Thread-safe, platform-agnostic randomizer.

Some places in mert use srandom()/random(), but these are POSIX-specific.
The standard alternative, srand()/rand(), is not thread-safe.  This module
wraps srand()/rand() in mutexes (very short-lived, so should not cost much)
so that it relies on just Boost and the C standard library, not on a Unix-like
environment.

This may reduce the width of the random numbers on some platforms: it goes
from "long int" to just "int".  If that is a problem, we may have to use
Boost's randomizer utilities, or eventually, the C++ ones.

1 files changed, 4 insertions, 3 deletions

diff --git a/mert/evaluator.cpp b/mert/evaluator.cpp
index 026abf397..61775a354 100644
--- a/mert/evaluator.cpp
+++ b/mert/evaluator.cpp
@@ -16,6 +16,7 @@
 #include "Timer.h"
 #include "Util.h"
 #include "Data.h"
+#include "util/random.hh"
 
 using namespace std;
 using namespace MosesTuning;
@@ -94,7 +95,7 @@ void EvaluatorUtil::evaluate(const string& candFile, int bootstrap, bool nbest_i
     for (int i = 0; i < bootstrap; ++i) {
       ScoreData scoredata(g_scorer);
       for (int j = 0; j < n; ++j) {
-        int randomIndex = random() % n;
+        int randomIndex = util::rand_int() % n;
         scoredata.add(entries[randomIndex], j);
       }
       g_scorer->setScoreData(&scoredata);
@@ -284,10 +285,10 @@ void InitSeed(const ProgramOption *opt)
 {
   if (opt->has_seed) {
     cerr << "Seeding random numbers with " << opt->seed << endl;
-    srandom(opt->seed);
+    util::rand_int_init(opt->seed);
   } else {
     cerr << "Seeding random numbers with system clock " << endl;
-    srandom(time(NULL));
+    util::rand_int_init();
   }
 }