCOST ((sizeof(TString) + 4) / 4)
+#define GCFINMAX 10
-/* maximum number of elements to sweep in each single step */
-#define GCSWEEPMAX (cast_int((GCSTEPSIZE / GCSWEEPCOST) / 4))
-/* cost of calling one finalizer */
-#define GCFINALIZECOST GCSWEEPCOST
+/*
+** Cost of calling one finalizer.
+*/
+#define GCFINALIZECOST 50
/*
-** macro to adjust 'stepmul': 'stepmul' is actually used like
-** 'stepmul / STEPMULADJ' (value chosen by tests)
+** The equivalent, in bytes, of one unit of "work" (visiting a slot,
+** sweeping an object, etc.)
*/
-#define STEPMULADJ 200
+#define WORK2MEM sizeof(TValue)
/*
@@ -59,30 +60,42 @@
#define PAUSEADJ 100
-/*
-** 'makewhite' erases all color bits then sets only the current white
-** bit
-*/
-#define maskcolors (~(bitmask(BLACKBIT) | WHITEBITS))
+/* 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)))
+ (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)))
-#define checkdeadkey(n) lua_assert(!ttisdeadkey(gkey(n)) || ttisnil(gval(n)))
+#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)); }
+
#define markobject(g,t) { if (iswhite(t)) reallymarkobject(g, obj2gco(t)); }
/*
@@ -92,6 +105,8 @@
#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);
/*
@@ -104,28 +119,59 @@ static void reallymarkobject (global_State *g, GCObject *o);
/*
** one after last element in a hash array
*/
-#define gnodelast(h) gnode(h, cast(size_t, sizenode(h)))
+#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 collectable object 'o' into list pointed by 'p'
+** Link a generic collectable object 'o' into the list 'p'.
*/
-#define linkgclist(o,p) ((o)->gclist = (p), (p) = obj2gco(o))
+#define linkobjgclist(o,p) linkgclist_(obj2gco(o), getgclist(o), &(p))
+
/*
-** If key is not marked, mark its entry as dead. This allows key to be
-** collected, but keeps its entry in the table. A dead node is needed
-** when Lua looks up for a key (it may be part of a chain) and when
-** traversing a weak table (key might be removed from the table during
-** traversal). Other places never manipulate dead keys, because its
-** associated nil value is enough to signal that the entry is logically
-** empty.
+** 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 removeentry (Node *n) {
- lua_assert(ttisnil(gval(n)));
- if (valiswhite(gkey(n)))
- setdeadvalue(wgkey(n)); /* unused and unmarked key; remove it */
+static void clearkey (Node *n) {
+ lua_assert(isempty(gval(n)));
+ if (keyiscollectable(n))
+ setdeadkey(n); /* unused key; remove it */
}
@@ -136,30 +182,43 @@ static void removeentry (Node *n) {
** 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 TValue *o) {
- if (!iscollectable(o)) return 0;
- else if (ttisstring(o)) {
- markobject(g, tsvalue(o)); /* strings are 'values', so are never weak */
+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(gcvalue(o));
+ else return iswhite(o);
}
/*
-** barrier that moves collector forward, that is, mark the white object
-** being pointed by a black object. (If in sweep phase, clear the black
-** object to white [sweep it] to avoid other barrier calls for this
-** same object.)
+** 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? */
+ 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));
- 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 */
}
}
@@ -168,33 +227,24 @@ void luaC_barrier_ (lua_State *L, GCObject *o, GCObject *v) {
** 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, Table *t) {
+void luaC_barrierback_ (lua_State *L, GCObject *o) {
global_State *g = G(L);
- lua_assert(isblack(t) && !isdead(g, t));
- black2gray(t); /* make table gray (again) */
- linkgclist(t, g->grayagain);
-}
-
-
-/*
-** barrier for assignments to closed upvalues. Because upvalues are
-** shared among closures, it is impossible to know the color of all
-** closures pointing to it. So, we assume that the object being assigned
-** must be marked.
