Add FuzzyEquals example.

java/.gitignore

@@ -0,0 +1 @@
+target

java/pom.xml

@@ -0,0 +1,67 @@
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+  xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+  <modelVersion>4.0.0</modelVersion>
+
+  <groupId>com.cloudera.impala</groupId>
+  <artifactId>hive-udf-samples</artifactId>
+  <version>1.0</version>
+  <packaging>jar</packaging>
+
+  <name>hive-udf-samples</name>
+
+  <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+    <hadoop.version>${env.IMPALA_HADOOP_VERSION}</hadoop.version>
+    <hive.version>${env.IMPALA_HIVE_VERSION}</hive.version>
+  </properties>
+
+  <dependencies>
+    <dependency>
+      <groupId>org.apache.hadoop</groupId>
+      <artifactId>hadoop-common</artifactId>
+      <version>${hadoop.version}</version>
+    </dependency>
+    <dependency>
+      <groupId>org.apache.hive</groupId>
+      <artifactId>hive-exec</artifactId>
+      <scope>system</scope>
+      <version>${hive.version}</version>
+      <systemPath>${env.IMPALA_HOME}/thirdparty/hive-${hive.version}/lib/hive-exec-${hive.version}.jar</systemPath>
+    </dependency>
+  </dependencies>
+
+  <repositories>
+    <repository>
+      <id>cdh.rcs.releases.repo</id>
+      <url>https://repository.cloudera.com/content/groups/cdh-releases-rcs</url>
+      <name>CDH Releases Repository</name>
+      <snapshots>
+        <enabled>true</enabled>
+      </snapshots>
+    </repository>
+    <repository>
+      <id>cdh.releases.repo</id>
+      <url>https://repository.cloudera.com/content/repositories/releases</url>
+      <name>CDH Releases Repository</name>
+      <snapshots>
+        <enabled>false</enabled>
+      </snapshots>
+    </repository>
+    <repository>
+      <id>cdh.snapshots.repo</id>
+      <url>https://repository.cloudera.com/content/repositories/snapshots</url>
+      <name>CDH Snapshots Repository</name>
+      <snapshots>
+        <enabled>true</enabled>
+      </snapshots>
+    </repository>
+    <repository>
+      <id>cloudera.thirdparty.repo</id>
+      <url>https://repository.cloudera.com/content/repositories/third-party</url>
+      <name>Cloudera Third Party Repository</name>
+      <snapshots>
+        <enabled>false</enabled>
+      </snapshots>
+    </repository>
+  </repositories>
+</project>

java/src/main/java/com/cloudera/FuzzyEqualsUdf.java

@@ -0,0 +1,44 @@
+//
+// Licensed 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.cloudera.impala;
+
+import org.apache.hadoop.hive.ql.exec.UDF;
+import org.apache.hadoop.hive.serde2.io.ByteWritable;
+import org.apache.hadoop.hive.serde2.io.DoubleWritable;
+import org.apache.hadoop.hive.serde2.io.ShortWritable;
+import org.apache.hadoop.hive.serde2.io.TimestampWritable;
+import org.apache.hadoop.io.BooleanWritable;
+import org.apache.hadoop.io.BytesWritable;
+import org.apache.hadoop.io.FloatWritable;
+import org.apache.hadoop.io.IntWritable;
+import org.apache.hadoop.io.LongWritable;
+import org.apache.hadoop.io.Text;
+
+/**
+ * Udf that returns true if two double arguments  are approximately equal.
+ * Usage: > create fuzzy_equals(double, double) returns boolean
+ *          location '/user/cloudera/hive-udf-samples-1.0.jar'
+ *          SYMBOL='com.cloudera.impala.FuzzyEqualsUdf';
+ *        > select fuzzy_equals(1, 1.000001);
+ */
+public class FuzzyEqualsUdf extends UDF {
+  public FuzzyEqualsUdf() {
+  }
+
+  public BooleanWritable evaluate(DoubleWritable x, DoubleWritable y) {
+    double EPSILON = 0.000001f;
+    if (x == null || y == null) return null;
+    return new BooleanWritable(Math.abs(x.get() - y.get()) < EPSILON);
+  }
+}

udf-sample-test.cc

@@ -32,6 +32,12 @@ int main(int argc, char** argv) {
   passed &= UdfTestHarness::ValidateUdf<IntVal, IntVal, IntVal>(
       AddUdf, IntVal::null(), IntVal(2), IntVal::null());
 
+  // Test FuzzyEquals sample.
+  passed &= UdfTestHarness::ValidateUdf<BooleanVal, DoubleVal, DoubleVal>(
+      FuzzyEquals, DoubleVal(1.0), DoubleVal(1.0000000001), BooleanVal(true));
+  passed &= UdfTestHarness::ValidateUdf<BooleanVal, DoubleVal, DoubleVal>(
+      FuzzyEquals, DoubleVal(1.1), DoubleVal(1.0), BooleanVal(false));
+
   cout << "Tests " << (passed ? "Passed." : "Failed.") << endl;
   return !passed;
 }

udf-sample.cc

@@ -13,6 +13,7 @@
 // limitations under the License.
 
 #include "udf-sample.h"
+#include <math.h>
 
 // In this sample we are declaring a UDF that adds two ints and returns an int.
 IntVal AddUdf(FunctionContext* context, const IntVal& arg1, const IntVal& arg2) {
@@ -22,3 +23,11 @@ IntVal AddUdf(FunctionContext* context, const IntVal& arg1, const IntVal& arg2)
 
 // Multiple UDFs can be defined in the same file
 
+BooleanVal FuzzyEquals(FunctionContext* ctx, const DoubleVal& x, const DoubleVal& y) {
+  const double EPSILON = 0.000001f;
+  if (x.is_null || y.is_null) return BooleanVal::null();
+  double delta = fabs(x.val - y.val);
+  return BooleanVal(delta < EPSILON);
+}
+
+

udf-sample.h

@@ -20,6 +20,15 @@
 
 using namespace impala_udf;
 
+// Usage: > create function add(int, int) returns int
+//          location '/user/cloudera/libudfsample.so' SYMBOL='AddUdf';
+//        > select add(1, 2);
 IntVal AddUdf(FunctionContext* context, const IntVal& arg1, const IntVal& arg2);
 
+// Returns true if x is approximately equal to y.
+// Usage: > create function fuzzy_equals(double, double) returns boolean
+//          location '/user/cloudera/libudfsample.so' SYMBOL='FuzzyEquals';
+//        > select fuzzy_equals(1, 1.00000001);
+BooleanVal FuzzyEquals(FunctionContext* context, const DoubleVal& x, const DoubleVal& y);
+
 #endif