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size of short strings stored in a single byte, to reduce the size

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of struct 'TString'
This commit is contained in:
Roberto Ierusalimschy
2015-01-16 14:54:37 -02:00
parent 5b01cb39b5
commit 7e2015a46d
9 changed files with 69 additions and 45 deletions
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10
lapi.c
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: lapi.c,v 2.243 2014/11/12 13:28:54 roberto Exp roberto $ ** $Id: lapi.c,v 2.244 2014/12/26 14:43:45 roberto Exp roberto $
** Lua API ** Lua API
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -382,15 +382,17 @@ LUA_API const char *lua_tolstring (lua_State *L, int idx, size_t *len) {
luaO_tostring(L, o); luaO_tostring(L, o);
lua_unlock(L); lua_unlock(L);
} }
if (len != NULL) *len = tsvalue(o)->len; if (len != NULL)
*len = vslen(o);
return svalue(o); return svalue(o);
} }
LUA_API size_t lua_rawlen (lua_State *L, int idx) { LUA_API size_t lua_rawlen (lua_State *L, int idx) {
StkId o = index2addr(L, idx); StkId o = index2addr(L, idx);
switch (ttnov(o)) { switch (ttype(o)) {
case LUA_TSTRING: return tsvalue(o)->len; case LUA_TSHRSTR: return tsvalue(o)->shrlen;
case LUA_TLNGSTR: return tsvalue(o)->u.lnglen;
case LUA_TUSERDATA: return uvalue(o)->len; case LUA_TUSERDATA: return uvalue(o)->len;
case LUA_TTABLE: return luaH_getn(hvalue(o)); case LUA_TTABLE: return luaH_getn(hvalue(o));
default: return 0; default: return 0;

4
ldump.c
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: ldump.c,v 2.33 2014/07/18 13:36:14 roberto Exp roberto $ ** $Id: ldump.c,v 2.34 2014/11/02 19:19:04 roberto Exp roberto $
** save precompiled Lua chunks ** save precompiled Lua chunks
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -74,7 +74,7 @@ static void DumpString (const TString *s, DumpState *D) {
if (s == NULL) if (s == NULL)
DumpByte(0, D); DumpByte(0, D);
else { else {
size_t size = s->len + 1; /* include trailing '\0' */ size_t size = tsslen(s) + 1; /* include trailing '\0' */
if (size < 0xFF) if (size < 0xFF)
DumpByte(cast_int(size), D); DumpByte(cast_int(size), D);
else { else {

15
lgc.c
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: lgc.c,v 2.200 2014/11/02 19:19:04 roberto Exp roberto $ ** $Id: lgc.c,v 2.201 2014/12/20 13:58:15 roberto Exp roberto $
** Garbage Collector ** Garbage Collector
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -226,10 +226,14 @@ static void reallymarkobject (global_State *g, GCObject *o) {
reentry: reentry:
white2gray(o); white2gray(o);
switch (o->tt) { switch (o->tt) {
case LUA_TSHRSTR: case LUA_TSHRSTR: {
gray2black(o);
g->GCmemtrav += sizelstring(gco2ts(o)->shrlen);
break;
}
case LUA_TLNGSTR: { case LUA_TLNGSTR: {
gray2black(o); gray2black(o);
g->GCmemtrav += sizestring(gco2ts(o)); g->GCmemtrav += sizelstring(gco2ts(o)->u.lnglen);
break; break;
} }
case LUA_TUSERDATA: { case LUA_TUSERDATA: {
@@ -689,9 +693,10 @@ static void freeobj (lua_State *L, GCObject *o) {
case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break; case LUA_TUSERDATA: luaM_freemem(L, o, sizeudata(gco2u(o))); break;
case LUA_TSHRSTR: case LUA_TSHRSTR:
luaS_remove(L, gco2ts(o)); /* remove it from hash table */ luaS_remove(L, gco2ts(o)); /* remove it from hash table */
/* go through */ luaM_freemem(L, o, sizelstring(gco2ts(o)->shrlen));
break;
case LUA_TLNGSTR: { case LUA_TLNGSTR: {
luaM_freemem(L, o, sizestring(gco2ts(o))); luaM_freemem(L, o, sizelstring(gco2ts(o)->u.lnglen));
break; break;
} }
default: lua_assert(0); default: lua_assert(0);

