Added lp_flush() which flushes contents of a linear pool, leaving all the

memory available for subsequent allocations from the same pool. Both flushing
and re-using the memory costs just few instructions.

diff --git a/lib/mempool.c b/lib/mempool.c
index f3b84a576e7c2a80180f1279546da83a11bbd36f..49e6e900c47504baccf04e6597cf13bbc8641844 100644 (file)
--- a/lib/mempool.c
+++ b/lib/mempool.c
@@ -1,7 +1,7 @@
 /*
  *     BIRD Resource Manager -- Memory Pools
  *
- *     (c) 1998 Martin Mares <mj@ucw.cz>
+ *     (c) 1998--1999 Martin Mares <mj@ucw.cz>
  *
  *     Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -20,8 +20,9 @@ struct lp_chunk {
 struct linpool {
   resource r;
   byte *ptr, *end;
-  struct lp_chunk *first, **plast;
-  unsigned chunk_size, threshold, total;
+  struct lp_chunk *first, *current, **plast;   /* Normal (reusable) chunks */
+  struct lp_chunk *first_large;                        /* Large chunks */
+  unsigned chunk_size, threshold, total, total_large;
 };
 
 void lp_free(resource *);
@@ -39,11 +40,12 @@ linpool
 {
   linpool *m = ralloc(p, &lp_class);
   m->ptr = m->end = NULL;
-  m->first = NULL;
+  m->first = m->current = NULL;
   m->plast = &m->first;
+  m->first_large = NULL;
   m->chunk_size = blk;
   m->threshold = 3*blk/4;
-  m->total = 0;
+  m->total = m->total_large = 0;
   return m;
 }
 
@@ -63,19 +65,30 @@ lp_alloc(linpool *m, unsigned size)
       struct lp_chunk *c;
       if (size >= m->threshold)
        {
+         /* Too large => allocate large chunk */
          c = xmalloc(sizeof(struct lp_chunk) + size);
-         m->total += size;
+         m->total_large += size;
+         c->next = m->first_large;
+         m->first_large = c->next;
        }
       else
        {
-         c = xmalloc(sizeof(struct lp_chunk) + m->chunk_size);
+         if (m->current && m->current->next)
+           /* Still have free chunks from previous incarnation (before lp_flush()) */
+           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;
+           }
+         m->current = c;
          m->ptr = c->data + size;
          m->end = c->data + m->chunk_size;
-         m->total += m->chunk_size;
        }
-      *m->plast = c;
-      m->plast = &c->next;
-      c->next = NULL;
       return c->data;
     }
 }
@@ -103,6 +116,22 @@ lp_allocz(linpool *m, unsigned size)
   return z;
 }
 
+void
+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;
+  while (c = m->first_large)
+    {
+      m->first_large = c->next;
+      xfree(c);
+    }
+  m->total_large = 0;
+}
+
 void
 lp_free(resource *r)
 {

diff --git a/lib/resource.h b/lib/resource.h
index 1d83b07fca41c9c84684aa7c6cf03d32d1b7c1ea..1a9939780abe9d09b009e9075e02b6f7faaf9f50 100644 (file)
--- a/lib/resource.h
+++ b/lib/resource.h
@@ -1,7 +1,7 @@
 /*
  *     BIRD Resource Manager
  *
- *     (c) 1998 Martin Mares <mj@ucw.cz>
+ *     (c) 1998--1999 Martin Mares <mj@ucw.cz>
  *
  *     Can be freely distributed and used under the terms of the GNU GPL.
  */
@@ -54,6 +54,7 @@ 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 */
 
 /* Slabs */