You should have received a copy of the GNU General Public License
along with GNU Emacs; see the file COPYING. If not, write to
-the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA. */
+the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
+Boston, MA 02111-1307, USA. */
/* NOTES:
but they never move.
We try to make just one heap and make it larger as necessary.
- But sometimes we can't do that, because we can't get continguous
+ But sometimes we can't do that, because we can't get contiguous
space to add onto the heap. When that happens, we start a new heap. */
typedef struct heap
/* These structures are allocated in the malloc arena.
The linked list is kept in order of increasing '.data' members.
The data blocks abut each other; if b->next is non-nil, then
- b->data + b->size == b->next->data. */
+ b->data + b->size == b->next->data.
+
+ An element with variable==NIL denotes a freed block, which has not yet
+ been collected. They may only appear while r_alloc_freeze > 0, and will be
+ freed when the arena is thawed. Currently, these blocs are not reusable,
+ while the arena is frozen. Very inefficient. */
+
typedef struct bp
{
struct bp *next;
POINTER *variable;
POINTER data;
SIZE size;
- POINTER new_data; /* tmporarily used for relocation */
- /* Heap this bloc is in. */
- struct heap *heap;
+ POINTER new_data; /* temporarily used for relocation */
+ struct heap *heap; /* Heap this bloc is in. */
} *bloc_ptr;
#define NIL_BLOC ((bloc_ptr) 0)
/* Head and tail of the list of relocatable blocs. */
static bloc_ptr first_bloc, last_bloc;
+static int use_relocatable_buffers;
+
+/* If >0, no relocation whatsoever takes place. */
+static int r_alloc_freeze_level;
+
\f
/* Functions to get and return memory from the system. */
if we can get that many within one heap.
If enough space is not presently available in our reserve, this means
- getting more page-aligned space from the system. If the retuned space
- is not contiguos to the last heap, allocate a new heap, and append it
+ getting more page-aligned space from the system. If the returned space
+ is not contiguous to the last heap, allocate a new heap, and append it
obtain does not try to keep track of whether space is in use
or not in use. It just returns the address of SIZE bytes that
{
register bloc_ptr b = bloc;
+ /* No need to ever call this if arena is frozen, bug somewhere! */
+ if (r_alloc_freeze_level)
+ abort();
+
while (b)
{
/* If bloc B won't fit within HEAP,
/* Add up the size of all the following blocs. */
while (tb != NIL_BLOC)
{
- s += tb->size;
+ if (tb->variable)
+ s += tb->size;
+
tb = tb->next;
}
/* Record the new address of this bloc
and update where the next bloc can start. */
b->new_data = address;
- address += b->size;
+ if (b->variable)
+ address += b->size;
b = b->next;
}
POINTER address;
SIZE old_size;
+ /* No need to ever call this if arena is frozen, bug somewhere! */
+ if (r_alloc_freeze_level)
+ abort();
+
if (bloc == NIL_BLOC || size == bloc->size)
return 1;
{
for (b = last_bloc; b != bloc; b = b->prev)
{
- safe_bcopy (b->data, b->new_data, b->size);
- *b->variable = b->data = b->new_data;
+ if (!b->variable)
+ {
+ b->size = 0;
+ b->data = b->new_data;
+ }
+ else
+ {
+ safe_bcopy (b->data, b->new_data, b->size);
+ *b->variable = b->data = b->new_data;
+ }
+ }
+ if (!bloc->variable)
+ {
+ bloc->size = 0;
+ bloc->data = bloc->new_data;
+ }
+ else
+ {
+ safe_bcopy (bloc->data, bloc->new_data, old_size);
+ bzero (bloc->new_data + old_size, size - old_size);
+ *bloc->variable = bloc->data = bloc->new_data;
}
- safe_bcopy (bloc->data, bloc->new_data, old_size);
- bzero (bloc->new_data + old_size, size - old_size);
- *bloc->variable = bloc->data = bloc->new_data;
}
else
{
for (b = bloc; b != NIL_BLOC; b = b->next)
{
- safe_bcopy (b->data, b->new_data, b->size);
- *b->variable = b->data = b->new_data;
+ if (!b->variable)
+ {
+ b->size = 0;
+ b->data = b->new_data;
+ }
+ else
+ {
+ safe_bcopy (b->data, b->new_data, b->size);
+ *b->variable = b->data = b->new_data;
+ }
}
}
{
heap_ptr heap = bloc->heap;
+ if (r_alloc_freeze_level)
+ {
+ bloc->variable = (POINTER *) NIL;
+ return;
+ }
+
resize_bloc (bloc, 0);
if (bloc == first_bloc && bloc == last_bloc)
\f
/* Interface routines. */
-static int use_relocatable_buffers;
-static int r_alloc_freeze_level;
-
/* Obtain SIZE bytes of storage from the free pool, or the system, as
necessary. If relocatable blocs are in use, this means relocating
them. This function gets plugged into the GNU malloc's __morecore
{
/* Allocate a page-aligned space. GNU malloc would reclaim an
extra space if we passed an unaligned one. But we could
- not always find a space which is contiguos to the previous. */
+ not always find a space which is contiguous to the previous. */
POINTER new_bloc_start;
heap_ptr h = first_heap;
SIZE get = ROUNDUP (size);
{
get += extra_bytes + page_size;
- if (r_alloc_freeze_level > 0 || ! obtain (address, get))
+ if (! obtain (address, get))
return 0;
if (first_heap == last_heap)
if (first_heap->bloc_start < new_bloc_start)
{
+ /* This is no clean solution - no idea how to do it better. */
+ if (r_alloc_freeze_level)
+ return NIL;
+
+ /* There is a bug here: if the above obtain call succeeded, but the
+ relocate_blocs call below does not succeed, we need to free
+ the memory that we got with obtain. */
+
/* Move all blocs upward. */
- if (r_alloc_freeze_level > 0
- || ! relocate_blocs (first_bloc, h, new_bloc_start))
+ if (! relocate_blocs (first_bloc, h, new_bloc_start))
return 0;
/* Note that (POINTER)(h+1) <= new_bloc_start since
update_heap_bloc_correspondence (first_bloc, h);
}
-
if (h != first_heap)
{
/* Give up managing heaps below the one the new
the data is returned in *PTR. PTR is thus the address of some variable
which will use the data area.