13
lobject.h
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: lobject.h,v 2.105 2014/12/19 13:36:32 roberto Exp roberto $ ** $Id: lobject.h,v 2.106 2015/01/05 13:52:37 roberto Exp roberto $
** Type definitions for Lua objects ** Type definitions for Lua objects
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -303,9 +303,12 @@ typedef TValue *StkId; /* index to stack elements */
typedef struct TString { typedef struct TString {
CommonHeader; CommonHeader;
lu_byte extra; /* reserved words for short strings; "has hash" for longs */ lu_byte extra; /* reserved words for short strings; "has hash" for longs */
lu_byte shrlen; /* length for short strings */
unsigned int hash; unsigned int hash;
size_t len; /* number of characters in string */ union {
size_t lnglen; /* length for long strings */
struct TString *hnext; /* linked list for hash table */ struct TString *hnext; /* linked list for hash table */
} u;
} TString; } TString;
@@ -329,6 +332,12 @@ typedef union UTString {
/* get the actual string (array of bytes) from a Lua value */ /* get the actual string (array of bytes) from a Lua value */
#define svalue(o) getstr(tsvalue(o)) #define svalue(o) getstr(tsvalue(o))
/* get string length from 'TString *s' */
#define tsslen(s) ((s)->tt == LUA_TSHRSTR ? (s)->shrlen : (s)->u.lnglen)
/* get string length from 'TValue *o' */
#define vslen(o) tsslen(tsvalue(o))
/* /*
** Header for userdata; memory area follows the end of this structure ** Header for userdata; memory area follows the end of this structure

