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From j...@apache.org
Subject cassandra git commit: Fix randomness of stress values
Date Tue, 06 Jun 2017 13:43:25 GMT
Repository: cassandra
Updated Branches:
  refs/heads/trunk 106691b2f -> f1f5f1946


Fix randomness of stress values

Patch by Ben Slater; Reviewed by tjake for CASSANDRA-12744


Project: http://git-wip-us.apache.org/repos/asf/cassandra/repo
Commit: http://git-wip-us.apache.org/repos/asf/cassandra/commit/f1f5f194
Tree: http://git-wip-us.apache.org/repos/asf/cassandra/tree/f1f5f194
Diff: http://git-wip-us.apache.org/repos/asf/cassandra/diff/f1f5f194

Branch: refs/heads/trunk
Commit: f1f5f194620d3f9e11492f0051b6b71018033413
Parents: 106691b
Author: T Jake Luciani <jake@apache.org>
Authored: Tue May 30 10:24:38 2017 -0400
Committer: T Jake Luciani <jake@apache.org>
Committed: Tue Jun 6 09:42:27 2017 -0400

----------------------------------------------------------------------
 CHANGES.txt                                     |  1 +
 .../cassandra/stress/generate/SeedManager.java  | 44 +++++++++++++-------
 2 files changed, 29 insertions(+), 16 deletions(-)
----------------------------------------------------------------------


http://git-wip-us.apache.org/repos/asf/cassandra/blob/f1f5f194/CHANGES.txt
----------------------------------------------------------------------
diff --git a/CHANGES.txt b/CHANGES.txt
index f34b325..aed0036 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -1,4 +1,5 @@
 4.0
+ * Fix Randomness of stress values (CASSANDRA-12744)
  * Allow selecting Map values and Set elements (CASSANDRA-7396)
  * Fast and garbage-free Streaming Histogram (CASSANDRA-13444)
  * Update repairTime for keyspaces on completion (CASSANDRA-13539)

http://git-wip-us.apache.org/repos/asf/cassandra/blob/f1f5f194/tools/stress/src/org/apache/cassandra/stress/generate/SeedManager.java
----------------------------------------------------------------------
diff --git a/tools/stress/src/org/apache/cassandra/stress/generate/SeedManager.java b/tools/stress/src/org/apache/cassandra/stress/generate/SeedManager.java
index 5020b45..ae442e7 100644
--- a/tools/stress/src/org/apache/cassandra/stress/generate/SeedManager.java
+++ b/tools/stress/src/org/apache/cassandra/stress/generate/SeedManager.java
@@ -38,37 +38,43 @@ public class SeedManager
     final Distribution sample;
     final long sampleOffset;
     final int sampleSize;
+    final long sampleMultiplier;
     final boolean updateSampleImmediately;
 
     public SeedManager(StressSettings settings)
     {
+        Distribution sample = settings.insert.revisit.get();
+        this.sampleOffset = Math.min(sample.minValue(), sample.maxValue());
+        long sampleSize = 1 + Math.max(sample.minValue(), sample.maxValue()) - sampleOffset;
+        if (sampleOffset < 0 || sampleSize > Integer.MAX_VALUE)
+            throw new IllegalArgumentException("sample range is invalid");
+
+        // need to get a big numerical range even if a small number of discrete values
+        // one plus so we still get variation at the low order numbers as well as high
+        this.sampleMultiplier = 1 + Math.round(Math.pow(10D, 22 - Math.log10(sampleSize)));
+
         Generator writes, reads;
         if (settings.generate.sequence != null)
         {
             long[] seq = settings.generate.sequence;
             if (settings.generate.readlookback != null)
             {
-                LookbackableWriteGenerator series = new LookbackableWriteGenerator(seq[0],
seq[1], settings.generate.wrap, settings.generate.readlookback.get());
+                LookbackableWriteGenerator series = new LookbackableWriteGenerator(seq[0],
seq[1], settings.generate.wrap, settings.generate.readlookback.get(), sampleMultiplier);
                 writes = series;
                 reads = series.reads;
             }
             else
             {
-                writes = reads = new SeriesGenerator(seq[0], seq[1], settings.generate.wrap);
+                writes = reads = new SeriesGenerator(seq[0], seq[1], settings.generate.wrap,
sampleMultiplier);
             }
         }
         else
         {
-            writes = reads = new RandomGenerator(settings.generate.distribution.get());
+            writes = reads = new RandomGenerator(settings.generate.distribution.get(), sampleMultiplier);
         }
         this.visits = settings.insert.visits.get();
         this.writes = writes;
         this.reads = reads;
-        Distribution sample = settings.insert.revisit.get();
-        this.sampleOffset = Math.min(sample.minValue(), sample.maxValue());
-        long sampleSize = 1 + Math.max(sample.minValue(), sample.maxValue()) - sampleOffset;
-        if (sampleOffset < 0 || sampleSize > Integer.MAX_VALUE)
-            throw new IllegalArgumentException("sample range is invalid");
         this.sampleFrom = new LockedDynamicList<>((int) sampleSize);
         this.sample = DistributionInverted.invert(sample);
         this.sampleSize = (int) sampleSize;
@@ -132,15 +138,18 @@ public class SeedManager
     {
 
         final Distribution distribution;
+        final long multiplier;
 
-        public RandomGenerator(Distribution distribution)
+        public RandomGenerator(Distribution distribution, long multiplier)
         {
+
             this.distribution = distribution;
+            this.multiplier = multiplier;
         }
 
         public Seed next(int visits)
         {
-            return new Seed(distribution.next(), visits);
+            return new Seed(distribution.next() * multiplier, visits);
         }
     }
 
@@ -150,15 +159,18 @@ public class SeedManager
         final long start;
         final long totalCount;
         final boolean wrap;
+        final long multiplier;
         final AtomicLong next = new AtomicLong();
 
-        public SeriesGenerator(long start, long end, boolean wrap)
+        public SeriesGenerator(long start, long end, boolean wrap, long multiplier)
         {
             this.wrap = wrap;
             if (start > end)
                 throw new IllegalStateException();
             this.start = start;
             this.totalCount = 1 + end - start;
+            this.multiplier = multiplier;
+
         }
 
         public Seed next(int visits)
@@ -166,7 +178,7 @@ public class SeedManager
             long next = this.next.getAndIncrement();
             if (!wrap && next >= totalCount)
                 return null;
-            return new Seed(start + (next % totalCount), visits);
+            return new Seed((start + (next % totalCount))*multiplier, visits);
         }
     }
 
@@ -177,9 +189,9 @@ public class SeedManager
         final ConcurrentSkipListMap<Seed, Seed> afterMin = new ConcurrentSkipListMap<>();
         final LookbackReadGenerator reads;
 
-        public LookbackableWriteGenerator(long start, long end, boolean wrap, Distribution
readLookback)
+        public LookbackableWriteGenerator(long start, long end, boolean wrap, Distribution
readLookback, long multiplier)
         {
-            super(start, end, wrap);
+            super(start, end, wrap, multiplier);
             this.writeCount.set(0);
             reads = new LookbackReadGenerator(readLookback);
         }
@@ -189,12 +201,12 @@ public class SeedManager
             long next = this.next.getAndIncrement();
             if (!wrap && next >= totalCount)
                 return null;
-            return new Seed(start + (next % totalCount), visits);
+            return new Seed((start + (next % totalCount)) * multiplier, visits);
         }
 
         void finishWrite(Seed seed)
         {
-            if (seed.seed <= writeCount.get())
+            if (seed.seed/multiplier <= writeCount.get())
                 return;
             afterMin.put(seed, seed);
             while (true)


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