[GitHub] [trafficserver] shinrich commented on a change in pull request #6241: Make Allocator.h less silly (no creepy "proto" object).

[GitBox <gi...@apache.org>]

shinrich commented on a change in pull request #6241:
URL: https://github.com/apache/trafficserver/pull/6241#discussion_r567086211



##########
File path: include/tscore/Allocator.h
##########
@@ -108,29 +109,39 @@ class Allocator
     ink_freelist_madvise_init(&this->fl, name, element_size, chunk_size, alignment, advice);
   }
 
+  // Dummies
+  void
+  destroy_if_enabled(void *)
+  {
+  }
+  Allocator &
+  raw()
+  {
+    return *this;
+  }
+
 protected:
   InkFreeList *fl;
 };
 
 /**
-  Allocator for Class objects. It uses a prototype object to do
-  fast initialization. Prototype of the template class is created
-  when the fast allocator is created. This is instantiated with
-  default (no argument) constructor. Constructor is not called for
-  the allocated objects. Instead, the prototype is just memory
-  copied onto the new objects. This is done for performance reasons.
+  Allocator for Class objects.
 
 */
-template <class C> class ClassAllocator : public Allocator
+template <class C, bool Destruct_on_free_ = false> class ClassAllocator : private Allocator
 {
 public:
-  /** Allocates objects of the templated type. */
+  using Value_type                   = C;
+  static bool const Destruct_on_free = Destruct_on_free_;
+
+  /** Allocates objects of the templated type.  Arguments are forwarded to the constructor for the object. */
+  template <typename... Args>
   C *
-  alloc()
+  alloc(Args &&... args)
   {
     void *ptr = ink_freelist_new(this->fl);
 
-    memcpy(ptr, (void *)&this->proto.typeObject, sizeof(C));
+    ::new (ptr) C(std::forward<Args>(args)...);

Review comment:
       Running with ASAN seems to initialize the allocated memory to a highly probably "bad" pattern.  Once I fixed the cacheVC, the rest of the system seems to be running fine.  At least this explains why we didn't see the CacheVC::od problem before.




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