Github user JPercivall commented on a diff in the pull request:
https://github.com/apache/nifi/pull/483#discussion_r70257596
--- Diff:
nifi-nar-bundles/nifi-email-bundle/nifi-email-processors/src/main/java/org/apache/nifi/processors/email/smtp/handler/SMTPMessageHandlerFactory.java
---
@@ -0,0 +1,147 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.nifi.processors.email.smtp.handler;
+
+import java.io.IOException;
+import java.io.InputStream;
+import java.security.cert.X509Certificate;
+import java.util.concurrent.LinkedBlockingQueue;
+import java.util.concurrent.TimeUnit;
+
+import org.apache.nifi.logging.ComponentLog;
+import org.apache.nifi.stream.io.ByteArrayOutputStream;
+import org.apache.nifi.util.StopWatch;
+import org.subethamail.smtp.DropConnectionException;
+import org.subethamail.smtp.MessageContext;
+import org.subethamail.smtp.MessageHandler;
+import org.subethamail.smtp.MessageHandlerFactory;
+import org.subethamail.smtp.RejectException;
+import org.subethamail.smtp.TooMuchDataException;
+import org.subethamail.smtp.server.SMTPServer;
+
+import org.apache.nifi.processors.email.smtp.event.SmtpEvent;
+
+
+public class SMTPMessageHandlerFactory implements MessageHandlerFactory {
+ final LinkedBlockingQueue<SmtpEvent> incomingMessages;
+ final ComponentLog logger;
+
+ public SMTPMessageHandlerFactory(LinkedBlockingQueue<SmtpEvent>
incomingMessages, ComponentLog logger) {
+ this.incomingMessages = incomingMessages;
+ this.logger = logger;
+ }
+
+ @Override
+ public MessageHandler create(MessageContext messageContext) {
+ return new Handler(messageContext, incomingMessages, logger);
+ }
+
+ class Handler implements MessageHandler {
+ final MessageContext messageContext;
+ String from;
+ String recipient;
+ byte [] messageBody;
+
+
+ public Handler(MessageContext messageContext,
LinkedBlockingQueue<SmtpEvent> incomingMessages, ComponentLog logger){
+ this.messageContext = messageContext;
+ }
+
+ @Override
+ public void from(String from) throws RejectException {
+ // TODO: possibly whitelist senders?
+ this.from = from;
+ }
+
+ @Override
+ public void recipient(String recipient) throws RejectException {
+ // TODO: possibly whitelist receivers?
+ this.recipient = recipient;
+ }
+
+ @Override
+ public void data(InputStream inputStream) throws RejectException,
TooMuchDataException, IOException {
+ // Start counting the timer...
+
+ StopWatch watch = new StopWatch(false);
+
+ SMTPServer server = messageContext.getSMTPServer();
+
+ ByteArrayOutputStream baos = new ByteArrayOutputStream();
+
+ byte [] buffer = new byte[1024];
+ int rd;
+
+ while ((rd = inputStream.read(buffer, 0, buffer.length)) !=
-1) {
+ baos.write(buffer, 0, rd);
+ }
+ if (baos.getBufferLength() > server.getMaxMessageSize()) {
+ throw new TooMuchDataException("Data exceeds the amount
allowed.");
+ }
+
+ baos.flush();
+ this.messageBody = baos.toByteArray();
+
+
+ X509Certificate[] certificates = new X509Certificate[]{};
--- End diff --
I really like the idea to move the processing to data() and be able to tell
the client to retry. This allows the processor to handle back-pressure and
failures in a way that aligns with the transmitting protocol. Very nice!
That said, this new flow of logic requires us to think through the new
scenarios that may pop up. I will comment in the places that require attention.
FYI, in the future there may be an improvement ticket opened to always
accept messages (like you were doing before) but this is a great start and
until someone needs that functionality I'm good to forgo it.
Also, for an intro to Java Concurrency this tutorial[1] may be of use.
Disclaimer, I haven't read through all of it but Jenkov's tutorials tend to be
pretty good at explaining some in depth concepts.
[1] http://tutorials.jenkov.com/java-concurrency/index.html
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