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Merge "Use system property to set dns cache size"

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Brad Fitzpatrick 2011-04-11 09:42:30 -07:00 committed by Android Code Review
commit 3ef36b2115
1 changed files with 51 additions and 13 deletions
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64
libc/netbsd/resolv/res_cache.c
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@ -34,6 +34,7 @@
#include <errno.h>
#include "arpa_nameser.h"
#include <sys/system_properties.h>
/* This code implements a small and *simple* DNS resolver cache.
*
@ -106,7 +107,7 @@
*/
#define CONFIG_SECONDS (60*10) /* 10 minutes */
/* maximum number of entries kept in the cache. This value has been
/* default number of entries kept in the cache. This value has been
* determined by browsing through various sites and counting the number
* of corresponding requests. Keep in mind that our framework is currently
* performing two requests per name lookup (one for IPv4, the other for IPv6)
@ -125,10 +126,16 @@
* most high-level websites use lots of media/ad servers with different names
* but these are generally reused when browsing through the site.
*
* As such, a valud of 64 should be relatively conformtable at the moment.
* As such, a value of 64 should be relatively comfortable at the moment.
*
* The system property ro.net.dns_cache_size can be used to override the default
* value with a custom value
*/
#define CONFIG_MAX_ENTRIES 64
/* name of the system property that can be used to set the cache size */
#define DNS_CACHE_SIZE_PROP_NAME "ro.net.dns_cache_size"
/****************************************************************************/
/****************************************************************************/
/***** *****/
@ -1147,15 +1154,15 @@ entry_equals( const Entry* e1, const Entry* e2 )
* for simplicity, the hash-table fields 'hash' and 'hlink' are
* inlined in the Entry structure.
*/
#define MAX_HASH_ENTRIES (2*CONFIG_MAX_ENTRIES)
typedef struct resolv_cache {
int max_entries;
int num_entries;
Entry mru_list;
pthread_mutex_t lock;
unsigned generation;
int last_id;
Entry* entries[ MAX_HASH_ENTRIES ];
Entry* entries;
} Cache;
@ -1167,9 +1174,9 @@ _cache_flush_locked( Cache* cache )
int nn;
time_t now = _time_now();
for (nn = 0; nn < MAX_HASH_ENTRIES; nn++)
for (nn = 0; nn < cache->max_entries; nn++)
{
Entry** pnode = &cache->entries[nn];
Entry** pnode = (Entry**) &cache->entries[nn];
while (*pnode != NULL) {
Entry* node = *pnode;
@ -1187,6 +1194,30 @@ _cache_flush_locked( Cache* cache )
"*************************");
}
/* Return max number of entries allowed in the cache,
* i.e. cache size. The cache size is either defined
* by system property ro.net.dns_cache_size or by
* CONFIG_MAX_ENTRIES if system property not set
* or set to invalid value. */
static int
_res_cache_get_max_entries( void )
{
int result = -1;
char cache_size[PROP_VALUE_MAX];
if (__system_property_get(DNS_CACHE_SIZE_PROP_NAME, cache_size) > 0) {
result = atoi(cache_size);
}
// ro.net.dns_cache_size not set or set to negative value
if (result <= 0) {
result = CONFIG_MAX_ENTRIES;
}
XLOG("cache size: %d", result);
return result;
}
static struct resolv_cache*
_resolv_cache_create( void )
{
@ -1194,10 +1225,17 @@ _resolv_cache_create( void )
cache = calloc(sizeof(*cache), 1);
if (cache) {
cache->generation = ~0U;
pthread_mutex_init( &cache->lock, NULL );
cache->mru_list.mru_prev = cache->mru_list.mru_next = &cache->mru_list;
XLOG("%s: cache created\n", __FUNCTION__);
cache->max_entries = _res_cache_get_max_entries();
cache->entries = calloc(sizeof(*cache->entries), cache->max_entries);
if (cache->entries) {
cache->generation = ~0U;
pthread_mutex_init( &cache->lock, NULL );
cache->mru_list.mru_prev = cache->mru_list.mru_next = &cache->mru_list;
XLOG("%s: cache created\n", __FUNCTION__);
} else {
free(cache);
cache = NULL;
}
}
return cache;
}
@ -1288,8 +1326,8 @@ static Entry**
_cache_lookup_p( Cache* cache,
Entry* key )
{
int index = key->hash % MAX_HASH_ENTRIES;
Entry** pnode = &cache->entries[ key->hash % MAX_HASH_ENTRIES ];
int index = key->hash % cache->max_entries;
Entry** pnode = (Entry**) &cache->entries[ index ];
while (*pnode != NULL) {
Entry* node = *pnode;
@ -1470,7 +1508,7 @@ _resolv_cache_add( struct resolv_cache* cache,
goto Exit;
}
if (cache->num_entries >= CONFIG_MAX_ENTRIES) {
if (cache->num_entries >= cache->max_entries) {
_cache_remove_oldest(cache);
/* need to lookup again */
lookup = _cache_lookup_p(cache, key);