hashnode
ht_lookup_with_hash (hash_table *table, const unsigned char *str,
size_t len, unsigned int hash,
enum ht_lookup_option insert)
{
unsigned int hash2;
unsigned int index;
size_t sizemask;
hashnode node;
sizemask = table->nslots - 1;
index = hash & sizemask;
table->searches++;
node = table->entries[index];
if (node != NULL)
{
if (node->hash_value == hash
&& HT_LEN (node) == (unsigned int) len
&& !memcmp (HT_STR (node), str, len))
{
if (insert == HT_ALLOCED)
/* The string we search for was placed at the end of the
obstack. Release it. */
obstack_free (&table->stack, (void *) str);
return node;
}
/* hash2 must be odd, so we're guaranteed to visit every possible
location in the table during rehashing. */
hash2 = ((hash * 17) & sizemask) | 1;
for (;;)
{
table->collisions++;
index = (index + hash2) & sizemask;
node = table->entries[index];
if (node == NULL)
break;
if (node->hash_value == hash
&& HT_LEN (node) == (unsigned int) len
&& !memcmp (HT_STR (node), str, len))
{
if (insert == HT_ALLOCED)
/* The string we search for was placed at the end of the
obstack. Release it. */
obstack_free (&table->stack, (void *) str);
return node;
}
}
}
if (insert == HT_NO_INSERT)
return NULL;
node = (*table->alloc_node) (table);
table->entries[index] = node;
HT_LEN (node) = (unsigned int) len;
node->hash_value = hash;
if (insert == HT_ALLOC)
HT_STR (node) = (const unsigned char *) obstack_copy0 (&table->stack,
str, len);
else
HT_STR (node) = str;
if (++table->nelements * 4 >= table->nslots * 3)
/* Must expand the string table. */
ht_expand (table);
return node;
}
void
ht_dump_statistics (hash_table *table)
{
size_t nelts, nids, overhead, headers;
size_t total_bytes, longest;
double sum_of_squares, exp_len, exp_len2, exp2_len;
hashnode *p, *limit;
#define SCALE(x) ((unsigned long) ((x) < 1024*10 \
? (x) \
: ((x) < 1024*1024*10 \
? (x) / 1024 \
: (x) / (1024*1024))))
#define LABEL(x) ((x) < 1024*10 ? ' ' : ((x) < 1024*1024*10 ? 'k' : 'M'))
total_bytes = longest = sum_of_squares = nids = 0;
p = table->entries;
limit = p + table->nslots;
do
if (*p)
{
size_t n = HT_LEN (*p);
total_bytes += n;
sum_of_squares += (double) n * n;
if (n > longest)
longest = n;
nids++;
}
while (++p < limit);
nelts = table->nelements;
overhead = obstack_memory_used (&table->stack) - total_bytes;
headers = table->nslots * sizeof (hashnode);
fprintf (stderr, "\nString pool\nentries\t\t%lu\n",
(unsigned long) nelts);
fprintf (stderr, "identifiers\t%lu (%.2f%%)\n",
(unsigned long) nids, nids * 100.0 / nelts);
fprintf (stderr, "slots\t\t%lu\n",
(unsigned long) table->nslots);
fprintf (stderr, "bytes\t\t%lu%c (%lu%c overhead)\n",
SCALE (total_bytes), LABEL (total_bytes),
SCALE (overhead), LABEL (overhead));
fprintf (stderr, "table size\t%lu%c\n",
SCALE (headers), LABEL (headers));
exp_len = (double)total_bytes / (double)nelts;
exp2_len = exp_len * exp_len;
exp_len2 = (double) sum_of_squares / (double) nelts;
fprintf (stderr, "coll/search\t%.4f\n",
(double) table->collisions / (double) table->searches);
fprintf (stderr, "ins/search\t%.4f\n",
(double) nelts / (double) table->searches);
fprintf (stderr, "avg. entry\t%.2f bytes (+/- %.2f)\n",
exp_len, approx_sqrt (exp_len2 - exp2_len));
fprintf (stderr, "longest entry\t%lu\n",
(unsigned long) longest);
#undef SCALE
#undef LABEL
}
hashnode
ht_lookup_with_hash (cpp_hash_table *table, const unsigned char *str,
size_t len, unsigned int hash,
enum ht_lookup_option insert)
{
unsigned int hash2;
unsigned int index;
unsigned int deleted_index = table->nslots;
size_t sizemask;
hashnode node;
sizemask = table->nslots - 1;
index = hash & sizemask;
table->searches++;
node = table->entries[index];
if (node != NULL)
{
if (node == DELETED)
deleted_index = index;
else if (node->hash_value == hash
&& HT_LEN (node) == (unsigned int) len
&& !memcmp (HT_STR (node), str, len))
return node;
/* hash2 must be odd, so we're guaranteed to visit every possible
location in the table during rehashing. */
hash2 = ((hash * 17) & sizemask) | 1;
for (;;)
{
table->collisions++;
index = (index + hash2) & sizemask;
node = table->entries[index];
if (node == NULL)
break;
if (node == DELETED)
{
if (deleted_index != table->nslots)
deleted_index = index;
}
else if (node->hash_value == hash
&& HT_LEN (node) == (unsigned int) len
&& !memcmp (HT_STR (node), str, len))
return node;
}
}
if (insert == HT_NO_INSERT)
return NULL;
/* We prefer to overwrite the first deleted slot we saw. */
if (deleted_index != table->nslots)
index = deleted_index;
node = (*table->alloc_node) (table);
table->entries[index] = node;
HT_LEN (node) = (unsigned int) len;
node->hash_value = hash;
if (table->alloc_subobject)
{
char *chars = (char *) table->alloc_subobject (len + 1);
memcpy (chars, str, len);
chars[len] = '\0';
HT_STR (node) = (const unsigned char *) chars;
}
else
HT_STR (node) = (const unsigned char *) obstack_copy0 (&table->stack,
str, len);
if (++table->nelements * 4 >= table->nslots * 3)
/* Must expand the string table. */
ht_expand (table);
return node;
}
