1 /* 2 ** $Id: lstate.h $ 3 ** Global State 4 ** See Copyright Notice in lua.h 5 */ 6 7 #ifndef lstate_h 8 #define lstate_h 9 10 #include "lua.h" 11 12 #include "lobject.h" 13 #include "ltm.h" 14 #include "lzio.h" 15 16 17 /* 18 ** Some notes about garbage-collected objects: All objects in Lua must 19 ** be kept somehow accessible until being freed, so all objects always 20 ** belong to one (and only one) of these lists, using field 'next' of 21 ** the 'CommonHeader' for the link: 22 ** 23 ** 'allgc': all objects not marked for finalization; 24 ** 'finobj': all objects marked for finalization; 25 ** 'tobefnz': all objects ready to be finalized; 26 ** 'fixedgc': all objects that are not to be collected (currently 27 ** only small strings, such as reserved words). 28 ** 29 ** For the generational collector, some of these lists have marks for 30 ** generations. Each mark points to the first element in the list for 31 ** that particular generation; that generation goes until the next mark. 32 ** 33 ** 'allgc' -> 'survival': new objects; 34 ** 'survival' -> 'old': objects that survived one collection; 35 ** 'old1' -> 'reallyold': objects that became old in last collection; 36 ** 'reallyold' -> NULL: objects old for more than one cycle. 37 ** 38 ** 'finobj' -> 'finobjsur': new objects marked for finalization; 39 ** 'finobjsur' -> 'finobjold1': survived """"; 40 ** 'finobjold1' -> 'finobjrold': just old """"; 41 ** 'finobjrold' -> NULL: really old """". 42 ** 43 ** All lists can contain elements older than their main ages, due 44 ** to 'luaC_checkfinalizer' and 'udata2finalize', which move 45 ** objects between the normal lists and the "marked for finalization" 46 ** lists. Moreover, barriers can age young objects in young lists as 47 ** OLD0, which then become OLD1. However, a list never contains 48 ** elements younger than their main ages. 49 ** 50 ** The generational collector also uses a pointer 'firstold1', which 51 ** points to the first OLD1 object in the list. It is used to optimize 52 ** 'markold'. (Potentially OLD1 objects can be anywhere between 'allgc' 53 ** and 'reallyold', but often the list has no OLD1 objects or they are 54 ** after 'old1'.) Note the difference between it and 'old1': 55 ** 'firstold1': no OLD1 objects before this point; there can be all 56 ** ages after it. 57 ** 'old1': no objects younger than OLD1 after this point. 58 */ 59 60 /* 61 ** Moreover, there is another set of lists that control gray objects. 62 ** These lists are linked by fields 'gclist'. (All objects that 63 ** can become gray have such a field. The field is not the same 64 ** in all objects, but it always has this name.) Any gray object 65 ** must belong to one of these lists, and all objects in these lists 66 ** must be gray (with two exceptions explained below): 67 ** 68 ** 'gray': regular gray objects, still waiting to be visited. 69 ** 'grayagain': objects that must be revisited at the atomic phase. 70 ** That includes 71 ** - black objects got in a write barrier; 72 ** - all kinds of weak tables during propagation phase; 73 ** - all threads. 74 ** 'weak': tables with weak values to be cleared; 75 ** 'ephemeron': ephemeron tables with white->white entries; 76 ** 'allweak': tables with weak keys and/or weak values to be cleared. 77 ** 78 ** The exceptions to that "gray rule" are: 79 ** - TOUCHED2 objects in generational mode stay in a gray list (because 80 ** they must be visited again at the end of the cycle), but they are 81 ** marked black because assignments to them must activate barriers (to 82 ** move them back to TOUCHED1). 83 ** - Open upvales are kept gray to avoid barriers, but they stay out 84 ** of gray lists. (They don't even have a 'gclist' field.) 85 */ 86 87 88 89 /* 90 ** About 'nCcalls': each thread in Lua (a lua_State) keeps a count of 91 ** how many "C calls" it still can do in the C stack, to avoid C-stack 92 ** overflow. This count is very rough approximation; it considers only 93 ** recursive functions inside the interpreter, as non-recursive calls 94 ** can be considered using a fixed (although unknown) amount of stack 95 ** space. 