27
lstring.c
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: lstring.c,v 2.44 2014/07/21 16:02:10 roberto Exp roberto $ ** $Id: lstring.c,v 2.45 2014/11/02 19:19:04 roberto Exp roberto $
** String table (keeps all strings handled by Lua) ** String table (keeps all strings handled by Lua)
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -36,10 +36,10 @@
** equality for long strings ** equality for long strings
*/ */
int luaS_eqlngstr (TString *a, TString *b) { int luaS_eqlngstr (TString *a, TString *b) {
size_t len = a->len; size_t len = a->u.lnglen;
lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR); lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR);
return (a == b) || /* same instance or... */ return (a == b) || /* same instance or... */
((len == b->len) && /* equal length and ... */ ((len == b->u.lnglen) && /* equal length and ... */
(memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */ (memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */
} }
@@ -69,9 +69,9 @@ void luaS_resize (lua_State *L, int newsize) {
TString *p = tb->hash[i]; TString *p = tb->hash[i];
tb->hash[i] = NULL; tb->hash[i] = NULL;
while (p) { /* for each node in the list */ while (p) { /* for each node in the list */
TString *hnext = p->hnext; /* save next */ TString *hnext = p->u.hnext; /* save next */
unsigned int h = lmod(p->hash, newsize); /* new position */ unsigned int h = lmod(p->hash, newsize); /* new position */
p->hnext = tb->hash[h]; /* chain it */ p->u.hnext = tb->hash[h]; /* chain it */
tb->hash[h] = p; tb->hash[h] = p;
p = hnext; p = hnext;
} }
@@ -97,7 +97,6 @@ static TString *createstrobj (lua_State *L, const char *str, size_t l,
totalsize = sizelstring(l); totalsize = sizelstring(l);
o = luaC_newobj(L, tag, totalsize); o = luaC_newobj(L, tag, totalsize);
ts = gco2ts(o); ts = gco2ts(o);
ts->len = l;
ts->hash = h; ts->hash = h;
ts->extra = 0; ts->extra = 0;
memcpy(getaddrstr(ts), str, l * sizeof(char)); memcpy(getaddrstr(ts), str, l * sizeof(char));
@@ -110,8 +109,8 @@ void luaS_remove (lua_State *L, TString *ts) {
stringtable *tb = &G(L)->strt; stringtable *tb = &G(L)->strt;
TString **p = &tb->hash[lmod(ts->hash, tb->size)]; TString **p = &tb->hash[lmod(ts->hash, tb->size)];
while (*p != ts) /* find previous element */ while (*p != ts) /* find previous element */
p = &(*p)->hnext; p = &(*p)->u.hnext;
*p = (*p)->hnext; /* remove element from its list */ *p = (*p)->u.hnext; /* remove element from its list */
tb->nuse--; tb->nuse--;
} }
@@ -124,8 +123,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
global_State *g = G(L); global_State *g = G(L);
unsigned int h = luaS_hash(str, l, g->seed); unsigned int h = luaS_hash(str, l, g->seed);
TString **list = &g->strt.hash[lmod(h, g->strt.size)]; TString **list = &g->strt.hash[lmod(h, g->strt.size)];
for (ts = *list; ts != NULL; ts = ts->hnext) { for (ts = *list; ts != NULL; ts = ts->u.hnext) {
if (l == ts->len && if (l == ts->shrlen &&
(memcmp(str, getstr(ts), l * sizeof(char)) == 0)) { (memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
/* found! */ /* found! */
if (isdead(g, ts)) /* dead (but not collected yet)? */ if (isdead(g, ts)) /* dead (but not collected yet)? */
@@ -138,7 +137,8 @@ static TString *internshrstr (lua_State *L, const char *str, size_t l) {
list = &g->strt.hash[lmod(h, g->strt.size)]; /* recompute with new size */ list = &g->strt.hash[lmod(h, g->strt.size)]; /* recompute with new size */
} }
ts = createstrobj(L, str, l, LUA_TSHRSTR, h); ts = createstrobj(L, str, l, LUA_TSHRSTR, h);
ts->hnext = *list; ts->shrlen = cast_byte(l);
ts->u.hnext = *list;
*list = ts; *list = ts;
g->strt.nuse++; g->strt.nuse++;
return ts; return ts;
@@ -152,9 +152,12 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
if (l <= LUAI_MAXSHORTLEN) /* short string? */ if (l <= LUAI_MAXSHORTLEN) /* short string? */
return internshrstr(L, str, l); return internshrstr(L, str, l);
else { else {
TString *ts;
if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char)) if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char))
luaM_toobig(L); luaM_toobig(L);
return createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed); ts = createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
ts->u.lnglen = l;
return ts;
} }
} }

3
lstring.h
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: lstring.h,v 1.54 2014/03/19 18:51:42 roberto Exp roberto $ ** $Id: lstring.h,v 1.56 2014/07/18 14:46:47 roberto Exp roberto $
** String table (keep all strings handled by Lua) ** String table (keep all strings handled by Lua)
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -13,7 +13,6 @@
#define sizelstring(l) (sizeof(union UTString) + ((l) + 1) * sizeof(char)) #define sizelstring(l) (sizeof(union UTString) + ((l) + 1) * sizeof(char))
#define sizestring(s) sizelstring((s)->len)
#define sizeludata(l) (sizeof(union UUdata) + (l)) #define sizeludata(l) (sizeof(union UUdata) + (l))
#define sizeudata(u) sizeludata((u)->len) #define sizeudata(u) sizeludata((u)->len)

4
ltable.c
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: ltable.c,v 2.99 2014/11/02 19:19:04 roberto Exp roberto $ ** $Id: ltable.c,v 2.100 2015/01/05 13:52:37 roberto Exp roberto $
** Lua tables (hash) ** Lua tables (hash)
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -127,7 +127,7 @@ static Node *mainposition (const Table *t, const TValue *key) {
case LUA_TLNGSTR: { case LUA_TLNGSTR: {
TString *s = tsvalue(key); TString *s = tsvalue(key);
if (s->extra == 0) { /* no hash? */ if (s->extra == 0) { /* no hash? */
s->hash = luaS_hash(getstr(s), s->len, s->hash); s->hash = luaS_hash(getstr(s), s->u.lnglen, s->hash);
s->extra = 1; /* now it has its hash */ s->extra = 1; /* now it has its hash */
} }
return hashstr(t, tsvalue(key)); return hashstr(t, tsvalue(key));

