/*

 * 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

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 */

#ifndef SHARE_VM_UTILITIES_NATIVE_CALL_STACK_HPP

#define SHARE_VM_UTILITIES_NATIVE_CALL_STACK_HPP

#include "memory/allocation.hpp"

#include "services/nmtCommon.hpp"

#include "utilities/ostream.hpp"

/*

 * This class represents a native call path (does not include Java frame)

 *

 * This class is developed in the context of native memory tracking, it can

 * be an useful tool for debugging purpose.

 *

 * For example, following code should print out native call path:

 *

 *   ....

 *   NativeCallStack here;

 *   here.print_on(tty);

 *   ....

 *

 * However, there are a couple of restrictions on this class. If the restrictions are

 * not strictly followed, it may break native memory tracking badly.

 *

 * 1. Number of stack frames to capture, is defined by native memory tracking.

 *    This number has impacts on how much memory to be used by native

 *    memory tracking.

 * 2. The class is strict stack object, no heap or virtual memory can be allocated

 *    from it.

 */

class NativeCallStack : public StackObj {

  address       _stack[NMT_TrackingStackDepth];

  unsigned int  _hash_value;

  NativeCallStack(int toSkip = 0, bool fillStack = false);

  NativeCallStack(address* pc, int frameCount);

  // if it is an empty stack

  inline bool is_empty() const {

    return _stack[0] == NULL;

  }

  // number of stack frames captured

  int frames() const;

  inline int compare(const NativeCallStack& other) const {

    return memcmp(_stack, other._stack, sizeof(_stack));

  }

  inline bool equals(const NativeCallStack& other) const {

    // compare hash values

    if (hash() != other.hash()) return false;

    // compare each frame

    return compare(other) == 0;

  }

  inline address get_frame(int index) const {

    assert(index >= 0 && index < NMT_TrackingStackDepth, "Index out of bound");

    return _stack[index];

  }

  // Hash code. Any better algorithm?

  unsigned int hash() const;

  void print_on(outputStream* out) const;

  void print_on(outputStream* out, int indent) const;

};

#endif