Merge pull request #84 from microsoft/bug-fix

Bug fix

src/mem/alloc.h

@@ -1084,13 +1084,13 @@ namespace snmalloc
 
       SNMALLOC_ASSUME(size <= SLAB_SIZE);
       sizeclass_t sizeclass = size_to_sizeclass(size);
-      stats().sizeclass_alloc(sizeclass);
 
       assert(sizeclass < NUM_SMALL_CLASSES);
       auto& fl = small_fast_free_lists[sizeclass];
       void* head = fl.value;
       if (likely(head != nullptr))
       {
+        stats().sizeclass_alloc(sizeclass);
         // Read the next slot from the memory that's about to be allocated.
         fl.value = Metaslab::follow_next(head);
 
@@ -1113,6 +1113,9 @@ namespace snmalloc
         return reinterpret_cast<Allocator*>(replacement)
           ->template small_alloc_slow<zero_mem, allow_reserve>(sizeclass);
       }
+
+      stats().sizeclass_alloc(sizeclass);
+
       handle_message_queue();
       size_t rsize = sizeclass_to_size(sizeclass);
       auto& sl = small_classes[sizeclass];

src/mem/allocstats.h

@@ -141,7 +141,9 @@ namespace snmalloc
       UNUSED(size);
 
 #ifdef USE_SNMALLOC_STATS
-      bucketed_requests[bits::to_exp_mant<BUCKETS_BITS>(size)]++;
+      auto index = (size == 0) ? 0 : bits::to_exp_mant<BUCKETS_BITS>(size);
+      assert(index < TOTAL_BUCKETS);
+      bucketed_requests[index]++;
 #endif
     }
 

src/mem/globalalloc.h

@@ -107,28 +107,26 @@ namespace snmalloc
 #endif
     }
 
-    void debug_check_empty()
+    /**
+      If you pass a pointer to a bool, then it returns whether all the
+      allocators are empty. If you don't pass a pointer to a bool, then will
+      raise an error all the allocators are not empty.
+     */
+    void debug_check_empty(bool* result = nullptr)
     {
 #ifndef USE_MALLOC
       // This is a debugging function. It checks that all memory from all
       // allocators has been freed.
-      size_t alloc_count = 0;
-
       auto* alloc = Parent::iterate();
 
-      // Count the linked allocators.
-      while (alloc != nullptr)
-      {
-        alloc = Parent::iterate(alloc);
-        alloc_count++;
-      }
-
       bool done = false;
 
+      size_t non_empty_count = 0;
       while (!done)
       {
         done = true;
         alloc = Parent::iterate();
+        non_empty_count = 0;
 
         while (alloc != nullptr)
         {
@@ -142,6 +140,10 @@ namespace snmalloc
             p = next;
           }
 
+          // Check that the allocator has freed all memory.
+          if (!alloc->stats().is_empty())
+            non_empty_count++;
+
           // Place the static stub message on the queue.
           alloc->init_message_queue();
 
@@ -158,20 +160,16 @@ namespace snmalloc
         }
       }
 
-      alloc = Parent::iterate();
-      size_t empty_count = 0;
-
-      while (alloc != nullptr)
+      if (result != nullptr)
       {
-        // Check that the allocator has freed all memory.
-        if (alloc->stats().is_empty())
-          empty_count++;
-
-        alloc = Parent::iterate(alloc);
+        *result = non_empty_count == 0;
+        return;
       }
 
-      if (alloc_count != empty_count)
-        error("Incorrect number of allocators");
+      if (non_empty_count != 0)
+      {
+        error("debug_check_empty: found non-empty allocators");
+      }
 #endif
     }
   };