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      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 
    229