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From yu...@apache.org
Subject [6/6] git commit: Fix M3P ownership calculation; patch by yukim reviewed by Sylvain Lebresne for CASSANDRA-5076
Date Wed, 19 Dec 2012 18:43:58 GMT
Fix M3P ownership calculation; patch by yukim reviewed by Sylvain Lebresne for CASSANDRA-5076


Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo
Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/e7ae7c90
Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/e7ae7c90
Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/e7ae7c90

Branch: refs/heads/cassandra-1.2
Commit: e7ae7c9040135b6ecae5204efd7e41ad2e6ba4ee
Parents: 620a4b7
Author: Yuki Morishita <yukim@apache.org>
Authored: Wed Dec 19 12:43:23 2012 -0600
Committer: Yuki Morishita <yukim@apache.org>
Committed: Wed Dec 19 12:43:23 2012 -0600

----------------------------------------------------------------------
 CHANGES.txt                                        |    1 +
 .../apache/cassandra/dht/Murmur3Partitioner.java   |   14 +++--
 .../apache/cassandra/dht/PartitionerTestCase.java  |   40 ++++++++++++++-
 3 files changed, 48 insertions(+), 7 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/cassandra/blob/e7ae7c90/CHANGES.txt
----------------------------------------------------------------------
diff --git a/CHANGES.txt b/CHANGES.txt
index 6edf7bb..7786b09 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -11,6 +11,7 @@ Merged from 1.1:
  * Fix ALTER TABLE overriding compression options with defaults
    (CASSANDRA-4996, 5066)
  * fix specifying and altering crc_check_chance (CASSANDRA-5053)
+ * fix Murmur3Partitioner ownership% calculation (CASSANDRA-5076)
 
 
 1.2-rc1

http://git-wip-us.apache.org/repos/asf/cassandra/blob/e7ae7c90/src/java/org/apache/cassandra/dht/Murmur3Partitioner.java
----------------------------------------------------------------------
diff --git a/src/java/org/apache/cassandra/dht/Murmur3Partitioner.java b/src/java/org/apache/cassandra/dht/Murmur3Partitioner.java
index 3e98e32..ad3579a 100644
--- a/src/java/org/apache/cassandra/dht/Murmur3Partitioner.java
+++ b/src/java/org/apache/cassandra/dht/Murmur3Partitioner.java
@@ -17,6 +17,7 @@
  */
 package org.apache.cassandra.dht;
 
+import java.math.BigDecimal;
 import java.math.BigInteger;
 import java.nio.ByteBuffer;
 import java.util.HashMap;
@@ -125,20 +126,21 @@ public class Murmur3Partitioner extends AbstractPartitioner<LongToken>
         // n-case
         else
         {
-            final float ri = MAXIMUM;                                            //  (used
for addition later)
-            Token start = (Token) i.next(); Long ti = ((LongToken)start).token;  // The first
token and its value
-            Token t; Long tim1 = ti;                                             // The last
token and its value (after loop)
+            final BigInteger ri = BigInteger.valueOf(MAXIMUM).subtract(BigInteger.valueOf(MINIMUM.token
+ 1));  //  (used for addition later)
+            final BigDecimal r  = new BigDecimal(ri);
+            Token start = (Token) i.next();BigInteger ti = BigInteger.valueOf(((LongToken)start).token);
 // The first token and its value
+            Token t; BigInteger tim1 = ti;                                              
                 // The last token and its value (after loop)
 
             while (i.hasNext())
             {
-                t = (Token) i.next(); ti = ((LongToken) t).token; // The next token and its
value
-                float age = ((ti - tim1 + ri) % ri) / ri;         // %age = ((T(i) - T(i-1)
+ R) % R) / R
+                t = (Token) i.next(); ti = BigInteger.valueOf(((LongToken) t).token); //
The next token and its value
+                float age = new BigDecimal(ti.subtract(tim1).add(ri).mod(ri)).divide(r, 6,
BigDecimal.ROUND_HALF_EVEN).floatValue(); // %age = ((T(i) - T(i-1) + R) % R) / R
                 ownerships.put(t, age);                           // save (T(i) -> %age)
                 tim1 = ti;                                        // -> advance loop
             }
 
             // The start token's range extends backward to the last token, which is why both
were saved above.
-            float x = ((((LongToken) start).token - ti + ri) % ri) / ri;
+            float x = new BigDecimal(BigInteger.valueOf(((LongToken)start).token).subtract(ti).add(ri).mod(ri)).divide(r,
6, BigDecimal.ROUND_HALF_EVEN).floatValue();
             ownerships.put(start, x);
         }
 

http://git-wip-us.apache.org/repos/asf/cassandra/blob/e7ae7c90/test/unit/org/apache/cassandra/dht/PartitionerTestCase.java
----------------------------------------------------------------------
diff --git a/test/unit/org/apache/cassandra/dht/PartitionerTestCase.java b/test/unit/org/apache/cassandra/dht/PartitionerTestCase.java
index 720ba3e..79b0d78 100644
--- a/test/unit/org/apache/cassandra/dht/PartitionerTestCase.java
+++ b/test/unit/org/apache/cassandra/dht/PartitionerTestCase.java
@@ -19,11 +19,14 @@
 package org.apache.cassandra.dht;
 
 import java.nio.ByteBuffer;
-import java.util.Random;
+import java.util.*;
 
 import org.junit.Before;
 import org.junit.Test;
 
+import static junit.framework.Assert.assertEquals;
+import static junit.framework.Assert.fail;
+
 public abstract class PartitionerTestCase<T extends Token>
 {
     protected IPartitioner<T> partitioner;
@@ -115,4 +118,39 @@ public abstract class PartitionerTestCase<T extends Token>
         Token.TokenFactory factory = partitioner.getTokenFactory();
         assert tok("a").compareTo(factory.fromString(factory.toString(tok("a")))) == 0;
     }
+
+    @Test
+    public void testDescribeOwnership()
+    {
+        try
+        {
+            testDescribeOwnershipWith(0);
+            fail();
+        }
+        catch (RuntimeException e)
+        {
+            // success
+        }
+        testDescribeOwnershipWith(1);
+        testDescribeOwnershipWith(2);
+        testDescribeOwnershipWith(256);
+    }
+
+    private void testDescribeOwnershipWith(int numTokens)
+    {
+        List<Token> tokens = new ArrayList<Token>();
+        while (tokens.size() < numTokens)
+        {
+            Token randomToken = partitioner.getRandomToken();
+            if (!tokens.contains(randomToken))
+                tokens.add(randomToken);
+        }
+        Collections.sort(tokens);
+        Map<Token, Float> owns = partitioner.describeOwnership(tokens);
+
+        float totalOwnership = 0;
+        for (float ownership : owns.values())
+            totalOwnership += ownership;
+        assertEquals(1.0, totalOwnership, 0.001);
+    }
 }


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