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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

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 * 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).

 *

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 * 2 along with this work; if not, write to the Free Software Foundation,

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#ifndef SHARE_VM_GC_G1_G1COLLECTIONSET_HPP

#define SHARE_VM_GC_G1_G1COLLECTIONSET_HPP

#include "gc/g1/collectionSetChooser.hpp"

#include "utilities/debug.hpp"

#include "utilities/globalDefinitions.hpp"

class G1CollectedHeap;

class G1CollectorState;

class G1GCPhaseTimes;

class G1Policy;

class G1SurvivorRegions;

class HeapRegion;

class G1CollectionSet {

  G1CollectedHeap* _g1h;

  G1Policy* _policy;

  CollectionSetChooser* _cset_chooser;

  uint _eden_region_length;

  uint _survivor_region_length;

  uint _old_region_length;

  // The actual collection set as a set of region indices.

  // All entries in _collection_set_regions below _collection_set_cur_length are

  // assumed to be valid entries.

  // We assume that at any time there is at most only one writer and (one or more)

  // concurrent readers. This means we are good with using storestore and loadload

  // barriers on the writer and reader respectively only.

  uint* _collection_set_regions;

  volatile size_t _collection_set_cur_length;

  size_t _collection_set_max_length;

  // The number of bytes in the collection set before the pause. Set from

  // the incrementally built collection set at the start of an evacuation

  // pause, and incremented in finalize_old_part() when adding old regions

  // (if any) to the collection set.

  size_t _bytes_used_before;

  size_t _recorded_rs_lengths;

  // The associated information that is maintained while the incremental

  // collection set is being built with young regions. Used to populate

  // the recorded info for the evacuation pause.

  enum CSetBuildType {

    Active,             // We are actively building the collection set

    Inactive            // We are not actively building the collection set

  };

  CSetBuildType _inc_build_state;

  // The number of bytes in the incrementally built collection set.

  // Used to set _collection_set_bytes_used_before at the start of

  // an evacuation pause.

  size_t _inc_bytes_used_before;

  // The RSet lengths recorded for regions in the CSet. It is updated

  // by the thread that adds a new region to the CSet. We assume that

  // only one thread can be allocating a new CSet region (currently,

  // it does so after taking the Heap_lock) hence no need to

  // synchronize updates to this field.

  size_t _inc_recorded_rs_lengths;

  // A concurrent refinement thread periodically samples the young

  // region RSets and needs to update _inc_recorded_rs_lengths as

  // the RSets grow. Instead of having to synchronize updates to that

  // field we accumulate them in this field and add it to

  // _inc_recorded_rs_lengths_diffs at the start of a GC.

  ssize_t _inc_recorded_rs_lengths_diffs;

  // The predicted elapsed time it will take to collect the regions in

  // the CSet. This is updated by the thread that adds a new region to

  // the CSet. See the comment for _inc_recorded_rs_lengths about

  // MT-safety assumptions.

  double _inc_predicted_elapsed_time_ms;

  // See the comment for _inc_recorded_rs_lengths_diffs.

  double _inc_predicted_elapsed_time_ms_diffs;

  G1CollectorState* collector_state();

  G1GCPhaseTimes* phase_times();

  double predict_region_elapsed_time_ms(HeapRegion* hr);

  void verify_young_cset_indices() const NOT_DEBUG_RETURN;

public:

  G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy);

  ~G1CollectionSet();

  // Initializes the collection set giving the maximum possible length of the collection set.

  void initialize(uint max_region_length);

  CollectionSetChooser* cset_chooser();

  void init_region_lengths(uint eden_cset_region_length,

                           uint survivor_cset_region_length);

  void set_recorded_rs_lengths(size_t rs_lengths);

  uint region_length() const       { return young_region_length() +

                                            old_region_length(); }

  uint young_region_length() const { return eden_region_length() +

                                            survivor_region_length(); }

  uint eden_region_length() const     { return _eden_region_length;     }

  uint survivor_region_length() const { return _survivor_region_length; }

  uint old_region_length() const      { return _old_region_length;      }

  // Incremental collection set support

  // Initialize incremental collection set info.

  void start_incremental_building();

  // Perform any final calculations on the incremental collection set fields

  // before we can use them.

  void finalize_incremental_building();

  // Reset the contents of the collection set.

  void clear();

  // Iterate over the collection set, applying the given HeapRegionClosure on all of them.

  // If may_be_aborted is true, iteration may be aborted using the return value of the

  // called closure method.

  void iterate(HeapRegionClosure* cl) const;

  // Iterate over the collection set, applying the given HeapRegionClosure on all of them,

  // trying to optimally spread out starting position of total_workers workers given the

  // caller's worker_id.

  void iterate_from(HeapRegionClosure* cl, uint worker_id, uint total_workers) const;

  // Stop adding regions to the incremental collection set.

  void stop_incremental_building() { _inc_build_state = Inactive; }

  size_t recorded_rs_lengths() { return _recorded_rs_lengths; }

  size_t bytes_used_before() const {

    return _bytes_used_before;

  }

  void reset_bytes_used_before() {

    _bytes_used_before = 0;

  }

  // Choose a new collection set.  Marks the chosen regions as being

  // "in_collection_set".

  double finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors);

  void finalize_old_part(double time_remaining_ms);

  // Add old region "hr" to the collection set.

  void add_old_region(HeapRegion* hr);

  // Update information about hr in the aggregated information for

  // the incrementally built collection set.

  void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length);

  // Add eden region to the collection set.

  void add_eden_region(HeapRegion* hr);

  // Add survivor region to the collection set.

  void add_survivor_regions(HeapRegion* hr);

#ifndef PRODUCT

  bool verify_young_ages();

  void print(outputStream* st);

#endif // !PRODUCT

private:

  // Update the incremental collection set information when adding a region.

  void add_young_region_common(HeapRegion* hr);

};

#endif // SHARE_VM_GC_G1_G1COLLECTIONSET_HPP