/*
 * 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 "precompiled.hpp"
#include "classfile/backtrace.hpp"
#include "classfile/javaClasses.hpp"
#include "runtime/atomic.hpp"
#include "runtime/jniHandles.hpp"

void Backtrace::oops_do(OopClosure* f) {
  f->do_oop(&_throwable);
}

// List of backtraces to mark Method pointers for RedefineClasses.
Backtrace* BacktraceList::_backtraces_head = NULL;
volatile int BacktraceList::_bt_count = 0;

void BacktraceList::add(oop throwable) {
  Backtrace* bt = new Backtrace(throwable);
  Backtrace* next = _backtraces_head;
  do {
    bt->set_next(next);
    Backtrace* exchanged = (Backtrace*)Atomic::cmpxchg_ptr(bt, &_backtraces_head, next);
    if (exchanged == next) {
      // added the backtrace to the list.
      Atomic::inc(&_bt_count);
      return;
    }
    next = exchanged;
  } while (true);
}

void BacktraceList::oops_do(OopClosure* f) {
  Backtrace* bt = _backtraces_head;
  while (bt != NULL) {
    bt->oops_do(f);
    bt = bt->next();
  }
} 

void BacktraceList::mark_on_stack() {
  Backtrace* bt = _backtraces_head;
  while (bt != NULL) {
    assert(bt->throwable() != NULL, "shouldn't have null throwable");
    java_lang_Throwable::mark_on_stack(bt->throwable());
    bt = bt->next();
  }
}

void BacktraceList::unlink(BoolObjectClosure* is_alive) {
  assert(SafepointSynchronize::is_at_safepoint(), "only called at safepoint");
  Backtrace* bt = _backtraces_head;
  Backtrace* prev = NULL;
  while (bt != NULL) {
    if (!is_alive->do_object_b(bt->throwable())) {
      // delete this backtrace object
      Backtrace* next = bt->next();
      // Delete bt object
      delete bt;
      // Remove from throwable list.
      bt = next;
      if (prev != NULL) {
        prev->set_next(bt);
      } else {
        _backtraces_head = bt;
      }
      Atomic::dec(&_bt_count);
    } else {
      prev = bt;
      bt = bt->next();
    }
  }
}