Adding experimental (and optional) support of log4cxx logging.
Also, adding a sample logging configuration
diff --git a/model/sync-log.h b/model/sync-log.h
new file mode 100644
index 0000000..a2fcd70
--- /dev/null
+++ b/model/sync-log.h
@@ -0,0 +1,71 @@
+/* -*- Mode: C++; c-file-style: "gnu"; indent-tabs-mode:nil -*- */
+/*
+ * Copyright (c) 2012 University of California, Los Angeles
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2 as
+ * published by the Free Software Foundation;
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ * Author: Zhenkai Zhu <zhenkai@cs.ucla.edu>
+ * 卞超轶 Chaoyi Bian <bcy@pku.edu.cn>
+ * Alexander Afanasyev <alexander.afanasyev@ucla.edu>
+ */
+
+#ifndef SYNC_LOG_H
+#define SYNC_LOG_H
+
+#ifdef HAVE_LOG4CXX
+
+#include <log4cxx/logger.h>
+
+#define INIT_LOGGER(name) \
+ static log4cxx::LoggerPtr staticModuleLogger = log4cxx::Logger::getLogger (name);
+
+#define _LOG_DEBUG(x) \
+ LOG4CXX_DEBUG(staticModuleLogger, x);
+
+#define _LOG_TRACE(x) \
+ LOG4CXX_TRACE(staticModuleLogger, x);
+
+#define _LOG_FUNCTION(x) \
+ LOG4CXX_TRACE(staticModuleLogger, __FUNCTION__ << "(" << x << ")");
+
+#define _LOG_FUNCTION_NOARGS \
+ LOG4CXX_TRACE(staticModuleLogger, __FUNCTION__ << "()");
+
+void
+INIT_LOGGERS ();
+
+#else
+
+#define INIT_LOGGER(name)
+#define _LOG_FUNCTION(x)
+#define _LOG_FUNCTION_NOARGS
+#define _LOG_TRACE(x)
+#define INIT_LOGGERS(x)
+
+#ifdef _DEBUG
+
+#include <boost/thread/thread.hpp>
+#include <boost/date_time/posix_time/posix_time.hpp>
+#include <iostream>
+
+#define _LOG_DEBUG(x) \
+ std::clog << boost::get_system_time () << " " << boost::this_thread::get_id () << " " << x << endl;
+
+#else
+#define _LOG_DEBUG(x)
+#endif
+
+#endif // HAVE_LOG4CXX
+
+#endif // SYNC_LOG_H