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/* -*- C++ -*- */
//=============================================================================
/**
* @file Widget_Part_Impl.cpp
*
* $Id$
*
* @author Christopher Kohlhoff <chris@kohlhoff.com>
*/
//=============================================================================
#include "Widget_Part_Impl.h"
#include "ace/ACE.h"
#include "ace/Log_Msg.h"
#include "ace/Refcounted_Auto_Ptr.h"
#include "ace/Unbounded_Queue.h"
#include "ace/Null_Mutex.h"
Widget_Part_Impl::Widget_Part_Impl (Widget *owner, const char* name, int size)
: owner_ (owner),
name_ (ACE::strnew (name)),
size_ (size)
{
ACE_DEBUG ((LM_DEBUG, "Widget_Part_Impl constructor\n"));
}
Widget_Part_Impl::~Widget_Part_Impl (void)
{
ACE_DEBUG ((LM_DEBUG, "Widget_Part_Impl destructor\n"));
delete [] name_;
}
void Widget_Part_Impl::print_info (void)
{
ACE_DEBUG ((LM_INFO, "Widget part: name=%s size=%d\n", name_, size_));
}
void Widget_Part_Impl::remove_from_owner (void)
{
// Since we only have a raw pointer to refer to the owner, we have no way of
// checking whether the owner still exists, and if it does guaranteeing that
// it will continue to exist for the duration of this call. This is not an
// issue in this limited example program, but in multithreaded applications
// this function may be called from a different thread to that managing the
// lifetime of the owner object. See the Gadget example for how
// ACE_Strong_Bound_Ptr/ACE_Weak_Bound_Ptr can be used to address the problem.
// Take all existing parts from the owner and build up a temporary queue. If
// we find ourselves then we won't add ourselves to the queue. We will
// actually store ACE_Refcounted_Auto_Ptr instances in the queue, and since we
// know that there is only one thread involved we can use ACE_Null_Mutex to
// eliminate the locking overhead.
ACE_Unbounded_Queue<ACE_Refcounted_Auto_Ptr<Widget_Part, ACE_Null_Mutex> > parts;
for (;;)
{
ACE_Refcounted_Auto_Ptr<Widget_Part, ACE_Null_Mutex> part (owner_->remove_part ());
if (part.null ())
break;
if (part.get () == this)
// Someone else will be responsible for our lifetime.
part.release();
else
parts.enqueue_tail (part);
}
// Add the remaining parts back to the gadget.
while (!parts.is_empty ())
{
ACE_Refcounted_Auto_Ptr<Widget_Part, ACE_Null_Mutex> part;
parts.dequeue_head (part);
owner_->add_part (part.release ());
}
}
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