lua

lstate.h (16101B)

---

 /*
 ** $Id: lstate.h $
 ** Global State
 ** See Copyright Notice in lua.h
 */
 
 #ifndef lstate_h
 #define lstate_h
 
 #include "lua.h"
 
 
 /* Some header files included here need this definition */
 typedef struct CallInfo CallInfo;
 
 
 #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 two exceptions 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 exceptions to that "gray rule" are:
 ** - TOUCHED2 objects in generational mode 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).
 ** - Open upvales are kept gray to avoid barriers, but they stay out
 ** of gray lists. (They don't even have a 'gclist' field.)
 */
 
 
 
 /*
 ** About 'nCcalls':  This count has two parts: the lower 16 bits counts
 ** the number of recursive invocations in the C stack; the higher
 ** 16 bits counts the number of non-yieldable calls in the stack.
 ** (They are together so that we can change and save both with one
 ** instruction.)
 */
 
 
 /* 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)
 
 /* Non-yieldable call increment */
 #define nyci	(0x10000 | 1)
 
 
 
 
 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. This
 ** space is not included in 'stack_last'. It is used only to avoid stack
 ** checks, either because the element will be promptly popped or because
 ** there will be a stack check soon after the push. Function frames
 ** never use this extra space, so it does not need to be kept clean.
 */
 #define EXTRA_STACK   5
 
 
 /*
 ** Size of cache for strings in the API. 'N' is the number of
 ** sets (better be a prime) and "M" is the size of each set.
 ** (M == 1 makes a direct cache.)
 */
 #if !defined(STRCACHE_N)
 #define STRCACHE_N              53
 #define STRCACHE_M              2
 #endif
 
 
 #define BASIC_STACK_SIZE        (2*LUA_MINSTACK)
 
 #define stacksize(th)	cast_int((th)->stack_last.p - (th)->stack.p)
 
 
 /* kinds of Garbage Collection */
 #define KGC_INC		0	/* incremental gc */
 #define KGC_GENMINOR	1	/* generational gc in minor (regular) mode */
 #define KGC_GENMAJOR	2	/* generational in major mode */
 
 
 typedef struct stringtable {
   TString **hash;  /* array of buckets (linked lists of strings) */
   int nuse;  /* number of elements */
   int size;  /* number of buckets */
 } stringtable;
 
 
 /*
 ** Information about a call.
 ** About union 'u':
 ** - field 'l' is used only for Lua functions;
 ** - field 'c' is used only for C functions.
 ** About union 'u2':
 ** - field 'funcidx' is used only by C functions while doing a
 ** protected call;
 ** - field 'nyield' is used only while a function is "doing" an
 ** yield (from the yield until the next resume);
 ** - field 'nres' is used only while closing tbc variables when
 ** returning from a function;
 */
 struct CallInfo {
   StkIdRel func;  /* function index in the stack */
   StkIdRel 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;  /* function is tracing lines/counts */
       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 */
     int nres;  /* number of values returned */
   } u2;
   l_uint32 callstatus;
 };
 
 
 /*
 ** Maximum expected number of results from a function
 ** (must fit in CIST_NRESULTS).
 */
 #define MAXRESULTS	250
 
 
 /*
 ** Bits in CallInfo status
 */
 /* bits 0-7 are the expected number of results from this function + 1 */
 #define CIST_NRESULTS	0xffu
 
 /* bits 8-11 count call metamethods (and their extra arguments) */
 #define CIST_CCMT	8  /* the offset, not the mask */
 #define MAX_CCMT	(0xfu << CIST_CCMT)
 
 /* Bits 12-14 are used for CIST_RECST (see below) */
 #define CIST_RECST	12  /* the offset, not the mask */
 
 /* call is running a C function (still in first 16 bits) */
 #define CIST_C		(1u << (CIST_RECST + 3))
 /* call is on a fresh "luaV_execute" frame */
 #define CIST_FRESH	cast(l_uint32, CIST_C << 1)
 /* function is closing tbc variables */
 #define CIST_CLSRET	(CIST_FRESH << 1)
 /* function has tbc variables to close */
 #define CIST_TBC	(CIST_CLSRET << 1)
 /* original value of 'allowhook' */
 #define CIST_OAH	(CIST_TBC << 1)
 /* call is running a debug hook */
 #define CIST_HOOKED	(CIST_OAH << 1)
 /* doing a yieldable protected call */
 #define CIST_YPCALL	(CIST_HOOKED << 1)
 /* call was tail called */
 #define CIST_TAIL	(CIST_YPCALL << 1)
 /* last hook called yielded */
 #define CIST_HOOKYIELD	(CIST_TAIL << 1)
 /* function "called" a finalizer */
 #define CIST_FIN	(CIST_HOOKYIELD << 1)
 #if defined(LUA_COMPAT_LT_LE)
 /* using __lt for __le */
 #define CIST_LEQ	(CIST_FIN << 1)
 #endif
 
