1 /*
 2  * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
 3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 4  *
 5  * This code is free software; you can redistribute it and/or modify it
 6  * under the terms of the GNU General Public License version 2 only, as
 7  * published by the Free Software Foundation.
 8  *
 9  * This code is distributed in the hope that it will be useful, but WITHOUT
10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
12  * version 2 for more details (a copy is included in the LICENSE file that
13  * accompanied this code).
14  *
15  * You should have received a copy of the GNU General Public License version
16  * 2 along with this work; if not, write to the Free Software Foundation,
17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18  *
19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20  * or visit www.oracle.com if you need additional information or have any
21  * questions.
22  *
23  */
24 
25 #include "precompiled.hpp"
26 #include "jfr/recorder/checkpoint/types/traceid/jfrTraceIdEpoch.hpp"
27 #include "runtime/safepoint.hpp"
28 
29 JfrSignal JfrTraceIdEpoch::_tag_state;
30 bool JfrTraceIdEpoch::_epoch_state = false;
31 bool JfrTraceIdEpoch::_synchronizing = false;
32 
33 void JfrTraceIdEpoch::begin_epoch_shift() {
34   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
35   _synchronizing = true;
36   OrderAccess::fence();
37 }
38 
39 void JfrTraceIdEpoch::end_epoch_shift() {
40   assert(SafepointSynchronize::is_at_safepoint(), "invariant");
41   assert(_synchronizing, "invariant");
42   _epoch_state = !_epoch_state;
43   OrderAccess::storestore();
44   _synchronizing = false;
45 }
46