liblua/lstate.h

   1 /*
   2 ** $Id: lstate.h,v 2.82 2012/07/02 13:37:04 roberto Exp $
   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
  19 ** Some notes about garbage-collected objects:  All objects in Lua must
  20 ** be kept somehow accessible until being freed.
  21 **
  22 ** Lua keeps most objects linked in list g->allgc. The link uses field
  23 ** 'next' of the CommonHeader.
  24 **
  25 ** Strings are kept in several lists headed by the array g->strt.hash.
  26 **
  27 ** Open upvalues are not subject to independent garbage collection. They
  28 ** are collected together with their respective threads. Lua keeps a
  29 ** double-linked list with all open upvalues (g->uvhead) so that it can
  30 ** mark objects referred by them. (They are always gray, so they must
  31 ** be remarked in the atomic step. Usually their contents would be marked
  32 ** when traversing the respective threads, but the thread may already be
  33 ** dead, while the upvalue is still accessible through closures.)
  34 **
  35 ** Objects with finalizers are kept in the list g->finobj.
  36 **
  37 ** The list g->tobefnz links all objects being finalized.
  38
  39 */
  40
  41
  42 struct lua_longjmp;  /* defined in ldo.c */
  43
  44
  45
  46 /* extra stack space to handle TM calls and some other extras */
  47 #define EXTRA_STACK   5
  48
  49
  50 #define BASIC_STACK_SIZE        (2*LUA_MINSTACK)
  51
  52
  53 /* kinds of Garbage Collection */
  54 #define KGC_NORMAL      0
  55 #define KGC_EMERGENCY   1       /* gc was forced by an allocation failure */
  56 #define KGC_GEN         2       /* generational collection */
  57
  58
  59 typedef struct stringtable {
  60   GCObject **hash;
  61   lu_int32 nuse;  /* number of elements */
  62   int size;
  63 } stringtable;
  64
  65
  66 /*
  67 ** information about a call
  68 */
  69 typedef struct CallInfo {
  70   StkId func;  /* function index in the stack */
  71   StkId top;  /* top for this function */
  72   struct CallInfo *previous, *next;  /* dynamic call link */
  73   short nresults;  /* expected number of results from this function */
  74   lu_byte callstatus;
  75   ptrdiff_t extra;
  76   union {
  77     struct {  /* only for Lua functions */
  78       StkId base;  /* base for this function */
  79       const Instruction *savedpc;
  80     } l;
  81     struct {  /* only for C functions */
  82       int ctx;  /* context info. in case of yields */
  83       lua_CFunction k;  /* continuation in case of yields */
  84       ptrdiff_t old_errfunc;
  85       lu_byte old_allowhook;
  86       lu_byte status;
  87     } c;
  88   } u;
  89 } CallInfo;
  90
  91
  92 /*
  93 ** Bits in CallInfo status
  94 */
  95 #define CIST_LUA        (1<<0)  /* call is running a Lua function */
  96 #define CIST_HOOKED     (1<<1)  /* call is running a debug hook */
  97 #define CIST_REENTRY    (1<<2)  /* call is running on same invocation of
  98                                    luaV_execute of previous call */
  99 #define CIST_YIELDED    (1<<3)  /* call reentered after suspension */
 100 #define CIST_YPCALL     (1<<4)  /* call is a yieldable protected call */
 101 #define CIST_STAT       (1<<5)  /* call has an error status (pcall) */
 102 #define CIST_TAIL       (1<<6)  /* call was tail called */
 103 #define CIST_HOOKYIELD  (1<<7)  /* last hook called yielded */
 104
 105
 106 #define isLua(ci)       ((ci)->callstatus & CIST_LUA)
 107
 108
 109 /*
 110 ** `global state', shared by all threads of this state
 111 */
 112 typedef struct global_State {
 113   lua_Alloc frealloc;  /* function to reallocate memory */
 114   void *ud;         /* auxiliary data to `frealloc' */
 115   lu_mem totalbytes;  /* number of bytes currently allocated - GCdebt */
 116   l_mem GCdebt;  /* bytes allocated not yet compensated by the collector */
 117   lu_mem GCmemtrav;  /* memory traversed by the GC */
 118   lu_mem GCestimate;  /* an estimate of the non-garbage memory in use */
 119   stringtable strt;  /* hash table for strings */
 120   TValue l_registry;
 121   unsigned int seed;  /* randomized seed for hashes */
 122   lu_byte currentwhite;
 123   lu_byte gcstate;  /* state of garbage collector */
 124   lu_byte gckind;  /* kind of GC running */
 125   lu_byte gcrunning;  /* true if GC is running */