-*/
-void luaC_upvalbarrier_ (lua_State *L, UpVal *uv) {
- global_State *g = G(L);
- GCObject *o = gcvalue(uv->v);
- lua_assert(!upisopen(uv)); /* ensured by macro luaC_upvalbarrier */
- if (keepinvariant(g))
- markobject(g, o);
+ 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! */
- 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 */
g->fixedgc = o;
@@ -227,55 +277,45 @@ 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.)
+** 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) {
- reentry:
- white2gray(o);
switch (o->tt) {
- case LUA_TSHRSTR: {
- gray2black(o);
- g->GCmemtrav += sizelstring(gco2ts(o)->shrlen);
+ case LUA_VSHRSTR:
+ case LUA_VLNGSTR: {
+ set2black(o); /* nothing to visit */
break;
}
- case LUA_TLNGSTR: {
- gray2black(o);
- g->GCmemtrav += sizelstring(gco2ts(o)->u.lnglen);
+ 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_TUSERDATA: {
- TValue uvalue;
- markobjectN(g, gco2u(o)->metatable); /* mark its metatable */
- gray2black(o);
- g->GCmemtrav += sizeudata(gco2u(o));
- getuservalue(g->mainthread, gco2u(o), &uvalue);
- if (valiswhite(&uvalue)) { /* markvalue(g, &uvalue); */
- o = gcvalue(&uvalue);
- goto reentry;
+ 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;
}
- break;
- }
- case LUA_TLCL: {
- linkgclist(gco2lcl(o), g->gray);
- break;
- }
- case LUA_TCCL: {
- linkgclist(gco2ccl(o), g->gray);
- break;
- }
- case LUA_TTABLE: {
- linkgclist(gco2t(o), g->gray);
- break;
- }
- case LUA_TTHREAD: {
- linkgclist(gco2th(o), g->gray);
- break;
- }
- case LUA_TPROTO: {
- linkgclist(gco2p(o), g->gray);
+ /* 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;
@@ -296,38 +336,58 @@ static void markmt (global_State *g) {
/*
** mark all objects in list of being-finalized
*/
-static void markbeingfnz (global_State *g) {
+static lu_mem markbeingfnz (global_State *g) {
GCObject *o;
- for (o = g->tobefnz; o != NULL; o = o->next)
+ lu_mem count = 0;
+ for (o = g->tobefnz; o != NULL; o = o->next) {
+ count++;
markobject(g, o);
+ }
+ return count;
}
/*
-** 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 void remarkupvals (global_State *g) {
+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) {
- lua_assert(!isblack(thread)); /* threads are never black */
- if (isgray(thread) && thread->openupval != 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) {
- if (uv->u.open.touched) {
- markvalue(g, uv->v); /* remark upvalue's value */
- uv->u.open.touched = 0;
+ 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;
}
@@ -335,8 +395,7 @@ static void remarkupvals (global_State *g) {
** 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);
@@ -352,6 +411,26 @@ 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
@@ -362,22 +441,21 @@ 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->sizearray > 0);
+ int hasclears = (h->alimit > 0);
for (n = gnode(h, 0); n < limit; n++) { /* traverse hash part */
- checkdeadkey(n);
- if (ttisnil(gval(n))) /* entry is empty? */
- removeentry(n); /* remove it */
+ if (isempty(gval(n))) /* entry is empty? */
+ clearkey(n); /* clear its key */
else {
- lua_assert(!ttisnil(gkey(n)));
- markvalue(g, gkey(n)); /* mark key */
- if (!hasclears && iscleared(g, gval(n))) /* is there a white value? */
+ 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 == GCSpropagate)
- linkgclist(h, g->grayagain); /* must retraverse it in atomic phase */
- else if (hasclears)
+ 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 */
}
@@ -389,27 +467,31 @@ 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 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) {