 
 #define get_nresults(cs)  (cast_int((cs) & CIST_NRESULTS) - 1)
 
 /*
 ** Field CIST_RECST stores the "recover status", used to keep the error
 ** status while closing to-be-closed variables in coroutines, so that
 ** Lua can correctly resume after an yield from a __close method called
 ** because of an error.  (Three bits are enough for error status.)
 */
 #define getcistrecst(ci)     (((ci)->callstatus >> CIST_RECST) & 7)
 #define setcistrecst(ci,st)  \
   check_exp(((st) & 7) == (st),   /* status must fit in three bits */  \
             ((ci)->callstatus = ((ci)->callstatus & ~(7u << CIST_RECST))  \
                                 | (cast(l_uint32, st) << CIST_RECST)))
 
 
 /* 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)))
 
 
 #define setoah(ci,v)  \
   ((ci)->callstatus = ((v) ? (ci)->callstatus | CIST_OAH  \
                            : (ci)->callstatus & ~CIST_OAH))
 #define getoah(ci)  (((ci)->callstatus & CIST_OAH) ? 1 : 0)
 
 
 /*
 ** 'per thread' state
 */
 struct lua_State {
   CommonHeader;
   lu_byte allowhook;
   TStatus status;
   StkIdRel top;  /* first free slot in the stack */
   struct global_State *l_G;
   CallInfo *ci;  /* call info for current function */
   StkIdRel stack_last;  /* end of stack (last element + 1) */
   StkIdRel stack;  /* stack base */
   UpVal *openupval;  /* list of open upvalues in this stack */
   StkIdRel tbclist;  /* list of to-be-closed variables */
   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 host) */
   volatile lua_Hook hook;
   ptrdiff_t errfunc;  /* current error handling function (stack index) */
   l_uint32 nCcalls;  /* number of nested non-yieldable or C calls */
   int oldpc;  /* last pc traced */
   int nci;  /* number of items in 'ci' list */
   int basehookcount;
   int hookcount;
   volatile l_signalT hookmask;
   struct {  /* info about transferred values (for call/return hooks) */
     int ftransfer;  /* offset of first value transferred */
     int ntransfer;  /* number of values transferred */
   } transferinfo;
 };
 
 
 /*
 ** thread state + extra space
 */
 typedef struct LX {
   lu_byte extra_[LUA_EXTRASPACE];
   lua_State l;
 } LX;
 
 
 /*
 ** '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 GCtotalbytes;  /* number of bytes currently allocated + debt */
   l_mem GCdebt;  /* bytes counted but not yet allocated */
   l_mem GCmarked;  /* number of objects marked in a GC cycle */
   l_mem GCmajorminor;  /* auxiliary counter to control major-minor shifts */
   stringtable strt;  /* hash table for strings */
   TValue l_registry;
   TValue nilvalue;  /* a nil value */
   unsigned int seed;  /* randomized seed for hashes */
   lu_byte gcparams[LUA_GCPN];
   lu_byte currentwhite;
   lu_byte gcstate;  /* state of garbage collector */
   lu_byte gckind;  /* kind of GC running */
   lu_byte gcstopem;  /* stops emergency collections */
   lu_byte gcstp;  /* control whether GC is running */
   lu_byte gcemergency;  /* true if this is an emergency collection */
   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 */
   TString *memerrmsg;  /* message for memory-allocation errors */
   TString *tmname[TM_N];  /* array with tag-method names */
   struct Table *mt[LUA_NUMTYPES];  /* 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' */
   LX mainth;  /* main thread of this state */
 } global_State;
 
 
 #define G(L)	(L->l_G)
 #define mainthread(G)	(&(G)->mainth.l)
 
 /*
 ** 'g->nilvalue' being a nil value flags that the state was completely
 ** build.
 */
 #define completestate(g)	ttisnil(&g->nilvalue)
 
 
 /*
 ** Union of all collectable objects (only for conversions)
 ** ISO C99, 6.5.2.3 p.5:
 ** "if a union contains several structures that share a common initial
 ** sequence [...], and if the union object currently contains one
 ** of these structures, it is permitted to inspect the common initial
 ** part of any of them anywhere that a declaration of the complete type
 ** of the union is visible."
 */
 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;
 };
 
 
 /*
 ** ISO C99, 6.7.2.1 p.14:
 ** "A pointer to a union object, suitably converted, points to each of
 ** its members [...], and vice versa."
 */
 #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 memory allocated */
 #define gettotalbytes(g)	((g)->GCtotalbytes - (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 lu_mem luaE_threadsize (lua_State *L);
 LUAI_FUNC CallInfo *luaE_extendCI (lua_State *L);
 LUAI_FUNC void luaE_shrinkCI (lua_State *L);
 LUAI_FUNC void luaE_checkcstack (lua_State *L);
 LUAI_FUNC void luaE_incCstack (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);
 LUAI_FUNC TStatus luaE_resetthread (lua_State *L, TStatus status);
 
 
 #endif