Github user mattyb149 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/1737#discussion_r116506707
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/LogString.java
---
@@ -0,0 +1,208 @@
+/*
+ * 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.standard;
+
+import org.apache.nifi.annotation.behavior.EventDriven;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.InputRequirement.Requirement;
+import org.apache.nifi.annotation.behavior.SideEffectFree;
+import org.apache.nifi.annotation.behavior.SupportsBatching;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.flowfile.FlowFile;
+import org.apache.nifi.logging.ComponentLog;
+import org.apache.nifi.processor.AbstractProcessor;
+import org.apache.nifi.processor.ProcessContext;
+import org.apache.nifi.processor.ProcessSession;
+import org.apache.nifi.processor.ProcessorInitializationContext;
+import org.apache.nifi.processor.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+import org.eclipse.jetty.util.StringUtil;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+@EventDriven
+@SideEffectFree
+@SupportsBatching
+@Tags({"attributes", "logging"})
+@InputRequirement(Requirement.INPUT_REQUIRED)
+@CapabilityDescription("Emits a log message at the specified log level")
+public class LogString extends AbstractProcessor {
+
+ public static final PropertyDescriptor LOG_LEVEL = new
PropertyDescriptor.Builder()
+ .name("Log Level")
+ .required(true)
+ .description("The Log Level to use when logging the message")
+ .allowableValues(MessageLogLevel.values())
+ .defaultValue(MessageLogLevel.info.toString())
+ .expressionLanguageSupported(true)
+ .build();
+
+ public static final PropertyDescriptor LOG_PREFIX = new
PropertyDescriptor.Builder()
+ .name("Log prefix")
+ .required(false)
+ .description("Log prefix appended to the log lines. " +
+ "It helps to distinguish the output of multiple
LogString processors.")
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .expressionLanguageSupported(true)
+ .build();
+
+ public static final PropertyDescriptor LOG_MESSAGE = new
PropertyDescriptor.Builder()
+ .name("Log message")
+ .required(false)
+ .description("The log message to emit")
+ .addValidator(StandardValidators.NON_EMPTY_VALIDATOR)
+ .expressionLanguageSupported(true)
+ .build();
+
+ public static final Relationship REL_SUCCESS = new
Relationship.Builder()
+ .name("success")
+ .description("All FlowFiles are routed to this relationship")
+ .build();
+
+ private static final int CHUNK_SIZE = 50;
+
+ enum MessageLogLevel {
+
+ trace, debug, info, warn, error
+ }
+
+ private Set<Relationship> relationships;
+ private List<PropertyDescriptor> supportedDescriptors;
+
+ @Override
+ protected void init(final ProcessorInitializationContext context) {
+ final Set<Relationship> procRels = new HashSet<>();
+ procRels.add(REL_SUCCESS);
+ relationships = Collections.unmodifiableSet(procRels);
+
+ // descriptors
+ final List<PropertyDescriptor> supDescriptors = new ArrayList<>();
+ supDescriptors.add(LOG_LEVEL);
+ supDescriptors.add(LOG_PREFIX);
+ supDescriptors.add(LOG_MESSAGE);
+ supportedDescriptors =
Collections.unmodifiableList(supDescriptors);
+ }
+
+ @Override
+ public Set<Relationship> getRelationships() {
+ return relationships;
+ }
+
+ @Override
+ protected List<PropertyDescriptor> getSupportedPropertyDescriptors() {
+ return supportedDescriptors;
+ }
+
+ @Override
+ public void onTrigger(final ProcessContext context, final
ProcessSession session) {
+
+ final String logLevelValue =
context.getProperty(LOG_LEVEL).getValue().toLowerCase();
+
+ final MessageLogLevel logLevel;
+ try {
+ logLevel = MessageLogLevel.valueOf(logLevelValue);
+ } catch (Exception e) {
+ throw new ProcessException(e);
+ }
+
+ final ComponentLog logger = getLogger();
+ boolean isLogLevelEnabled = false;
+ switch (logLevel) {
+ case trace:
+ isLogLevelEnabled = logger.isTraceEnabled();
+ break;
+ case debug:
+ isLogLevelEnabled = logger.isDebugEnabled();
+ break;
+ case info:
+ isLogLevelEnabled = logger.isInfoEnabled();
+ break;
+ case warn:
+ isLogLevelEnabled = logger.isWarnEnabled();
+ break;
+ case error:
+ isLogLevelEnabled = logger.isErrorEnabled();
+ break;
+ }
+
+ if (!isLogLevelEnabled) {
+ transferChunk(session);
+ return;
+ }
+
+ final FlowFile flowFile = session.get();
+ if (flowFile == null) {
+ return;
+ }
+
+ processFlowFile(logger, logLevel, flowFile, context);
+ session.transfer(flowFile, REL_SUCCESS);
+ }
+
+ private void processFlowFile(
+ final ComponentLog logger,
+ final MessageLogLevel logLevel,
+ final FlowFile flowFile,
+ final ProcessContext context) {
+
+ String logPrefix =
context.getProperty(LOG_PREFIX).evaluateAttributeExpressions(flowFile).getValue();
+ String logMessage =
context.getProperty(LOG_MESSAGE).evaluateAttributeExpressions(flowFile).getValue();
+
+ String messageToWrite;
+ if (StringUtil.isBlank(logPrefix)) {
+ messageToWrite = logMessage;
+ } else {
+ messageToWrite = String.format("%s %s", logPrefix, logMessage);
--- End diff --
Do you think the extra space between the prefix and message could throw off
the user at first? Certainly if they look in the logs they could see there is a
space between what they have specified for the prefix vs the message, but I'm
wondering if it is best to omit the space or update the property documentation
to make it clear there will or will not be whitespace between the prefix and
message. I mention it only because I left a space at the end of my prefix and
tried to search for the prefix+message and didn't find it right away. Again,
not a requirement, just a suggestion/question :)
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