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** $Id: lstate.h $
** 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).
** For the generational collector, some of these lists have marks for
** generations. Each mark points to the first element in the list for
** that particular generation; that generation goes until the next mark.
** 'allgc' -> 'survival': new objects;
** 'survival' -> 'old': objects that survived one collection;
** 'old1' -> 'reallyold': objects that became old in last collection;
** 'reallyold' -> NULL: objects old for more than one cycle.
** 'finobj' -> 'finobjsur': new objects marked for finalization;
** 'finobjsur' -> 'finobjold1': survived """";
** 'finobjold1' -> 'finobjrold': just old """";
** 'finobjrold' -> NULL: really old """".
** All lists can contain elements older than their main ages, due
** to 'luaC_checkfinalizer' and 'udata2finalize', which move
** objects between the normal lists and the "marked for finalization"
** lists. Moreover, barriers can age young objects in young lists as
** OLD0, which then become OLD1. However, a list never contains
** elements younger than their main ages.
** The generational collector also uses a pointer 'firstold1', which
** points to the first OLD1 object in the list. It is used to optimize
** 'markold'. (Potentially OLD1 objects can be anywhere between 'allgc'
** and 'reallyold', but often the list has no OLD1 objects or they are
** after 'old1'.) Note the difference between it and 'old1':
** 'firstold1': no OLD1 objects before this point; there can be all
** ages after it.
** 'old1': no objects younger than OLD1 after this point.
** 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 (with one exception explained below):
** '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 exception to that "gray rule" is the TOUCHED2 objects in
** generational mode. Those objects stay in a gray list (because they
** must be visited again at the end of the cycle), but they are marked
** black (because assignments to them must activate barriers, to move
** them back to TOUCHED1).
** About 'nCcalls': each thread in Lua (a lua_State) keeps a count of
** how many "C calls" it still can do in the C stack, to avoid C-stack
** overflow. This count is very rough approximation; it considers only
** recursive functions inside the interpreter, as non-recursive calls
** can be considered using a fixed (although unknown) amount of stack
** space.
** The count has two parts: the lower part is the count itself; the
** higher part counts the number of non-yieldable calls in the stack.
** (They are together so that we can change both with one instruction.)
** Because calls to external C functions can use an unknown amount
** of space (e.g., functions using an auxiliary buffer), calls
** to these functions add more than one to the count (see CSTACKCF).
** The proper count excludes the number of CallInfo structures allocated
** by Lua, as a kind of "potential" calls. So, when Lua calls a function
** (and "consumes" one CallInfo), it needs neither to decrement nor to
** check 'nCcalls', as its use of C stack is already accounted for.
/* number of "C stack slots" used by an external C function */
#define CSTACKCF 10
** The C-stack size is sliced in the following zones:
** - larger than CSTACKERR: normal stack;
** - [CSTACKMARK, CSTACKERR]: buffer zone to signal a stack overflow;
** - [CSTACKCF, CSTACKERRMARK]: error-handling zone;
** - below CSTACKERRMARK: buffer zone to signal overflow during overflow;
** (Because the counter can be decremented CSTACKCF at once, we need
** the so called "buffer zones", with at least that size, to properly
** detect a change from one zone to the next.)
/* initial limit for the C-stack of threads */
/* true if this thread does not have non-yieldable calls in the stack */
#define yieldable(L) (((L)->nCcalls & 0xffff0000) == 0)
/* real number of C calls */
#define getCcalls(L) ((L)->nCcalls & 0xffff)
/* Increment the number of non-yieldable calls */
#define incnny(L) ((L)->nCcalls += 0x10000)
/* Decrement the number of non-yieldable calls */
#define decnny(L) ((L)->nCcalls -= 0x10000)
/* Increment the number of non-yieldable calls and decrement nCcalls */
#define incXCcalls(L) ((L)->nCcalls += 0x10000 - CSTACKCF)
/* Decrement the number of non-yieldable calls and increment nCcalls */
#define decXCcalls(L) ((L)->nCcalls -= 0x10000 - CSTACKCF)
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
/* extra stack space to handle TM calls and some other extras */
#define EXTRA_STACK 5
/* kinds of Garbage Collection */
#define KGC_INC 0 /* incremental gc */
#define KGC_GEN 1 /* generational gc */
typedef struct stringtable {
TString **hash;
int nuse; /* number of elements */
int size;
} stringtable;
