Written by Fred Fish <fnf@cygnus.com>
Rewritten by Jim Blandy <jimb@cygnus.com>
- Copyright (C) 1999, 2000, 2002, 2003, 2007, 2008
+ Copyright (C) 1999, 2000, 2002, 2003, 2007, 2008, 2009, 2010
Free Software Foundation, Inc.
This file is part of GDB.
16 bits of hash values) hit, but the corresponding combined
length/data compare missed. */
unsigned long half_hash_miss_count;
+
+ /* Hash function to be used for this bcache object. */
+ unsigned long (*hash_function)(const void *addr, int length);
+
+ /* Compare function to be used for this bcache object. */
+ int (*compare_function)(const void *, const void *, int length);
};
/* The old hash function was stolen from SDBM. This is what DB 3.0 uses now,
unsigned long
hash(const void *addr, int length)
{
- const unsigned char *k, *e;
- unsigned long h;
-
- k = (const unsigned char *)addr;
- e = k+length;
- for (h=0; k< e;++k)
- {
- h *=16777619;
- h ^= *k;
- }
- return (h);
+ return hash_continue (addr, length, 0);
+}
+
+/* Continue the calculation of the hash H at the given address. */
+
+unsigned long
+hash_continue (const void *addr, int length, unsigned long h)
+{
+ const unsigned char *k, *e;
+
+ k = (const unsigned char *)addr;
+ e = k+length;
+ for (; k< e;++k)
+ {
+ h *=16777619;
+ h ^= *k;
+ }
+ return (h);
}
\f
/* Growing the bcache's hash table. */
/* Allocate the new table. */
{
size_t new_size = new_num_buckets * sizeof (new_buckets[0]);
+
new_buckets = (struct bstring **) xmalloc (new_size);
memset (new_buckets, 0, new_size);
if (added)
*added = 0;
+ /* Lazily initialize the obstack. This can save quite a bit of
+ memory in some cases. */
+ if (bcache->total_count == 0)
+ {
+ /* We could use obstack_specify_allocation here instead, but
+ gdb_obstack.h specifies the allocation/deallocation
+ functions. */
+ obstack_init (&bcache->cache);
+ }
+
/* If our average chain length is too high, expand the hash table. */
if (bcache->unique_count >= bcache->num_buckets * CHAIN_LENGTH_THRESHOLD)
expand_hash_table (bcache);
bcache->total_count++;
bcache->total_size += length;
- full_hash = hash (addr, length);
+ full_hash = bcache->hash_function (addr, length);
+
half_hash = (full_hash >> 16);
hash_index = full_hash % bcache->num_buckets;
if (s->half_hash == half_hash)
{
if (s->length == length
- && ! memcmp (&s->d.data, addr, length))
+ && bcache->compare_function (&s->d.data, addr, length))
return &s->d.data;
else
bcache->half_hash_miss_count++;
{
struct bstring *new
= obstack_alloc (&bcache->cache, BSTRING_SIZE (length));
+
memcpy (&new->d.data, addr, length);
new->length = length;
new->next = bcache->bucket[hash_index];
}
}
\f
+
+/* Compare the byte string at ADDR1 of lenght LENGHT to the
+ string at ADDR2. Return 1 if they are equal. */
+
+static int
+bcache_compare (const void *addr1, const void *addr2, int length)
+{
+ return memcmp (addr1, addr2, length) == 0;
+}
+
/* Allocating and freeing bcaches. */
+/* Allocated a bcache. HASH_FUNCTION and COMPARE_FUNCTION can be used
+ to pass in custom hash, and compare functions to be used by this
+ bcache. If HASH_FUNCTION is NULL hash() is used and if COMPARE_FUNCTION
+ is NULL memcmp() is used. */
+
struct bcache *
-bcache_xmalloc (void)
+bcache_xmalloc (unsigned long (*hash_function)(const void *, int length),
+ int (*compare_function)(const void *, const void *, int length))
{
/* Allocate the bcache pre-zeroed. */
struct bcache *b = XCALLOC (1, struct bcache);
- /* We could use obstack_specify_allocation here instead, but
- gdb_obstack.h specifies the allocation/deallocation
- functions. */
- obstack_init (&b->cache);
+
+ if (hash_function)
+ b->hash_function = hash_function;
+ else
+ b->hash_function = hash;
+
+ if (compare_function)
+ b->compare_function = compare_function;
+ else
+ b->compare_function = bcache_compare;
return b;
}
{
if (bcache == NULL)
return;
- obstack_free (&bcache->cache, 0);
+ /* Only free the obstack if we actually initialized it. */
+ if (bcache->total_count > 0)
+ obstack_free (&bcache->cache, 0);
xfree (bcache->bucket);
xfree (bcache);
}
\f
/* Printing statistics. */
-static int
-compare_ints (const void *ap, const void *bp)
-{
- /* Because we know we're comparing two ints which are positive,
- there's no danger of overflow here. */
- return * (int *) ap - * (int *) bp;
-}
-
-
static void
print_percentage (int portion, int total)
{
/* To compute the median, we need the set of chain lengths sorted. */
qsort (chain_length, c->num_buckets, sizeof (chain_length[0]),
- compare_ints);
+ compare_positive_ints);
qsort (entry_size, c->unique_count, sizeof (entry_size[0]),
- compare_ints);
+ compare_positive_ints);
if (c->num_buckets > 0)
{
int
bcache_memory_used (struct bcache *bcache)
{
+ if (bcache->total_count == 0)
+ return 0;
return obstack_memory_used (&bcache->cache);
}