 126   int sweepstrgc;  /* position of sweep in `strt' */
 127   GCObject *allgc;  /* list of all collectable objects */
 128   GCObject *finobj;  /* list of collectable objects with finalizers */
 129   GCObject **sweepgc;  /* current position of sweep in list 'allgc' */
 130   GCObject **sweepfin;  /* current position of sweep in list 'finobj' */
 131   GCObject *gray;  /* list of gray objects */
 132   GCObject *grayagain;  /* list of objects to be traversed atomically */
 133   GCObject *weak;  /* list of tables with weak values */
 134   GCObject *ephemeron;  /* list of ephemeron tables (weak keys) */
 135   GCObject *allweak;  /* list of all-weak tables */
 136   GCObject *tobefnz;  /* list of userdata to be GC */
 137   UpVal uvhead;  /* head of double-linked list of all open upvalues */
 138   Mbuffer buff;  /* temporary buffer for string concatenation */
 139   int gcpause;  /* size of pause between successive GCs */
 140   int gcmajorinc;  /* pause between major collections (only in gen. mode) */
 141   int gcstepmul;  /* GC `granularity' */
 142   lua_CFunction panic;  /* to be called in unprotected errors */
 143   struct lua_State *mainthread;
 144   const lua_Number *version;  /* pointer to version number */
 145   TString *memerrmsg;  /* memory-error message */
 146   TString *tmname[TM_N];  /* array with tag-method names */
 147   struct Table *mt[LUA_NUMTAGS];  /* metatables for basic types */
 148 } global_State;
 149
 150
 151 /*
 152 ** `per thread' state
 153 */
 154 struct lua_State {
 155   CommonHeader;
 156   lu_byte status;
 157   StkId top;  /* first free slot in the stack */
 158   global_State *l_G;
 159   CallInfo *ci;  /* call info for current function */
 160   const Instruction *oldpc;  /* last pc traced */
 161   StkId stack_last;  /* last free slot in the stack */
 162   StkId stack;  /* stack base */
 163   int stacksize;
 164   unsigned short nny;  /* number of non-yieldable calls in stack */
 165   unsigned short nCcalls;  /* number of nested C calls */
 166   lu_byte hookmask;
 167   lu_byte allowhook;
 168   int basehookcount;
 169   int hookcount;
 170   lua_Hook hook;
 171   GCObject *openupval;  /* list of open upvalues in this stack */
 172   GCObject *gclist;
 173   struct lua_longjmp *errorJmp;  /* current error recover point */
 174   ptrdiff_t errfunc;  /* current error handling function (stack index) */
 175   CallInfo base_ci;  /* CallInfo for first level (C calling Lua) */
 176 };
 177
 178
 179 #define G(L)    (L->l_G)
 180
 181
 182 /*
 183 ** Union of all collectable objects
 184 */
 185 union GCObject {
 186   GCheader gch;  /* common header */
 187   union TString ts;
 188   union Udata u;
 189   union Closure cl;
 190   struct Table h;
 191   struct Proto p;
 192   struct UpVal uv;
 193   struct lua_State th;  /* thread */
 194 };
 195
 196
 197 #define gch(o)          (&(o)->gch)
 198
 199 /* macros to convert a GCObject into a specific value */
 200 #define rawgco2ts(o)  \
 201         check_exp(novariant((o)->gch.tt) == LUA_TSTRING, &((o)->ts))
 202 #define gco2ts(o)       (&rawgco2ts(o)->tsv)
 203 #define rawgco2u(o)     check_exp((o)->gch.tt == LUA_TUSERDATA, &((o)->u))
 204 #define gco2u(o)        (&rawgco2u(o)->uv)
 205 #define gco2lcl(o)      check_exp((o)->gch.tt == LUA_TLCL, &((o)->cl.l))
 206 #define gco2ccl(o)      check_exp((o)->gch.tt == LUA_TCCL, &((o)->cl.c))
 207 #define gco2cl(o)  \
 208         check_exp(novariant((o)->gch.tt) == LUA_TFUNCTION, &((o)->cl))
 209 #define gco2t(o)        check_exp((o)->gch.tt == LUA_TTABLE, &((o)->h))
 210 #define gco2p(o)        check_exp((o)->gch.tt == LUA_TPROTO, &((o)->p))
 211 #define gco2uv(o)       check_exp((o)->gch.tt == LUA_TUPVAL, &((o)->uv))
 212 #define gco2th(o)       check_exp((o)->gch.tt == LUA_TTHREAD, &((o)->th))
 213
 214 /* macro to convert any Lua object into a GCObject */
 215 #define obj2gco(v)      (cast(GCObject *, (v)))
 216
 217
 218 /* actual number of total bytes allocated */
 219 #define gettotalbytes(g)        ((g)->totalbytes + (g)->GCdebt)
 220
 221 LUAI_FUNC void luaE_setdebt (global_State *g, l_mem debt);
 222 LUAI_FUNC void luaE_freethread (lua_State *L, lua_State *L1);
 223 LUAI_FUNC CallInfo *luaE_extendCI (lua_State *L);
 224 LUAI_FUNC void luaE_freeCI (lua_State *L);
 225
 226
 227 #endif
 228