+ The allocation of 0 bytes is valid.
+ In case r_alloc_freeze is set, a best fit of unused blocs could be done
+ before allocating a new area. Not yet done.
+
If we can't allocate the necessary memory, set *PTR to zero, and
return zero. */
SIZE is less than or equal to the current bloc size, in which case
do nothing.
+ In case r_alloc_freeze is set, a new bloc is allocated, and the
+ memory copied to it. Not very efficient. We could traverse the
+ bloc_list for a best fit of free blocs first.
+
Change *PTR to reflect the new bloc, and return this value.
If more memory cannot be allocated, then leave *PTR unchanged, and
if (! r_alloc_initialized)
r_alloc_init ();
+ if (!*ptr)
+ return r_alloc (ptr, size);
+ if (!size)
+ {
+ r_alloc_free (ptr);
+ return r_alloc (ptr, 0);
+ }
+
bloc = find_bloc (ptr);
if (bloc == NIL_BLOC)
abort ();
- if (size <= bloc->size)
- /* Wouldn't it be useful to actually resize the bloc here? */
- return *ptr;
-
- if (! resize_bloc (bloc, MEM_ROUNDUP (size)))
- return 0;
-
+ if (size < bloc->size)
+ {
+ /* Wouldn't it be useful to actually resize the bloc here? */
+ /* I think so too, but not if it's too expensive... */
+ if ((bloc->size - MEM_ROUNDUP (size) >= page_size)
+ && r_alloc_freeze_level == 0)
+ {
+ resize_bloc (bloc, MEM_ROUNDUP (size));
+ /* Never mind if this fails, just do nothing... */
+ /* It *should* be infallible! */
+ }
+ }
+ else if (size > bloc->size)
+ {
+ if (r_alloc_freeze_level)
+ {
+ bloc_ptr new_bloc;
+ new_bloc = get_bloc (MEM_ROUNDUP (size));
+ if (new_bloc)
+ {
+ new_bloc->variable = ptr;
+ *ptr = new_bloc->data;
+ bloc->variable = (POINTER *) NIL;
+ }
+ else
+ return NIL;
+ }
+ else
+ {
+ if (! resize_bloc (bloc, MEM_ROUNDUP (size)))
+ return NIL;
+ }
+ }
return *ptr;
}
void
r_alloc_thaw ()
{
+
+ if (! r_alloc_initialized)
+ r_alloc_init ();
+
if (--r_alloc_freeze_level < 0)
abort ();
+
+ /* This frees all unused blocs. It is not too inefficient, as the resize
+ and bcopy is done only once. Afterwards, all unreferenced blocs are
+ already shrunk to zero size. */
+ if (!r_alloc_freeze_level)
+ {
+ bloc_ptr *b = &first_bloc;
+ while (*b)
+ if (!(*b)->variable)
+ free_bloc (*b);
+ else
+ b = &(*b)->next;
+ }
}
+
\f
/* The hook `malloc' uses for the function which gets more space
from the system. */
{
assert (h->prev == ph);
assert ((POINTER) ROUNDUP (h->end) == h->end);
+#if 0 /* ??? The code in ralloc.c does not really try to ensure
+ the heap start has any sort of alignment.
+ Perhaps it should. */
assert ((POINTER) MEM_ROUNDUP (h->start) == h->start);
+#endif
assert ((POINTER) MEM_ROUNDUP (h->bloc_start) == h->bloc_start);
assert (h->start <= h->bloc_start && h->bloc_start <= h->end);
HCoop / bpt / emacs.git / blobdiff