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, 2 insertions, 1 deletions

diff --git a/mert/Data.cpp b/mert/Data.cpp
index 49c1239e5..428886b99 100644
--- a/mert/Data.cpp
+++ b/mert/Data.cpp
@@ -17,6 +17,7 @@
 #include "util/exception.hh"
 
 #include "util/file_piece.hh"
+#include "util/random.hh"
 #include "util/tokenize_piece.hh"
 #include "util/string_piece.hh"
 #include "FeatureDataIterator.h"
@@ -286,7 +287,7 @@ void Data::createShards(size_t shard_count, float shard_size, const string& scor
     } else {
       //create shards by randomly sampling
       for (size_t i = 0; i < floor(shard_size+0.5); ++i) {
-        shard_contents.push_back(rand() % data_size);
+        shard_contents.push_back(util::rand_int() % data_size);
       }
     }