+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" */
- Node *n, *limit = gnodelast(h);
unsigned int i;
+ unsigned int asize = luaH_realasize(h);
+ unsigned int nsize = sizenode(h);
/* traverse array part */
- for (i = 0; i < h->sizearray; i++) {
+ for (i = 0; i < asize; i++) {
if (valiswhite(&h->array[i])) {
marked = 1;
reallymarkobject(g, gcvalue(&h->array[i]));
}
}
- /* traverse hash part */
- for (n = gnode(h, 0); n < limit; n++) {
- checkdeadkey(n);
- if (ttisnil(gval(n))) /* entry is empty? */
- removeentry(n); /* remove it */
- else if (iscleared(g, gkey(n))) { /* key is not marked (yet)? */
+ /* 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 */
@@ -426,6 +508,8 @@ static int traverseephemeron (global_State *g, Table *h) {
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;
}
@@ -433,18 +517,19 @@ static int traverseephemeron (global_State *g, Table *h) {
static void traversestrongtable (global_State *g, Table *h) {
Node *n, *limit = gnodelast(h);
unsigned int i;
- for (i = 0; i < h->sizearray; i++) /* traverse array part */
+ 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 */
- checkdeadkey(n);
- if (ttisnil(gval(n))) /* entry is empty? */
- removeentry(n); /* remove it */
+ if (isempty(gval(n))) /* entry is empty? */
+ clearkey(n); /* clear its key */
else {
- lua_assert(!ttisnil(gkey(n)));
- markvalue(g, gkey(n)); /* mark key */
- markvalue(g, gval(n)); /* mark value */
+ lua_assert(!keyisnil(n));
+ markkey(g, n);
+ markvalue(g, gval(n));
}
}
+ genlink(g, obj2gco(h));
}
@@ -453,21 +538,29 @@ static lu_mem traversetable (global_State *g, Table *h) {
const TValue *mode = gfasttm(g, h->metatable, TM_MODE);
markobjectN(g, h->metatable);
if (mode && ttisstring(mode) && /* is there a weak mode? */
- ((weakkey = strchr(svalue(mode), 'k')),
- (weakvalue = strchr(svalue(mode), 'v')),
+ (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? */
- traverseephemeron(g, h);
+ traverseephemeron(g, h, 0);
else /* all weak */
linkgclist(h, g->allweak); /* nothing to traverse now */
}
else /* not weak */
traversestrongtable(g, h);
- return sizeof(Table) + sizeof(TValue) * h->sizearray +
- sizeof(Node) * cast(size_t, allocsizenode(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;
}
@@ -478,8 +571,6 @@ static lu_mem traversetable (global_State *g, Table *h) {
*/
static int traverseproto (global_State *g, Proto *f) {
int i;
- if (f->cache && iswhite(f->cache))
- f->cache = NULL; /* allow cache to be collected */
markobjectN(g, f->source);
for (i = 0; i < f->sizek; i++) /* mark literals */
markvalue(g, &f->k[i]);
@@ -489,137 +580,125 @@ static int traverseproto (global_State *g, Proto *f) {
markobjectN(g, f->p[i]);
for (i = 0; i < f->sizelocvars; i++) /* mark local-variable names */
markobjectN(g, f->locvars[i].varname);
- return sizeof(Proto) + sizeof(Instruction) * f->sizecode +
- sizeof(Proto *) * f->sizep +
- sizeof(TValue) * f->sizek +
- sizeof(int) * f->sizelineinfo +
- sizeof(LocVar) * f->sizelocvars +
- sizeof(Upvaldesc) * f->sizeupvalues;
+ return 1 + f->sizek + f->sizeupvalues + f->sizep + f->sizelocvars;
}
-static lu_mem traverseCclosure (global_State *g, CClosure *cl) {
+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 sizeCclosure(cl->nupvalues);
+ return 1 + cl->nupvalues;
}
/*
-** open upvalues point to values in a thread, so those values should
-** be marked when the thread is traversed except in the atomic phase
-** (because then the value cannot be changed by the thread and the
-** thread may not be traversed again)
+** Traverse a Lua closure, marking its prototype and its upvalues.
+** (Both can be NULL while closure is being created.)
