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  1. /*
  2. ** $Id: lmem.c,v 1.83 2011/11/30 12:42:49 roberto Exp $
  3. ** Interface to Memory Manager
  4. ** See Copyright Notice in lua.h
  5. */
  6.  
  7.  
  8. #include <stddef.h>
  9.  
  10. #define lmem_c
  11. #define LUA_CORE
  12.  
  13. #include "lua.h"
  14.  
  15. #include "ldebug.h"
  16. #include "ldo.h"
  17. #include "lgc.h"
  18. #include "lmem.h"
  19. #include "lobject.h"
  20. #include "lstate.h"
  21.  
  22.  
  23.  
  24. /*
  25. ** About the realloc function:
  26. ** void * frealloc (void *ud, void *ptr, size_t osize, size_t nsize);
  27. ** (`osize' is the old size, `nsize' is the new size)
  28. **
  29. ** * frealloc(ud, NULL, x, s) creates a new block of size `s' (no
  30. ** matter 'x').
  31. **
  32. ** * frealloc(ud, p, x, 0) frees the block `p'
  33. ** (in this specific case, frealloc must return NULL);
  34. ** particularly, frealloc(ud, NULL, 0, 0) does nothing
  35. ** (which is equivalent to free(NULL) in ANSI C)
  36. **
  37. ** frealloc returns NULL if it cannot create or reallocate the area
  38. ** (any reallocation to an equal or smaller size cannot fail!)
  39. */
  40.  
  41.  
  42.  
  43. #define MINSIZEARRAY    4
  44.  
  45.  
  46. void *luaM_growaux_ (lua_State *L, void *block, int *size, size_t size_elems,
  47.                      int limit, const char *what) {
  48.   void *newblock;
  49.   int newsize;
  50.   if (*size >= limit/2) {  /* cannot double it? */
  51.     if (*size >= limit)  /* cannot grow even a little? */
  52.       luaG_runerror(L, "too many %s (limit is %d)", what, limit);
  53.     newsize = limit;  /* still have at least one free place */
  54.   }
  55.   else {
  56.     newsize = (*size)*2;
  57.     if (newsize < MINSIZEARRAY)
  58.       newsize = MINSIZEARRAY;  /* minimum size */
  59.   }
  60.   newblock = luaM_reallocv(L, block, *size, newsize, size_elems);
  61.   *size = newsize;  /* update only when everything else is OK */
  62.   return newblock;
  63. }
  64.  
  65.  
  66. l_noret luaM_toobig (lua_State *L) {
  67.   luaG_runerror(L, "memory allocation error: block too big");
  68. }
  69.  
  70.  
  71.  
  72. /*
  73. ** generic allocation routine.
  74. */
  75. void *luaM_realloc_ (lua_State *L, void *block, size_t osize, size_t nsize) {
  76.   void *newblock;
  77.   global_State *g = G(L);
  78.   size_t realosize = (block) ? osize : 0;
  79.   lua_assert((realosize == 0) == (block == NULL));
  80. #if defined(HARDMEMTESTS)
  81.   if (nsize > realosize && g->gcrunning)
  82.     luaC_fullgc(L, 1);  /* force a GC whenever possible */
  83. #endif
  84.   newblock = (*g->frealloc)(g->ud, block, osize, nsize);
  85.   if (newblock == NULL && nsize > 0) {
  86.     api_check(L, nsize > realosize,
  87.                  "realloc cannot fail when shrinking a block");
  88.     if (g->gcrunning) {
  89.       luaC_fullgc(L, 1);  /* try to free some memory... */
  90.       newblock = (*g->frealloc)(g->ud, block, osize, nsize);  /* try again */
  91.     }
  92.     if (newblock == NULL)
  93.       luaD_throw(L, LUA_ERRMEM);
  94.   }
  95.   lua_assert((nsize == 0) == (newblock == NULL));
  96.   g->GCdebt = (g->GCdebt + nsize) - realosize;
  97. #if defined(TRACEMEM)
  98.   { /* auxiliary patch to monitor garbage collection.
  99.     ** To plot, gnuplot with following command:
  100.     ** plot TRACEMEM using 1:2 with lines, TRACEMEM using 1:3 with lines
  101.     */
  102.     static unsigned long total = 0;  /* our "time" */
  103.     static FILE *f = NULL;  /* output file */
  104.     total++;  /* "time" always grows */
  105.     if ((total % 200) == 0) {
  106.       if (f == NULL) f = fopen(TRACEMEM, "w");
  107.       fprintf(f, "%lu %u %d %d\n", total,
  108.               gettotalbytes(g), g->GCdebt, g->gcstate * 10000);
  109.     }
  110.   }
  111. #endif
  112.  
  113.   return newblock;
  114. }
  115.  
  116.