Add cross-platform randomizer module.

The code uses two mechanisms for generating random numbers: srand()/rand(),
which is not thread-safe, and srandom()/random(), which is POSIX-specific.

Here I add a util/random.cc module that centralizes these calls, and unifies
some common usage patterns.  If the implementation is not good enough, we can
now change it in a single place.

To keep things simple, this uses the portable srand()/rand() but protects them
with a lock to avoid concurrency problems.

The hard part was to keep the regression tests passing: they rely on fixed
sequences of random numbers, so a small code change could break them very
thoroughly.  Util::rand(), for wide types like size_t, calls std::rand() not
once but twice.  This behaviour was generalized into utils::wide_rand() and
friends.

1 files changed, 2 insertions, 1 deletions

diff --git a/moses/Parameter.cpp b/moses/Parameter.cpp
index e43c69d22..b6773fa13 100644
--- a/moses/Parameter.cpp
+++ b/moses/Parameter.cpp
@@ -31,6 +31,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA
 #include "InputFileStream.h"
 #include "StaticData.h"
 #include "util/exception.hh"
+#include "util/random.hh"
 #include <boost/program_options.hpp>
 
 
@@ -1392,7 +1393,7 @@ struct Credit {
     this->contact							= contact						;
     this->currentPursuits			= currentPursuits		;
     this->areaResponsibility	= areaResponsibility;
-    this->sortId							= rand() % 1000;
+    this->sortId							= util::rand_excl(1000);
   }
 
   bool operator<(const Credit &other) const {