96 ** 97 ** The count has two parts: the lower part is the count itself; the 98 ** higher part counts the number of non-yieldable calls in the stack. 99 ** (They are together so that we can change both with one instruction.) 100 ** 101 ** Because calls to external C functions can use an unknown amount 102 ** of space (e.g., functions using an auxiliary buffer), calls 103 ** to these functions add more than one to the count (see CSTACKCF). 104 ** 105 ** The proper count excludes the number of CallInfo structures allocated 106 ** by Lua, as a kind of "potential" calls. So, when Lua calls a function 107 ** (and "consumes" one CallInfo), it needs neither to decrement nor to 108 ** check 'nCcalls', as its use of C stack is already accounted for. 109 */ 110 111 /* number of "C stack slots" used by an external C function */ 112 #define CSTACKCF 10 113 114 115 /* 116 ** The C-stack size is sliced in the following zones: 117 ** - larger than CSTACKERR: normal stack; 118 ** - [CSTACKMARK, CSTACKERR]: buffer zone to signal a stack overflow; 119 ** - [CSTACKCF, CSTACKERRMARK]: error-handling zone; 120 ** - below CSTACKERRMARK: buffer zone to signal overflow during overflow; 121 ** (Because the counter can be decremented CSTACKCF at once, we need 122 ** the so called "buffer zones", with at least that size, to properly 123 ** detect a change from one zone to the next.) 124 */ 125 #define CSTACKERR (8 * CSTACKCF) 126 #define CSTACKMARK (CSTACKERR - (CSTACKCF + 2)) 127 #define CSTACKERRMARK (CSTACKCF + 2) 128 129 130 /* initial limit for the C-stack of threads */ 131 #define CSTACKTHREAD (2 * CSTACKERR) 132 133 134 /* true if this thread does not have non-yieldable calls in the stack */ 135 #define yieldable(L) (((L)->nCcalls & 0xffff0000) == 0) 136 137 /* real number of C calls */ 138 #define getCcalls(L) ((L)->nCcalls & 0xffff) 139 140 141 /* Increment the number of non-yieldable calls */ 142 #define incnny(L) ((L)->nCcalls += 0x10000) 143 144 /* Decrement the number of non-yieldable calls */ 145 #define decnny(L) ((L)->nCcalls -= 0x10000) 146 147 /* Increment the number of non-yieldable calls and decrement nCcalls */ 148 #define incXCcalls(L) ((L)->nCcalls += 0x10000 - CSTACKCF) 149 150 /* Decrement the number of non-yieldable calls and increment nCcalls */ 151 #define decXCcalls(L) ((L)->nCcalls -= 0x10000 - CSTACKCF) 152 153 154 155 156 157 158 struct lua_longjmp; /* defined in ldo.c */ 159 160 161 /* 162 ** Atomic type (relative to signals) to better ensure that 'lua_sethook' 163 ** is thread safe 164 */ 165 #if !defined(l_signalT) 166 #include <signal.h> 167 #define l_signalT sig_atomic_t 168 #endif 169 170 171 /* extra stack space to handle TM calls and some other extras */ 172 #define EXTRA_STACK 5 173 174 175 #define BASIC_STACK_SIZE (2*LUA_MINSTACK) 176 177 178 /* kinds of Garbage Collection */ 179 #define KGC_INC 0 /* incremental gc */ 180 #define KGC_GEN 1 /* generational gc */ 181 182 183 typedef struct stringtable { 184 TString **hash; 185 int nuse; /* number of elements */ 186 int size; 187 } stringtable; 188 189 190 /* 191 ** Information about a call. 192 */ 193 typedef struct CallInfo { 194 StkId func; /* function index in the stack */ 195 StkId top; /* top for this function */ 196 struct CallInfo *previous, *next; /* dynamic call link */ 197 union { 198 struct { /* only for Lua functions */ 199 const Instruction *savedpc; 200 volatile l_signalT trap; 201 int nextraargs; /* # of extra arguments in vararg functions */ 202 } l; 203 struct { /* only for C functions */ 204 lua_KFunction k; /* continuation in case of yields */ 205 ptrdiff_t old_errfunc; 206 lua_KContext ctx; /* context info. in case of yields */ 207 } c; 208 } u; 209 union { 210 int funcidx; /* called-function index */ 211 int nyield; /* number of values yielded */ 212 struct { /* info about transferred values (for call/return