moved random_bit into random_utils namespace

Author: AlexanderSaydakov

common/include/common_defs.hpp

@@ -35,20 +35,19 @@ static const uint64_t DEFAULT_SEED = 9001;
 
 enum resize_factor { X1 = 0, X2, X4, X8 };
 
-template<typename A> using AllocChar = typename std::allocator_traits<A>::template rebind_alloc<char>;
-template<typename A> using string = std::basic_string<char, std::char_traits<char>, AllocChar<A>>;
-
-// thread-safe random bit
-static thread_local std::independent_bits_engine<std::mt19937, 1, uint32_t>
-  random_bit(static_cast<uint32_t>(std::chrono::system_clock::now().time_since_epoch().count() 
-    + std::hash<std::thread::id>{}(std::this_thread::get_id())));
+template<typename A> using string = std::basic_string<char, std::char_traits<char>, typename std::allocator_traits<A>::template rebind_alloc<char>>;
 
 // common random declarations
 namespace random_utils {
   static std::random_device rd; // possibly unsafe in MinGW with GCC < 9.2
   static thread_local std::mt19937_64 rand(rd());
   static thread_local std::uniform_real_distribution<> next_double(0.0, 1.0);
 
+  // thread-safe random bit
+  static thread_local std::independent_bits_engine<std::mt19937, 1, uint32_t>
+    random_bit(static_cast<uint32_t>(std::chrono::system_clock::now().time_since_epoch().count()
+      + std::hash<std::thread::id>{}(std::this_thread::get_id())));
+
   inline void override_seed(uint64_t s) {
     rand.seed(s);
   }

density/include/density_sketch_impl.hpp

@@ -143,7 +143,7 @@ template<typename T, typename K, typename A>
 void density_sketch<T, K, A>::compact_level(unsigned height) {
   auto& level = levels_[height];
   std::vector<bool> bits(level.size());
-  bits[0] = random_bit();
+  bits[0] = random_utils::random_bit();
   std::random_shuffle(level.begin(), level.end());
   for (unsigned i = 1; i < level.size(); ++i) {
     T delta = 0;

kll/include/kll_helper_impl.hpp

@@ -99,7 +99,7 @@ void kll_helper::randomly_halve_down(T* buf, uint32_t start, uint32_t length) {
 #ifdef KLL_VALIDATION
   const uint32_t offset = deterministic_offset();
 #else
-  const uint32_t offset = random_bit();
+  const uint32_t offset = random_utils::random_bit();
 #endif
   uint32_t j = start + offset;
   for (uint32_t i = start; i < (start + half_length); i++) {
@@ -115,7 +115,7 @@ void kll_helper::randomly_halve_up(T* buf, uint32_t start, uint32_t length) {
 #ifdef KLL_VALIDATION
   const uint32_t offset = deterministic_offset();
 #else
-  const uint32_t offset = random_bit();
+  const uint32_t offset = random_utils::random_bit();
 #endif
   uint32_t j = (start + length) - 1 - offset;
   for (uint32_t i = (start + length) - 1; i >= (start + half_length); i--) {

quantiles/include/quantiles_sketch_impl.hpp

@@ -958,7 +958,7 @@ void quantiles_sketch<T, C, A>::zip_buffer(Level& buf_in, Level& buf_out) {
   uint32_t rand_offset = next_offset;
   next_offset = 1 - next_offset;
 #else
-  uint32_t rand_offset = random_bit();
+  uint32_t rand_offset = random_utils::random_bit();
 #endif
   if ((buf_in.size() != 2 * buf_out.capacity())
     || (buf_out.size() > 0)) {

req/include/req_compactor_impl.hpp

@@ -277,7 +277,7 @@ std::pair<uint32_t, uint32_t> req_compactor<T, C, A>::compact(req_compactor& nex
   if (compaction_range.second - compaction_range.first < 2) throw std::logic_error("compaction range error");
 
   if ((state_ & 1) == 1) { coin_ = !coin_; } // for odd flip coin;
-  else { coin_ = random_bit(); } // random coin flip
+  else { coin_ = random_utils::random_bit(); } // random coin flip
 
   const auto num = (compaction_range.second - compaction_range.first) / 2;
   next.ensure_space(num);
@@ -493,7 +493,7 @@ comparator_(comparator),
 allocator_(allocator),
 lg_weight_(lg_weight),
 hra_(hra),
-coin_(random_bit()),
+coin_(random_utils::random_bit()),
 sorted_(sorted),
 section_size_raw_(section_size_raw),
 section_size_(nearest_even(section_size_raw)),