/*

 * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.

 *

 * 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/shenandoah/heuristics/shenandoahTraversalAggressiveHeuristics.hpp"

#include "gc/shenandoah/shenandoahCollectionSet.hpp"

#include "gc/shenandoah/shenandoahFreeSet.hpp"

#include "gc/shenandoah/shenandoahHeap.inline.hpp"

#include "gc/shenandoah/shenandoahHeuristics.hpp"

#include "gc/shenandoah/shenandoahTraversalGC.hpp"

#include "logging/log.hpp"

#include "logging/logTag.hpp"

#include "utilities/quickSort.hpp"

ShenandoahTraversalAggressiveHeuristics::ShenandoahTraversalAggressiveHeuristics() : ShenandoahHeuristics(),

  _last_cset_select(0) {

  // Do not shortcut evacuation

  SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100);

  // Aggressive runs with max speed for allocation, to capture races against mutator

  SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahPacing);

  // Aggressive evacuates everything, so it needs as much evac space as it can get

  SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahEvacReserveOverflow);

  // If class unloading is globally enabled, aggressive does unloading even with

  // concurrent cycles.

  if (ClassUnloading) {

    SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUnloadClassesFrequency, 1);

  }

}

bool ShenandoahTraversalAggressiveHeuristics::is_experimental() {

  return true;

}

bool ShenandoahTraversalAggressiveHeuristics::is_diagnostic() {

  return true;

}

const char* ShenandoahTraversalAggressiveHeuristics::name() {

  return "traversal-aggressive";

}

void ShenandoahTraversalAggressiveHeuristics::choose_collection_set(ShenandoahCollectionSet* collection_set) {

  ShenandoahHeap* heap = ShenandoahHeap::heap();

  ShenandoahTraversalGC* traversal_gc = heap->traversal_gc();

  ShenandoahHeapRegionSet* traversal_set = traversal_gc->traversal_set();

  traversal_set->clear();

  RegionData *data = get_region_data_cache(heap->num_regions());

  size_t cnt = 0;

  // Step 0. Prepare all regions

  for (size_t i = 0; i < heap->num_regions(); i++) {

    ShenandoahHeapRegion* r = heap->get_region(i);

    if (r->used() > 0) {

      if (r->is_regular()) {

        data[cnt]._region = r;

        data[cnt]._garbage = r->garbage();

        data[cnt]._seqnum_last_alloc = r->seqnum_last_alloc_mutator();

        cnt++;

      }

      traversal_set->add_region(r);

    }

  }

  for (size_t i = 0; i < cnt; i++) {

    if (data[i]._seqnum_last_alloc > _last_cset_select) continue;

    ShenandoahHeapRegion* r = data[i]._region;

    assert (r->is_regular(), "should have been filtered before");

   if (r->garbage() > 0) {

      assert(!collection_set->is_in(r), "must not yet be in cset");

      collection_set->add_region(r);

    }

  }

  // Clear liveness data

  // TODO: Merge it with step 0, but save live data in RegionData before.

  for (size_t i = 0; i < heap->num_regions(); i++) {

    ShenandoahHeapRegion* r = heap->get_region(i);

    if (r->used() > 0) {

      r->clear_live_data();

    }

  }

  collection_set->update_region_status();

  _last_cset_select = ShenandoahHeapRegion::seqnum_current_alloc();

}

void ShenandoahTraversalAggressiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* set,

                                                                                    RegionData* data, size_t data_size,

                                                                                    size_t free) {

  ShouldNotReachHere();

}

bool ShenandoahTraversalAggressiveHeuristics::should_start_gc() const {

  log_info(gc)("Trigger: Start next cycle immediately");

  return true;

}