/*

 * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#include "runtime/threadLocalStorage.hpp"

#include <pthread.h>

static pthread_key_t _thread_key;

static bool _initialized = false;

// Restore the thread pointer if the destructor is called. This is in case

// someone from JNI code sets up a destructor with pthread_key_create to run

// detachCurrentThread on thread death. Unless we restore the thread pointer we

// will hang or crash. When detachCurrentThread is called the key will be set

// to null and we will not be called again. If detachCurrentThread is never

// called we could loop forever depending on the pthread implementation.

extern "C" void restore_thread_pointer(void* p) {

  ThreadLocalStorage::set_thread((Thread*) p);

}

void ThreadLocalStorage::init() {

  assert(!_initialized, "initializing TLS more than once!");

  int rslt = pthread_key_create(&_thread_key, restore_thread_pointer);

  // If this assert fails we will get a recursive assertion failure

  // and not see the actual error message or get a hs_err file

  assert_status(rslt == 0, rslt, "pthread_key_create");

  _initialized = true;

}

bool ThreadLocalStorage::is_initialized() {

  return _initialized;

}

Thread* ThreadLocalStorage::thread() {

  // If this assert fails we will get a recursive assertion failure

  // and not see the actual error message or get a hs_err file.

  // Which most likely indicates we have taken an error path early in

  // the initialization process, which is using Thread::current without

  // checking TLS is initialized - see java.cpp vm_exit

  assert(_initialized, "TLS not initialized yet!");

  return (Thread*) pthread_getspecific(_thread_key); // may be NULL

}

void ThreadLocalStorage::set_thread(Thread* current) {

  assert(_initialized, "TLS not initialized yet!");

  int rslt = pthread_setspecific(_thread_key, current);

  assert_status(rslt == 0, rslt, "pthread_setspecific");

}