Written by Fred Fish <fnf@cygnus.com>
Rewritten by Jim Blandy <jimb@cygnus.com>
- Copyright 1999, 2000, 2002, 2003 Free Software Foundation, Inc.
+ Copyright (C) 1999, 2000, 2002, 2003, 2007, 2008, 2009
+ Free Software Foundation, Inc.
This file is part of GDB.
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
- the Free Software Foundation; either version 2 of the License, or
+ the Free Software Foundation; either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
- along with this program; if not, write to the Free Software
- Foundation, Inc., 59 Temple Place - Suite 330,
- Boston, MA 02111-1307, USA. */
+ along with this program. If not, see <http://www.gnu.org/licenses/>. */
#include "defs.h"
#include "gdb_obstack.h"
struct bstring
{
+ /* Hash chain. */
struct bstring *next;
- size_t length;
+ /* Assume the data length is no more than 64k. */
+ unsigned short length;
+ /* The half hash hack. This contains the upper 16 bits of the hash
+ value and is used as a pre-check when comparing two strings and
+ avoids the need to do length or memcmp calls. It proves to be
+ roughly 100% effective. */
+ unsigned short half_hash;
union
{
expand_hash_count. */
unsigned long expand_count;
unsigned long expand_hash_count;
+ /* Number of times that the half-hash compare hit (compare the upper
+ 16 bits of hash values) hit, but the corresponding combined
+ length/data compare missed. */
+ unsigned long half_hash_miss_count;
};
/* The old hash function was stolen from SDBM. This is what DB 3.0 uses now,
/* Find a copy of the LENGTH bytes at ADDR in BCACHE. If BCACHE has
never seen those bytes before, add a copy of them to BCACHE. In
either case, return a pointer to BCACHE's copy of that string. */
-void *
+const void *
bcache (const void *addr, int length, struct bcache *bcache)
{
+ return bcache_full (addr, length, bcache, NULL);
+}
+
+/* Find a copy of the LENGTH bytes at ADDR in BCACHE. If BCACHE has
+ never seen those bytes before, add a copy of them to BCACHE. In
+ either case, return a pointer to BCACHE's copy of that string. If
+ optional ADDED is not NULL, return 1 in case of new entry or 0 if
+ returning an old entry. */
+
+const void *
+bcache_full (const void *addr, int length, struct bcache *bcache, int *added)
+{
+ unsigned long full_hash;
+ unsigned short half_hash;
int hash_index;
struct bstring *s;
+ 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;
- hash_index = hash (addr, length) % bcache->num_buckets;
+ full_hash = hash (addr, length);
+ half_hash = (full_hash >> 16);
+ hash_index = full_hash % bcache->num_buckets;
- /* Search the hash bucket for a string identical to the caller's. */
+ /* Search the hash bucket for a string identical to the caller's.
+ As a short-circuit first compare the upper part of each hash
+ values. */
for (s = bcache->bucket[hash_index]; s; s = s->next)
- if (s->length == length
- && ! memcmp (&s->d.data, addr, length))
- return &s->d.data;
+ {
+ if (s->half_hash == half_hash)
+ {
+ if (s->length == length
+ && ! memcmp (&s->d.data, addr, length))
+ return &s->d.data;
+ else
+ bcache->half_hash_miss_count++;
+ }
+ }
/* The user's string isn't in the list. Insert it after *ps. */
{
memcpy (&new->d.data, addr, length);
new->length = length;
new->next = bcache->bucket[hash_index];
+ new->half_hash = half_hash;
bcache->bucket[hash_index] = new;
bcache->unique_count++;
bcache->unique_size += length;
bcache->structure_size += BSTRING_SIZE (length);
+ if (added)
+ *added = 1;
+
return &new->d.data;
}
}
-
\f
/* Allocating and freeing bcaches. */
{
/* Allocate the bcache pre-zeroed. */
struct bcache *b = XCALLOC (1, struct bcache);
- obstack_specify_allocation (&b->cache, 0, 0, xmalloc, xfree);
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);
}
print_percentage (int portion, int total)
{
if (total == 0)
- printf_filtered ("(not applicable)\n");
+ /* i18n: Like "Percentage of duplicates, by count: (not applicable)" */
