[GitHub] [nifi] ijokarumawak commented on a change in pull request #3541: NIFI-6387 Implemented RetryFlowFile

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ijokarumawak commented on a change in pull request #3541: NIFI-6387 Implemented RetryFlowFile
URL: https://github.com/apache/nifi/pull/3541#discussion_r300207121
 
 

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 File path: nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/RetryFlowFile.java
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+/*
+ * 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.DynamicProperty;
+import org.apache.nifi.annotation.behavior.InputRequirement;
+import org.apache.nifi.annotation.behavior.ReadsAttribute;
+import org.apache.nifi.annotation.behavior.SideEffectFree;
+import org.apache.nifi.annotation.behavior.SupportsBatching;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.configuration.DefaultSettings;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.annotation.lifecycle.OnScheduled;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.expression.ExpressionLanguageScope;
+import org.apache.nifi.flowfile.FlowFile;
+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.apache.nifi.util.StringUtils;
+
+import java.util.ArrayList;
+import java.util.Collections;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+@Tags({"Retry", "FlowFile"})
+@CapabilityDescription("FlowFiles passed to this Processor have a 'Retry Attribute' value checked against a " +
+        "configured 'Maximum Retries' value. If the current attribute value is below the configured maximum, the " +
+        "FlowFile is passed to a retry relationship. The FlowFile may or may not be penalized in that condition. " +
+        "If the FlowFile's attribute value exceeds the configured maximum, the FlowFile will be passed to a " +
+        "'retries_exceeded' relationship. WARNING: If the incoming FlowFile has a non-numeric value in the " +
+        "configured 'Retry Attribute' attribute, it will be reset to '1'. You may choose to fail the FlowFile " +
+        "instead of performing the reset. Additional dynamic properties can be defined for any attributes you " +
+        "wish to add to the FlowFiles transferred to 'retries_exceeded'. These attributes support attribute " +
+        "expression language.")
+@InputRequirement(InputRequirement.Requirement.INPUT_REQUIRED)
+@SupportsBatching
+@SideEffectFree
+@DefaultSettings(penaltyDuration = "2 min")
+@ReadsAttribute(attribute = "Retry Attribute",
+        description = "Will read the attribute or attribute expression language result as defined in 'Retry Attribute'")
+@WritesAttribute(attribute = "Retry Attribute",
+        description = "User defined retry attribute is updated with the current retry count")
+@DynamicProperty(name = "Exceeded FlowFile Attribute Key",
+        value = "The value of the attribute added to the FlowFile",
+        description = "One or more dynamic properties can be used to add attributes to FlowFiles passed to " +
+                "the 'retries_exceeded' relationship",
+        expressionLanguageScope = ExpressionLanguageScope.FLOWFILE_ATTRIBUTES)
+public class RetryFlowFile extends AbstractProcessor {
+    private List<PropertyDescriptor> properties;
+    private Set<Relationship> relationships;
+    private String retryAttribute;
+    private Integer maximumRetries;
+    private Boolean penalizeRetried;
+    private Boolean failOnOverwrite;
+
+    public static final PropertyDescriptor RETRY_ATTRIBUTE = new PropertyDescriptor.Builder()
+            .name("Retry Attribute")
+            .description("The name of the attribute that contains the current retry count for the FlowFile. " +
+                    "WARNING: If the name matches an attribute already on the FlowFile that does not contain a " +
+                    "numerical value, the processor will either overwrite that attribute with '1' or fail " +
+                    "based on configuration.")
+            .required(true)
+            .addValidator(StandardValidators.NON_EMPTY_EL_VALIDATOR)
+            .expressionLanguageSupported(ExpressionLanguageScope.VARIABLE_REGISTRY)
+            .defaultValue("flowfile.retries")
+            .build();
+    public static final PropertyDescriptor MAXIMUM_RETRIES = new PropertyDescriptor.Builder()
+            .name("Maximum Retries")
+            .description("The maximum number of times a FlowFile can be retried before being " +
+                    "passed to the 'retries_exceeded' relationship")
+            .required(true)
+            .addValidator(StandardValidators.createLongValidator(1, Integer.MAX_VALUE, true))
+            .defaultValue("3")
+            .build();
 
 Review comment:
   Yeah, you'd need to:
   - Change instance variable `maximumRetries` to a local variable inside `onTrigger`
   - Evaluate EL at `onTrigger` using the current FlowFile
   
   I think having different max retry per FlowFile may be a valid use-case. Especially where a common retry route is used from different places.

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