*/
-static lu_mem traverseLclosure (global_State *g, LClosure *cl) {
+static int traverseLclosure (global_State *g, LClosure *cl) {
int i;
markobjectN(g, cl->p); /* mark its prototype */
- for (i = 0; i < cl->nupvalues; i++) { /* mark its upvalues */
+ for (i = 0; i < cl->nupvalues; i++) { /* visit its upvalues */
UpVal *uv = cl->upvals[i];
- if (uv != NULL) {
- if (upisopen(uv) && g->gcstate != GCSinsideatomic)
- uv->u.open.touched = 1; /* can be marked in 'remarkupvals' */
- else
- markvalue(g, uv->v);
- }
+ markobjectN(g, uv); /* mark upvalue */
}
- return sizeLclosure(cl->nupvalues);
+ return 1 + cl->nupvalues;
}
-static lu_mem traversethread (global_State *g, lua_State *th) {
+/*
+** 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 == GCSinsideatomic ||
+ lua_assert(g->gcstate == GCSatomic ||
th->openupval == NULL || isintwups(th));
for (; o < th->top; o++) /* mark live elements in the stack */
- markvalue(g, o);
- if (g->gcstate == GCSinsideatomic) { /* final traversal? */
- StkId lim = th->stack + th->stacksize; /* real end of stack */
- for (; o < lim; o++) /* clear not-marked stack slice */
- setnilvalue(o);
+ 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->gckind != KGC_EMERGENCY)
+ else if (!g->gcemergency)
luaD_shrinkstack(th); /* do not change stack in emergency cycle */
- return (sizeof(lua_State) + sizeof(TValue) * th->stacksize +
- sizeof(CallInfo) * th->nci);
+ return 1 + stacksize(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 void propagatemark (global_State *g) {
- lu_mem size;
+static lu_mem propagatemark (global_State *g) {
GCObject *o = g->gray;
- lua_assert(isgray(o));
- gray2black(o);
+ nw2black(o);
+ g->gray = *getgclist(o); /* remove from 'gray' list */
switch (o->tt) {
- case LUA_TTABLE: {
- Table *h = gco2t(o);
- g->gray = h->gclist; /* remove from 'gray' list */
- size = traversetable(g, h);
- break;
- }
- case LUA_TLCL: {
- LClosure *cl = gco2lcl(o);
- g->gray = cl->gclist; /* remove from 'gray' list */
- size = traverseLclosure(g, cl);
- break;
- }
- case LUA_TCCL: {
- CClosure *cl = gco2ccl(o);
- g->gray = cl->gclist; /* remove from 'gray' list */
- size = traverseCclosure(g, cl);
- break;
- }
- case LUA_TTHREAD: {
- lua_State *th = gco2th(o);
- g->gray = th->gclist; /* remove from 'gray' list */
- linkgclist(th, g->grayagain); /* insert into 'grayagain' list */
- black2gray(o);
- size = traversethread(g, th);
- break;
- }
- case LUA_TPROTO: {
- Proto *p = gco2p(o);
- g->gray = p->gclist; /* remove from 'gray' list */
- size = traverseproto(g, p);
- break;
- }
- default: lua_assert(0); return;
+ 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;
}
- g->GCmemtrav += size;
}
-static void propagateall (global_State *g) {
- while (g->gray) propagatemark(g);
+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) {
- next = gco2t(w)->gclist;
- if (traverseephemeron(g, gco2t(w))) { /* traverse marked some value? */
+ 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 */
}
}
- } while (changed);
+ dir = !dir; /* invert direction next time */
+ } while (changed); /* repeat until no more changes */
}
/* }====================================================== */
@@ -633,18 +712,18 @@ static void convergeephemerons (global_State *g) {
/*
-** clear entries with unmarked keys from all weaktables in list 'l' up
-** to element 'f'
+** clear entries with unmarked keys from all weaktables in list 'l'
*/
-static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
- for (; l != f; l = gco2t(l)->gclist) {
+static void clearbykeys (global_State *g, GCObject *l) {
+ for (; l; l = gco2t(l)->gclist) {
Table *h = gco2t(l);
- Node *n, *limit = gnodelast(h);
+ Node *limit = gnodelast(h);
+ Node *n;
for (n = gnode(h, 0); n < limit; n++) {
- if (!ttisnil(gval(n)) && (iscleared(g, gkey(n)))) {
- setnilvalue(gval(n)); /* remove value ... */
