mirror of https://github.com/lua/lua
weak keys are removed only after finalization
This commit is contained in:
Roberto Ierusalimschy
parent
5fabed21a1
commit
9f4b5b5232
54
lgc.c
54
lgc.c
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@ -1,5 +1,5 @@
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/*
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** $Id: lgc.c,v 1.138 2002/06/24 17:19:43 roberto Exp roberto $
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** $Id: lgc.c,v 1.139 2002/06/25 19:17:42 roberto Exp roberto $
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** Garbage Collector
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** See Copyright Notice in lua.h
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*/
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@ -31,6 +31,17 @@ typedef struct GCState {
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#define strmark(s) {if ((s)->tsv.marked == 0) (s)->tsv.marked = 1;}
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/* unmarked tables are represented by pointing `mark' to themselves */
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#define ismarked(x) ((x)->mark != (x))
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/* `Table.flag' bits to indicate whether table is key-weak and/or value-weak */
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#define KEYWEAKBIT (TM_MODE+1) /* ORDER TM */
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#define VALUEWEAKBIT (TM_MODE+2)
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#define KEYWEAK (1<<KEYWEAKBIT)
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#define VALUEWEAK (1<<VALUEWEAKBIT)
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/* mark tricks for userdata */
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#define isudmarked(u) (u->uv.len & 1)
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#define markud(u) (u->uv.len |= 1)
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@ -202,8 +213,8 @@ static void separateudata (lua_State *L) {
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static void removekey (Node *n) {
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lua_assert(ttype(val(n)) == LUA_TNIL);
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if (ttype(key(n)) != LUA_TNIL && ttype(key(n)) != LUA_TNUMBER)
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setnilvalue(val(n)); /* remove corresponding value ... */
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if (ismarkable(key(n)))
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setttype(key(n), LUA_TNONE); /* dead key; remove it */
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}
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@ -221,6 +232,8 @@ static void traversetable (GCState *st, Table *h) {
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st->toclear = h; /* ...put in the appropriate list */
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weakkey = (strchr(svalue(mode), 'k') != NULL);
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weakvalue = (strchr(svalue(mode), 'v') != NULL);
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h->flags &= ~(KEYWEAK | VALUEWEAK); /* clear bits */
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h->flags |= (weakkey << KEYWEAKBIT) | (weakvalue << VALUEWEAKBIT);
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}
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if (!weakvalue) {
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i = sizearray(h);
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@ -265,11 +278,33 @@ static int hasmark (const TObject *o) {
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/*
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** clear (set to nil) keys and values from weaktables that were collected
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** clear collected keys from weaktables
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*/
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static void cleartables (Table *h) {
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for (; h; h = h->mark) {
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static void cleartablekeys (GCState *st) {
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Table *h;
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for (h = st->toclear; h; h = h->mark) {
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int i;
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if (!(h->flags & KEYWEAK)) continue;
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lua_assert(strchr(svalue(fasttm(st->L, h->metatable, TM_MODE)), 'k'));
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i = sizenode(h);
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while (i--) {
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Node *n = node(h, i);
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if (!hasmark(key(n)))
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removekey(n); /* ... and key */
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}
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}
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}
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/*
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** clear collected values from weaktables
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*/
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static void cleartablevalues (GCState *st) {
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Table *h;
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for (h = st->toclear; h; h = h->mark) {
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int i;
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if (!(h->flags & VALUEWEAK)) continue;
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lua_assert(strchr(svalue(fasttm(st->L, h->metatable, TM_MODE)), 'v'));
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i = sizearray(h);
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while (i--) {
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TObject *o = &h->array[i];
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@ -279,10 +314,8 @@ static void cleartables (Table *h) {
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i = sizenode(h);
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while (i--) {
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Node *n = node(h, i);
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if (!hasmark(val(n)) || !hasmark(key(n))) {
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setnilvalue(val(n)); /* remove value ... */
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if (!hasmark(val(n)))
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removekey(n); /* ... and key */
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}
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}
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}
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}
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@ -458,10 +491,11 @@ void luaC_collectgarbage (lua_State *L) {
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st.toclear = NULL;
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markstacks(&st); /* mark all stacks */
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propagatemarks(&st); /* mark all reachable objects */
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cleartables(st.toclear);
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cleartablevalues(&st);
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separateudata(L); /* separate userdata to be preserved */
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marktmu(&st); /* mark `preserved' userdata */
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propagatemarks(&st); /* remark */
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cleartablekeys(&st);
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luaC_collect(L, 0);
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checkMbuffer(L);
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G(L)->GCthreshold = 2*G(L)->nblocks; /* new threshold */
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@ -1,5 +1,5 @@
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/*
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** $Id: lobject.h,v 1.137 2002/06/24 13:08:45 roberto Exp roberto $
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** $Id: lobject.h,v 1.138 2002/06/24 20:17:59 roberto Exp roberto $
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** Type definitions for Lua objects
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** See Copyright Notice in lua.h
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*/
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@ -217,9 +217,6 @@ typedef struct Table {
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} Table;
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/* unmarked tables are represented by pointing `mark' to themselves */
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#define ismarked(x) ((x)->mark != (x))
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/*
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** `module' operation for hashing (size is always a power of 2)
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9
ltm.h
9
ltm.h
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@ -1,5 +1,5 @@
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/*
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** $Id: ltm.h,v 1.36 2002/06/24 20:17:59 roberto Exp roberto $
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** $Id: ltm.h,v 1.37 2002/06/25 19:17:22 roberto Exp roberto $
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** Tag methods
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** See Copyright Notice in lua.h
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*/
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@ -10,6 +10,13 @@
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#include "lobject.h"
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/*
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** Important: garbage collection uses two extra bits of `Table.flags'
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** (after TM_MODE), so the maximum number of `fast tag methods' is six
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** (at least while `flags' is a byte).
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*/
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/*
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* WARNING: if you change the order of this enumeration,
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* grep "ORDER TM"
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