SERVER-13237: benchRun should use a thread-safe random number generator

(cherry picked from commit acc1ebc194ab01f81750a4e60dc78a3a9bac650f)

5 files changed, 42 insertions, 22 deletions

diff --git a/src/mongo/scripting/bson_template_evaluator.cpp b/src/mongo/scripting/bson_template_evaluator.cpp
index 8b6e42756a2..634a478b613 100644
--- a/src/mongo/scripting/bson_template_evaluator.cpp
+++ b/src/mongo/scripting/bson_template_evaluator.cpp
@@ -48,7 +48,7 @@ namespace mongo {
         addOperator("VARIABLE", &BsonTemplateEvaluator::evalVariable);
     }
 
-    BsonTemplateEvaluator::BsonTemplateEvaluator() : _id(0) {
+    BsonTemplateEvaluator::BsonTemplateEvaluator(int64_t seed) : _id(0), rng(seed) {
         initializeEvaluator();
     }
 
@@ -169,7 +169,8 @@ namespace mongo {
         const int max  = range["1"].numberInt();
         if (max <= min)
             return StatusOpEvaluationError;
-        int randomNum = min + (rand() % (max - min));
+        // range of max-min
+        int randomNum = min + (btl->rng.nextInt32() % (max - min));
         if (range.nFields() == 3) {
             if (!range[2].isNumber())
                 return StatusOpEvaluationError;
@@ -192,7 +193,7 @@ namespace mongo {
         const int max  = range["1"].numberInt();
         if (max <= min)
             return StatusOpEvaluationError;
-        int randomNum = min + (rand() % (max - min));
+        int randomNum = min + (btl->rng.nextInt32() % (max - min));
         randomNum += ((max - min) * btl->_id);
         out.append(fieldName, randomNum);
         return StatusSuccess;
@@ -269,11 +270,11 @@ namespace mongo {
                                        "0123456789+/";
         static const size_t alphaNumLength = sizeof(alphanum) - 1;
         BOOST_STATIC_ASSERT(alphaNumLength == 64);
-        unsigned currentRand = 0;
+        int32_t currentRand = 0;
         std::string str;
         for (int i = 0; i < length; ++i, currentRand >>= 6) {
             if (i % 5 == 0)
-                currentRand = rand();
+                currentRand = btl->rng.nextInt32();
             str.push_back(alphanum[currentRand % alphaNumLength]);
         }
         out.append(fieldName, str);
diff --git a/src/mongo/scripting/bson_template_evaluator.h b/src/mongo/scripting/bson_template_evaluator.h
index d5fe8353524..67c3c5bf7d0 100644
--- a/src/mongo/scripting/bson_template_evaluator.h
+++ b/src/mongo/scripting/bson_template_evaluator.h
@@ -50,6 +50,7 @@
 
 #include "mongo/db/jsobj.h"
 #include "mongo/stdx/functional.h"
+#include "mongo/platform/random.h"
 
 namespace mongo {
 
@@ -97,7 +98,10 @@ namespace mongo {
         typedef stdx::function< Status (BsonTemplateEvaluator* btl, const char* fieldName,
                                          const BSONObj& in, BSONObjBuilder& builder) > OperatorFn;
 
-        BsonTemplateEvaluator();
+        /*
+         * @params seed : Random seed to be used when generating random data
+         */
+        BsonTemplateEvaluator(int64_t seed);
         ~BsonTemplateEvaluator();
 
         /**
@@ -235,6 +239,9 @@ namespace mongo {
         static Status evalVariable(BsonTemplateEvaluator* btl, const char* fieldName,
                                    const BSONObj& in, BSONObjBuilder& out);
 
+        // Per object pseudo random number generator
+        PseudoRandom rng;
+
     };
 
 } // end namespace
diff --git a/src/mongo/scripting/bson_template_evaluator_test.cpp b/src/mongo/scripting/bson_template_evaluator_test.cpp
index 5321ee02b7a..c589617f34f 100644
--- a/src/mongo/scripting/bson_template_evaluator_test.cpp
+++ b/src/mongo/scripting/bson_template_evaluator_test.cpp
@@ -68,7 +68,7 @@ namespace mongo {
 
         TEST(BSONTemplateEvaluatorTest, RAND_INT) {
 
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(1234567);
             int randValue1, randValue2;
 
             common_rand_tests("#RAND_INT", &t);
@@ -158,7 +158,7 @@ namespace mongo {
 
         TEST(BSONTemplateEvaluatorTest, RAND_INT_PLUS_THREAD) {
 
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(2345678);
             t.setId(1);
             int randValue1, randValue2;
 
@@ -248,7 +248,7 @@ namespace mongo {
             ASSERT_LESS_THAN_OR_EQUALS(randValue1, 10);
 
             // Test success with a single element for a zero _id
-            BsonTemplateEvaluator t2;
+            BsonTemplateEvaluator t2(3456789);
             t2.setId(0);
 
             BSONObjBuilder builder13;
@@ -264,7 +264,7 @@ namespace mongo {
 
         TEST(BSONTemplateEvaluatorTest, SEQ_INT) {
 
-            boost::scoped_ptr<BsonTemplateEvaluator> t(new BsonTemplateEvaluator());
+            boost::scoped_ptr<BsonTemplateEvaluator> t(new BsonTemplateEvaluator(131415));
             BSONObj seqObj;
             BSONObj expectedObj;
 