- removeentry(n); /* and remove entry from table */
- }
+ if (iscleared(g, gckeyN(n))) /* unmarked key? */
+ setempty(gval(n)); /* remove entry */
+ if (isempty(gval(n))) /* is entry empty? */
+ clearkey(n); /* clear its key */
}
}
}
@@ -654,65 +733,72 @@ static void clearkeys (global_State *g, GCObject *l, GCObject *f) {
** clear entries with unmarked values from all weaktables in list 'l' up
** to element 'f'
*/
-static void clearvalues (global_State *g, GCObject *l, GCObject *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;
- for (i = 0; i < h->sizearray; i++) {
+ unsigned int asize = luaH_realasize(h);
+ for (i = 0; i < asize; i++) {
TValue *o = &h->array[i];
- if (iscleared(g, o)) /* value was collected? */
- setnilvalue(o); /* remove value */
+ if (iscleared(g, gcvalueN(o))) /* value was collected? */
+ setempty(o); /* remove entry */
}
for (n = gnode(h, 0); n < limit; n++) {
- if (!ttisnil(gval(n)) && iscleared(g, gval(n))) {
- setnilvalue(gval(n)); /* remove value ... */
- removeentry(n); /* and remove entry from table */
- }
+ 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 */
}
}
}
-void luaC_upvdeccount (lua_State *L, UpVal *uv) {
- lua_assert(uv->refcount > 0);
- uv->refcount--;
- if (uv->refcount == 0 && !upisopen(uv))
- luaM_free(L, uv);
-}
-
-
-static void freeLclosure (lua_State *L, LClosure *cl) {
- int i;
- for (i = 0; i < cl->nupvalues; i++) {
- UpVal *uv = cl->upvals[i];
- if (uv)
- luaC_upvdeccount(L, uv);
- }
- luaM_freemem(L, cl, sizeLclosure(cl->nupvalues));
+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_TPROTO: luaF_freeproto(L, gco2p(o)); break;
- case LUA_TLCL: {
- freeLclosure(L, gco2lcl(o));
+ 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_TCCL: {
- luaM_freemem(L, o, sizeCclosure(gco2ccl(o)->nupvalues));
+ case LUA_VCCL: {
+ CClosure *cl = gco2ccl(o);
+ luaM_freemem(L, cl, sizeCclosure(cl->nupvalues));
break;
}
- case LUA_TTABLE: luaH_free(L, gco2t(o)); break;
- case LUA_TTHREAD: luaE_freethread(L, gco2th(o)); break;
- case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
- case LUA_TSHRSTR:
- luaS_remove(L, gco2ts(o)); /* remove it from hash table */
- luaM_freemem(L, o, sizelstring(gco2ts(o)->shrlen));
+ case LUA_VTABLE:
+ luaH_free(L, gco2t(o));
+ break;
+ case LUA_VTHREAD:
+ luaE_freethread(L, gco2th(o));
break;
- case LUA_TLNGSTR: {
- luaM_freemem(L, o, sizelstring(gco2ts(o)->u.lnglen));
+ 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);
@@ -720,22 +806,20 @@ static void freeobj (lua_State *L, GCObject *o) {
}
-#define sweepwholelist(L,p) sweeplist(L,p,MAX_LUMEM)
-static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count);
-
-
/*
-** sweep at most 'count' elements from a list of GCObjects erasing dead
+** 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.
+** list is finished. ('*countout' gets the number of elements traversed.)
*/
-static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
+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 */
- while (*p != NULL && count-- > 0) {
+ for (i = 0; *p != NULL && i < countin; i++) {
GCObject *curr = *p;
int marked = curr->marked;
if (isdeadm(ow, marked)) { /* is 'curr' dead? */
@@ -743,10 +827,12 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
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 */
}
}
+ if (countout)
+ *countout = i; /* number of elements traversed */
return (*p == NULL) ? NULL : p;
}
@@ -757,7 +843,7 @@ static GCObject **sweeplist (lua_State *L, GCObject **p, lu_mem count) {
static GCObject **sweeptolive (lua_State *L, GCObject **p) {
GCObject **old = p;
do {
- p = sweeplist(L, p, 1);
+ p = sweeplist(L, p, 1, NULL);
} while (p == old);
return p;
}
@@ -772,18 +858,23 @@ static GCObject **sweeptolive (lua_State *L, GCObject **p) {
*/
/*
-** If possible, shrink string table
+** If possible, shrink string table.
