flann: use OpenCV theRNG()

alalek · alalek · commit 147f3ebf0add · 2017-03-02T13:45:12.000+03:00
std::rand() has no thread-safe guarantee.
diff --git a/modules/flann/include/opencv2/flann/kdtree_index.h b/modules/flann/include/opencv2/flann/kdtree_index.h
@@ -125,7 +125,12 @@ class KDTreeIndex : public NNIndex<Distance>
         /* Construct the randomized trees. */
         for (int i = 0; i < trees_; i++) {
             /* Randomize the order of vectors to allow for unbiased sampling. */
+#ifndef OPENCV_FLANN_USE_STD_RAND
+            cv::randShuffle(vind_);
+#else
             std::random_shuffle(vind_.begin(), vind_.end());
+#endif
+
             tree_roots_[i] = divideTree(&vind_[0], int(size_) );
         }
     }
diff --git a/modules/flann/include/opencv2/flann/lsh_table.h b/modules/flann/include/opencv2/flann/lsh_table.h
@@ -350,7 +350,11 @@ inline LshTable<unsigned char>::LshTable(unsigned int feature_size, unsigned int
     // A bit brutal but fast to code
     std::vector<size_t> indices(feature_size * CHAR_BIT);
     for (size_t i = 0; i < feature_size * CHAR_BIT; ++i) indices[i] = i;
+#ifndef OPENCV_FLANN_USE_STD_RAND
+    cv::randShuffle(indices);
+#else
     std::random_shuffle(indices.begin(), indices.end());
+#endif
 
     // Generate a random set of order of subsignature_size_ bits
     for (unsigned int i = 0; i < key_size_; ++i) {
diff --git a/modules/flann/include/opencv2/flann/random.h b/modules/flann/include/opencv2/flann/random.h
@@ -40,13 +40,31 @@
 namespace cvflann
 {
 
+inline int rand()
+{
+#ifndef OPENCV_FLANN_USE_STD_RAND
+#   if INT_MAX == RAND_MAX
+    int v = cv::theRNG().next() & INT_MAX;
+#   else
+    int v = cv::theRNG().uniform(0, RAND_MAX + 1);
+#   endif
+#else
+    int v = std::rand();
+#endif // OPENCV_FLANN_USE_STD_RAND
+    return v;
+}
+
 /**
  * Seeds the random number generator
  *  @param seed Random seed
  */
 inline void seed_random(unsigned int seed)
 {
-    srand(seed);
+#ifndef OPENCV_FLANN_USE_STD_RAND
+    cv::theRNG() = cv::RNG(seed);
+#else
+    std::srand(seed);
+#endif
 }
 
 /*
@@ -60,7 +78,7 @@ inline void seed_random(unsigned int seed)
  */
 inline double rand_double(double high = 1.0, double low = 0)
 {
-    return low + ((high-low) * (std::rand() / (RAND_MAX + 1.0)));
+    return low + ((high-low) * (rand() / (RAND_MAX + 1.0)));
 }
 
 /**
@@ -71,7 +89,7 @@ inline double rand_double(double high = 1.0, double low = 0)
  */
 inline int rand_int(int high = RAND_MAX, int low = 0)
 {
-    return low + (int) ( double(high-low) * (std::rand() / (RAND_MAX + 1.0)));
+    return low + (int) ( double(high-low) * (rand() / (RAND_MAX + 1.0)));
 }
 
 /**
@@ -107,7 +125,11 @@ class UniqueRandom
         for (int i = 0; i < size_; ++i) vals_[i] = i;
 
         // shuffle the elements in the array
+#ifndef OPENCV_FLANN_USE_STD_RAND
+        cv::randShuffle(vals_);
+#else
         std::random_shuffle(vals_.begin(), vals_.end());
+#endif
 
         counter_ = 0;
     }

Original file line number	Diff line number	Diff line change
`@@ -125,7 +125,12 @@ class KDTreeIndex : public NNIndex<Distance>`
`125`	`125`	`/* Construct the randomized trees. */`
`126`	`126`	`for (int i = 0; i < trees_; i++) {`
`127`	`127`	`/* Randomize the order of vectors to allow for unbiased sampling. */`
	`128`	`+#ifndef OPENCV_FLANN_USE_STD_RAND`
	`129`	`+ cv::randShuffle(vind_);`
	`130`	`+#else`
`128`	`131`	`std::random_shuffle(vind_.begin(), vind_.end());`
	`132`	`+#endif`
	`133`	`+`
`129`	`134`	`tree_roots_[i] = divideTree(&vind_[0], int(size_) );`
`130`	`135`	`}`
`131`	`136`	`}`