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Further tuning of the fast hostfile reading code.

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Use the packet buffer for hash-buckets, better hash function.
This commit is contained in:
Simon Kelley
2012-01-12 11:33:16 +00:00
parent 915363f976
commit 1ab62aec37
2 changed files with 19 additions and 25 deletions
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43
src/cache.c
View File

@@ -635,7 +635,7 @@ struct crec *cache_find_by_addr(struct crec *crecp, struct all_addr *addr,
}
static void add_hosts_entry(struct crec *cache, struct all_addr *addr, int addrlen,
unsigned short flags, int index, struct crec **rhash)
unsigned short flags, int index, struct crec **rhash, int hashsz)
{
struct crec *lookup = cache_find_by_name(NULL, cache->name.sname, 0, flags & (F_IPV4 | F_IPV6));
int i, nameexists = 0;
@@ -656,20 +656,18 @@ static void add_hosts_entry(struct crec *cache, struct all_addr *addr, int addrl
/* Ensure there is only one address -> name mapping (first one trumps)
We do this by steam here, The entries are kept in hash chains, linked
by ->next (which is unused at this point) held in hash buckets in
the array rhash. Note that rhash and the values in ->next are only valid
whilst reading hosts files: the buckets are then freed, and the
->next pointer used for other things.
the array rhash, hashed on address. Note that rhash and the values
in ->next are only valid whilst reading hosts files: the buckets are
then freed, and the ->next pointer used for other things.
Only insert each unique address one into this hashing structure.
Only insert each unique address once into this hashing structure.
This complexity avoids O(n^2) divergent CPU use whilst reading
large (10000 entry) hosts files. */
/* hash address */
for (j = 0, i = 0; i < addrlen; i++)
j += ((unsigned char *)addr)[i] + (j << 6) + (j << 16) - j;
j = j % RHASHSIZE;
j = (j*2 +((unsigned char *)addr)[i]) % hashsz;
for (lookup = rhash[j]; lookup; lookup = lookup->next)
if ((lookup->flags & F_HOSTS) &&
@@ -753,7 +751,7 @@ static int gettok(FILE *f, char *token)
}
}
static int read_hostsfile(char *filename, int index, int cache_size, struct crec **rhash)
static int read_hostsfile(char *filename, int index, int cache_size, struct crec **rhash, int hashsz)
{
FILE *f = fopen(filename, "r");
char *token = daemon->namebuff, *domain_suffix = NULL;
@@ -833,13 +831,13 @@ static int read_hostsfile(char *filename, int index, int cache_size, struct crec
strcpy(cache->name.sname, canon);
strcat(cache->name.sname, ".");
strcat(cache->name.sname, domain_suffix);
add_hosts_entry(cache, &addr, addrlen, flags, index, rhash);
add_hosts_entry(cache, &addr, addrlen, flags, index, rhash, hashsz);
name_count++;
}
if ((cache = whine_malloc(sizeof(struct crec) + strlen(canon)+1-SMALLDNAME)))
{
strcpy(cache->name.sname, canon);
add_hosts_entry(cache, &addr, addrlen, flags, index, rhash);
add_hosts_entry(cache, &addr, addrlen, flags, index, rhash, hashsz);
name_count++;
}
free(canon);
@@ -861,9 +859,8 @@ static int read_hostsfile(char *filename, int index, int cache_size, struct crec
void cache_reload(void)
{
struct crec *cache, **up, *tmp;
int i, total_size = daemon->cachesize;
int revhashsz, i, total_size = daemon->cachesize;
struct hostsfile *ah;
struct crec **reverse_hash;
cache_inserted = cache_live_freed = 0;
@@ -896,22 +893,20 @@ void cache_reload(void)
my_syslog(LOG_INFO, _("cleared cache"));
return;
}
if (!(reverse_hash = whine_malloc(sizeof(struct crec *) * RHASHSIZE)))
return;
for (i = 0; i < RHASHSIZE; i++)
reverse_hash[i] = NULL;
/* borrow the packet buffer for a temporary by-address hash */
memset(daemon->packet, 0, daemon->packet_buff_sz);
revhashsz = daemon->packet_buff_sz / sizeof(struct crec *);
/* we overwrote the buffer... */
daemon->srv_save = NULL;
if (!option_bool(OPT_NO_HOSTS))
total_size = read_hostsfile(HOSTSFILE, 0, total_size, reverse_hash);
total_size = read_hostsfile(HOSTSFILE, 0, total_size, (struct crec **)daemon->packet, revhashsz);
daemon->addn_hosts = expand_filelist(daemon->addn_hosts);
for (ah = daemon->addn_hosts; ah; ah = ah->next)
if (!(ah->flags & AH_INACTIVE))
total_size = read_hostsfile(ah->fname, ah->index, total_size, reverse_hash);
free(reverse_hash);
total_size = read_hostsfile(ah->fname, ah->index, total_size, (struct crec **)daemon->packet, revhashsz);
}
char *get_domain(struct in_addr addr)

1
src/config.h
View File

@@ -15,7 +15,6 @@
*/
#define FTABSIZ 150 /* max number of outstanding requests (default) */
#define RHASHSIZE 1024 /* hash buckets for address lookup during hostfile read */
#define MAX_PROCS 20 /* max no children for TCP requests */
#define CHILD_LIFETIME 150 /* secs 'till terminated (RFC1035 suggests > 120s) */
#define EDNS_PKTSZ 4096 /* default max EDNS.0 UDP packet from RFC5625 */