/*
 * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates.
 * 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/gc.hpp"
#include "gc/shared/gcFactory.hpp"
#include "gc/serial/serialGC.hpp"
#include "runtime/globals.hpp"
#include "runtime/globals_extension.hpp"
#include "runtime/java.hpp"
#include "runtime/os.hpp"
#include "utilities/macros.hpp"

#if INCLUDE_ALL_GCS
#include "gc/parallel/parallelGC.hpp"
#include "gc/cms/cmsGC.hpp"
#include "gc/g1/g1GC.hpp"
#endif

GC* GCFactory::_gc = NULL;

GC* GCFactory::gc() {
  assert(_gc != NULL, "GC not yet created");
  return _gc;
}

bool GCFactory::is_initialized() {
  return _gc != NULL;
}

bool GCFactory::gc_selected() {
#if INCLUDE_ALL_GCS
  return UseSerialGC || UseParallelGC || UseParallelOldGC || UseConcMarkSweepGC || UseG1GC;
#else
  return UseSerialGC;
#endif // INCLUDE_ALL_GCS
}

void GCFactory::select_gc() {
  if (!gc_selected()) {
    select_gc_ergonomically();
    if (!gc_selected()) {
      vm_exit_during_initialization("Garbage collector not selected (default collector explicitly disabled)", NULL);
    }
  }
}

void GCFactory::select_gc_ergonomically() {
#if INCLUDE_ALL_GCS
  if (os::is_server_class_machine()) {
    FLAG_SET_ERGO_IF_DEFAULT(bool, UseG1GC, true);
  } else {
    FLAG_SET_ERGO_IF_DEFAULT(bool, UseSerialGC, true);
  }
#else
  UNSUPPORTED_OPTION(UseG1GC);
  UNSUPPORTED_OPTION(UseParallelGC);
  UNSUPPORTED_OPTION(UseParallelOldGC);
  UNSUPPORTED_OPTION(UseConcMarkSweepGC);
  FLAG_SET_ERGO_IF_DEFAULT(bool, UseSerialGC, true);
#endif // INCLUDE_ALL_GCS
}

void GCFactory::initialize_flags_global() {
#if INCLUDE_ALL_GCS
  if (AssumeMP && !UseSerialGC) {
    if (FLAG_IS_DEFAULT(ParallelGCThreads) && ParallelGCThreads == 1) {
      warning("If the number of processors is expected to increase from one, then"
              " you should configure the number of parallel GC threads appropriately"
              " using -XX:ParallelGCThreads=N");
    }
  }
  if (MinHeapFreeRatio == 100) {
    // Keeping the heap 100% free is hard ;-) so limit it to 99%.
    FLAG_SET_ERGO(uintx, MinHeapFreeRatio, 99);
  }

  // If class unloading is disabled, also disable concurrent class unloading.
  if (!ClassUnloading) {
    FLAG_SET_CMDLINE(bool, CMSClassUnloadingEnabled, false);
    FLAG_SET_CMDLINE(bool, ClassUnloadingWithConcurrentMark, false);
  }
#endif // INCLUDE_ALL_GCS
}

jint GCFactory::initialize() {
  assert(_gc == NULL, "GC already created");

  select_gc();

#if !INCLUDE_ALL_GCS
  if (UseParallelGC || UseParallelOldGC) {
    fatal("UseParallelGC not supported in this VM.");
  } else if (UseG1GC) {
    fatal("UseG1GC not supported in this VM.");
  } else if (UseConcMarkSweepGC) {
    fatal("UseConcMarkSweepGC not supported in this VM.");
#else
  if (UseParallelGC || UseParallelOldGC) {
    _gc = new ParallelGC();
  } else if (UseG1GC) {
    _gc = new G1GC();
  } else if (UseConcMarkSweepGC) {
    _gc = new CMSGC();
#endif
  } else if (UseSerialGC) {
    _gc = new SerialGC();
  } else {
    ShouldNotReachHere();
  }
  return JNI_OK;
}