*/
static void checkSizes (lua_State *L, global_State *g) {
- if (g->gckind != KGC_EMERGENCY) {
- l_mem olddebt = g->GCdebt;
- if (g->strt.nuse < g->strt.size / 4) /* string table too big? */
- luaS_resize(L, g->strt.size / 2); /* shrink it a little */
- g->GCestimate += g->GCdebt - olddebt; /* update estimate */
+ 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));
@@ -793,6 +884,8 @@ 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;
}
@@ -803,51 +896,42 @@ static void dothecall (lua_State *L, void *ud) {
}
-static void GCTM (lua_State *L, int propagateerrors) {
+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 (tm != NULL && ttisfunction(tm)) { /* is there a finalizer? */
+ if (!notm(tm)) { /* is there a finalizer? */
int status;
lu_byte oldah = L->allowhook;
- int running = g->gcrunning;
+ int oldgcstp = g->gcstp;
+ g->gcstp |= GCSTPGC; /* avoid GC steps */
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 + 1, &v); /* ... and its argument */
- L->top += 2; /* and (next line) call the finalizer */
+ 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 (status != LUA_OK && propagateerrors) { /* error while running __gc? */
- if (status == LUA_ERRRUN) { /* is there an error object? */
- const char *msg = (ttisstring(L->top - 1))
- ? svalue(L->top - 1)
- : "no message";
- luaO_pushfstring(L, "error in __gc metamethod (%s)", msg);
- status = LUA_ERRGCMM; /* error in __gc metamethod */
- }
- luaD_throw(L, status); /* re-throw error */
+ g->gcstp = oldgcstp; /* restore state */
+ if (l_unlikely(status != LUA_OK)) { /* error while running __gc? */
+ luaE_warnerror(L, "__gc");
+ L->top--; /* pops error object */
}
}
}
/*
-** call a few (up to 'g->gcfinnum') finalizers
+** Call a few finalizers
*/
-static int runafewfinalizers (lua_State *L) {
+static int runafewfinalizers (lua_State *L, int n) {
global_State *g = G(L);
- unsigned int i;
- lua_assert(!g->tobefnz || g->gcfinnum > 0);
- for (i = 0; g->tobefnz && i < g->gcfinnum; i++)
- GCTM(L, 1); /* call one finalizer */
- g->gcfinnum = (!g->tobefnz) ? 0 /* nothing more to finalize? */
- : g->gcfinnum * 2; /* else call a few more next time */
+ int i;
+ for (i = 0; i < n && g->tobefnz; i++)
+ GCTM(L); /* call one finalizer */
return i;
}
@@ -858,7 +942,7 @@ static int runafewfinalizers (lua_State *L) {
static void callallpendingfinalizers (lua_State *L) {
global_State *g = G(L);
while (g->tobefnz)
- GCTM(L, 0);
+ GCTM(L);
}
@@ -873,18 +957,23 @@ static GCObject **findlast (GCObject **p) {
/*
-** move all unreachable objects (or 'all' objects) that need
-** finalization from list 'finobj' to list 'tobefnz' (to be finalized)
+** 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) != NULL) { /* 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 */
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;
@@ -895,13 +984,35 @@ 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.
*/
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? */
+ gfasttm(g, mt, TM_GC) == NULL || /* or has no finalizer... */
+ (g->gcstp & GCSTPCLS)) /* or closing state? */
return; /* nothing to be done */
else { /* move 'o' to 'finobj' list */
GCObject **p;
@@ -910,6 +1021,8 @@ 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
+ 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 */
@@ -922,6 +1035,412 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
/* }====================================================== */
+/*
+** {======================================================
+** 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));
+}
+
+/* }====================================================== */
+
/*
** {======================================================
@@ -931,26 +1450,28 @@ void luaC_checkfinalizer (lua_State *L, GCObject *o, Table *mt) {
/*
-** Set a reasonable "time" to wait before starting a new GC cycle; cycle
-** will start when memory use hits threshold. (Division by 'estimate'
-** should be OK: it cannot be zero (because Lua cannot even start with
-** less than PAUSEADJ bytes).
+** 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 = (g->gcpause < MAX_LMEM / estimate) /* overflow? */
- ? estimate * g->gcpause /* no overflow */
+ 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 'sweeplist' tries to make pointer point to an object
+** 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.
