Get rid of non-portable drand48. (#1349)

Summary: Pull Request resolved: https://github.com/facebookresearch/faiss/pull/1349

Reviewed By: mdouze

Differential Revision: D23289393

Pulled By: beauby

fbshipit-source-id: a626bbf252ced4ae01abbc3dce4be50d9e628728

tests/test_sliding_ivf.cpp

@@ -9,6 +9,7 @@
 #include <cstdlib>
 
 #include <memory>
+#include <random>
 #include <vector>
 
 #include <gtest/gtest.h>
@@ -19,6 +20,7 @@
 #include <faiss/clone_index.h>
 #include <faiss/IVFlib.h>
 
+
 using namespace faiss;
 
 typedef Index::idx_t idx_t;
@@ -47,8 +49,10 @@ int window_size = 10;
 std::vector<float> make_data(size_t n)
 {
     std::vector <float> database (n * d);
+    std::mt19937 rng;
+    std::uniform_real_distribution<> distrib;
     for (size_t i = 0; i < n * d; i++) {
-        database[i] = drand48();
+        database[i] = distrib(rng);
     }
     return database;
 }
@@ -92,8 +96,10 @@ void make_index_slices (const Index* trained_index,
 
         auto xb = make_data(nb * d);
         std::vector<faiss::Index::idx_t> ids (nb);
+        std::mt19937 rng;
+        std::uniform_int_distribution<> distrib;
         for (int j = 0; j < nb; j++) {
-            ids[j] = lrand48();
+            ids[j] = distrib(rng);
         }
         index->add_with_ids (nb, xb.data(), ids.data());
     }