Adding experimental (and optional) support of log4cxx logging.
Also, adding a sample logging configuration
diff --git a/model/sync-log.cc b/model/sync-log.cc
new file mode 100644
index 0000000..0ddd95c
--- /dev/null
+++ b/model/sync-log.cc
@@ -0,0 +1,61 @@
+/* -*- 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>
+ */
+
+#include "sync-log.h"
+
+#ifdef HAVE_LOG4CXX
+
+#include <log4cxx/logger.h>
+#include <log4cxx/basicconfigurator.h>
+#include <log4cxx/consoleappender.h>
+#include <log4cxx/patternlayout.h>
+#include <log4cxx/level.h>
+#include <log4cxx/propertyconfigurator.h>
+#include <log4cxx/defaultconfigurator.h>
+#include <log4cxx/helpers/exception.h>
+using namespace log4cxx;
+using namespace log4cxx::helpers;
+
+#include <unistd.h>
+
+void
+INIT_LOGGERS ()
+{
+ static bool configured = false;
+
+ if (configured) return;
+
+ if (access ("log4cxx.properties", R_OK)==0)
+ PropertyConfigurator::configureAndWatch ("log4cxx.properties");
+ else
+ {
+ PatternLayoutPtr layout (new PatternLayout ("%d{HH:mm:ss} %p %c{1} - %m%n"));
+ ConsoleAppenderPtr appender (new ConsoleAppender (layout));
+
+ BasicConfigurator::configure( appender );
+ Logger::getRootLogger()->setLevel (log4cxx::Level::getInfo ());
+ }
+
+ configured = true;
+}
+
+#endif