1 files changed, 74 insertions, 0 deletions
diff --git a/ACE/examples/Smart_Pointers/Widget_Part_Impl.cpp b/ACE/examples/Smart_Pointers/Widget_Part_Impl.cpp
new file mode 100644
index 00000000000..6e803c98cd5
--- /dev/null
+++ b/ACE/examples/Smart_Pointers/Widget_Part_Impl.cpp
@@ -0,0 +1,74 @@
+/* -*- 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 ());
+    }
+}