From a80cada9142f9e967c710e37934067a708224161 Mon Sep 17 00:00:00 2001 From: Roberto Ierusalimschy Date: Wed, 4 Mar 2015 10:31:21 -0300 Subject: [PATCH] new cache for interning strings --- lgc.c | 16 +++++++++++++++- llimits.h | 10 +++++++++- lstate.c | 10 ++-------- lstate.h | 3 ++- lstring.c | 34 +++++++++++++++++++++++++++++++--- lstring.h | 3 ++- 6 files changed, 61 insertions(+), 15 deletions(-) diff --git a/lgc.c b/lgc.c index 1695ea74..db4259e0 100644 --- a/lgc.c +++ b/lgc.c @@ -1,5 +1,5 @@ /* -** $Id: lgc.c,v 2.201 2014/12/20 13:58:15 roberto Exp roberto $ +** $Id: lgc.c,v 2.202 2015/01/16 16:54:37 roberto Exp roberto $ ** Garbage Collector ** See Copyright Notice in lua.h */ @@ -967,6 +967,19 @@ void luaC_freeallobjects (lua_State *L) { } +/* +** Clear API string cache. (Entries cannot be empty, so fill them with +** a non-collectable string.) +*/ +static void clearapihash (global_State *g) { + int i; + for (i = 0; i < STRCACHE_SIZE; i++) { + if (iswhite(g->strcache[i])) /* will entry be collected? */ + g->strcache[i] = g->memerrmsg; /* replace it with something fixed */ + } +} + + static l_mem atomic (lua_State *L) { global_State *g = G(L); l_mem work; @@ -1007,6 +1020,7 @@ static l_mem atomic (lua_State *L) { /* clear values from resurrected weak tables */ clearvalues(g, g->weak, origweak); clearvalues(g, g->allweak, origall); + clearapihash(g); g->currentwhite = cast_byte(otherwhite(g)); /* flip current white */ work += g->GCmemtrav; /* complete counting */ return work; /* estimate of memory marked by 'atomic' */ diff --git a/llimits.h b/llimits.h index 961ff53b..7ff282ca 100644 --- a/llimits.h +++ b/llimits.h @@ -1,5 +1,5 @@ /* -** $Id: llimits.h,v 1.131 2015/02/09 15:41:56 roberto Exp roberto $ +** $Id: llimits.h,v 1.132 2015/03/03 19:53:13 roberto Exp roberto $ ** Limits, basic types, and some other 'installation-dependent' definitions ** See Copyright Notice in lua.h */ @@ -187,6 +187,14 @@ typedef unsigned long Instruction; #endif +/* +** Size of cache for strings in the API (better be a prime) +*/ +#if !defined(STRCACHE_SIZE) +#define STRCACHE_SIZE 127 +#endif + + /* minimum size for string buffer */ #if !defined(LUA_MINBUFFER) #define LUA_MINBUFFER 32 diff --git a/lstate.c b/lstate.c index d42f0e82..3a9b8e98 100644 --- a/lstate.c +++ b/lstate.c @@ -1,5 +1,5 @@ /* -** $Id: lstate.c,v 2.126 2014/11/02 19:19:04 roberto Exp roberto $ +** $Id: lstate.c,v 2.127 2014/11/02 19:33:33 roberto Exp roberto $ ** Global State ** See Copyright Notice in lua.h */ @@ -37,9 +37,6 @@ #endif -#define MEMERRMSG "not enough memory" - - /* ** a macro to help the creation of a unique random seed when a state is ** created; the seed is used to randomize hashes. @@ -200,12 +197,9 @@ static void f_luaopen (lua_State *L, void *ud) { UNUSED(ud); stack_init(L, L); /* init stack */ init_registry(L, g); - luaS_resize(L, MINSTRTABSIZE); /* initial size of string table */ + luaS_init(L); luaT_init(L); luaX_init(L); - /* pre-create memory-error message */ - g->memerrmsg = luaS_newliteral(L, MEMERRMSG); - luaC_fix(L, obj2gco(g->memerrmsg)); /* it should never be collected */ g->gcrunning = 1; /* allow gc */ g->version = lua_version(NULL); luai_userstateopen(L); diff --git a/lstate.h b/lstate.h index fb2e91b4..285dfd82 100644 --- a/lstate.h +++ b/lstate.h @@ -1,5 +1,5 @@ /* -** $Id: lstate.h,v 2.118 2014/10/25 11:50:46 roberto Exp roberto $ +** $Id: lstate.h,v 2.119 2014/10/30 18:53:28 roberto Exp roberto $ ** Global State ** See Copyright Notice in lua.h */ @@ -140,6 +140,7 @@ typedef struct global_State { TString *memerrmsg; /* memory-error message */ TString *tmname[TM_N]; /* array with tag-method names */ struct Table *mt[LUA_NUMTAGS]; /* metatables for basic types */ + TString *strcache[STRCACHE_SIZE]; /* cache for strings in API */ } global_State; diff --git a/lstring.c b/lstring.c index 29e4630c..638f3dec 100644 --- a/lstring.c +++ b/lstring.c @@ -1,5 +1,5 @@ /* -** $Id: lstring.c,v 2.45 2014/11/02 19:19:04 roberto Exp roberto $ +** $Id: lstring.c,v 2.46 2015/01/16 16:54:37 roberto Exp roberto $ ** String table (keeps all strings handled by Lua) ** See Copyright Notice in lua.h */ @@ -22,6 +22,8 @@ #include "lstring.h" +#define MEMERRMSG "not enough memory" + /* ** Lua will use at most ~(2^LUAI_HASHLIMIT) bytes from a string to @@ -85,6 +87,21 @@ void luaS_resize (lua_State *L, int newsize) { } +/* +** Initialize the string table and the string cache +*/ +void luaS_init (lua_State *L) { + global_State *g = G(L); + int i; + luaS_resize(L, MINSTRTABSIZE); /* initial size of string table */ + /* pre-create memory-error message */ + g->memerrmsg = luaS_newliteral(L, MEMERRMSG); + luaC_fix(L, obj2gco(g->memerrmsg)); /* it should never be collected */ + for (i = 0; i < STRCACHE_SIZE; i++) + g->strcache[i] = g->memerrmsg; /* fill cache with valid strings */ +} + + /* ** creates a new string object @@ -163,10 +180,21 @@ TString *luaS_newlstr (lua_State *L, const char *str, size_t l) { /* -** new zero-terminated string +** Create or reuse a zero-terminated string, first checking in the +** cache (using the string address as a key). The cache can contain +** only zero-terminated strings, so it is safe to use 'strcmp' to +** check hits. */ TString *luaS_new (lua_State *L, const char *str) { - return luaS_newlstr(L, str, strlen(str)); + unsigned int i = point2uint(str) % STRCACHE_SIZE; /* hash */ + TString **p = &G(L)->strcache[i]; + if (strcmp(str, getstr(*p)) == 0) /* hit? */ + return *p; /* that it is */ + else { /* normal route */ + TString *s = luaS_newlstr(L, str, strlen(str)); + *p = s; + return s; + } } diff --git a/lstring.h b/lstring.h index 573daf9a..2b06afaf 100644 --- a/lstring.h +++ b/lstring.h @@ -1,5 +1,5 @@ /* -** $Id: lstring.h,v 1.56 2014/07/18 14:46:47 roberto Exp roberto $ +** $Id: lstring.h,v 1.57 2015/01/16 16:54:37 roberto Exp roberto $ ** String table (keep all strings handled by Lua) ** See Copyright Notice in lua.h */ @@ -36,6 +36,7 @@ LUAI_FUNC unsigned int luaS_hash (const char *str, size_t l, unsigned int seed); LUAI_FUNC int luaS_eqlngstr (TString *a, TString *b); LUAI_FUNC void luaS_resize (lua_State *L, int newsize); +LUAI_FUNC void luaS_init (lua_State *L); LUAI_FUNC void luaS_remove (lua_State *L, TString *ts); LUAI_FUNC Udata *luaS_newudata (lua_State *L, size_t s); LUAI_FUNC TString *luaS_newlstr (lua_State *L, const char *str, size_t l);