Github user mattyb149 commented on a diff in the pull request:
https://github.com/apache/nifi/pull/1496#discussion_r110380550
--- Diff:
nifi-nar-bundles/nifi-standard-bundle/nifi-standard-processors/src/main/java/org/apache/nifi/processors/standard/EnforceOrder.java
---
@@ -0,0 +1,538 @@
+/*
+ * 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.Stateful;
+import org.apache.nifi.annotation.behavior.TriggerSerially;
+import org.apache.nifi.annotation.behavior.WritesAttribute;
+import org.apache.nifi.annotation.behavior.WritesAttributes;
+import org.apache.nifi.annotation.documentation.CapabilityDescription;
+import org.apache.nifi.annotation.documentation.Tags;
+import org.apache.nifi.components.PropertyDescriptor;
+import org.apache.nifi.components.PropertyValue;
+import org.apache.nifi.components.ValidationContext;
+import org.apache.nifi.components.ValidationResult;
+import org.apache.nifi.components.state.Scope;
+import org.apache.nifi.components.state.StateMap;
+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.Relationship;
+import org.apache.nifi.processor.exception.ProcessException;
+import org.apache.nifi.processor.util.StandardValidators;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
+import java.util.Comparator;
+import java.util.HashMap;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+import java.util.TreeMap;
+import java.util.concurrent.TimeUnit;
+import java.util.concurrent.atomic.AtomicInteger;
+import java.util.concurrent.atomic.AtomicReference;
+import java.util.function.Function;
+import java.util.stream.Collectors;
+
+import static org.apache.commons.lang3.StringUtils.isBlank;
+
+@EventDriven
+@Tags({"sort", "order"})
+@InputRequirement(Requirement.INPUT_REQUIRED)
+@TriggerSerially
+@CapabilityDescription("Enforces expected ordering of FlowFiles those
belong to the same data group. " +
+ " Although PriorityAttributePrioritizer can be used on a
connection to ensure that flow files going through that connection are in
priority order," +
+ " depending on error-handling, branching, and other flow designs,
it is possible for FlowFiles to get out-of-order." +
+ " EnforceOrder can be used to enforce original ordering for those
FlowFiles." +
+ " [IMPORTANT] In order to take effect of EnforceOrder,
FirstInFirstOutPrioritizer should be used at EVERY downstream relationship" +
+ " UNTIL the order of FlowFiles physically get FIXED by operation
such as MergeContent or being stored to the final destination.")
+@Stateful(scopes = Scope.LOCAL, description = "EnforceOrder uses following
states per ordering group:" +
+ " '<groupId>.target' is a order number which is being waited to
arrive next." +
+ " When a FlowFile with a matching order arrives, or a FlowFile
overtakes the FlowFile being waited for because of wait timeout," +
+ " target order will be updated to (FlowFile.order + 1)." +
+ " '<groupId>.max is the maximum order number for a group." +
+ " '<groupId>.updatedAt' is a timestamp when the order of a group
was updated last time." +
+ " These managed states will be removed automatically once a group
is determined as inactive, see 'Inactive Timeout' for detail.")
+@WritesAttributes({
+ @WritesAttribute(attribute = EnforceOrder.ATTR_STARTED_AT,
+ description = "All FlowFiles going through this processor will
have this attribute. This value is used to determine wait timeout."),
+ @WritesAttribute(attribute = EnforceOrder.ATTR_RESULT,
+ description = "All FlowFiles going through this processor will
have this attribute denoting which relationship it was routed to."),
+ @WritesAttribute(attribute = EnforceOrder.ATTR_DETAIL,
+ description = "FlowFiles routed to 'failure' or 'skipped'
relationship will have this attribute describing details."),
+ @WritesAttribute(attribute = EnforceOrder.ATTR_EXPECTED_ORDER,
+ description = "FlowFiles routed to 'wait' or 'skipped'
relationship will have this attribute denoting expected order when the FlowFile
was processed.")
+})
+public class EnforceOrder extends AbstractProcessor {
+
+ public static final String ATTR_STARTED_AT = "EnforceOrder.startedAt";
+ public static final String ATTR_EXPECTED_ORDER =
"EnforceOrder.expectedOrder";
+ public static final String ATTR_RESULT = "EnforceOrder.result";
+ public static final String ATTR_DETAIL = "EnforceOrder.detail";
+ private static final Function<String, String> STATE_TARGET_ORDER =
groupId -> groupId + ".target";
+ private static final String STATE_SUFFIX_UPDATED_AT = ".updatedAt";
+ private static final Function<String, String> STATE_UPDATED_AT =
groupId -> groupId + STATE_SUFFIX_UPDATED_AT;
+ private static final Function<String, String> STATE_MAX_ORDER =
groupId -> groupId + ".max";
+
+ public static final PropertyDescriptor GROUP_IDENTIFIER = new
PropertyDescriptor.Builder()
+ .name("group-id")
+ .displayName("Group Identifier")
+ .description("EnforceOrder is capable of multiple ordering
groups." +
+ " 'Group Identifier' is used to determine which group a
FlowFile belongs to." +
+ " This property will be evaluated with each incoming
FlowFile." +
+ " If evaluated result is empty, the FlowFile will be
routed to failure.")
+ .required(true)
+ .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+ .expressionLanguageSupported(true)
+ .defaultValue("${filename}")
+ .build();
+
+ public static final PropertyDescriptor ORDER_ATTRIBUTE = new
PropertyDescriptor.Builder()
+ .name("order-attribute")
+ .displayName("Order Attribute")
+ .description("A name of FlowFile attribute whose value will be
used to enforce order of FlowFiles within a group." +
+ " If a FlowFile does not have this attribute, or its value
is not an integer, the FlowFile will be routed to failure.")
+ .required(true)
+ .addValidator(StandardValidators.NON_BLANK_VALIDATOR)
+ .expressionLanguageSupported(false)
+ .build();
+
+ public static final PropertyDescriptor INITIAL_ORDER = new
PropertyDescriptor.Builder()
+ .name("initial-order")
+ .displayName("Initial Order")
+ .description("When the first FlowFile of a group arrives, initial
target order will be computed and stored in the managed state." +
+ " After that, target order will start being tracked by
EnforceOrder and stored in the state management store." +
+ " If Expression Language is used but evaluated result was
not an integer, then the FlowFile will be routed to failure," +
+ " and initial order will be left unknown until consecutive
FlowFiles provide a valid initial order.")
+ .required(true)
+ .addValidator(StandardValidators.NON_NEGATIVE_INTEGER_VALIDATOR)
+ .expressionLanguageSupported(true)
+ .defaultValue("1")
--- End diff --
A number of processors (the Split processors, CaptureChange, etc.) use zero
as the first index / sequence ID by default, I'm thinking we should default
this property to zero as well.
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