/*

 * Copyright (c) 2018, 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 "gc/shared/gcConfig.hpp"

#include "runtime/java.hpp"

#include "runtime/os.hpp"

#include "utilities/macros.hpp"

#include "gc/cms/cmsArguments.hpp"

#include "gc/g1/g1Arguments.hpp"

struct SupportedGC {

  bool&               _flag;

  CollectedHeap::Name _name;

  GCArguments&        _arguments;

  const char*         _hs_err_name;

  SupportedGC(bool& flag, CollectedHeap::Name name, GCArguments& arguments, const char* hs_err_name) :

      _flag(flag), _name(name), _arguments(arguments), _hs_err_name(hs_err_name) {}

};

// Table of supported GCs, for translating between command

// line flag, CollectedHeap::Name and GCArguments instance.

static const SupportedGC SupportedGCs[] = {

};

#define FOR_EACH_SUPPORTED_GC(var) \

  for (const SupportedGC* var = &SupportedGCs[0]; var < &SupportedGCs[ARRAY_SIZE(SupportedGCs)]; var++)

GCArguments* GCConfig::_arguments = NULL;

bool GCConfig::_gc_selected_ergonomically = false;

void GCConfig::select_gc_ergonomically() {

  if (os::is_server_class_machine()) {

    FLAG_SET_ERGO_IF_DEFAULT(bool, UseG1GC, true);

  } else {

    FLAG_SET_ERGO_IF_DEFAULT(bool, UseSerialGC, true);

  }

}

bool GCConfig::is_no_gc_selected() {

  FOR_EACH_SUPPORTED_GC(gc) {

    if (gc->_flag) {

      return false;

    }

  }

  return true;

}

bool GCConfig::is_exactly_one_gc_selected() {

  CollectedHeap::Name selected = CollectedHeap::None;

  FOR_EACH_SUPPORTED_GC(gc) {

    if (gc->_flag) {

      if (gc->_name == selected || selected == CollectedHeap::None) {

        // Selected

        selected = gc->_name;

      } else {

        // More than one selected

        return false;

      }

    }

  }

  return selected != CollectedHeap::None;

}

GCArguments* GCConfig::select_gc() {

  if (is_no_gc_selected()) {

    // Try select GC ergonomically

    select_gc_ergonomically();

    if (is_no_gc_selected()) {

      // Failed to select GC ergonomically

      vm_exit_during_initialization("Garbage collector not selected "

                                    "(default collector explicitly disabled)", NULL);

    }

    // Succeeded to select GC ergonomically

    _gc_selected_ergonomically = true;

  }

    }

  }

  return NULL;

}

void GCConfig::initialize() {

  assert(_arguments == NULL, "Already initialized");

  _arguments = select_gc();

}

bool GCConfig::is_gc_supported(CollectedHeap::Name name) {

  FOR_EACH_SUPPORTED_GC(gc) {

    if (gc->_name == name) {

      // Supported

      return true;

    }

  }

  // Not supported

  return false;

}

bool GCConfig::is_gc_selected(CollectedHeap::Name name) {

  FOR_EACH_SUPPORTED_GC(gc) {

    if (gc->_name == name && gc->_flag) {

      // Selected

      return true;

    }

  }

  // Not selected

  return false;

}

bool GCConfig::is_gc_selected_ergonomically() {

  return _gc_selected_ergonomically;

}

const char* GCConfig::hs_err_name() {

  if (is_exactly_one_gc_selected()) {

    // Exacly one GC selected

    FOR_EACH_SUPPORTED_GC(gc) {

      if (gc->_flag) {

        return gc->_hs_err_name;

      }

    }

  }

  // Zero or more than one GC selected

  return "unknown gc";

}

GCArguments* GCConfig::arguments() {

  assert(_arguments != NULL, "Not initialized");

  return _arguments;

}