hooks) */ 213 unsigned short ftransfer; /* offset of first value transferred */ 214 unsigned short ntransfer; /* number of values transferred */ 215 } transferinfo; 216 } u2; 217 short nresults; /* expected number of results from this function */ 218 unsigned short callstatus; 219 } CallInfo; 220 221 222 /* 223 ** Bits in CallInfo status 224 */ 225 #define CIST_OAH (1<<0) /* original value of 'allowhook' */ 226 #define CIST_C (1<<1) /* call is running a C function */ 227 #define CIST_HOOKED (1<<2) /* call is running a debug hook */ 228 #define CIST_YPCALL (1<<3) /* call is a yieldable protected call */ 229 #define CIST_TAIL (1<<4) /* call was tail called */ 230 #define CIST_HOOKYIELD (1<<5) /* last hook called yielded */ 231 #define CIST_FIN (1<<6) /* call is running a finalizer */ 232 #define CIST_TRAN (1<<7) /* 'ci' has transfer information */ 233 #if defined(LUA_COMPAT_LT_LE) 234 #define CIST_LEQ (1<<8) /* using __lt for __le */ 235 #endif 236 237 /* active function is a Lua function */ 238 #define isLua(ci) (!((ci)->callstatus & CIST_C)) 239 240 /* call is running Lua code (not a hook) */ 241 #define isLuacode(ci) (!((ci)->callstatus & (CIST_C | CIST_HOOKED))) 242 243 /* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */ 244 #define setoah(st,v) ((st) = ((st) & ~CIST_OAH) | (v)) 245 #define getoah(st) ((st) & CIST_OAH) 246 247 248 /* 249 ** 'global state', shared by all threads of this state 250 */ 251 typedef struct global_State { 252 lua_Alloc frealloc; /* function to reallocate memory */ 253 void *ud; /* auxiliary data to 'frealloc' */ 254 l_mem totalbytes; /* number of bytes currently allocated - GCdebt */ 255 l_mem GCdebt; /* bytes allocated not yet compensated by the collector */ 256 lu_mem GCestimate; /* an estimate of the non-garbage memory in use */ 257 lu_mem lastatomic; /* see function 'genstep' in file 'lgc.c' */ 258 stringtable strt; /* hash table for strings */ 259 TValue l_registry; 260 TValue nilvalue; /* a nil value */ 261 unsigned int seed; /* randomized seed for hashes */ 262 lu_byte currentwhite; 263 lu_byte gcstate; /* state of garbage collector */ 264 lu_byte gckind; /* kind of GC running */ 265 lu_byte genminormul; /* control for minor generational collections */ 266 lu_byte genmajormul; /* control for major generational collections */ 267 lu_byte gcrunning; /* true if GC is running */ 268 lu_byte gcemergency; /* true if this is an emergency collection */ 269 lu_byte gcpause; /* size of pause between successive GCs */ 270 lu_byte gcstepmul; /* GC "speed" */ 271 lu_byte gcstepsize; /* (log2 of) GC granularity */ 272 GCObject *allgc; /* list of all collectable objects */ 273 GCObject **sweepgc; /* current position of sweep in list */ 274 GCObject *finobj; /* list of collectable objects with finalizers */ 275 GCObject *gray; /* list of gray objects */ 276 GCObject *grayagain; /* list of objects to be traversed atomically */ 277 GCObject *weak; /* list of tables with weak values */ 278 GCObject *ephemeron; /* list of ephemeron tables (weak keys) */ 279 GCObject *allweak; /* list of all-weak tables */ 280 GCObject *tobefnz; /* list of userdata to be GC */ 281 GCObject *fixedgc; /* list of objects not to be collected */ 282 /* fields for generational collector */ 283 GCObject *survival; /* start of objects that survived one GC cycle */ 284 GCObject *old1; /* start of old1 objects */ 285 GCObject *reallyold; /* objects more than one cycle old ("really old") */ 286 GCObject *firstold1; /* first OLD1 object in the list (if any) */ 287 GCObject *finobjsur; /* list of survival objects with finalizers */ 288 GCObject *finobjold1; /* list of old1 objects with finalizers */ 289 GCObject *finobjrold; /* list of really old objects with finalizers */ 290 struct lua_State *twups; /* list of threads with open upvalues */ 291 lua_CFunction panic; /* to be called in unprotected errors */ 292 struct lua_State *mainthread; 293 TString *memerrmsg; /* message for memory-allocation errors */ 294 TString *tmname[TM_N]; /* array