mirror of
https://github.com/cloudwu/skynet.git
synced 2026-07-22 11:03:12 +00:00
444 lines
10 KiB
C
444 lines
10 KiB
C
/*
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** $Id: lstring.c,v 2.49 2015/06/01 16:34:37 roberto Exp $
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** String table (keeps all strings handled by Lua)
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** See Copyright Notice in lua.h
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*/
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#define lstring_c
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#define LUA_CORE
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#include "lprefix.h"
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#include <string.h>
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#include "lua.h"
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#include "ldebug.h"
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#include "ldo.h"
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#include "lmem.h"
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#include "lobject.h"
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#include "lstate.h"
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#include "lstring.h"
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#define MEMERRMSG "not enough memory"
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/*
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** Lua will use at most ~(2^LUAI_HASHLIMIT) bytes from a string to
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** compute its hash
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*/
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#if !defined(LUAI_HASHLIMIT)
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#define LUAI_HASHLIMIT 5
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#endif
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/*
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** equality for long strings
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*/
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int luaS_eqlngstr (TString *a, TString *b) {
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size_t len = a->u.lnglen;
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lua_assert(a->tt == LUA_TLNGSTR && b->tt == LUA_TLNGSTR);
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return (a == b) || /* same instance or... */
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((len == b->u.lnglen) && /* equal length and ... */
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(memcmp(getstr(a), getstr(b), len) == 0)); /* equal contents */
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}
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unsigned int luaS_hash (const char *str, size_t l, unsigned int seed) {
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unsigned int h = seed ^ cast(unsigned int, l);
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size_t l1;
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size_t step = (l >> LUAI_HASHLIMIT) + 1;
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for (l1 = l; l1 >= step; l1 -= step)
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h = h ^ ((h<<5) + (h>>2) + cast_byte(str[l1 - 1]));
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return h;
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}
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/*
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** resizes the string table
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*/
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void luaS_resize (lua_State *L, int newsize) {
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int i;
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stringtable *tb = &G(L)->strt;
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if (newsize > tb->size) { /* grow table if needed */
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luaM_reallocvector(L, tb->hash, tb->size, newsize, TString *);
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for (i = tb->size; i < newsize; i++)
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tb->hash[i] = NULL;
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}
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for (i = 0; i < tb->size; i++) { /* rehash */
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TString *p = tb->hash[i];
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tb->hash[i] = NULL;
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while (p) { /* for each node in the list */
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TString *hnext = p->u.hnext; /* save next */
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unsigned int h = lmod(p->hash, newsize); /* new position */
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p->u.hnext = tb->hash[h]; /* chain it */
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tb->hash[h] = p;
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p = hnext;
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}
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}
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if (newsize < tb->size) { /* shrink table if needed */
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/* vanishing slice should be empty */
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lua_assert(tb->hash[newsize] == NULL && tb->hash[tb->size - 1] == NULL);
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luaM_reallocvector(L, tb->hash, tb->size, newsize, TString *);
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}
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tb->size = newsize;
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}
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/*
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** Clear API string cache. (Entries cannot be empty, so fill them with
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** a non-collectable string.)
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*/
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void luaS_clearcache (global_State *g) {
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int i;
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for (i = 0; i < STRCACHE_SIZE; i++) {
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if (iswhite(g->strcache[i][0])) /* will entry be collected? */
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g->strcache[i][0] = g->memerrmsg; /* replace it with something fixed */
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}
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}
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/*
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** Initialize the string table and the string cache
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*/
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void luaS_init (lua_State *L) {
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global_State *g = G(L);
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int i;
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luaS_resize(L, MINSTRTABSIZE); /* initial size of string table */
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/* pre-create memory-error message */
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g->memerrmsg = luaS_newliteral(L, MEMERRMSG);
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luaC_fix(L, obj2gco(g->memerrmsg)); /* it should never be collected */
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for (i = 0; i < STRCACHE_SIZE; i++) /* fill cache with valid strings */
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g->strcache[i][0] = g->memerrmsg;
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}
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/*
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** creates a new string object
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*/
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static TString *createstrobj (lua_State *L, const char *str, size_t l,
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int tag, unsigned int h) {
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TString *ts;
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GCObject *o;
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size_t totalsize; /* total size of TString object */
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totalsize = sizelstring(l);
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o = luaC_newobj(L, tag, totalsize);
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ts = gco2ts(o);
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ts->hash = h;
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ts->extra = 0;
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memcpy(getaddrstr(ts), str, l * sizeof(char));
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getaddrstr(ts)[l] = '\0'; /* ending 0 */
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return ts;
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}
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void luaS_remove (lua_State *L, TString *ts) {
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stringtable *tb = &G(L)->strt;
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TString **p = &tb->hash[lmod(ts->hash, tb->size)];
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while (*p != ts) /* find previous element */
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p = &(*p)->u.hnext;
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*p = (*p)->u.hnext; /* remove element from its list */
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tb->nuse--;
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}
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/*
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** checks whether short string exists and reuses it or creates a new one
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*/
