delay() refactoring

cores/esp8266/Arduino.h

@@ -209,6 +209,7 @@ unsigned long millis(void);
 unsigned long micros(void);
 uint64_t micros64(void);
 void delay(unsigned long);
+void interruptable_delay(unsigned long ms);
 void delayMicroseconds(unsigned int us);
 unsigned long pulseIn(uint8_t pin, uint8_t state, unsigned long timeout);
 unsigned long pulseInLong(uint8_t pin, uint8_t state, unsigned long timeout);

cores/esp8266/core_esp8266_wiring.cpp

@@ -43,7 +43,7 @@ void delay_end(void* arg) {
     esp_schedule();
 }
 
-void delay(unsigned long ms) {
+void interruptable_delay(unsigned long ms) {
     if(ms) {
         os_timer_setfn(&delay_timer, (os_timer_func_t*) &delay_end, 0);
         os_timer_arm(&delay_timer, ms, ONCE);
@@ -56,6 +56,21 @@ void delay(unsigned long ms) {
     }
 }
 
+void delay(unsigned long ms) {
+    if (ms) {
+        unsigned long delay_start = millis();
+        while(millis() - delay_start < ms) {
+            os_timer_setfn(&delay_timer, (os_timer_func_t*) &delay_end, 0);
+            os_timer_arm(&delay_timer, 1, ONCE);
+            esp_yield();
+            os_timer_disarm(&delay_timer);
+        }
+    } else {
+        esp_schedule();
+        esp_yield();
+    }
+}
+
 void micros_overflow_tick(void* arg) {
     (void) arg;
     uint32_t m = system_get_time();

libraries/ESP8266WiFi/src/ESP8266WiFiGeneric.cpp

@@ -565,7 +565,11 @@ int ESP8266WiFiGenericClass::hostByName(const char* aHostname, IPAddress& aResul
         aResult = IPAddress(&addr);
     } else if(err == ERR_INPROGRESS) {
         _dns_lookup_pending = true;
-        delay(timeout_ms);
+        // Following delay will be interrupted by dns found callback
+        for (decltype(timeout_ms) i = 0; _dns_lookup_pending && i < timeout_ms; i++) {
+               // let a chance to recurrent scheduled functions (ethernet)
+               delay(1);
+       }
         _dns_lookup_pending = false;
         // will return here when dns_found_callback fires
         if(aResult.isSet()) {
@@ -597,6 +601,7 @@ void wifi_dns_found_callback(const char *name, CONST ip_addr_t *ipaddr, void *ca
     if(ipaddr) {
         (*reinterpret_cast<IPAddress*>(callback_arg)) = IPAddress(ipaddr);
     }
+    _dns_lookup_pending = false;
     esp_schedule(); // resume the hostByName function
 }