1 /* Change the size of a block allocated by `mmalloc'.
2 Copyright 1990, 1991 Free Software Foundation
3 Written May 1989 by Mike Haertel. */
5 /* Copyright (c) 2010. The SimGrid Team.
6 * All rights reserved. */
8 /* This program is free software; you can redistribute it and/or modify it
9 * under the terms of the license (GNU LGPL) which comes with this package. */
11 #include <string.h> /* Prototypes for memcpy, memmove, memset, etc */
12 #include <stdlib.h> /* abort */
14 #include "mmprivate.h"
16 /* Resize the given region to the new size, returning a pointer
17 to the (possibly moved) region. This is optimized for speed;
18 some benchmarks seem to indicate that greater compactness is
19 achieved by unconditionally allocating and copying to a
20 new region. This module has incestuous knowledge of the
21 internals of both mfree and mmalloc. */
23 void *mrealloc(xbt_mheap_t mdp, void *ptr, size_t size)
27 size_t block, blocks, oldlimit;
29 /* Only keep real realloc, and reroute hidden malloc and free to the relevant functions */
32 return mmalloc(mdp, 0);
33 } else if (ptr == NULL) {
34 return mmalloc(mdp, size);
37 //printf("(%s)realloc %p to %d...",xbt_thread_self_name(),ptr,(int)size);
39 if ((char *) ptr < (char *) mdp->heapbase || BLOCK(ptr) > mdp->heapsize) {
41 ("FIXME. Ouch, this pointer is not mine, refusing to proceed (another solution would be to malloc it instead of reallocing it, see source code)\n");
42 result = mmalloc(mdp, size);
47 size_t requested_size = size; // The amount of memory requested by user, for real
49 /* Work even if the user was stupid enough to ask a ridicullously small block (even 0-length),
50 * ie return a valid block that can be realloced and freed.
51 * glibc malloc does not use this trick but return a constant pointer, but we need to enlist the free fragments later on.
53 if (size < SMALLEST_POSSIBLE_MALLOC)
54 size = SMALLEST_POSSIBLE_MALLOC;
58 type = mdp->heapinfo[block].type;
62 fprintf(stderr, "Asked realloc a fragment coming from a *free* block. I'm puzzled.\n");
67 /* Maybe reallocate a large block to a small fragment. */
69 if (size <= BLOCKSIZE / 2) { // Full block -> Fragment; no need to optimize for time
71 result = mmalloc(mdp, size);
72 if (result != NULL) { // useless (mmalloc never returns NULL), but harmless
73 memcpy(result, ptr, requested_size);
79 /* Full blocks -> Full blocks; see if we can hold it in place. */
80 blocks = BLOCKIFY(size);
81 if (blocks < mdp->heapinfo[block].busy_block.size) {
83 /* The new size is smaller; return excess memory to the free list. */
84 //printf("(%s) return excess memory...",xbt_thread_self_name());
85 for (it= block+blocks; it< mdp->heapinfo[block].busy_block.size ; it++)
86 mdp->heapinfo[it].type = 0; // FIXME that should be useless, type should already be 0 here
88 mdp->heapinfo[block + blocks].busy_block.size
89 = mdp->heapinfo[block].busy_block.size - blocks;
90 mfree(mdp, ADDRESS(block + blocks));
92 mdp->heapinfo[block].busy_block.size = blocks;
93 mdp->heapinfo[block].busy_block.busy_size = requested_size;
96 } else if (blocks == mdp->heapinfo[block].busy_block.size) {
98 /* No block size change necessary; only update the requested size */
100 mdp->heapinfo[block].busy_block.busy_size = requested_size;
103 /* Won't fit, so allocate a new region that will.
104 Free the old region first in case there is sufficient adjacent free space to grow without moving.
105 This trick mandates using a specific version of mmalloc that does not memset the memory to 0 after
106 action for obvious reasons. */
107 blocks = mdp->heapinfo[block].busy_block.size;
108 /* Prevent free from actually returning memory to the system. */
109 oldlimit = mdp->heaplimit;
112 mdp->heaplimit = oldlimit;
114 result = mmalloc_no_memset(mdp, requested_size);
115 //fprintf(stderr,"remalloc(%zu)~>%p\n",requested_size,result);
118 memmove(result, ptr, blocks * BLOCKSIZE);
119 /* FIXME: we should memset the end of the recently area */
123 default: /* Fragment -> ??; type=logarithm to base two of the fragment size. */
125 if (size > (size_t) (1 << (type - 1)) && size <= (size_t) (1 << type)) {
126 /* The new size is the same kind of fragment. */
127 //printf("(%s) new size is same kind of fragment...",xbt_thread_self_name());
130 int frag_nb = RESIDUAL(result, BLOCKSIZE) >> type;
131 mdp->heapinfo[block].busy_frag.frag_size[frag_nb] = requested_size;
133 } else { /* fragment -> Either other fragment, or block */
134 /* The new size is different; allocate a new space,
135 and copy the lesser of the new size and the old. */
136 //printf("(%s) new size is different...",xbt_thread_self_name());
138 result = mmalloc(mdp, requested_size);
140 memcpy(result, ptr, MIN(requested_size, (size_t) 1 << type));
145 //printf("(%s) Done reallocing: %p\n",xbt_thread_self_name(),result);fflush(stdout);