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Subject: [boost] storing intrusive_ptr in atomic?!
From: Oliver Kowalke (oliver.kowalke_at_[hidden])
Date: 2013-10-25 03:35:55


do you confirm that it is valid to store a intrusive_ptr inside an atomic?!

struct X {
   std::size_t use_count;
   X() : use_count( 0) {}
   friend inline void intrusive_ptr_add_ref( X * p) BOOST_NOEXCEPT
   { ++p->use_count; }
   friend inline void intrusive_ptr_release( X * p)
   { if ( 0 == --p->use_count) delete p; }

X::ptr_t x1( new X()

X::ptr_t x2( new X()

boost::atomic< X::ptr_t > av1(

BOOST_ASSERT( av1.compare_exchange_strong( x1, x2) );
BOOST_ASSERT( av1.load() != x1);
BOOST_ASSERT( av1.load() == x2);

A type T used in generic template atomic<T> is required to be trivial
copy-able, e.g.
I think it is trivial copy-able (std::memcpy) only the use_count will not
The memory layout of intrusive_ptr is a raw-pointer so trivial copy-able
should be correct.

What do you think?


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