1/*
2 * Copyright (c) 2015, 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 "runtime/threadLocalStorage.hpp"
26#include <pthread.h>
27
28static pthread_key_t _thread_key;
29static bool _initialized = false;
30
31// Restore the thread pointer if the destructor is called. This is in case
32// someone from JNI code sets up a destructor with pthread_key_create to run
33// detachCurrentThread on thread death. Unless we restore the thread pointer we
34// will hang or crash. When detachCurrentThread is called the key will be set
35// to null and we will not be called again. If detachCurrentThread is never
36// called we could loop forever depending on the pthread implementation.
37extern "C" void restore_thread_pointer(void* p) {
38 ThreadLocalStorage::set_thread((Thread*) p);
39}
40
41void ThreadLocalStorage::init() {
42 assert(!_initialized, "initializing TLS more than once!");
43 int rslt = pthread_key_create(&_thread_key, restore_thread_pointer);
44 // If this assert fails we will get a recursive assertion failure
45 // and not see the actual error message or get a hs_err file
46 assert_status(rslt == 0, rslt, "pthread_key_create");
47 _initialized = true;
48}
49
50bool ThreadLocalStorage::is_initialized() {
51 return _initialized;
52}
53
54Thread* ThreadLocalStorage::thread() {
55 // If this assert fails we will get a recursive assertion failure
56 // and not see the actual error message or get a hs_err file.
57 // Which most likely indicates we have taken an error path early in
58 // the initialization process, which is using Thread::current without
59 // checking TLS is initialized - see java.cpp vm_exit
60 assert(_initialized, "TLS not initialized yet!");
61 return (Thread*) pthread_getspecific(_thread_key); // may be NULL
62}
63
64void ThreadLocalStorage::set_thread(Thread* current) {
65 assert(_initialized, "TLS not initialized yet!");
66 int rslt = pthread_setspecific(_thread_key, current);
67 assert_status(rslt == 0, rslt, "pthread_setspecific");
68}
69