with tag-method names */ 295 struct Table *mt[LUA_NUMTAGS]; /* metatables for basic types */ 296 TString *strcache[STRCACHE_N][STRCACHE_M]; /* cache for strings in API */ 297 lua_WarnFunction warnf; /* warning function */ 298 void *ud_warn; /* auxiliary data to 'warnf' */ 299 unsigned int Cstacklimit; /* current limit for the C stack */ 300 } global_State; 301 302 303 /* 304 ** 'per thread' state 305 */ 306 struct lua_State { 307 CommonHeader; 308 lu_byte status; 309 lu_byte allowhook; 310 unsigned short nci; /* number of items in 'ci' list */ 311 StkId top; /* first free slot in the stack */ 312 global_State *l_G; 313 CallInfo *ci; /* call info for current function */ 314 StkId stack_last; /* last free slot in the stack */ 315 StkId stack; /* stack base */ 316 UpVal *openupval; /* list of open upvalues in this stack */ 317 GCObject *gclist; 318 struct lua_State *twups; /* list of threads with open upvalues */ 319 struct lua_longjmp *errorJmp; /* current error recover point */ 320 CallInfo base_ci; /* CallInfo for first level (C calling Lua) */ 321 volatile lua_Hook hook; 322 ptrdiff_t errfunc; /* current error handling function (stack index) */ 323 l_uint32 nCcalls; /* number of allowed nested C calls - 'nci' */ 324 int oldpc; /* last pc traced */ 325 int stacksize; 326 int basehookcount; 327 int hookcount; 328 volatile l_signalT hookmask; 329 }; 330 331 332 #define G(L) (L->l_G) 333 334 335 /* 336 ** Union of all collectable objects (only for conversions) 337 ** ISO C99, 6.5.2.3 p.5: 338 ** "if a union contains several structures that share a common initial 339 ** sequence [...], and if the union object currently contains one 340 ** of these structures, it is permitted to inspect the common initial 341 ** part of any of them anywhere that a declaration of the complete type 342 ** of the union is visible." 343 */ 344 union GCUnion { 345 GCObject gc; /* common header */ 346 struct TString ts; 347 struct Udata u; 348 union Closure cl; 349 struct Table h; 350 struct Proto p; 351 struct lua_State th; /* thread */ 352 struct UpVal upv; 353 }; 354 355 356 /* 357 ** ISO C99, 6.7.2.1 p.14: 358 ** "A pointer to a union object, suitably converted, points to each of 359 ** its members [...], and vice versa." 360 */ 361 #define cast_u(o) cast(union GCUnion *, (o)) 362 363 /* macros to convert a GCObject into a specific value */ 364 #define gco2ts(o) \ 365 check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts)) 366 #define gco2u(o) check_exp((o)->tt == LUA_VUSERDATA, &((cast_u(o))->u)) 367 #define gco2lcl(o) check_exp((o)->tt == LUA_VLCL, &((cast_u(o))->cl.l)) 368 #define gco2ccl(o) check_exp((o)->tt == LUA_VCCL, &((cast_u(o))->cl.c)) 369 #define gco2cl(o) \ 370 check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl)) 371 #define gco2t(o) check_exp((o)->tt == LUA_VTABLE, &((cast_u(o))->h)) 372 #define gco2p(o) check_exp((o)->tt == LUA_VPROTO, &((cast_u(o))->p)) 373 #define gco2th(o) check_exp((o)->tt == LUA_VTHREAD, &((cast_u(o))->th)) 374 #define gco2upv(o) check_exp((o)->tt == LUA_VUPVAL, &((cast_u(o))->upv)) 375 376 377 /* 378 ** macro to convert a Lua object into a GCObject 379 ** (The access to 'tt' tries to ensure that 'v' is actually a Lua object.) 380 */ 381 #define obj2gco(v) check_exp((v)->tt >= LUA_TSTRING, &(cast_u(v)->gc)) 382 383 384 /* actual number of total bytes allocated */ 385 #define gettotalbytes(g) cast(lu_mem, (g)->totalbytes + (g)->GCdebt) 386 387 LUAI_FUNC void luaE_setdebt (global_State *g, l_mem debt); 388 LUAI_FUNC void luaE_freethread (lua_State *L, lua_State *L1); 389 LUAI_FUNC CallInfo *luaE_extendCI (lua_State *L); 390 LUAI_FUNC void luaE_freeCI (lua_State *L); 391 LUAI_FUNC void luaE_shrinkCI (lua_State *L); 392 LUAI_FUNC void luaE_enterCcall (lua_State *L); 393 LUAI_FUNC void luaE_warning (lua_State *L, const char *msg, int tocont); 394 LUAI_FUNC void luaE_warnerror (lua_State *L, const char *where); 395 396 397 #define luaE_exitCcall(L) ((L)->nCcalls++) 398 399 #endif 400 401