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authorJustus Winter <justus@gnupg.org>2016-04-28 20:11:27 +0200
committerJustus Winter <justus@gnupg.org>2016-04-29 22:39:06 +0200
commit39031d37fd82c119b4b16af256a8ceae5d8c6ea8 (patch)
treefc63fd59c5346bfb415a2eee45eddb1953e6e7bc
parent74d373342f799a45e9193c2f56189843b7b42c04 (diff)
libihash: keep track of free slots
* libihash/ihash.c (hurd_ihash_init): Init new field 'nr_free'. (add_one): Decrement counter if a free slot is used. (hurd_ihash_locp_add): Likewise. (hurd_ihash_add): Reset counter on reallocation. * libihash/ihash.h (struct hurd_ihash): New field 'nr_free'. (hurd_ihash_get_effective_load): New function.
-rw-r--r--libihash/ihash.c9
-rw-r--r--libihash/ihash.h11
2 files changed, 20 insertions, 0 deletions
diff --git a/libihash/ihash.c b/libihash/ihash.c
index 01ba23bd..800f4923 100644
--- a/libihash/ihash.c
+++ b/libihash/ihash.c
@@ -131,6 +131,7 @@ hurd_ihash_init (hurd_ihash_t ht, intptr_t locp_offs)
ht->cleanup = 0;
ht->fct_hash = NULL;
ht->fct_cmp = NULL;
+ ht->nr_free = 0;
}
@@ -246,6 +247,11 @@ add_one (hurd_ihash_t ht, hurd_ihash_key_t key, hurd_ihash_value_t value)
if (index_empty (ht, idx))
{
ht->nr_items++;
+ if (ht->items[idx].value == _HURD_IHASH_EMPTY)
+ {
+ assert (ht->nr_free > 0);
+ ht->nr_free--;
+ }
ht->items[idx].value = value;
ht->items[idx].key = key;
@@ -290,6 +296,8 @@ hurd_ihash_locp_add (hurd_ihash_t ht, hurd_ihash_locp_t locp,
{
item->key = key;
ht->nr_items += 1;
+ assert (ht->nr_free > 0);
+ ht->nr_free -= 1;
}
else
{
@@ -335,6 +343,7 @@ hurd_ihash_add (hurd_ihash_t ht, hurd_ihash_key_t key, hurd_ihash_value_t item)
ht->size = HURD_IHASH_MIN_SIZE;
else
ht->size <<= 1;
+ ht->nr_free = ht->size;
/* calloc() will initialize all values to _HURD_IHASH_EMPTY implicitly. */
ht->items = calloc (ht->size, sizeof (struct _hurd_ihash_item));
diff --git a/libihash/ihash.h b/libihash/ihash.h
index 356f6473..80679f14 100644
--- a/libihash/ihash.h
+++ b/libihash/ihash.h
@@ -113,6 +113,9 @@ struct hurd_ihash
/* User-supplied functions for the generalized key interface. */
hurd_ihash_fct_hash_t fct_hash;
hurd_ihash_fct_cmp_t fct_cmp;
+
+ /* Number of free slots. */
+ size_t nr_free;
};
typedef struct hurd_ihash *hurd_ihash_t;
@@ -225,6 +228,14 @@ hurd_ihash_get_load (hurd_ihash_t ht)
return d >= 0 ? ht->nr_items >> d : ht->nr_items << -d;
}
+/* Similar, but counts tombstones as well. */
+static inline unsigned int
+hurd_ihash_get_effective_load (hurd_ihash_t ht)
+{
+ int d = __builtin_ctzl (ht->size) - 7;
+ return
+ d >= 0 ? (ht->size - ht->nr_free) >> d : (ht->size - ht->nr_free) << -d;
+}
/* Add ITEM to the hash table HT under the key KEY. If there already
is an item under this key, call the cleanup function (if any) for