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Re: Fix hashtable node deallocation


Gentle reminder, we still have this issue pending.

    * include/bits/hashtable_policy.h
(_Hashtable_alloc<>::_M_deallocate_node_ptr(__node_type*)): New.
    (_Hashtable_alloc<>::_M_deallocate_node(__node_type*)): Use latter.
(_ReuseOrAllocNode<>::operator<_Arg>()(_Arg&&)): Likewise.
    * libstdc++-v3/testsuite/util/testsuite_allocator.h
    (CustomPointerAlloc<>::allocate(size_t, pointer)): Replace by...
    (CustomPointerAlloc<>::allocate(size_t, const_void_pointer)): ...this.

François

On 11/29/18 7:08 AM, François Dumont wrote:
I am unclear about this patch, is it accepted ?


On 11/19/18 10:19 PM, François Dumont wrote:
On 11/19/18 1:34 PM, Jonathan Wakely wrote:
On 10/11/18 22:40 +0100, François Dumont wrote:
While working on a hashtable enhancement I noticed that we are not using the correct method to deallocate node if the constructor throws in _ReuseOrAllocNode operator(). I had to introduce a new _M_deallocate_node_ptr for that as node value shall not be destroy again.

I also check other places and noticed that a __node_type destructor call was missing.

That's intentional. The type has a trivial destructor, so its storage
can just be reused, we don't need to destroy it.


Ok, do you want to also remove the other call to ~__node_type() then ?

Here is the updated patch and the right ChangeLog entry:

    * include/bits/hashtable_policy.h
(_Hashtable_alloc<>::_M_deallocate_node_ptr(__node_type*)): New.
(_Hashtable_alloc<>::_M_deallocate_node(__node_type*)): Use latter.
(_ReuseOrAllocNode<>::operator<_Arg>()(_Arg&&)): Likewise.
    (_Hashtable_alloc<>::_M_allocate_node): Add ~__node_type call.
    * libstdc++-v3/testsuite/util/testsuite_allocator.h
    (CustomPointerAlloc<>::allocate(size_t, pointer)): Replace by...
    (CustomPointerAlloc<>::allocate(size_t, const_void_pointer)): ...this.
    * testsuite/23_containers/unordered_set/allocator/ext_ptr.cc: Add
    check.

Ok to commit ?

François



diff --git a/libstdc++-v3/include/bits/hashtable_policy.h b/libstdc++-v3/include/bits/hashtable_policy.h
index b843c955797..aa4808eab31 100644
--- a/libstdc++-v3/include/bits/hashtable_policy.h
+++ b/libstdc++-v3/include/bits/hashtable_policy.h
@@ -148,8 +148,7 @@ namespace __detail
 		}
 	      __catch(...)
 		{
-		  __node->~__node_type();
-		  __node_alloc_traits::deallocate(__a, __node, 1);
+		  _M_h._M_deallocate_node_ptr(__node);
 		  __throw_exception_again;
 		}
 	      return __node;
@@ -2116,6 +2115,9 @@ namespace __detail
       void
       _M_deallocate_node(__node_type* __n);
 
+      void
+      _M_deallocate_node_ptr(__node_type* __n);
+
       // Deallocate the linked list of nodes pointed to by __n
       void
       _M_deallocate_nodes(__node_type* __n);
@@ -2154,10 +2156,17 @@ namespace __detail
   template<typename _NodeAlloc>
     void
     _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node(__node_type* __n)
+    {
+      __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
+      _M_deallocate_node_ptr(__n);
+    }
+
+  template<typename _NodeAlloc>
+    void
+    _Hashtable_alloc<_NodeAlloc>::_M_deallocate_node_ptr(__node_type* __n)
     {
       typedef typename __node_alloc_traits::pointer _Ptr;
       auto __ptr = std::pointer_traits<_Ptr>::pointer_to(*__n);
-      __node_alloc_traits::destroy(_M_node_allocator(), __n->_M_valptr());
       __n->~__node_type();
       __node_alloc_traits::deallocate(_M_node_allocator(), __ptr, 1);
     }
diff --git a/libstdc++-v3/testsuite/util/testsuite_allocator.h b/libstdc++-v3/testsuite/util/testsuite_allocator.h
index b0fecfb59a3..c18223475c9 100644
--- a/libstdc++-v3/testsuite/util/testsuite_allocator.h
+++ b/libstdc++-v3/testsuite/util/testsuite_allocator.h
@@ -582,7 +582,7 @@ namespace __gnu_test
       typedef Ptr<void>		void_pointer;
       typedef Ptr<const void>	const_void_pointer;
 
-      pointer allocate(std::size_t n, pointer = {})
+      pointer allocate(std::size_t n, const_void_pointer = {})
       { return pointer(std::allocator<Tp>::allocate(n)); }
 
       void deallocate(pointer p, std::size_t n)

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