@@ -959,140 +1480,161 @@ static void entersweep (lua_State *L) {
global_State *g = G(L);
g->gcstate = GCSswpallgc;
lua_assert(g->sweepgc == NULL);
- g->sweepgc = sweeplist(L, &g->allgc, 1);
+ 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);
+ g->gcstp = GCSTPCLS; /* no extra finalizers after here */
+ luaC_changemode(L, KGC_INC);
separatetobefnz(g, 1); /* separate all objects with finalizers */
lua_assert(g->finobj == NULL);
callallpendingfinalizers(L);
- lua_assert(g->tobefnz == NULL);
- g->currentwhite = WHITEBITS; /* this "white" makes all objects look dead */
- g->gckind = KGC_NORMAL;
- sweepwholelist(L, &g->finobj);
- sweepwholelist(L, &g->allgc);
- sweepwholelist(L, &g->fixedgc); /* collect fixed objects */
+ deletelist(L, g->allgc, obj2gco(g->mainthread));
+ lua_assert(g->finobj == NULL); /* no new finalizers */
+ deletelist(L, g->fixedgc, NULL); /* collect fixed objects */
lua_assert(g->strt.nuse == 0);
}
-static l_mem atomic (lua_State *L) {
+static lu_mem atomic (lua_State *L) {
global_State *g = G(L);
- l_mem work;
+ 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 = GCSinsideatomic;
- g->GCmemtrav = 0; /* start counting work */
+ 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 */
- remarkupvals(g);
- propagateall(g); /* propagate changes */
- work = g->GCmemtrav; /* stop counting (do not recount 'grayagain') */
+ work += remarkupvals(g);
+ work += propagateall(g); /* propagate changes */
g->gray = grayagain;
- propagateall(g); /* traverse 'grayagain' list */
- g->GCmemtrav = 0; /* restart counting */
+ 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 */
- clearvalues(g, g->weak, NULL);
- clearvalues(g, g->allweak, NULL);
+ clearbyvalues(g, g->weak, NULL);
+ clearbyvalues(g, g->allweak, NULL);
origweak = g->weak; origall = g->allweak;
- work += g->GCmemtrav; /* stop counting (objects being finalized) */
separatetobefnz(g, 0); /* separate objects to be finalized */
- g->gcfinnum = 1; /* there may be objects to be finalized */
- markbeingfnz(g); /* mark objects that will be finalized */
- propagateall(g); /* remark, to propagate 'resurrection' */
- g->GCmemtrav = 0; /* restart counting */
+ 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 */
- clearkeys(g, g->ephemeron, NULL); /* clear keys from all ephemeron tables */
- clearkeys(g, g->allweak, NULL); /* clear keys from all 'allweak' 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 */
- clearvalues(g, g->weak, origweak);
- clearvalues(g, g->allweak, origall);
+ clearbyvalues(g, g->weak, origweak);
+ clearbyvalues(g, g->allweak, origall);
luaS_clearcache(g);
g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */
- work += g->GCmemtrav; /* complete counting */
- return work; /* estimate of memory marked by 'atomic' */
+ lua_assert(g->gray == NULL);
+ return work; /* estimate of slots marked by 'atomic' */
}
-static lu_mem sweepstep (lua_State *L, global_State *g,
- int nextstate, GCObject **nextlist) {
+static int sweepstep (lua_State *L, global_State *g,
+ int nextstate, GCObject **nextlist) {
if (g->sweepgc) {
l_mem olddebt = g->GCdebt;
- g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX);
+ int count;
+ g->sweepgc = sweeplist(L, g->sweepgc, GCSWEEPMAX, &count);
g->GCestimate += g->GCdebt - olddebt; /* update estimate */
- if (g->sweepgc) /* is there still something to sweep? */
- return (GCSWEEPMAX * GCSWEEPCOST);
+ return count;
+ }
+ else { /* enter next state */
+ g->gcstate = nextstate;
+ g->sweepgc = nextlist;
+ return 0; /* no work done */
}
- /* else enter next state */
- g->gcstate = nextstate;
- g->sweepgc = nextlist;
- return 0;
}
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: {
- g->GCmemtrav = g->strt.size * sizeof(GCObject*);
