From b14bdb068a462dd25281ff3a06e2e211c1e23ced Mon Sep 17 00:00:00 2001
From: Scott Schurr <scott@ripple.com>
Date: Fri, 22 Jun 2018 18:50:02 -0700
Subject: [PATCH] Standardize on default_prng() for non-crypto shuffling

---
 src/test/basics/PerfLog_test.cpp   | 12 +++++-------
 src/test/ledger/Directory_test.cpp | 10 ++++------
 2 files changed, 9 insertions(+), 13 deletions(-)

diff --git a/src/test/basics/PerfLog_test.cpp b/src/test/basics/PerfLog_test.cpp
index 7c0bdd6c83..452edeef19 100644
--- a/src/test/basics/PerfLog_test.cpp
+++ b/src/test/basics/PerfLog_test.cpp
@@ -18,6 +18,7 @@
 //==============================================================================
 
 #include <ripple/basics/PerfLog.h>
+#include <ripple/basics/random.h>
 #include <ripple/beast/unit_test.h>
 #include <ripple/json/json_reader.h>
 #include <ripple/protocol/JsonFields.h>
@@ -48,9 +49,6 @@ class PerfLog_test : public beast::unit_test::suite
     test::jtx::Env env_ {*this};
     beast::Journal j_ {env_.app().journal ("PerfLog_test")};
 
-    // Use this to make calls to random_shuffle() less predictable.
-    std::default_random_engine shuffler_ {std::random_device{}()};
-
     // A PerfLog needs a Parent that is a Stoppable and a function to
     // call if it wants to shutdown the system.  This class provides both.
     struct PerfLogParent : public RootStoppable
@@ -370,7 +368,7 @@ public:
         // Get the all the labels we can use for RPC interfaces without
         // causing an assert.
         std::vector<char const*> labels {ripple::RPC::getHandlerNames()};
-        std::shuffle (labels.begin(), labels.end(), shuffler_);
+        std::shuffle (labels.begin(), labels.end(), default_prng());
 
         // Get two IDs to associate with each label.  Errors tend to happen at
         // boundaries, so we pick IDs starting from zero and ending at
@@ -383,7 +381,7 @@ public:
         std::generate_n (std::back_inserter (ids), labels.size(),
             [i = std::numeric_limits<std::uint64_t>::max()]()
             mutable { return i--; });
-        std::shuffle (ids.begin(), ids.end(), shuffler_);
+        std::shuffle (ids.begin(), ids.end(), default_prng());
 
         // Start all of the RPC commands twice to show they can all be tracked
         // simultaneously.
@@ -591,7 +589,7 @@ public:
                 jobs.emplace_back (job.first, job.second.name());
             }
         }
-        std::shuffle (jobs.begin(), jobs.end(), shuffler_);
+        std::shuffle (jobs.begin(), jobs.end(), default_prng());
 
         // Walk through all of the jobs, enqueuing every job once.  Check
         // the jobs data with every addition.
@@ -926,7 +924,7 @@ public:
 
             std::uniform_int_distribution<> dis(0, jobTypes.size() - 1);
             auto iter {jobTypes.begin()};
-            std::advance (iter, dis (shuffler_));
+            std::advance (iter, dis (default_prng()));
 
             jobType = iter->second.type();
             jobTypeName = iter->second.name();
diff --git a/src/test/ledger/Directory_test.cpp b/src/test/ledger/Directory_test.cpp
index c1287b1be8..6c5fb76123 100644
--- a/src/test/ledger/Directory_test.cpp
+++ b/src/test/ledger/Directory_test.cpp
@@ -15,7 +15,7 @@
 */
 //==============================================================================
 
-#include <ripple/beast/xor_shift_engine.h>
+#include <ripple/basics/random.h>
 #include <ripple/ledger/BookDirs.h>
 #include <ripple/ledger/Directory.h>
 #include <ripple/ledger/Sandbox.h>
@@ -184,8 +184,6 @@ struct Directory_test : public beast::unit_test::suite
         auto const charlie = Account ("charlie");
         auto const gw = Account ("gw");
 
-        beast::xor_shift_engine eng;
-
         Env env(*this);
 
         env.fund(XRP(1000000), alice, charlie, gw);
@@ -228,7 +226,7 @@ struct Directory_test : public beast::unit_test::suite
 
             BEAST_EXPECT(! dirIsEmpty (*env.closed(), keylet::ownerDir(alice)));
 
-            std::shuffle (cl.begin(), cl.end(), eng);
+            std::shuffle (cl.begin(), cl.end(), default_prng());
 
             for (auto const& c : cl)
             {
@@ -261,7 +259,7 @@ struct Directory_test : public beast::unit_test::suite
             // Now fill the offers in a random order. Offer
             // entries will drop, and be replaced by trust
             // lines that are implicitly created.
-            std::shuffle (cl.begin(), cl.end(), eng);
+            std::shuffle (cl.begin(), cl.end(), default_prng());
 
             for (auto const& c : cl)
             {
@@ -272,7 +270,7 @@ struct Directory_test : public beast::unit_test::suite
             // Finally, Alice now sends the funds back to
             // Charlie. The implicitly created trust lines
             // should drop away:
-            std::shuffle (cl.begin(), cl.end(), eng);
+            std::shuffle (cl.begin(), cl.end(), default_prng());
 
             for (auto const& c : cl)
             {