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static TString *queryshrstr (lua_State *L, const char *str, size_t l, unsigned int h) {
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TString *ts;
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global_State *g = G(L);
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TString **list = &g->strt.hash[lmod(h, g->strt.size)];
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for (ts = *list; ts != NULL; ts = ts->u.hnext) {
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if (l == ts->shrlen &&
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(memcmp(str, getstr(ts), l * sizeof(char)) == 0)) {
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/* found! */
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if (isdead(g, ts)) /* dead (but not collected yet)? */
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changewhite(ts); /* resurrect it */
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return ts;
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}
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}
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return NULL;
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}
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static TString *addshrstr (lua_State *L, const char *str, size_t l, unsigned int h) {
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TString *ts;
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global_State *g = G(L);
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TString **list = &g->strt.hash[lmod(h, g->strt.size)];
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if (g->strt.nuse >= g->strt.size && g->strt.size <= MAX_INT/2) {
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luaS_resize(L, g->strt.size * 2);
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list = &g->strt.hash[lmod(h, g->strt.size)]; /* recompute with new size */
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}
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ts = createstrobj(L, str, l, LUA_TSHRSTR, h);
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ts->shrlen = cast_byte(l);
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ts->u.hnext = *list;
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*list = ts;
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g->strt.nuse++;
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return ts;
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}
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static TString *internshrstr (lua_State *L, const char *str, size_t l);
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/*
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** new string (with explicit length)
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*/
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TString *luaS_newlstr (lua_State *L, const char *str, size_t l) {
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if (l <= LUAI_MAXSHORTLEN) /* short string? */
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return internshrstr(L, str, l);
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else {
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TString *ts;
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if (l + 1 > (MAX_SIZE - sizeof(TString))/sizeof(char))
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luaM_toobig(L);
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ts = createstrobj(L, str, l, LUA_TLNGSTR, G(L)->seed);
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ts->u.lnglen = l;
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return ts;
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}
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}
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/*
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** Create or reuse a zero-terminated string, first checking in the
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** cache (using the string address as a key). The cache can contain
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** only zero-terminated strings, so it is safe to use 'strcmp' to
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** check hits.
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*/
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TString *luaS_new (lua_State *L, const char *str) {
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unsigned int i = point2uint(str) % STRCACHE_SIZE; /* hash */
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TString **p = G(L)->strcache[i];
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if (strcmp(str, getstr(p[0])) == 0) /* hit? */
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return p[0]; /* that it is */
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else { /* normal route */
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TString *s = luaS_newlstr(L, str, strlen(str));
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p[0] = s;
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return s;
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}
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}
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Udata *luaS_newudata (lua_State *L, size_t s) {
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Udata *u;
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GCObject *o;
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if (s > MAX_SIZE - sizeof(Udata))
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luaM_toobig(L);
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o = luaC_newobj(L, LUA_TUSERDATA, sizeludata(s));
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u = gco2u(o);
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u->len = s;
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u->metatable = NULL;
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setuservalue(L, u, luaO_nilobject);
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return u;
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}
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/*
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* global shared table
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*/
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#include "rwlock.h"
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#include "atomic.h"
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#include <stdlib.h>
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#define SHRSTR_SLOT 0x10000
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#define HASH_NODE(h) ((h) % SHRSTR_SLOT)
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struct shrmap_slot {
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struct rwlock lock;
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TString *str;
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};
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struct shrmap {
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struct shrmap_slot h[SHRSTR_SLOT];
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int n;
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};
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static struct shrmap SSM;
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LUA_API void
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luaS_initshr() {
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struct shrmap * s = &SSM;
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int i;
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for (i=0;i<SHRSTR_SLOT;i++) {
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rwlock_init(&s->h[i].lock);
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}
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}
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LUA_API void
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luaS_exitshr() {
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int i;
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for (i=0;i<SHRSTR_SLOT;i++) {
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TString *str = SSM.h[i].str;
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while (str) {
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TString * next = str->u.hnext;
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free(str);
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str = next;
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}
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}
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}
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static TString *
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query_string(unsigned int h, const char *str, lu_byte l) {
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struct shrmap_slot *s = &SSM.h[HASH_NODE(h)];
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rwlock_rlock(&s->lock);
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TString *ts = s->str;
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while (ts) {
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if (ts->hash == h &&
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ts->shrlen == l &&
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memcmp(str, ts+1, l) == 0) {
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break;
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}
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ts = ts->u.hnext;
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}
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rwlock_runlock(&s->lock);
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return ts;
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}
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static TString *
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query_ptr(TString *t) {
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unsigned int h = t->hash;