4
ltests.c
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: ltests.c,v 2.200 2014/12/10 11:30:51 roberto Exp roberto $ ** $Id: ltests.c,v 2.201 2014/12/18 12:13:42 roberto Exp roberto $
** Internal Module for Debugging of the Lua Implementation ** Internal Module for Debugging of the Lua Implementation
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -724,7 +724,7 @@ static int string_query (lua_State *L) {
else if (s < tb->size) { else if (s < tb->size) {
TString *ts; TString *ts;
int n = 0; int n = 0;
for (ts = tb->hash[s]; ts != NULL; ts = ts->hnext) { for (ts = tb->hash[s]; ts != NULL; ts = ts->u.hnext) {
setsvalue2s(L, L->top, ts); setsvalue2s(L, L->top, ts);
api_incr_top(L); api_incr_top(L);
n++; n++;

32
lvm.c
View File

@@ -1,5 +1,5 @@
/* /*
** $Id: lvm.c,v 2.231 2014/12/19 13:36:32 roberto Exp roberto $ ** $Id: lvm.c,v 2.232 2014/12/27 20:30:38 roberto Exp roberto $
** Lua virtual machine ** Lua virtual machine
** See Copyright Notice in lua.h ** See Copyright Notice in lua.h
*/ */
@@ -73,7 +73,7 @@ int luaV_tonumber_ (const TValue *obj, lua_Number *n) {
return 1; return 1;
} }
else if (cvt2num(obj) && /* string convertible to number? */ else if (cvt2num(obj) && /* string convertible to number? */
luaO_str2num(svalue(obj), &v) == tsvalue(obj)->len + 1) { luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
*n = nvalue(&v); /* convert result of 'luaO_str2num' to a float */ *n = nvalue(&v); /* convert result of 'luaO_str2num' to a float */
return 1; return 1;
} }
@@ -106,7 +106,7 @@ static int tointeger_aux (const TValue *obj, lua_Integer *p, int mode) {
return 1; return 1;
} }
else if (cvt2num(obj) && else if (cvt2num(obj) &&
luaO_str2num(svalue(obj), &v) == tsvalue(obj)->len + 1) { luaO_str2num(svalue(obj), &v) == vslen(obj) + 1) {
obj = &v; obj = &v;
goto again; /* convert result from 'luaO_str2num' to an integer */ goto again; /* convert result from 'luaO_str2num' to an integer */
} }
@@ -239,9 +239,9 @@ void luaV_settable (lua_State *L, const TValue *t, TValue *key, StkId val) {
*/ */
static int l_strcmp (const TString *ls, const TString *rs) { static int l_strcmp (const TString *ls, const TString *rs) {
const char *l = getstr(ls); const char *l = getstr(ls);
size_t ll = ls->len; size_t ll = tsslen(ls);
const char *r = getstr(rs); const char *r = getstr(rs);
size_t lr = rs->len; size_t lr = tsslen(rs);
for (;;) { /* for each segment */ for (;;) { /* for each segment */
int temp = strcoll(l, r); int temp = strcoll(l, r);
if (temp != 0) /* not equal? */ if (temp != 0) /* not equal? */
@@ -354,6 +354,8 @@ int luaV_equalobj (lua_State *L, const TValue *t1, const TValue *t2) {
#define tostring(L,o) \ #define tostring(L,o) \
(ttisstring(o) || (cvt2str(o) && (luaO_tostring(L, o), 1))) (ttisstring(o) || (cvt2str(o) && (luaO_tostring(L, o), 1)))
#define isemptystr(o) (ttisshrstring(o) && tsvalue(o)->shrlen == 0)
/* /*
