Fix the Broken malloc_n Behavior

include/boost/pool/simple_segregated_storage.hpp

@@ -328,6 +328,19 @@ void * simple_segregated_storage<SizeType>::try_malloc_n(
     void * & start, size_type n, const size_type partition_size)
 {
   void * iter = nextof(start);
+  if (n == 1)
+  {
+    void * next = nextof(iter);
+    if (next != static_cast<char *>(iter) + partition_size)
+    {
+      start = iter;
+      return 0;
+    }
+    else
+    {
+      return iter;
+    }
+  }
   while (--n != 0)
   {
     void * next = nextof(iter);

test/test_pool_alloc.cpp

@@ -263,6 +263,34 @@ void test_mem_usage()
         //  This will clean up the memory leak from (*B*)
     }
 
+    {
+        pool_type pool(sizeof(int), 2);
+        void * ptr_0 = pool.malloc();
+        void * ptr_1 = pool.malloc();
+        void * ptr_2 = pool.malloc();
+        void * ptr_3 = pool.malloc();
+        pool.ordered_free(ptr_2);
+        pool.ordered_free(ptr_3);
+        BOOST_TEST(pool.release_memory());
+        pool.ordered_free(ptr_0);
+        pool.ordered_free(ptr_1);
+        BOOST_TEST(pool.release_memory());
+    }
+
+    {
+        pool_type pool(sizeof(int), 2);
+        void * ptr_0 = pool.malloc();
+        void * ptr_1 = pool.malloc();
+        void * ptr_2 = pool.malloc();
+        void * ptr_3 = pool.malloc();
+        pool.ordered_free(ptr_0);
+        pool.ordered_free(ptr_1);
+        BOOST_TEST(pool.release_memory());
+        pool.ordered_free(ptr_2);
+        pool.ordered_free(ptr_3);
+        BOOST_TEST(pool.release_memory());
+    }
+
     BOOST_TEST(track_alloc::ok());
 }
 

test/test_simple_seg_storage.cpp

@@ -277,6 +277,82 @@ int main()
             BOOST_TEST(nchunks == 3);
         }
 
+        {
+            char* const pc = track_allocator::malloc(4 * partition_sz);
+            test_simp_seg_store tstore;
+            tstore.add_ordered_block(pc, 4 * partition_sz, partition_sz);
+
+            void* pvret = tstore.malloc_n(1, partition_sz);
+            BOOST_TEST(pvret == pc);
+
+            // There should still be two contiguous
+            //  and one non-contiguous chunk left
+            std::size_t nchunks = 0;
+            while(!tstore.empty())
+            {
+                tstore.malloc();
+                ++nchunks;
+            }
+            BOOST_TEST(nchunks == 3);
+        }
+
+        {
+            char* const pc = track_allocator::malloc(4 * partition_sz);
+            test_simp_seg_store tstore;
+            tstore.add_ordered_block(pc, 4 * partition_sz, partition_sz);
+
+            void* pvret = tstore.malloc_n(2, partition_sz);
+            BOOST_TEST(pvret == pc);
+
+            // There should still be two contiguous
+            //  and one non-contiguous chunk left
+            std::size_t nchunks = 0;
+            while(!tstore.empty())
+            {
+                tstore.malloc();
+                ++nchunks;
+            }
+            BOOST_TEST(nchunks == 2);
+        }
+
+        {
+            char* const pc = track_allocator::malloc(4 * partition_sz);
+            test_simp_seg_store tstore;
+            tstore.add_ordered_block(pc, 4 * partition_sz, partition_sz);
+
+            void* pvret = tstore.malloc_n(1, 2 * partition_sz);
+            BOOST_TEST(pvret == 0);
+
+            // There should still be two contiguous
+            //  and one non-contiguous chunk left
+            std::size_t nchunks = 0;
+            while(!tstore.empty())
+            {
+                tstore.malloc();
+                ++nchunks;
+            }
+            BOOST_TEST(nchunks == 4);
+        }
+
+        {
+            char* const pc = track_allocator::malloc(4 * partition_sz);
+            test_simp_seg_store tstore;
+            tstore.add_ordered_block(pc, 4 * partition_sz, partition_sz);
+
+            void* pvret = tstore.malloc_n(2, 2 * partition_sz);
+            BOOST_TEST(pvret == 0);
+
+            // There should still be two contiguous
+            //  and one non-contiguous chunk left
+            std::size_t nchunks = 0;
+            while(!tstore.empty())
+            {
+                tstore.malloc();
+                ++nchunks;
+            }
+            BOOST_TEST(nchunks == 4);
+        }
+
         {
             char* const pc = track_allocator::malloc(12 * partition_sz);
             test_simp_seg_store tstore;