Use correct seed and don't use spare for randomNormalStable

3 files changed, 16 insertions, 13 deletions

diff --git a/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.cpp b/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.cpp
index 55b724285d6..5f3cf7fd063 100644
--- a/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.cpp
+++ b/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.cpp
@@ -1,4 +1,4 @@
-// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
 #include "random_normal_stable_feature.h"
 #include "utils.h"
@@ -13,7 +13,7 @@ namespace features {
 
 RandomNormalStableExecutor::RandomNormalStableExecutor(uint64_t seed, double mean, double stddev) :
     search::fef::FeatureExecutor(),
-    _rnd(mean, stddev, true),
+    _rnd(mean, stddev, false),  // don't use spares, as we reset seed on every generation
     _seed(seed)
 {
     LOG(debug, "RandomNormalStableExecutor: seed=%zu, mean=%f, stddev=%f", seed, mean, stddev);
@@ -61,7 +61,7 @@ RandomNormalStableBlueprint::setup(const search::fef::IIndexEnvironment & env,
         _stddev = params[1].asDouble();
     }
 
-    describeOutput("out" , "A random value drawn from the Gaussian distribution that is stable for a given Stable (document and query)");
+    describeOutput("out" , "A random value drawn from the Gaussian distribution that is stable for a given match (document and query)");
 
     return true;
 }
@@ -69,8 +69,11 @@ RandomNormalStableBlueprint::setup(const search::fef::IIndexEnvironment & env,
 search::fef::FeatureExecutor &
 RandomNormalStableBlueprint::createExecutor(const search::fef::IQueryEnvironment &env, vespalib::Stash &stash) const
 {
-    uint64_t seed = util::strToNum<uint64_t>
-            (env.getProperties().lookup(getName(), "seed").get("1024")); // default seed
+    uint64_t seed = _seed;
+    if (seed == 0) {
+        seed = util::strToNum<uint64_t>
+                (env.getProperties().lookup(getName(), "seed").get("1024")); // default seed
+    }
     return stash.create<RandomNormalStableExecutor>(seed, _mean, _stddev);
 }
 
diff --git a/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.h b/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.h
index e0b3232c5a1..129c929ba3d 100644
--- a/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.h
+++ b/searchlib/src/vespa/searchlib/features/random_normal_stable_feature.h
@@ -1,4 +1,4 @@
-// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
 #pragma once
 
@@ -17,7 +17,7 @@ namespace features {
  **/
 class RandomNormalStableExecutor : public fef::FeatureExecutor {
 private:
-    RandomNormal _rnd;       // seeded once per match
+    RandomNormal _rnd;  // seeded once per match
     uint64_t     _seed;
 
 public:
@@ -27,7 +27,7 @@ public:
 
 
 /**
- * Implements the blueprint for the random normal feature.
+ * Implements the blueprint for the random normal stable feature.
  */
 class RandomNormalStableBlueprint : public fef::Blueprint {
 private:
diff --git a/searchlib/src/vespa/searchlib/util/random_normal.h b/searchlib/src/vespa/searchlib/util/random_normal.h
index 68e98f871d3..74596066312 100644
--- a/searchlib/src/vespa/searchlib/util/random_normal.h
+++ b/searchlib/src/vespa/searchlib/util/random_normal.h
@@ -1,4 +1,4 @@
-// Copyright 2017 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
+// Copyright 2018 Yahoo Holdings. Licensed under the terms of the Apache 2.0 license. See LICENSE in the project root.
 
 #pragma once
 
@@ -7,6 +7,10 @@
 
 namespace search {
 
+/**
+ * Draws a random number from the Gaussian distribution
+ * using the Marsaglia polar method.
+ */
 class RandomNormal
 {
 private:
@@ -36,10 +40,6 @@ public:
         _rnd.srand48(seed);
     }
 
-    /**
-     * Draws a random number from the Gaussian distribution
-     * using the Marsaglia polar method.
-     */
     feature_t next() {
         feature_t result = _spare;
         if (_useSpare && _hasSpare) {