From 7f5ab42c7ed973fe24cd8e807dcd1f8de90c62d6 Mon Sep 17 00:00:00 2001
From: xueyunfei <xueyunfei@espressif.com>
Date: Tue, 11 Aug 2020 17:54:36 +0800
Subject: [PATCH] optimization lwip dns timer

---
 src/core/dns.c       | 40 ++++++++++++++++++++++++++++++++++++++++
 src/core/timeouts.c  |  2 +-
 test/unit/lwipopts.h |  1 +
 3 files changed, 42 insertions(+), 1 deletion(-)

diff --git a/src/core/dns.c b/src/core/dns.c
index 0517c2a2..e8b8a5c7 100644
--- a/src/core/dns.c
+++ b/src/core/dns.c
@@ -94,6 +94,12 @@
 #include "lwip/memp.h"
 #include "lwip/dns.h"
 #include "lwip/prot/dns.h"
+#include "lwip/timeouts.h"
+
+#if ESP_LWIP_DNS_TIMERS_ONDEMAND
+#include "stdbool.h"
+static bool is_tmr_start = false;
+#endif /* ESP_LWIP_DNS_TIMERS_ONDEMAND */
 
 #include <string.h>
 
@@ -422,6 +428,17 @@ dns_getserver(u8_t numdns)
   }
 }
 
+#if ESP_LWIP_DNS_TIMERS_ONDEMAND
+/**
+ * Wrapper function with matching prototype which calls the actual callback
+ */
+static void dns_timeout_cb(void *arg)
+{
+  LWIP_UNUSED_ARG(arg);
+  dns_tmr();
+}
+#endif /* ESP_LWIP_DNS_TIMERS_ONDEMAND */
+
 /**
  * The DNS resolver client timer - handle retries and timeouts and should
  * be called every DNS_TMR_INTERVAL milliseconds (every second by default).
@@ -429,8 +446,25 @@ dns_getserver(u8_t numdns)
 void
 dns_tmr(void)
 {
+#if ESP_LWIP_DNS_TIMERS_ONDEMAND
+  bool tmr_restart = false;
+#endif /* ESP_LWIP_DNS_TIMERS_ONDEMAND */
   LWIP_DEBUGF(DNS_DEBUG, ("dns_tmr: dns_check_entries\n"));
   dns_check_entries();
+#if ESP_LWIP_DNS_TIMERS_ONDEMAND
+  for (u8_t i = 0; i < DNS_TABLE_SIZE; ++i) {
+    if (dns_table[i].state != DNS_STATE_UNUSED) {
+      tmr_restart = true;
+      break;
+    }
+  }
+  if (tmr_restart) {
+    sys_timeout(DNS_TMR_INTERVAL, dns_timeout_cb, NULL);
+  } else {
+    sys_untimeout(dns_timeout_cb, NULL);
+    is_tmr_start = false;
+  }
+#endif/* ESP_LWIP_DNS_TIMERS_ONDEMAND */
 }
 
 #if DNS_LOCAL_HOSTLIST
@@ -1542,6 +1576,12 @@ dns_enqueue(const char *name, size_t hostnamelen, dns_found_callback found,
 
   /* force to send query without waiting timer */
   dns_check_entry(i);
+#if ESP_LWIP_DNS_TIMERS_ONDEMAND
+  if (!is_tmr_start) {
+    sys_timeout(DNS_TMR_INTERVAL, dns_timeout_cb, NULL);
+    is_tmr_start = true;
+  }
+#endif /* ESP_LWIP_DNS_TIMERS_ONDEMAND */
 
   /* dns query is enqueued */
   return ERR_INPROGRESS;
diff --git a/src/core/timeouts.c b/src/core/timeouts.c
index 98245604..234704e8 100644
--- a/src/core/timeouts.c
+++ b/src/core/timeouts.c
@@ -108,7 +108,7 @@ const struct lwip_cyclic_timer lwip_cyclic_timers[] = {
   {IGMP_TMR_INTERVAL, HANDLER(igmp_tmr)},
 #endif /* LWIP_IGMP */
 #endif /* LWIP_IPV4 */
-#if LWIP_DNS
+#if LWIP_DNS && !ESP_LWIP_DNS_TIMERS_ONDEMAND
   {DNS_TMR_INTERVAL, HANDLER(dns_tmr)},
 #endif /* LWIP_DNS */
 #if LWIP_IPV6
diff --git a/test/unit/lwipopts.h b/test/unit/lwipopts.h
index 324eacbd..5bed5f44 100644
--- a/test/unit/lwipopts.h
+++ b/test/unit/lwipopts.h
@@ -102,6 +102,7 @@
 #define ESP_PPP                                 1
 #define ESP_LWIP_IGMP_TIMERS_ONDEMAND           1
 #define ESP_LWIP_MLD6_TIMERS_ONDEMAND           1
+#define ESP_LWIP_DNS_TIMERS_ONDEMAND            1
 #define ESP_GRATUITOUS_ARP                      1
 #define ESP_LWIP_SELECT                         1
 #define ESP_LWIP_LOCK                           1