[incubator-pinot] branch master updated: Adding a hash code partition function (#4220)

[sn...@apache.org]

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snlee pushed a commit to branch master
in repository https://gitbox.apache.org/repos/asf/incubator-pinot.git


The following commit(s) were added to refs/heads/master by this push:
     new 6b5b091  Adding a hash code partition function (#4220)
6b5b091 is described below

commit 6b5b0912eb680db526bccd0d0bdf42b73b860063
Author: Seunghyun Lee <sn...@linkedin.com>
AuthorDate: Tue May 21 09:23:29 2019 -0700

    Adding a hash code partition function (#4220)
    
    - Adding a hash code partition function using object.hashCode()
    - Adding a unit test for hash code partition function
---
 .../data/partition/HashCodePartitionFunction.java  | 52 ++++++++++++++++++++++
 .../data/partition/PartitionFunctionFactory.java   |  5 ++-
 .../core/data/partition/PartitionFunctionTest.java | 26 +++++++++++
 3 files changed, 82 insertions(+), 1 deletion(-)

diff --git a/pinot-core/src/main/java/org/apache/pinot/core/data/partition/HashCodePartitionFunction.java b/pinot-core/src/main/java/org/apache/pinot/core/data/partition/HashCodePartitionFunction.java
new file mode 100644
index 0000000..763647e
--- /dev/null
+++ b/pinot-core/src/main/java/org/apache/pinot/core/data/partition/HashCodePartitionFunction.java
@@ -0,0 +1,52 @@
+/**
+ * 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.pinot.core.data.partition;
+
+import com.google.common.base.Preconditions;
+
+/**
+ * Hash code partition function, where:
+ * <ul>
+ *   <li> partitionId = value.hashCode() % {@link #_numPartitions}</li>
+ * </ul>
+ */
+public class HashCodePartitionFunction implements PartitionFunction {
+  private static final String NAME = "HashCode";
+  private final int _numPartitions;
+
+  public HashCodePartitionFunction(int numPartitions) {
+    Preconditions.checkArgument(numPartitions > 0, "Number of partitions must be > 0, specified", numPartitions);
+    _numPartitions = numPartitions;
+  }
+
+  @Override
+  public int getPartition(Object value) {
+    return Math.abs(value.hashCode()) % _numPartitions;
+  }
+
+  @Override
+  public int getNumPartitions() {
+    return _numPartitions;
+  }
+
+  @Override
+  public String toString() {
+    return NAME;
+  }
+}
diff --git a/pinot-core/src/main/java/org/apache/pinot/core/data/partition/PartitionFunctionFactory.java b/pinot-core/src/main/java/org/apache/pinot/core/data/partition/PartitionFunctionFactory.java
index b204e0e..7cb1b5b 100644
--- a/pinot-core/src/main/java/org/apache/pinot/core/data/partition/PartitionFunctionFactory.java
+++ b/pinot-core/src/main/java/org/apache/pinot/core/data/partition/PartitionFunctionFactory.java
@@ -29,7 +29,7 @@ import javax.annotation.Nonnull;
 public class PartitionFunctionFactory {
   // Enum for various partition functions to be added.
   public enum PartitionFunctionType {
-    Modulo, Murmur, ByteArray;
+    Modulo, Murmur, ByteArray, HashCode;
     // Add more functions here.
 
     private static final Map<String, PartitionFunctionType> VALUE_MAP = new HashMap<>();
@@ -75,6 +75,9 @@ public class PartitionFunctionFactory {
       case ByteArray:
         return new ByteArrayPartitionFunction(numPartitions);
 
+      case HashCode:
+        return new HashCodePartitionFunction(numPartitions);
+
       default:
         throw new IllegalArgumentException("Illegal partition function name: " + functionName);
     }
diff --git a/pinot-core/src/test/java/org/apache/pinot/core/data/partition/PartitionFunctionTest.java b/pinot-core/src/test/java/org/apache/pinot/core/data/partition/PartitionFunctionTest.java
index f0ce9b0..974d151 100644
--- a/pinot-core/src/test/java/org/apache/pinot/core/data/partition/PartitionFunctionTest.java
+++ b/pinot-core/src/test/java/org/apache/pinot/core/data/partition/PartitionFunctionTest.java
@@ -130,4 +130,30 @@ public class PartitionFunctionTest {
       }
     }
   }
+
+  @Test
+  public void testHashCodePartitioner() {
+    long seed = System.currentTimeMillis();
+    Random random = new Random(seed);
+
+    for (int i = 0; i < 1000; i++) {
+      int expectedNumPartitions = Math.abs(random.nextInt());
+
+      // Avoid divide-by-zero.
+      if (expectedNumPartitions == 0) {
+        expectedNumPartitions = 1;
+      }
+
+      String functionName = "HaShCoDe";
+      PartitionFunction partitionFunction =
+          PartitionFunctionFactory.getPartitionFunction(functionName, expectedNumPartitions);
+      Assert.assertEquals(partitionFunction.toString().toLowerCase(), functionName.toLowerCase());
+      Assert.assertEquals(partitionFunction.getNumPartitions(), expectedNumPartitions);
+
+      for (int j = 0; j < 1000; j++) {
+        Integer value = random.nextInt();
+        Assert.assertEquals(partitionFunction.getPartition(value), Math.abs(value.hashCode()) % expectedNumPartitions);
+      }
+    }
+  }
 }


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