** Main operation for concatenation: concat 'total' values in the stack, ** Main operation for concatenation: concat 'total' values in the stack,
** from 'L->top - total' up to 'L->top - 1'. ** from 'L->top - total' up to 'L->top - 1'.
@@ -365,19 +367,19 @@ void luaV_concat (lua_State *L, int total) {
int n = 2; /* number of elements handled in this pass (at least 2) */ int n = 2; /* number of elements handled in this pass (at least 2) */
if (!(ttisstring(top-2) || cvt2str(top-2)) || !tostring(L, top-1)) if (!(ttisstring(top-2) || cvt2str(top-2)) || !tostring(L, top-1))
luaT_trybinTM(L, top-2, top-1, top-2, TM_CONCAT); luaT_trybinTM(L, top-2, top-1, top-2, TM_CONCAT);
else if (tsvalue(top-1)->len == 0) /* second operand is empty? */ else if (isemptystr(top - 1)) /* second operand is empty? */
cast_void(tostring(L, top - 2)); /* result is first operand */ cast_void(tostring(L, top - 2)); /* result is first operand */
else if (ttisstring(top-2) && tsvalue(top-2)->len == 0) { else if (isemptystr(top - 2)) { /* first operand is an empty string? */
setobjs2s(L, top - 2, top - 1); /* result is second op. */ setobjs2s(L, top - 2, top - 1); /* result is second op. */
} }
else { else {
/* at least two non-empty string values; get as many as possible */ /* at least two non-empty string values; get as many as possible */
size_t tl = tsvalue(top-1)->len; size_t tl = vslen(top - 1);
char *buffer; char *buffer;
int i; int i;
/* collect total length */ /* collect total length */
for (i = 1; i < total && tostring(L, top-i-1); i++) { for (i = 1; i < total && tostring(L, top-i-1); i++) {
size_t l = tsvalue(top-i-1)->len; size_t l = vslen(top - i - 1);
if (l >= (MAX_SIZE/sizeof(char)) - tl) if (l >= (MAX_SIZE/sizeof(char)) - tl)
luaG_runerror(L, "string length overflow"); luaG_runerror(L, "string length overflow");
tl += l; tl += l;
@@ -386,7 +388,7 @@ void luaV_concat (lua_State *L, int total) {
tl = 0; tl = 0;
n = i; n = i;
do { /* copy all strings to buffer */ do { /* copy all strings to buffer */
size_t l = tsvalue(top-i)->len; size_t l = vslen(top - i);
memcpy(buffer+tl, svalue(top-i), l * sizeof(char)); memcpy(buffer+tl, svalue(top-i), l * sizeof(char));
tl += l; tl += l;
} while (--i > 0); } while (--i > 0);
@@ -403,7 +405,7 @@ void luaV_concat (lua_State *L, int total) {
*/ */
void luaV_objlen (lua_State *L, StkId ra, const TValue *rb) { void luaV_objlen (lua_State *L, StkId ra, const TValue *rb) {
const TValue *tm; const TValue *tm;
switch (ttnov(rb)) { switch (ttype(rb)) {
case LUA_TTABLE: { case LUA_TTABLE: {
Table *h = hvalue(rb); Table *h = hvalue(rb);
tm = fasttm(L, h->metatable, TM_LEN); tm = fasttm(L, h->metatable, TM_LEN);
@@ -411,8 +413,12 @@ void luaV_objlen (lua_State *L, StkId ra, const TValue *rb) {
setivalue(ra, luaH_getn(h)); /* else primitive len */ setivalue(ra, luaH_getn(h)); /* else primitive len */
return; return;
} }
case LUA_TSTRING: { case LUA_TSHRSTR: {
setivalue(ra, tsvalue(rb)->len); setivalue(ra, tsvalue(rb)->shrlen);
return;
}
case LUA_TLNGSTR: {
setivalue(ra, tsvalue(rb)->u.lnglen);
return; return;
} }
default: { /* try metamethod */ default: { /* try metamethod */