Merge pull request #152 from cmazakas/fix/rehash-allocation

Fix bug #147

include/boost/unordered/detail/implementation.hpp

@@ -3411,8 +3411,8 @@ namespace boost {
       template <typename Types>
       inline void table<Types>::rehash(std::size_t num_buckets)
       {
-        num_buckets = (std::max)(
+        num_buckets = buckets_.bucket_count_for(
-          min_buckets(size_, mlf_), buckets_.bucket_count_for(num_buckets));
+          (std::max)(min_buckets(size_, mlf_), num_buckets));
 
         if (num_buckets != this->bucket_count()) {
           this->rehash_impl(num_buckets);

test/unordered/rehash_tests.cpp

@@ -6,16 +6,48 @@
 
 #include "../helpers/unordered.hpp"
 
-#include "../helpers/test.hpp"
-#include "../helpers/random_values.hpp"
-#include "../helpers/tracker.hpp"
 #include "../helpers/metafunctions.hpp"
+#include "../helpers/random_values.hpp"
+#include "../helpers/test.hpp"
+#include "../helpers/tracker.hpp"
 #include "../objects/test.hpp"
 
 namespace rehash_tests {
 
   test::seed_t initialize_seed(2974);
 
+  static int count_allocations;
+  template <class T> struct monotonic_allocator
+  {
+    typedef T value_type;
+    monotonic_allocator() {}
+    monotonic_allocator(monotonic_allocator const&) {}
+
+    template <class U> monotonic_allocator(monotonic_allocator<U> const&) {}
+
+    friend bool operator==(
+      monotonic_allocator const&, monotonic_allocator const&)
+    {
+      return true;
+    }
+
+    friend bool operator!=(
+      monotonic_allocator const&, monotonic_allocator const&)
+    {
+      return false;
+    }
+
+    T* allocate(std::size_t n)
+    {
+      ++count_allocations;
+      return static_cast<T*>(::operator new(sizeof(T) * n));
+    }
+
+    void deallocate(T* p, std::size_t) { ::operator delete(p); }
+  };
+
+  void reset_counts() { count_allocations = 0; }
+
   template <class X> bool postcondition(X const& x, typename X::size_type n)
   {
     return static_cast<double>(x.bucket_count()) >=
@@ -321,9 +353,10 @@ namespace rehash_tests {
         BOOST_TEST_GT(x.bucket_count(), 0u);
 
         x.reserve(
-          2 * (static_cast<size_type>(
+          2 *
-                std::floor(static_cast<float>(x.size()) / x.max_load_factor()) +
+          (static_cast<size_type>(
-                std::floor(static_cast<float>(x.size()) * x.max_load_factor()))));
+            std::floor(static_cast<float>(x.size()) / x.max_load_factor()) +
+            std::floor(static_cast<float>(x.size()) * x.max_load_factor()))));
 
         BOOST_TEST_GT(x.bucket_count(), bucket_count);
 
@@ -376,6 +409,34 @@ namespace rehash_tests {
     }
   }
 
+  template <class X> void rehash_stability(X*, test::random_generator generator)
+  {
+    reset_counts();
+
+    typedef typename X::size_type size_type;
+
+    size_type bucket_count = 100;
+    X x(bucket_count);
+
+    size_type num_elems = x.bucket_count() - 1;
+
+    test::random_values<X> v(num_elems, generator);
+    test::ordered<X> tracker;
+    tracker.insert_range(v.begin(), v.end());
+
+    typename test::random_values<X>::iterator pos = v.begin();
+    for (size_type i = 0; i < num_elems; ++i) {
+      x.insert(*pos);
+      ++pos;
+    }
+
+    int const old_count = count_allocations;
+    x.rehash(0);
+
+    BOOST_TEST_EQ(count_allocations, old_count);
+    tracker.compare(x);
+  }
+
   template <class X> void rehash_test1(X*, test::random_generator generator)
   {
     test::random_values<X> v(1000, generator);
@@ -513,6 +574,13 @@ namespace rehash_tests {
     test::allocator1<std::pair<test::object const, test::object> > >*
     test_map_tracking;
 
+  boost::unordered_flat_set<test::object, test::hash, test::equal_to,
+    monotonic_allocator<test::object> >* test_set_monotonic;
+  boost::unordered_flat_map<test::object, test::object, test::hash,
+    test::equal_to,
+    monotonic_allocator<std::pair<test::object const, test::object> > >*
+    test_map_monotonic;
+
   UNORDERED_TEST(rehash_empty_test1, ((int_set_ptr)(test_map_ptr)))
   UNORDERED_TEST(rehash_empty_test2,
     ((int_set_ptr)(test_map_ptr))(
@@ -534,9 +602,11 @@ namespace rehash_tests {
   UNORDERED_TEST(rehash_empty_tracking,
     ((test_set_tracking)(test_map_tracking))(
       (default_generator)(generate_collisions)(limited_range)))
-  UNORDERED_TEST(rehash_nonempty_tracking,
+  UNORDERED_TEST(
-    ((test_set_tracking)(test_map_tracking))(
+    rehash_nonempty_tracking, ((test_set_tracking)(test_map_tracking))(
-      (default_generator)(generate_collisions)(limited_range)))
+                                (default_generator)(limited_range)))
+  UNORDERED_TEST(rehash_stability, ((test_set_monotonic)(test_map_monotonic))(
+                                     (default_generator)(limited_range)))
 #else
   boost::unordered_set<int>* int_set_ptr;
   boost::unordered_multiset<test::object, test::hash, test::equal_to,
@@ -557,6 +627,18 @@ namespace rehash_tests {
     test::allocator1<std::pair<test::object const, test::object> > >*
     test_multimap_tracking;
 
+  boost::unordered_set<test::object, test::hash, test::equal_to,
+    monotonic_allocator<test::object> >* test_set_monotonic;
+  boost::unordered_multiset<test::object, test::hash, test::equal_to,
+    monotonic_allocator<test::object> >* test_multiset_monotonic;
+  boost::unordered_map<test::object, test::object, test::hash, test::equal_to,
+    monotonic_allocator<std::pair<test::object const, test::object> > >*
+    test_map_monotonic;
+  boost::unordered_multimap<test::object, test::object, test::hash,
+    test::equal_to,
+    monotonic_allocator<std::pair<test::object const, test::object> > >*
+    test_multimap_monotonic;
+
   UNORDERED_TEST(rehash_empty_test1,
     ((int_set_ptr)(test_multiset_ptr)(test_map_ptr)(int_multimap_ptr)))
   UNORDERED_TEST(rehash_empty_test2,
@@ -584,7 +666,10 @@ namespace rehash_tests {
   UNORDERED_TEST(rehash_nonempty_tracking,
     ((test_set_tracking)(test_multiset_tracking)(test_map_tracking)(test_multimap_tracking))(
       (default_generator)(generate_collisions)(limited_range)))
+  UNORDERED_TEST(rehash_stability,
+    ((test_set_monotonic)(test_multiset_monotonic)(test_map_monotonic)(test_multimap_monotonic))(
+      (default_generator)(limited_range)))
 #endif
-}
+} // namespace rehash_tests
 
 RUN_TESTS()