From: "François Dumont" <frs.dumont@gmail.com>
To: libstdc++ <libstdc++@gcc.gnu.org>
Cc: gcc-patches <gcc-patches@gcc.gnu.org>
Subject: [PATCH][_Hahstable] Use RAII to guard node pointer while constructing
Date: Wed, 8 Nov 2023 21:00:03 +0100 [thread overview]
Message-ID: <fbbce12d-7613-4040-933b-047601274911@gmail.com> (raw)
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Another proposal to use RAII rather than __try/__catch block.
libstdc++: [_Hashtable] Use RAII type to guard node while constructing value
libstdc++-v3/ChangeLog:
* include/bits/hashtable_policy.h
(struct _NodePtrGuard<_HashtableAlloc, _NodePtr>): New.
(_ReuseAllocNode::operator()(_Args&&...)): Use latter to guard
allocated node
pointer while constructing in place the value_type instance.
Tested under Linux x64, ok to commit ?
François
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diff --git a/libstdc++-v3/include/bits/hashtable_policy.h b/libstdc++-v3/include/bits/hashtable_policy.h
index cd8943d8d05..c67eebd3b2b 100644
--- a/libstdc++-v3/include/bits/hashtable_policy.h
+++ b/libstdc++-v3/include/bits/hashtable_policy.h
@@ -173,6 +173,19 @@ namespace __detail
{ return __node_gen(std::forward<_Kt>(__k)); }
};
+ template<typename _HashtableAlloc, typename _NodePtr>
+ struct _NodePtrGuard
+ {
+ _HashtableAlloc& _M_h;
+ _NodePtr _M_ptr;
+
+ ~_NodePtrGuard()
+ {
+ if (_M_ptr)
+ _M_h._M_deallocate_node_ptr(_M_ptr);
+ }
+ };
+
template<typename _NodeAlloc>
struct _Hashtable_alloc;
@@ -201,27 +214,20 @@ namespace __detail
__node_ptr
operator()(_Args&&... __args) const
{
- if (_M_nodes)
- {
+ if (!_M_nodes)
+ return _M_h._M_allocate_node(std::forward<_Args>(__args)...);
+
__node_ptr __node = _M_nodes;
_M_nodes = _M_nodes->_M_next();
__node->_M_nxt = nullptr;
auto& __a = _M_h._M_node_allocator();
__node_alloc_traits::destroy(__a, __node->_M_valptr());
- __try
- {
+ _NodePtrGuard<__hashtable_alloc, __node_ptr> __guard { _M_h, __node };
__node_alloc_traits::construct(__a, __node->_M_valptr(),
std::forward<_Args>(__args)...);
- }
- __catch(...)
- {
- _M_h._M_deallocate_node_ptr(__node);
- __throw_exception_again;
- }
+ __guard._M_ptr = nullptr;
return __node;
}
- return _M_h._M_allocate_node(std::forward<_Args>(__args)...);
- }
private:
mutable __node_ptr _M_nodes;
next reply other threads:[~2023-11-08 20:00 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-11-08 20:00 François Dumont [this message]
2023-11-09 0:57 ` Jonathan Wakely
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