NIFI-883 Fixing issue HandleHttpRequest had with PrimaryNodeOnly scheduling

Signed-off-by: Mark Payne <markap14@hotmail.com>

nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/HandleHttpRequest.java

@@ -34,6 +34,7 @@ import java.util.UUID;
 import java.util.concurrent.BlockingQueue;
 import java.util.concurrent.LinkedBlockingQueue;
 import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicBoolean;
 import java.util.regex.Pattern;
 
 import javax.security.cert.X509Certificate;
@@ -226,6 +227,7 @@ public class HandleHttpRequest extends AbstractProcessor {
             .build();
 
     private volatile Server server;
+    private AtomicBoolean initialized = new AtomicBoolean(false);
     private final BlockingQueue<HttpRequestContainer> containerQueue = new LinkedBlockingQueue<>(50);
 
     @Override
@@ -255,7 +257,15 @@ public class HandleHttpRequest extends AbstractProcessor {
     }
 
     @OnScheduled
-    public void initializeServer(final ProcessContext context) throws Exception {
+    public void clearInit(){
+        initialized.set(false);
+    }
+
+    private synchronized void initializeServer(final ProcessContext context) throws Exception {
+        if(initialized.get()){
+            return;
+        }
+
         final String host = context.getProperty(HOSTNAME).getValue();
         final int port = context.getProperty(PORT).asInteger();
         final SSLContextService sslService = context.getProperty(SSL_CONTEXT).asControllerService(SSLContextService.class);
@@ -402,6 +412,8 @@ public class HandleHttpRequest extends AbstractProcessor {
         server.start();
 
         getLogger().info("Server started and listening on port " + getPort());
+
+        initialized.set(true);
     }
 
     protected int getPort() {
@@ -452,6 +464,15 @@ public class HandleHttpRequest extends AbstractProcessor {
 
     @Override
     public void onTrigger(final ProcessContext context, final ProcessSession session) throws ProcessException {
+        try {
+            if(!initialized.get()) {
+                initializeServer(context);
+            }
+        } catch (Exception e) {
+            context.yield();
+            throw new ProcessException("Failed to initialize the server",e);
+        }
+
         final HttpRequestContainer container = containerQueue.poll();
         if (container == null) {
             return;