1 files changed, 95 insertions, 0 deletions
diff --git a/ACE/examples/APG/Threads/Guards.cpp b/ACE/examples/APG/Threads/Guards.cpp
new file mode 100644
index 00000000000..7ef23e1e4da
--- /dev/null
+++ b/ACE/examples/APG/Threads/Guards.cpp
@@ -0,0 +1,95 @@
+// $Id$
+#include "ace/config-lite.h"
+#if defined (ACE_HAS_THREADS)
+
+#include "ace/OS_main.h"
+#include "ace/OS_Memory.h"
+#include "ace/Guard_T.h"
+#include "ace/Log_Msg.h"
+#include "ace/Thread_Mutex.h"
+
+// This file exists primarily to get code into the book to show different
+// ways to do the same thing. For complete context and explanation, please
+// see APG chapter 12.
+
+class HA_Device_Repository {
+public:
+  int update_device (int device_id);
+
+private:
+  ACE_Thread_Mutex  mutex_;
+};
+
+class Object {
+};
+static Object *object;
+
+#if 0
+// This is less-desired way to do this...
+
+// Listing 1 code/ch12
+int
+HA_Device_Repository::update_device (int device_id)
+{
+  this->mutex_.acquire ();
+  ACE_DEBUG ((LM_DEBUG, ACE_TEXT ("(%t) Updating device %d\n"),
+              device_id));
+
+  // Allocate a new object.
+  ACE_NEW_RETURN (object, Object, -1);
+  // ...
+  // Use the object
+
+  this->mutex_.release ();
+}
+// Listing 1
+// Listing 2 code/ch12
+int
+HA_Device_Repository::update_device (int device_id)
+{
+  // Construct a guard specifying the type of the mutex as
+  // a template parameter and passing in the mutex to hold
+  // as a parameter.
+  ACE_Guard<ACE_Thread_Mutex> guard (this->mutex_);
+
+  // This can throw an exception that is not caught here.
+  ACE_NEW_RETURN (object, Object, -1);
+  // ..
+  // Use the object.
+  // ..
+  // Guard is destroyed, automatically releasing the lock.
+}
+// Listing 2
+#endif /* 0 */
+
+// Listing 3 code/ch12
+int
+HA_Device_Repository::update_device (int /* device_id */)
+{
+  ACE_GUARD_RETURN (ACE_Thread_Mutex, mon, mutex_, -1);
+
+  ACE_NEW_RETURN (object, Object, -1);
+  // Use the object.
+  // ...
+  return 0;
+}
+// Listing 3
+
+int ACE_TMAIN (int, ACE_TCHAR *[])
+{
+  HA_Device_Repository rep;
+  rep.update_device (42);
+  return 0;
+}
+
+#else
+#include "ace/OS_main.h"
+#include "ace/OS_NS_stdio.h"
+
+int ACE_TMAIN (int, ACE_TCHAR *[])
+{
+  ACE_OS::puts (ACE_TEXT ("This example requires threads."));
+  return 0;
+}
+
+#endif /* ACE_HAS_THREADS */