WebServer.handleClient delay (espressif#4350)

* If WebServer.handleClient is run in a tight loop, it will starve other processes.  So, if there is no connection, throw in a delay(1).  Fixes espressif#4348

* Made a variable to control the delay behavior

Author: lbernstone

Diff for: libraries/WebServer/src/WebServer.cpp

@@ -45,6 +45,7 @@ WebServer::WebServer(IPAddress addr, int port)
 , _currentVersion(0)
 , _currentStatus(HC_NONE)
 , _statusChange(0)
+, _nullDelay(true)
 , _currentHandler(nullptr)
 , _firstHandler(nullptr)
 , _lastHandler(nullptr)
@@ -66,6 +67,7 @@ WebServer::WebServer(int port)
 , _currentVersion(0)
 , _currentStatus(HC_NONE)
 , _statusChange(0)
+, _nullDelay(true)
 , _currentHandler(nullptr)
 , _firstHandler(nullptr)
 , _lastHandler(nullptr)
@@ -280,6 +282,9 @@ void WebServer::handleClient() {
   if (_currentStatus == HC_NONE) {
     WiFiClient client = _server.available();
     if (!client) {
+      if (_nullDelay) {
+        delay(1);
+      }
       return;
     }
 
@@ -370,6 +375,10 @@ void WebServer::setContentLength(const size_t contentLength) {
     _contentLength = contentLength;
 }
 
+void WebServer::enableDelay(boolean value) {
+  _nullDelay = value;
+}
+
 void WebServer::enableCORS(boolean value) {
   _corsEnabled = value;
 }

Diff for: libraries/WebServer/src/WebServer.h

@@ -123,6 +123,7 @@ class WebServer
   void send_P(int code, PGM_P content_type, PGM_P content);
   void send_P(int code, PGM_P content_type, PGM_P content, size_t contentLength);
 
+  void enableDelay(boolean value);
   void enableCORS(boolean value = true);
   void enableCrossOrigin(boolean value = true);
 
@@ -176,6 +177,7 @@ class WebServer
   uint8_t     _currentVersion;
   HTTPClientStatus _currentStatus;
   unsigned long _statusChange;
+  boolean     _nullDelay;
 
   RequestHandler*  _currentHandler;
   RequestHandler*  _firstHandler;