lstate.h

Go to the documentation of this file.

/*
** $Id: lstate.h,v 2.133.1.1 2017/04/19 17:39:34 roberto Exp $
** Global State
** See Copyright Notice in lua.h
*/

#ifndef lstate_h
#define lstate_h

#include "lua.h"

#include "lobject.h"
#include "ltm.h"
#include "lzio.h"


/*

** Some notes about garbage-collected objects: All objects in Lua must
** be kept somehow accessible until being freed, so all objects always
** belong to one (and only one) of these lists, using field 'next' of
** the 'CommonHeader' for the link:
**
** 'allgc': all objects not marked for finalization;
** 'finobj': all objects marked for finalization;
** 'tobefnz': all objects ready to be finalized;
** 'fixedgc': all objects that are not to be collected (currently
** only small strings, such as reserved words).
**
** Moreover, there is another set of lists that control gray objects.
** These lists are linked by fields 'gclist'. (All objects that
** can become gray have such a field. The field is not the same
** in all objects, but it always has this name.) Any gray object
** must belong to one of these lists, and all objects in these lists
** must be gray:
**
** 'gray': regular gray objects, still waiting to be visited.
** 'grayagain': objects that must be revisited at the atomic phase.
** That includes
** - black objects got in a write barrier;
** - all kinds of weak tables during propagation phase;
** - all threads.
** 'weak': tables with weak values to be cleared;
** 'ephemeron': ephemeron tables with white->white entries;
** 'allweak': tables with weak keys and/or weak values to be cleared.
** The last three lists are used only during the atomic phase.

*/


struct lua_longjmp; /* defined in ldo.c */


/*
** Atomic type (relative to signals) to better ensure that 'lua_sethook'
** is thread safe
*/
#if !defined(l_signalT)
#include <signal.h>
#define l_signalT sig_atomic_t
#endif


/* extra stack space to handle TM calls and some other extras */
#define EXTRA_STACK 5


#define BASIC_STACK_SIZE (2*LUA_MINSTACK)


/* kinds of Garbage Collection */
#define KGC_NORMAL 0
#define KGC_EMERGENCY 1 /* gc was forced by an allocation failure */


typedef struct stringtable {
 TString **hash;
 int nuse; /* number of elements */
 int size;
} stringtable;


/*
** Information about a call.
** When a thread yields, 'func' is adjusted to pretend that the
** top function has only the yielded values in its stack; in that
** case, the actual 'func' value is saved in field 'extra'.
** When a function calls another with a continuation, 'extra' keeps
** the function index so that, in case of errors, the continuation
** function can be called with the correct top.
*/
typedef struct CallInfo {
 StkId func; /* function index in the stack */
 StkId top; /* top for this function */
 struct CallInfo *previous, *next; /* dynamic call link */
 union {
 struct { /* only for Lua functions */
 StkId base; /* base for this function */
 const Instruction *savedpc;
 } l;
 struct { /* only for C functions */
 lua_KFunction k; /* continuation in case of yields */
 ptrdiff_t old_errfunc;
 lua_KContext ctx; /* context info. in case of yields */
 } c;
 } u;
 ptrdiff_t extra;
 short nresults; /* expected number of results from this function */
 unsigned short callstatus;
} CallInfo;


/*
** Bits in CallInfo status
*/
#define CIST_OAH (1<<0) /* original value of 'allowhook' */
#define CIST_LUA (1<<1) /* call is running a Lua function */
#define CIST_HOOKED (1<<2) /* call is running a debug hook */
#define CIST_FRESH (1<<3) /* call is running on a fresh invocation
 of luaV_execute */
#define CIST_YPCALL (1<<4) /* call is a yieldable protected call */
#define CIST_TAIL (1<<5) /* call was tail called */
#define CIST_HOOKYIELD (1<<6) /* last hook called yielded */
#define CIST_LEQ (1<<7) /* using __lt for __le */
#define CIST_FIN (1<<8) /* call is running a finalizer */

#define isLua(ci) ((ci)->callstatus & CIST_LUA)

/* assume that CIST_OAH has offset 0 and that 'v' is strictly 0/1 */
#define setoah(st,v) ((st) = ((st) & ~CIST_OAH) | (v))
#define getoah(st) ((st) & CIST_OAH)


