static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
lua_State *L = (lua_State *)ud;
int mode = L == NULL ? 0 : G(L)->egcmode;
void *nptr;
if (nsize == 0) {
c_free(ptr);
return NULL;
}
if (L != NULL && (mode & EGC_ALWAYS)) /* always collect memory if requested */
luaC_fullgc(L);
if(nsize > osize && L != NULL) {
#if defined(LUA_STRESS_EMERGENCY_GC)
luaC_fullgc(L);
#endif
if(G(L)->memlimit > 0 && (mode & EGC_ON_MEM_LIMIT) && l_check_memlimit(L, nsize - osize))
return NULL;
}
nptr = (void *)c_realloc(ptr, nsize);
if (nptr == NULL && L != NULL && (mode & EGC_ON_ALLOC_FAILURE)) {
luaC_fullgc(L); /* emergency full collection. */
nptr = (void *)c_realloc(ptr, nsize); /* try allocation again */
}
return nptr;
}
/*
** In case of allocation fail, this function will call the GC to try
** to free some memory and then try the allocation again.
** (It should not be called when shrinking a block, because then the
** interpreter may be in the middle of a collection step.)
*/
static void *tryagain (lua_State *L, void *block,
size_t osize, size_t nsize) {
global_State *g = G(L);
if (ttisnil(&g->nilvalue)) { /* is state fully build? */
luaC_fullgc(L, 1); /* try to free some memory... */
return (*g->frealloc)(g->ud, block, osize, nsize); /* try again */
}
else return NULL; /* cannot free any memory without a full state */
}
/*
** generic allocation routine.
*/
void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
void *newblock;
global_State *g = G(L);
size_t realosize = (block) ? osize : 0;
lua_assert((realosize == 0) == (block == NULL));
#if defined(HARDMEMTESTS)
if (nsize > realosize && g->gcrunning)
luaC_fullgc(L, 1); /* force a GC whenever possible */
#endif
newblock = (*g->frealloc)(g->ud, block, osize, nsize);
if (newblock == NULL && nsize > 0) {
api_check(L, nsize > realosize,
"realloc cannot fail when shrinking a block");
if (g->gcrunning) {
luaC_fullgc(L, 1); /* try to free some memory... */
newblock = (*g->frealloc)(g->ud, block, osize, nsize); /* try again */
}
if (newblock == NULL)
luaD_throw(L, LUA_ERRMEM);
}
lua_assert((nsize == 0) == (newblock == NULL));
g->GCdebt = (g->GCdebt + nsize) - realosize;
#if defined(TRACEMEM)
{ /* auxiliary patch to monitor garbage collection.
** To plot, gnuplot with following command:
** plot TRACEMEM using 1:2 with lines, TRACEMEM using 1:3 with lines
*/
static unsigned long total = 0; /* our "time" */
static FILE *f = NULL; /* output file */
total++; /* "time" always grows */
if ((total % 200) == 0) {
if (f == NULL) f = fopen(TRACEMEM, "w");
fprintf(f, "%lu %u %d %d\n", total,
gettotalbytes(g), g->GCdebt, g->gcstate * 10000);
}
}
#endif
return newblock;
}
/**
* 调用此函数前，参数都经过检查, 保证了分配的内存块不会过大;
*
* 创建对象的函数 luaM_newobject 也调用此函数(lmem.h):
* #define luaM_newobject(L,tag,s) luaM_realloc_(L, NULL, tag, (s))
*
* nsize 为 0 表示释放内存
* #define luaM_freearray(L, b, n) luaM_realloc_(L, (b), (n)*sizeof(*(b)), 0)
*
* 内部调用 g->frealloc 来重新分配内存
*/
void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
void *newblock;
global_State *g = G(L);
size_t realosize = (block) ? osize : 0;
lua_assert((realosize == 0) == (block == NULL));
#if defined(HARDMEMTESTS)
if (nsize > realosize && g->gcrunning)
luaC_fullgc(L, 1); /* force a GC whenever possible */
#endif
newblock = (*g->frealloc)(g->ud, block, osize, nsize);
if (newblock == NULL && nsize > 0) {
api_check( nsize > realosize,
"realloc cannot fail when shrinking a block");
luaC_fullgc(L, 1); /* try to free some memory... */
newblock = (*g->frealloc)(g->ud, block, osize, nsize); /* try again */
if (newblock == NULL)
luaD_throw(L, LUA_ERRMEM);
}
lua_assert((nsize == 0) == (newblock == NULL));
g->GCdebt = (g->GCdebt + nsize) - realosize;
return newblock;
}
static void generationalcollection (lua_State *L) {
global_State *g = G(L);
if (g->lastmajormem == 0) { /* signal for another major collection? */
luaC_fullgc(L, 0); /* perform a full regular collection */
g->lastmajormem = gettotalbytes(g); /* update control */
}
else {
luaC_runtilstate(L, ~bitmask(GCSpause)); /* run complete cycle */
luaC_runtilstate(L, bitmask(GCSpause));
if (gettotalbytes(g) > g->lastmajormem/100 * g->gcmajorinc)
g->lastmajormem = 0; /* signal for a major collection */
}
luaE_setdebt(g, stddebt(g));
}
static void *l_alloc (void *ud, void *ptr, size_t osize, size_t nsize) {
lua_State *L = (lua_State *)ud;
void *nptr;
if (nsize == 0) {
free(ptr);
return NULL;
}
if(nsize > osize && L != NULL) {
if(G(L)->memlimit > 0 && l_check_memlimit(L, nsize - osize))
return NULL;
}
nptr = realloc(ptr, nsize);
if (nptr == NULL && L != NULL) {
luaC_fullgc(L); /* emergency full collection. */
nptr = realloc(ptr, nsize); /* try allocation again */
}
return nptr;
}
static void generationalcollection (lua_State *L) {
global_State *g = G(L);
lua_assert(g->gcstate == GCSpropagate);
if (g->GCestimate == 0) { /* signal for another major collection? */
luaC_fullgc(L, 0); /* perform a full regular collection */
g->GCestimate = gettotalbytes(g); /* update control */
}
else {
lu_mem estimate = g->GCestimate;
luaC_runtilstate(L, bitmask(GCSpause)); /* run complete (minor) cycle */
g->gcstate = GCSpropagate; /* skip restart */
if (gettotalbytes(g) > (estimate / 100) * g->gcmajorinc)
g->GCestimate = 0; /* signal for a major collection */
else
g->GCestimate = estimate; /* keep estimate from last major coll. */
}
setpause(g, gettotalbytes(g));
lua_assert(g->gcstate == GCSpropagate);
}
