Optimize prefetch hitime

src/dns_cache.c

@@ -3,6 +3,10 @@
 #include "tlog.h"
 #include <pthread.h>
 
+#define DNS_CACHE_MAX_HITNUM 5000
+#define DNS_CACHE_HITNUM_STEP 2
+#define DNS_CACHE_HITNUM_STEP_MAX 6
+
 struct dns_cache_head {
 	DECLARE_HASHTABLE(cache_hash, 10);
 	struct list_head cache_list;
@@ -159,7 +163,8 @@ int dns_cache_insert(char *domain, char *cname, int cname_ttl, int ttl, dns_type
 	dns_cache->cname[0] = 0;
 	dns_cache->qtype = qtype;
 	dns_cache->ttl = ttl;
-	atomic_set(&dns_cache->hitnum, 2);
+	atomic_set(&dns_cache->hitnum, 3);
+	dns_cache->hitnum_update_add = DNS_CACHE_HITNUM_STEP;
 	dns_cache->del_pending = 0;
 	dns_cache->speed = speed;
 	atomic_set(&dns_cache->ref, 1);
@@ -274,13 +279,33 @@ void dns_cache_delete(struct dns_cache *dns_cache)
 	pthread_mutex_unlock(&dns_cache_head.lock);
 }
 
+int dns_cache_hitnum_dec_get(struct dns_cache *dns_cache)
+{
+	int hitnum = 0;
+	pthread_mutex_lock(&dns_cache_head.lock);
+	hitnum = atomic_dec_return(&dns_cache->hitnum);
+	if (dns_cache->hitnum_update_add > DNS_CACHE_HITNUM_STEP) {
+		dns_cache->hitnum_update_add--;
+	}
+	pthread_mutex_unlock(&dns_cache_head.lock);
+
+	return hitnum;
+}
+
 void dns_cache_update(struct dns_cache *dns_cache)
 {
 	pthread_mutex_lock(&dns_cache_head.lock);
 	if (!list_empty(&dns_cache->list)) {
 		list_del_init(&dns_cache->list);
 		list_add_tail(&dns_cache->list, &dns_cache_head.cache_list);
-		atomic_inc(&dns_cache->hitnum);
+		atomic_add(dns_cache->hitnum_update_add, &dns_cache->hitnum);
+		if (atomic_read(&dns_cache->hitnum) > DNS_CACHE_MAX_HITNUM) {
+			atomic_set(&dns_cache->hitnum, DNS_CACHE_MAX_HITNUM);
+		}
+
+		if (dns_cache->hitnum_update_add < DNS_CACHE_HITNUM_STEP_MAX) {
+			dns_cache->hitnum_update_add++;
+		}
 	}
 	pthread_mutex_unlock(&dns_cache_head.lock);
 }

src/dns_cache.h

@@ -22,6 +22,7 @@ struct dns_cache {
 	unsigned int ttl;
 	int speed;
 	atomic_t hitnum;
+	int hitnum_update_add;
 	int del_pending;
 	time_t insert_time;
 	dns_type_t qtype;
@@ -46,6 +47,8 @@ void dns_cache_get(struct dns_cache *dns_cache);
 
 void dns_cache_release(struct dns_cache *dns_cache);
 
+int dns_cache_hitnum_dec_get(struct dns_cache *dns_cache);
+
 void dns_cache_update(struct dns_cache *dns_cache);
 
 typedef void dns_cache_preinvalid_callback(struct dns_cache *dns_cache);

src/dns_server.c

@@ -2602,12 +2602,13 @@ static void _dns_server_second_ping_check(struct dns_request *request)
 static void _dns_server_prefetch_domain(struct dns_cache *dns_cache)
 {
 	/* If there are still hits, continue pre-fetching */
-	if (atomic_dec_return(&dns_cache->hitnum) <= 0) {
+	int hitnum = dns_cache_hitnum_dec_get(dns_cache);
+	if (hitnum <= 0) {
 		return;
 	}
 
 	/* start prefetch domain */
-	tlog(TLOG_DEBUG, "prefetch by cache %s, qtype %d, ttl %d, hitnum %d", dns_cache->domain, dns_cache->qtype, dns_cache->ttl, atomic_read(&dns_cache->hitnum));
+	tlog(TLOG_DEBUG, "prefetch by cache %s, qtype %d, ttl %d, hitnum %d", dns_cache->domain, dns_cache->qtype, dns_cache->ttl, hitnum);
 	if (_dns_server_prefetch_request(dns_cache->domain, dns_cache->qtype) != 0) {
 		tlog(TLOG_ERROR, "prefetch domain %s, qtype %d, failed.", dns_cache->domain, dns_cache->qtype);
 	}