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Lib: Save/restore state for linpools

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Also change linpool.current ptr to really point to thr current chunk.
This commit is contained in:
Ondrej Zajicek (work) 2017-12-12 19:51:36 +01:00
parent ac48e72bf6
commit 1e11918c8c
2 changed files with 65 additions and 11 deletions
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69
lib/mempool.c
View File

@ -11,7 +11,7 @@
*
* Linear memory pools are collections of memory blocks which
* support very fast allocation of new blocks, but are able to free only
* the whole collection at once.
* the whole collection at once (or in stack order).
*
* Example: Each configuration is described by a complex system of structures,
* linked lists and function trees which are all allocated from a single linear
@ -37,7 +37,7 @@ const int lp_chunk_size = sizeof(struct lp_chunk);
struct linpool {
resource r;
byte *ptr, *end;
struct lp_chunk *first, *current, **plast; /* Normal (reusable) chunks */
struct lp_chunk *first, *current; /* Normal (reusable) chunks */
struct lp_chunk *first_large; /* Large chunks */
uint chunk_size, threshold, total, total_large;
};
@ -69,7 +69,6 @@ linpool
*lp_new(pool *p, uint blk)
{
linpool *m = ralloc(p, &lp_class);
m->plast = &m->first;
m->chunk_size = blk;
m->threshold = 3*blk/4;
return m;
@ -114,22 +113,25 @@ lp_alloc(linpool *m, uint size)
}
else
{
if (m->current)
if (m->current && m->current->next)
{
/* Still have free chunks from previous incarnation (before lp_flush()) */
c = m->current;
m->current = c->next;
c = m->current->next;
}
else
{
/* Need to allocate a new chunk */
c = xmalloc(sizeof(struct lp_chunk) + m->chunk_size);
m->total += m->chunk_size;
*m->plast = c;
m->plast = &c->next;
c->next = NULL;
c->size = m->chunk_size;
if (m->current)
m->current->next = c;
else
m->first = c;
}
m->current = c;
m->ptr = c->data + size;
m->end = c->data + m->chunk_size;
}
@ -190,9 +192,11 @@ lp_flush(linpool *m)
{
struct lp_chunk *c;
/* Relink all normal chunks to free list and free all large chunks */
m->ptr = m->end = NULL;
m->current = m->first;
/* Move ptr to the first chunk and free all large chunks */
m->current = c = m->first;
m->ptr = c ? c->data : NULL;
m->end = c ? c->data + m->chunk_size : NULL;
while (c = m->first_large)
{
m->first_large = c->next;
@ -201,6 +205,49 @@ lp_flush(linpool *m)
m->total_large = 0;
}
/**
* lp_save - save the state of a linear memory pool
* @m: linear memory pool
* @p: state buffer
*
* This function saves the state of a linear memory pool. Saved state can be
* used later to restore the pool (to free memory allocated since).
*/
void
lp_save(linpool *m, lp_state *p)
{
p->current = m->current;
p->large = m->first_large;
p->ptr = m->ptr;
}
/**
* lp_restore - restore the state of a linear memory pool
* @m: linear memory pool
* @p: saved state
*
* This function restores the state of a linear memory pool, freeing all memory
* allocated since the state was saved. Note that the function cannot un-free
* the memory, therefore the function also invalidates other states that were
* saved between (on the same pool).
*/
void
lp_restore(linpool *m, lp_state *p)
{
struct lp_chunk *c;
/* Move ptr to the saved pos and free all newer large chunks */
m->current = c = p->current;
m->ptr = p->ptr;
m->end = c ? c->data + m->chunk_size : NULL;
while ((c = m->first_large) && (c != p->large))
{
m->first_large = c->next;
xfree(c);
}
}
static void
lp_free(resource *r)
{

7
lib/resource.h
View File

@ -59,11 +59,18 @@ void mb_free(void *);
typedef struct linpool linpool;
typedef struct lp_state {
void *current, *large;
byte *ptr;
} lp_state;
linpool *lp_new(pool *, unsigned blk);
void *lp_alloc(linpool *, unsigned size); /* Aligned */
void *lp_allocu(linpool *, unsigned size); /* Unaligned */
void *lp_allocz(linpool *, unsigned size); /* With clear */
void lp_flush(linpool *); /* Free everything, but leave linpool */
void lp_save(linpool *m, lp_state *p); /* Save state */
void lp_restore(linpool *m, lp_state *p); /* Restore state */
extern const int lp_chunk_size;
#define LP_GAS 1024