/*
** 'global state', shared by all threads of this state
*/
typedef struct global_State {
 lua_Alloc frealloc; /* function to reallocate memory */
 void *ud; /* auxiliary data to 'frealloc' */
 l_mem totalbytes; /* number of bytes currently allocated - GCdebt */
 l_mem GCdebt; /* bytes allocated not yet compensated by the collector */
 lu_mem GCmemtrav; /* memory traversed by the GC */
 lu_mem GCestimate; /* an estimate of the non-garbage memory in use */
 stringtable strt; /* hash table for strings */
 TValue l_registry;
 unsigned int seed; /* randomized seed for hashes */
 lu_byte currentwhite;
 lu_byte gcstate; /* state of garbage collector */
 lu_byte gckind; /* kind of GC running */
 lu_byte gcrunning; /* true if GC is running */
 GCObject *allgc; /* list of all collectable objects */
 GCObject **sweepgc; /* current position of sweep in list */
 GCObject *finobj; /* list of collectable objects with finalizers */
 GCObject *gray; /* list of gray objects */
 GCObject *grayagain; /* list of objects to be traversed atomically */
 GCObject *weak; /* list of tables with weak values */
 GCObject *ephemeron; /* list of ephemeron tables (weak keys) */
 GCObject *allweak; /* list of all-weak tables */
 GCObject *tobefnz; /* list of userdata to be GC */
 GCObject *fixedgc; /* list of objects not to be collected */
 struct lua_State *twups; /* list of threads with open upvalues */
 unsigned int gcfinnum; /* number of finalizers to call in each GC step */
 int gcpause; /* size of pause between successive GCs */
 int gcstepmul; /* GC 'granularity' */
 lua_CFunction panic; /* to be called in unprotected errors */
 struct lua_State *mainthread;
 const lua_Number *version; /* pointer to version number */
 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_N][STRCACHE_M]; /* cache for strings in API */
} global_State;


/*
** 'per thread' state
*/
struct lua_State {
 CommonHeader;
 unsigned short nci; /* number of items in 'ci' list */
 lu_byte status;
 StkId top; /* first free slot in the stack */
 global_State *l_G;
 CallInfo *ci; /* call info for current function */
 const Instruction *oldpc; /* last pc traced */
 StkId stack_last; /* last free slot in the stack */
 StkId stack; /* stack base */
 UpVal *openupval; /* list of open upvalues in this stack */
 GCObject *gclist;
 struct lua_State *twups; /* list of threads with open upvalues */
 struct lua_longjmp *errorJmp; /* current error recover point */
 CallInfo base_ci; /* CallInfo for first level (C calling Lua) */
 volatile lua_Hook hook;
 ptrdiff_t errfunc; /* current error handling function (stack index) */
 int stacksize;
 int basehookcount;
 int hookcount;
 unsigned short nny; /* number of non-yieldable calls in stack */
 unsigned short nCcalls; /* number of nested C calls */
 l_signalT hookmask;
 lu_byte allowhook;
};


#define G(L) (L->l_G)


/*
** Union of all collectable objects (only for conversions)
*/
union GCUnion {
 GCObject gc; /* common header */
 struct TString ts;
 struct Udata u;
 union Closure cl;
 struct Table h;
 struct Proto p;
 struct lua_State th; /* thread */
};


#define cast_u(o) cast(union GCUnion *, (o))

/* macros to convert a GCObject into a specific value */
#define gco2ts(o) \
 check_exp(novariant((o)->tt) == LUA_TSTRING, &((cast_u(o))->ts))
#define gco2u(o) check_exp((o)->tt == LUA_TUSERDATA, &((cast_u(o))->u))
#define gco2lcl(o) check_exp((o)->tt == LUA_TLCL, &((cast_u(o))->cl.l))
#define gco2ccl(o) check_exp((o)->tt == LUA_TCCL, &((cast_u(o))->cl.c))
#define gco2cl(o) \
 check_exp(novariant((o)->tt) == LUA_TFUNCTION, &((cast_u(o))->cl))
#define gco2t(o) check_exp((o)->tt == LUA_TTABLE, &((cast_u(o))->h))
#define gco2p(o) check_exp((o)->tt == LUA_TPROTO, &((cast_u(o))->p))
#define gco2th(o) check_exp((o)->tt == LUA_TTHREAD, &((cast_u(o))->th))


/* macro to convert a Lua object into a GCObject */
#define obj2gco(v) \
 check_exp(novariant((v)->tt) < LUA_TDEADKEY, (&(cast_u(v)->gc)))


/* actual number of total bytes allocated */
#define gettotalbytes(g) cast(lu_mem, (g)->totalbytes + (g)->GCdebt)

LUAI_FUNC void luaE_setdebt (global_State *g, l_mem debt);
LUAI_FUNC void luaE_freethread (lua_State *L, lua_State *L1);
LUAI_FUNC CallInfo *luaE_extendCI (lua_State *L);
LUAI_FUNC void luaE_freeCI (lua_State *L);
LUAI_FUNC void luaE_shrinkCI (lua_State *L);


#endif