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struct shrmap_slot *s = &SSM.h[HASH_NODE(h)];
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rwlock_rlock(&s->lock);
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TString *ts = s->str;
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while (ts) {
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if (ts == t)
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break;
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ts = ts->u.hnext;
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}
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rwlock_runlock(&s->lock);
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return ts;
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}
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static TString *
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new_string(unsigned int h, const char *str, lu_byte l) {
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size_t sz = sizelstring(l);
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TString *ts = malloc(sz);
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memset(ts, 0, sz);
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ts->tt = LUA_TSHRSTR;
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ts->hash = h;
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ts->shrlen = l;
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memcpy(ts+1, str, l);
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return ts;
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}
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static TString *
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add_string(unsigned int h, const char *str, lu_byte l) {
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TString * tmp = new_string(h, str, l);
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struct shrmap_slot *s = &SSM.h[HASH_NODE(h)];
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rwlock_wlock(&s->lock);
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TString *ts = s->str;
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while (ts) {
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if (ts->hash == h &&
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ts->shrlen == l &&
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memcmp(str, ts+1, l) == 0) {
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break;
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}
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ts = ts->u.hnext;
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}
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if (ts == NULL) {
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ts = tmp;
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ts->u.hnext = s->str;
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s->str = ts;
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tmp = NULL;
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}
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rwlock_wunlock(&s->lock);
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if (tmp) {
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// string is create by other thread, so free tmp
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free(tmp);
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}
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return ts;
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}
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static TString *
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internshrstr (lua_State *L, const char *str, size_t l) {
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TString *ts;
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global_State *g = G(L);
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unsigned int h = luaS_hash(str, l, g->seed);
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unsigned int h0;
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// lookup global state of this L first
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ts = queryshrstr (L, str, l, h);
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if (ts)
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return ts;
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// lookup SSM again
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h0 = luaS_hash(str, l, 0);
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ts = query_string(h0, str, l);
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if (ts)
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return ts;
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// If SSM.n greate than 0, add it to SSM
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if (SSM.n > 0) {
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ATOM_DEC(&SSM.n);
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return add_string(h0, str, l);
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}
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// Else add it to global state (local)
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return addshrstr (L, str, l, h);
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}
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LUA_API void
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luaS_expandshr(int n) {
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ATOM_ADD(&SSM.n, n);
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}
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LUAI_FUNC TString *
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luaS_clonestring(lua_State *L, TString *ts) {
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unsigned int h;
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int l;
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const char * str = getaddrstr(ts);
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global_State *g = G(L);
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TString *result;
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if (ts->tt == LUA_TLNGSTR)
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return luaS_newlstr(L, str, ts->u.lnglen);
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// look up global state of this L first
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l = ts->shrlen;
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h = luaS_hash(str, l, g->seed);
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result = queryshrstr (L, str, l, h);
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if (result)
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return result;
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// look up SSM by ptr
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result = query_ptr(ts);
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if (result)
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return result;
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// ts is not in SSM, so recalc hash, and add it to SSM
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h = luaS_hash(str, l, 0);
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return add_string(h, str, l);
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}
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struct slotinfo {
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int len;
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int size;
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};
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static void
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getslot(struct shrmap_slot *s, struct slotinfo *info) {
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memset(info, 0, sizeof(*info));
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rwlock_rlock(&s->lock);
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TString *ts = s->str;
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while (ts) {
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++info->len;
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info->size += sizelstring(ts->shrlen);
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ts = ts->u.hnext;
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}
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rwlock_runlock(&s->lock);
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}
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LUA_API int
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luaS_shrinfo(lua_State *L) {
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struct slotinfo total;
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struct slotinfo tmp;
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memset(&total, 0, sizeof(total));
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int i;
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int len = 0;
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for (i=0;i<SHRSTR_SLOT;i++) {
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struct shrmap_slot *s = &SSM.h[i];
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getslot(s, &tmp);
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len += tmp.len;
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if (tmp.len > total.len) {
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total.len = tmp.len;
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}
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total.size += tmp.size;
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}
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lua_pushinteger(L, len);
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lua_pushinteger(L, total.size);
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lua_pushinteger(L, total.len);
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lua_pushinteger(L, SSM.n);
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return 4;
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}
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