1 files changed, 74 insertions, 0 deletions
diff --git a/ACE/examples/APG/ThreadSafety/Mutex.cpp b/ACE/examples/APG/ThreadSafety/Mutex.cpp
new file mode 100644
index 00000000000..6f679b7fb0c
--- /dev/null
+++ b/ACE/examples/APG/ThreadSafety/Mutex.cpp
@@ -0,0 +1,74 @@
+// $Id$
+
+#include "ace/config-lite.h"
+#if defined (ACE_HAS_THREADS)
+
+#include "ace/Synch.h"
+#include "ace/Guard_T.h"
+
+class LogMessage
+{
+public:
+  enum { CRITICAL, NORMAL};
+
+  virtual ~LogMessage ()
+  {
+  }
+
+  virtual int priority (void)
+  {
+    return NORMAL;
+  }
+};
+
+class CriticalLogMessage : public LogMessage
+{
+  virtual int priority (void)
+  {
+    return LogMessage::CRITICAL;
+  }
+};
+
+// Listing 1 code/ch14
+typedef ACE_Thread_Mutex MUTEX;
+class Logger
+{
+public:
+  void log (LogMessage *msg)
+  {
+    ACE_GUARD (MUTEX, mon, mutex_);
+    if (msg->priority () == LogMessage::CRITICAL)
+      logCritical (msg);
+  }
+
+  void logCritical (LogMessage *)
+  {
+    // Acquires the same mutex as log()!
+    ACE_GUARD(MUTEX, mon, mutex_);
+  }
+
+private:
+  MUTEX mutex_;
+};
+
+static Logger logger;
+
+int ACE_TMAIN (int, ACE_TCHAR *[])
+{
+  CriticalLogMessage cm;
+  logger.log(&cm);  // Will cause deadlock.
+  return 0;
+}
+// Listing 1
+
+#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 */