** Information about a call.
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 */
const Instruction *savedpc;
volatile l_signalT trap;
int nextraargs; /* # of extra arguments in vararg functions */
} 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;
union {
int funcidx; /* called-function index */
int nyield; /* number of values yielded */
struct { /* info about transferred values (for call/return hooks) */
unsigned short ftransfer; /* offset of first value transferred */
unsigned short ntransfer; /* number of values transferred */
} transferinfo;
} u2;
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_C (1<<1) /* call is running a C function */
#define CIST_HOOKED (1<<2) /* call is running a debug hook */
#define CIST_YPCALL (1<<3) /* call is a yieldable protected call */
#define CIST_TAIL (1<<4) /* call was tail called */
#define CIST_HOOKYIELD (1<<5) /* last hook called yielded */
#define CIST_FIN (1<<6) /* call is running a finalizer */
#define CIST_TRAN (1<<7) /* 'ci' has transfer information */
#if defined(LUA_COMPAT_LT_LE)
#define CIST_LEQ (1<<8) /* using __lt for __le */
/* active function is a Lua function */
#define isLua(ci) (!((ci)->callstatus & CIST_C))
/* call is running Lua code (not a hook) */
#define isLuacode(ci) (!((ci)->callstatus & (CIST_C | CIST_HOOKED)))
/* 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 GCestimate; /* an estimate of the non-garbage memory in use */
lu_mem lastatomic; /* see function 'genstep' in file 'lgc.c' */
stringtable strt; /* hash table for strings */
TValue l_registry;
TValue nilvalue; /* a nil value */
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 genminormul; /* control for minor generational collections */
lu_byte genmajormul; /* control for major generational collections */
lu_byte gcrunning; /* true if GC is running */
lu_byte gcemergency; /* true if this is an emergency collection */
lu_byte gcpause; /* size of pause between successive GCs */
lu_byte gcstepmul; /* GC "speed" */
lu_byte gcstepsize; /* (log2 of) GC granularity */
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 */
/* fields for generational collector */
GCObject *survival; /* start of objects that survived one GC cycle */
GCObject *old1; /* start of old1 objects */
GCObject *reallyold; /* objects more than one cycle old ("really old") */
GCObject *firstold1; /* first OLD1 object in the list (if any) */
GCObject *finobjsur; /* list of survival objects with finalizers */
GCObject *finobjold1; /* list of old1 objects with finalizers */
GCObject *finobjrold; /* list of really old objects with finalizers */
struct lua_State *twups; /* list of threads with open upvalues */
lua_CFunction panic; /* to be called in unprotected errors */
struct lua_State *mainthread;
TString *memerrmsg; /* message for memory-allocation errors */
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 */
lua_WarnFunction warnf; /* warning function */
void *ud_warn; /* auxiliary data to 'warnf' */
unsigned int Cstacklimit; /* current limit for the C stack */
} global_State;
** 'per thread' state
struct lua_State {
lu_byte status;
lu_byte allowhook;
unsigned short nci; /* number of items in 'ci' list */
StkId top; /* first free slot in the stack */
global_State *l_G;
CallInfo *ci; /* call info for current function */
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) */
l_uint32 nCcalls; /* number of allowed nested C calls - 'nci' */
int oldpc; /* last pc traced */
int stacksize;
int basehookcount;
int hookcount;
volatile l_signalT hookmask;
#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 */
struct UpVal upv;
#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_VUSERDATA, &((cast_u(o))->u))
#define gco2lcl(o) check_exp((o)->tt == LUA_VLCL, &((cast_u(o))->cl.l))
#define gco2ccl(o) check_exp((o)->tt == LUA_VCCL, &((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_VTABLE, &((cast_u(o))->h))
#define gco2p(o) check_exp((o)->tt == LUA_VPROTO, &((cast_u(o))->p))
#define gco2th(o) check_exp((o)->tt == LUA_VTHREAD, &((cast_u(o))->th))
#define gco2upv(o) check_exp((o)->tt == LUA_VUPVAL, &((cast_u(o))->upv))
** macro to convert a Lua object into a GCObject
** (The access to 'tt' tries to ensure that 'v' is actually a Lua object.)
#define obj2gco(v) check_exp((v)->tt >= LUA_TSTRING, &(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);
LUAI_FUNC void luaE_enterCcall (lua_State *L);
LUAI_FUNC void luaE_warning (lua_State *L, const char *msg, int tocont);
LUAI_FUNC void luaE_warnerror (lua_State *L, const char *where);
#define luaE_exitCcall(L) ((L)->nCcalls++)