htable: increase density from 75% to 87.5%

[ccan] / ccan / htable / htable.c

diff --git a/ccan/htable/htable.c b/ccan/htable/htable.c
index 3247bea0879af34e2db5f47e1a3c5f9ac8a9fa9f..c5f166f83e3fc0f188f9907a6a6da55f0e60cb5a 100644 (file)
--- a/ccan/htable/htable.c
+++ b/ccan/htable/htable.c
@@ -86,14 +86,16 @@ void htable_init(struct htable *ht,
        ht->table = &ht->common_bits;
 }
 
+/* Fill to 87.5% */
 static inline size_t ht_max(const struct htable *ht)
 {
-       return ((size_t)3 << ht->bits) / 4;
+       return ((size_t)7 << ht->bits) / 8;
 }
 
-static inline size_t ht_max_with_deleted(const struct htable *ht)
+/* Clean deleted if we're full, and more than 12.5% deleted */
+static inline size_t ht_max_deleted(const struct htable *ht)
 {
-       return ((size_t)9 << ht->bits) / 10;
+       return ((size_t)1 << ht->bits) / 8;
 }
 
 bool htable_init_sized(struct htable *ht,
@@ -103,7 +105,7 @@ bool htable_init_sized(struct htable *ht,
        htable_init(ht, rehash, priv);
 
        /* Don't go insane with sizing. */
-       for (ht->bits = 1; ((size_t)3 << ht->bits) / 4 < expect; ht->bits++) {
+       for (ht->bits = 1; ht_max(ht) < expect; ht->bits++) {
                if (ht->bits == 30)
                        break;
        }
@@ -379,10 +381,15 @@ bool htable_add_(struct htable *ht, size_t hash, const void *p)
        assert(p);
        assert(entry_is_valid((uintptr_t)p));
 
-       if (ht->elems+1 > ht_max(ht) && !double_table(ht))
-               return false;
-       if (ht->elems+1 + ht->deleted > ht_max_with_deleted(ht))
-               rehash_table(ht);
+       /* Getting too full? */
+       if (ht->elems+1 + ht->deleted > ht_max(ht)) {
+               /* If we're more than 1/8 deleted, clean those,
+                * otherwise double table size. */
+               if (ht->deleted > ht_max_deleted(ht))
+                       rehash_table(ht);
+               else if (!double_table(ht))
+                       return false;
+       }
        if (((uintptr_t)p & ht->common_mask) != ht->common_bits)
                update_common(ht, p);