@@ -401,7 +401,7 @@ namespace mongo {
 
         TEST(BSONTemplateEvaluatorTest, RAND_STRING) {
 
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(4567890);
 
             // Test failure when the arguments to RAND_STRING is not an integer
             BSONObjBuilder builder1;
@@ -506,7 +506,7 @@ namespace mongo {
 
         TEST(BSONTemplateEvaluatorTest, CONCAT) {
 
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(5678901);
 
             // Test failure when the arguments to #CONCAT has only one argument
             BSONObjBuilder builder1;
@@ -561,7 +561,7 @@ namespace mongo {
 
         TEST(BSONTemplateEvaluatorTest, OID) {
 
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(6789012);
             BSONObj oidObj = BSON( "#OID" << 1 );
 
             // Error: field must be "_id"
@@ -578,7 +578,7 @@ namespace mongo {
 
         TEST(BSONTemplateEvaluatorTest, COMBINED_OPERATORS) {
 
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(7890123);
             BSONObj randIntObj = BSON( "#RAND_INT" << BSON_ARRAY( 0 << 5 ) );
             BSONObj randStrObj = BSON( "#RAND_STRING" << BSON_ARRAY(5) );
 
@@ -612,7 +612,7 @@ namespace mongo {
 
         // Test #VARIABLE
         TEST(BSONTemplateEvaluatorTest, VARIABLE) {
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(8901234);
             int value1;
 
             // Test failure when the variable has not been set
@@ -638,7 +638,7 @@ namespace mongo {
         // Test template recursion and other general features
         TEST(BSONTemplateEvaluatorTest, NESTING) {
 
-            BsonTemplateEvaluator t;
+            BsonTemplateEvaluator t(8901234);
             int randValue1, randValue2;
 
             // Test failure when operators are arbitrarily nested
diff --git a/src/mongo/shell/bench.cpp b/src/mongo/shell/bench.cpp
index 069af0ee7c7..87b3da10a36 100644
--- a/src/mongo/shell/bench.cpp
+++ b/src/mongo/shell/bench.cpp
@@ -156,6 +156,7 @@ namespace mongo {
 
         throwGLE = false;
         breakOnTrap = true;
+        randomSeed = 1314159265358979323;
     }
 
     BenchRunConfig *BenchRunConfig::createFromBson( const BSONObj &args ) {
@@ -178,6 +179,8 @@ namespace mongo {
 
         if ( args["parallel"].isNumber() )
             this->parallel = args["parallel"].numberInt();
+        if ( args["randomSeed"].isNumber() )
+            this->randomSeed = args["randomSeed"].numberInt();
         if ( args["seconds"].isNumber() )
             this->seconds = args["seconds"].number();
         if ( ! args["hideResults"].eoo() )
@@ -320,8 +323,9 @@ namespace mongo {
         return b.obj();
     }
 
-    BenchRunWorker::BenchRunWorker(size_t id, const BenchRunConfig *config, BenchRunState *brState)
-        : _id(id), _config(config), _brState(brState) {
+    BenchRunWorker::BenchRunWorker(size_t id, const BenchRunConfig *config, BenchRunState *brState,
+                                   int64_t randomSeed)
+        : _id(id), _config(config), _brState(brState), _randomSeed(randomSeed) {
     }
 
     BenchRunWorker::~BenchRunWorker() {}
@@ -341,7 +345,7 @@ namespace mongo {
         long long count = 0;
         mongo::Timer timer;
 
-        BsonTemplateEvaluator bsonTemplateEvaluator;
+        BsonTemplateEvaluator bsonTemplateEvaluator(_randomSeed);
         invariant(bsonTemplateEvaluator.setId(_id) == BsonTemplateEvaluator::StatusSuccess);
 
         if (_config->username != "") {
@@ -786,8 +790,11 @@ namespace mongo {
              }
 
              // Start threads
-             for ( unsigned i = 0; i < _config->parallel; i++ ) {
-                 BenchRunWorker *worker = new BenchRunWorker(i, _config.get(), &_brState);
+             for ( int64_t i = 0; i < _config->parallel; i++ ) {
+                 // Make a unique random seed for the worker. 
+                 int64_t seed = _config->randomSeed +  i;
+                 BenchRunWorker *worker = new BenchRunWorker(i, _config.get(),
+                                                             &_brState, seed);
                  worker->start();
                  _workers.push_back(worker);
              }
diff --git a/src/mongo/shell/bench.h b/src/mongo/shell/bench.h
index f7a58799465..280d7c1399d 100644
--- a/src/mongo/shell/bench.h
+++ b/src/mongo/shell/bench.h
@@ -102,6 +102,9 @@ namespace mongo {
          */
         double seconds;
 
+        /// Base random seed for threads
+        int64_t randomSeed;
+
         bool hideResults;
         bool handleErrors;
         bool hideErrors;
@@ -325,7 +328,8 @@ namespace mongo {
          *
          * "id" is a positive integer which should uniquely identify the worker.
          */
-        BenchRunWorker(size_t id, const BenchRunConfig *config, BenchRunState *brState);
+        BenchRunWorker(size_t id, const BenchRunConfig *config,
+                       BenchRunState *brState, int64_t randomSeed);
         ~BenchRunWorker();
 
         /**
@@ -355,6 +359,7 @@ namespace mongo {
         const BenchRunConfig *_config;
         BenchRunState *_brState;
         BenchRunStats _stats;
+        int64_t _randomSeed;
     };
 
     /**