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https://issues.apache.org/jira/browse/APEXMALHAR-2082?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15298733#comment-15298733
]
ASF GitHub Bot commented on APEXMALHAR-2082:
--------------------------------------------
Github user chinmaykolhatkar commented on a diff in the pull request:
https://github.com/apache/incubator-apex-malhar/pull/270#discussion_r64455136
--- Diff:
library/src/main/java/com/datatorrent/lib/filter/FilterOperator.java ---
@@ -0,0 +1,210 @@
+/**
+ * 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 com.datatorrent.lib.filter;
+
+import java.util.LinkedList;
+import java.util.List;
+
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+import org.apache.hadoop.classification.InterfaceStability;
+
+import com.datatorrent.api.AutoMetric;
+import com.datatorrent.api.Context;
+import com.datatorrent.api.Context.PortContext;
+import com.datatorrent.api.DefaultInputPort;
+import com.datatorrent.api.DefaultOutputPort;
+
+import com.datatorrent.api.Operator;
+import com.datatorrent.api.annotation.InputPortFieldAnnotation;
+
+import com.datatorrent.common.util.BaseOperator;
+import com.datatorrent.lib.expression.Expression;
+import com.datatorrent.lib.util.PojoUtils;
+
+/**
+ * <b>FilterOperator</b>
+ * Filter Operator filter out tuples based on defined condition
+ *
+ * <b>Parameters</b>
+ * - condition: condition based on expression langugage
+ *
+ * <b>Input Port</b> takes POJOs as an input
+ *
+ * <b>Output Ports</b>
+ * - truePort emits POJOs meeting the given condition
+ * - falsePort emits POJOs not meeting the given condition
+ * - error port emits any error situation while evaluating expression
+ *
+ */
+@InterfaceStability.Evolving
+public class FilterOperator extends BaseOperator implements
Operator.ActivationListener
+{
+ private transient Class<?> inClazz = null;
+ private transient Expression<Boolean> expr = null;
+ private List<String> expressionFunctions = new LinkedList<>();
+
+ @AutoMetric
+ private long trueTuples;
+
+ @AutoMetric
+ private long falseTuples;
+
+ @AutoMetric
+ private long errorTuples;
+
+ protected String condition;
+
+ public final transient DefaultOutputPort<Object> truePort = new
DefaultOutputPort<Object>();
+
+ public final transient DefaultOutputPort<Object> falsePort = new
DefaultOutputPort<Object>();
+
+ public final transient DefaultOutputPort<Object> error = new
DefaultOutputPort<Object>();
+
+ public FilterOperator()
+ {
+ expressionFunctions.add("java.lang.Math.*");
+ expressionFunctions.add("org.apache.commons.lang3.StringUtils.*");
+
expressionFunctions.add("org.apache.commons.lang3.StringEscapeUtils.*");
+
expressionFunctions.add("org.apache.commons.lang3.time.DurationFormatUtils.*");
+
expressionFunctions.add("org.apache.commons.lang3.time.DateFormatUtils.*");
+ }
+
+ @InputPortFieldAnnotation(schemaRequired = true)
+ public transient DefaultInputPort<Object> input = new
DefaultInputPort<Object>()
+ {
+ public void setup(PortContext context)
+ {
+ inClazz = context.getValue(Context.PortContext.TUPLE_CLASS);
+ }
+
+ @Override
+ public void process(Object t)
+ {
+ processTuple(t);
+ }
+ };
+
+ @Override
+ public void activate(Context context)
+ {
+ createExpression();
+ }
+
+ @Override
+ public void deactivate()
+ {
+ }
+
+ @Override
+ public void beginWindow(long windowId)
+ {
+ errorTuples = trueTuples = falseTuples = 0;
+ }
+
+ /**
+ * createExpression: create an expression from condition of POJO fields
+ * Override this function for custom field expressions
+ */
+ protected void createExpression()
+ {
+ logger.info("Creating an expression for condition {}", condition);
+ expr = PojoUtils.createExpression(inClazz, condition, Boolean.class,
+ expressionFunctions.toArray(new
String[expressionFunctions.size()]));
+ }
+
+ /**
+ * evalExpression: Evaluate condition/expression
+ * Override this function for custom condition evaluation
+ */
+ protected Boolean evalExpression(Object t)
+ {
+ return expr.execute(t);
+ }
+
+ /**
+ * handleFilter: emit POJO meeting condition on truePort
+ * and if it did not meet condition then on falsePort
+ */
+ private void processTuple(Object t)
+ {
+ try {
+ if (evalExpression(t)) {
+ truePort.emit(t);
+ trueTuples++;
+ } else {
+ falsePort.emit(t);
+ falseTuples++;
+ }
+ } catch (Exception ex) {
+ logger.error("Error in expression eval: {}", ex.getMessage());
+ logger.debug("Exception: ", ex);
+ error.emit(t);
+ errorTuples++;
+ }
+ }
+
+ /**
+ * Returns condition/expression with which Filtering is done
+ *
+ * @return Condition parameter of Filter Operator
--- End diff --
C in Condition should be small. Otherwise javadoc won't be able to identify
it.
> Data Filter Operator
> ---------------------
>
> Key: APEXMALHAR-2082
> URL: https://issues.apache.org/jira/browse/APEXMALHAR-2082
> Project: Apache Apex Malhar
> Issue Type: New Feature
> Reporter: Pradeep A. Dalvi
>
> Data Filter Operator which will allow apex users to filter (select/drop)
> tuples based on the certain condition from incoming stream.
> Use case:
> -------------
> In many cases, not all tuples are of interest for the downstream operators.
> In such cases, one may want select/filter out tuples to downstream. Also one
> may want to process tuples which did not meet the condition/expression.
> Functionality:
> -----------------
> 1. Any tuple for which expression could not be evaluated shall be emitted on
> error output port.
> 2. Filter operator shall receive POJO as input tuple and emit POJO on either
> of remaining output ports i.e. truePort and falsePort. As the output ports'
> name signify, when condition is met then the POJO shall be emitted on
> truePort and if condition is not met then that POJO shall be emitted on
> falsePort.
> 3. Operator needs condition/expression as a input param. This condition is
> based on expression language support we already have in Malhar.
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