restartcollection(g);
g->gcstate = GCSpropagate;
- return g->GCmemtrav;
+ work = 1;
+ break;
}
case GCSpropagate: {
- g->GCmemtrav = 0;
- lua_assert(g->gray);
- propagatemark(g);
- if (g->gray == NULL) /* no more gray objects? */
- g->gcstate = GCSatomic; /* finish propagate phase */
- return g->GCmemtrav; /* memory traversed in this step */
+ 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 GCSatomic: {
- lu_mem work;
- propagateall(g); /* make sure gray list is empty */
+ case GCSenteratomic: {
work = atomic(L); /* work is what was traversed by 'atomic' */
entersweep(L);
g->GCestimate = gettotalbytes(g); /* first estimate */;
- return work;
+ break;
}
case GCSswpallgc: { /* sweep "regular" objects */
- return sweepstep(L, g, GCSswpfinobj, &g->finobj);
+ work = sweepstep(L, g, GCSswpfinobj, &g->finobj);
+ break;
}
case GCSswpfinobj: { /* sweep objects with finalizers */
- return sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
+ work = sweepstep(L, g, GCSswptobefnz, &g->tobefnz);
+ break;
}
case GCSswptobefnz: { /* sweep objects to be finalized */
- return sweepstep(L, g, GCSswpend, NULL);
+ work = sweepstep(L, g, GCSswpend, NULL);
+ break;
}
case GCSswpend: { /* finish sweeps */
- makewhite(g, g->mainthread); /* sweep main thread */
checkSizes(L, g);
g->gcstate = GCScallfin;
- return 0;
+ work = 0;
+ break;
}
case GCScallfin: { /* call remaining finalizers */
- if (g->tobefnz && g->gckind != KGC_EMERGENCY) {
- int n = runafewfinalizers(L);
- return (n * GCFINALIZECOST);
+ 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 */
- return 0;
+ work = 0;
}
+ break;
}
default: lua_assert(0); return 0;
}
+ g->gcstopem = 0;
+ return work;
}
@@ -1107,72 +1649,83 @@ void luaC_runtilstate (lua_State *L, int statesmask) {
}
-/*
-** get GC debt and convert it from Kb to 'work units' (avoid zero debt
-** and overflows)
-*/
-static l_mem getdebt (global_State *g) {
- l_mem debt = g->GCdebt;
- int stepmul = g->gcstepmul;
- if (debt <= 0) return 0; /* minimal debt */
- else {
- debt = (debt / STEPMULADJ) + 1;
- debt = (debt < MAX_LMEM / stepmul) ? debt * stepmul : MAX_LMEM;
- return debt;
- }
-}
/*
-** performs a basic GC step when collector is running
+** 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.
*/
-void luaC_step (lua_State *L) {
- global_State *g = G(L);
- l_mem debt = getdebt(g); /* GC deficit (be paid now) */
- if (!g->gcrunning) { /* not running? */
- luaE_setdebt(g, -GCSTEPSIZE * 10); /* avoid being called too often */
- return;
- }
+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 > -GCSTEPSIZE && g->gcstate != GCSpause);
+ } while (debt > -stepsize && g->gcstate != GCSpause);
if (g->gcstate == GCSpause)
setpause(g); /* pause until next cycle */
else {
- debt = (debt / g->gcstepmul) * STEPMULADJ; /* convert 'work units' to Kb */
+ debt = (debt / stepmul) * WORK2MEM; /* convert 'work units' to bytes */
luaE_setdebt(g, debt);
- runafewfinalizers(L);
+ }
+}
+
+/*
+** 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 (gcrunning(g)) { /* running? */
+ if(isdecGCmodegen(g))
+ genstep(L, g);
+ else
+ incstep(L, 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).
+** 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).
*/
-void luaC_fullgc (lua_State *L, int isemergency) {
- global_State *g = G(L);
- lua_assert(g->gckind == KGC_NORMAL);
- if (isemergency) g->gckind = KGC_EMERGENCY; /* set flag */
- if (keepinvariant(g)) { /* black objects? */
+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(GCSpause)); /* start new collection */
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 */
- g->gckind = KGC_NORMAL;
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;
+}
+
/* }====================================================== */