+ printf_filtered (_("(not applicable)\n"));
else
- printf_filtered ("%3d%%\n", portion * 100 / total);
+ printf_filtered ("%3d%%\n", (int) (portion * 100.0 / total));
}
xfree (entry_size);
}
- printf_filtered (" Cached '%s' statistics:\n", type);
- printf_filtered (" Total object count: %ld\n", c->total_count);
- printf_filtered (" Unique object count: %lu\n", c->unique_count);
- printf_filtered (" Percentage of duplicates, by count: ");
+ printf_filtered (_(" Cached '%s' statistics:\n"), type);
+ printf_filtered (_(" Total object count: %ld\n"), c->total_count);
+ printf_filtered (_(" Unique object count: %lu\n"), c->unique_count);
+ printf_filtered (_(" Percentage of duplicates, by count: "));
print_percentage (c->total_count - c->unique_count, c->total_count);
printf_filtered ("\n");
- printf_filtered (" Total object size: %ld\n", c->total_size);
- printf_filtered (" Unique object size: %ld\n", c->unique_size);
- printf_filtered (" Percentage of duplicates, by size: ");
+ printf_filtered (_(" Total object size: %ld\n"), c->total_size);
+ printf_filtered (_(" Unique object size: %ld\n"), c->unique_size);
+ printf_filtered (_(" Percentage of duplicates, by size: "));
print_percentage (c->total_size - c->unique_size, c->total_size);
printf_filtered ("\n");
- printf_filtered (" Max entry size: %d\n", max_entry_size);
- printf_filtered (" Average entry size: ");
+ printf_filtered (_(" Max entry size: %d\n"), max_entry_size);
+ printf_filtered (_(" Average entry size: "));
if (c->unique_count > 0)
printf_filtered ("%ld\n", c->unique_size / c->unique_count);
else
- printf_filtered ("(not applicable)\n");
- printf_filtered (" Median entry size: %d\n", median_entry_size);
+ /* i18n: "Average entry size: (not applicable)" */
+ printf_filtered (_("(not applicable)\n"));
+ printf_filtered (_(" Median entry size: %d\n"), median_entry_size);
printf_filtered ("\n");
- printf_filtered (" Total memory used by bcache, including overhead: %ld\n",
+ printf_filtered (_(" Total memory used by bcache, including overhead: %ld\n"),
c->structure_size);
- printf_filtered (" Percentage memory overhead: ");
+ printf_filtered (_(" Percentage memory overhead: "));
print_percentage (c->structure_size - c->unique_size, c->unique_size);
- printf_filtered (" Net memory savings: ");
+ printf_filtered (_(" Net memory savings: "));
print_percentage (c->total_size - c->structure_size, c->total_size);
printf_filtered ("\n");
- printf_filtered (" Hash table size: %3d\n", c->num_buckets);
- printf_filtered (" Hash table expands: %lu\n",
+ printf_filtered (_(" Hash table size: %3d\n"), c->num_buckets);
+ printf_filtered (_(" Hash table expands: %lu\n"),
c->expand_count);
- printf_filtered (" Hash table hashes: %lu\n",
+ printf_filtered (_(" Hash table hashes: %lu\n"),
c->total_count + c->expand_hash_count);
- printf_filtered (" Hash table population: ");
+ printf_filtered (_(" Half hash misses: %lu\n"),
+ c->half_hash_miss_count);
+ printf_filtered (_(" Hash table population: "));
print_percentage (occupied_buckets, c->num_buckets);
- printf_filtered (" Median hash chain length: %3d\n",
+ printf_filtered (_(" Median hash chain length: %3d\n"),
median_chain_length);
- printf_filtered (" Average hash chain length: ");
+ printf_filtered (_(" Average hash chain length: "));
if (c->num_buckets > 0)
printf_filtered ("%3lu\n", c->unique_count / c->num_buckets);
else
- printf_filtered ("(not applicable)\n");
- printf_filtered (" Maximum hash chain length: %3d\n", max_chain_length);
+ /* i18n: "Average hash chain length: (not applicable)" */
+ printf_filtered (_("(not applicable)\n"));
+ printf_filtered (_(" Maximum hash chain length: %3d\n"), max_chain_length);
printf_filtered ("\n");
}
int
bcache_memory_used (struct bcache *bcache)
{
+ if (bcache->total_count == 0)
+ return 0;
return obstack_memory_used (&bcache->cache);
}
projects / deliverable / binutils-gdb.git / blobdiff