--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/heapRegionManager.hpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,287 @@
+/*
+ * Copyright (c) 2001, 2017, 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.
+ *
+ */
+
+#ifndef SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP
+#define SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP
+
+#include "gc/g1/g1BiasedArray.hpp"
+#include "gc/g1/g1RegionToSpaceMapper.hpp"
+#include "gc/g1/heapRegionSet.hpp"
+#include "services/memoryUsage.hpp"
+
+class HeapRegion;
+class HeapRegionClosure;
+class HeapRegionClaimer;
+class FreeRegionList;
+class WorkGang;
+
+class G1HeapRegionTable : public G1BiasedMappedArray<HeapRegion*> {
+ protected:
+  virtual HeapRegion* default_value() const { return NULL; }
+};
+
+// This class keeps track of the actual heap memory, auxiliary data
+// and its metadata (i.e., HeapRegion instances) and the list of free regions.
+//
+// This allows maximum flexibility for deciding what to commit or uncommit given
+// a request from outside.
+//
+// HeapRegions are kept in the _regions array in address order. A region's
+// index in the array corresponds to its index in the heap (i.e., 0 is the
+// region at the bottom of the heap, 1 is the one after it, etc.). Two
+// regions that are consecutive in the array should also be adjacent in the
+// address space (i.e., region(i).end() == region(i+1).bottom().
+//
+// We create a HeapRegion when we commit the region's address space
+// for the first time. When we uncommit the address space of a
+// region we retain the HeapRegion to be able to re-use it in the
+// future (in case we recommit it).
+//
+// We keep track of three lengths:
+//
+// * _num_committed (returned by length()) is the number of currently
+//   committed regions. These may not be contiguous.
+// * _allocated_heapregions_length (not exposed outside this class) is the
+//   number of regions+1 for which we have HeapRegions.
+// * max_length() returns the maximum number of regions the heap can have.
+//
+
+class HeapRegionManager: public CHeapObj<mtGC> {
+  friend class VMStructs;
+  friend class HeapRegionClaimer;
+
+  G1HeapRegionTable _regions;
+
+  G1RegionToSpaceMapper* _heap_mapper;
+  G1RegionToSpaceMapper* _prev_bitmap_mapper;
+  G1RegionToSpaceMapper* _next_bitmap_mapper;
+  G1RegionToSpaceMapper* _bot_mapper;
+  G1RegionToSpaceMapper* _cardtable_mapper;
+  G1RegionToSpaceMapper* _card_counts_mapper;
+
+  FreeRegionList _free_list;
+
+  // Each bit in this bitmap indicates that the corresponding region is available
+  // for allocation.
+  CHeapBitMap _available_map;
+
+   // The number of regions committed in the heap.
+  uint _num_committed;
+
+  // Internal only. The highest heap region +1 we allocated a HeapRegion instance for.
+  uint _allocated_heapregions_length;
+
+  HeapWord* heap_bottom() const { return _regions.bottom_address_mapped(); }
+  HeapWord* heap_end() const {return _regions.end_address_mapped(); }
+
+  void make_regions_available(uint index, uint num_regions = 1, WorkGang* pretouch_gang = NULL);
+
+  // Pass down commit calls to the VirtualSpace.
+  void commit_regions(uint index, size_t num_regions = 1, WorkGang* pretouch_gang = NULL);
+  void uncommit_regions(uint index, size_t num_regions = 1);
+
+  // Notify other data structures about change in the heap layout.
+  void update_committed_space(HeapWord* old_end, HeapWord* new_end);
+
+  // Find a contiguous set of empty or uncommitted regions of length num and return
+  // the index of the first region or G1_NO_HRM_INDEX if the search was unsuccessful.
+  // If only_empty is true, only empty regions are considered.
+  // Searches from bottom to top of the heap, doing a first-fit.
+  uint find_contiguous(size_t num, bool only_empty);
+  // Finds the next sequence of unavailable regions starting from start_idx. Returns the
+  // length of the sequence found. If this result is zero, no such sequence could be found,
+  // otherwise res_idx indicates the start index of these regions.
+  uint find_unavailable_from_idx(uint start_idx, uint* res_idx) const;
+  // Finds the next sequence of empty regions starting from start_idx, going backwards in
+  // the heap. Returns the length of the sequence found. If this value is zero, no
+  // sequence could be found, otherwise res_idx contains the start index of this range.
+  uint find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const;
+  // Allocate a new HeapRegion for the given index.
+  HeapRegion* new_heap_region(uint hrm_index);
+#ifdef ASSERT
+public:
+  bool is_free(HeapRegion* hr) const;
+#endif
+  // Returns whether the given region is available for allocation.
+  bool is_available(uint region) const;
+
+ public:
+  // Empty constructor, we'll initialize it with the initialize() method.
+  HeapRegionManager() : _regions(), _heap_mapper(NULL), _num_committed(0),
+                    _next_bitmap_mapper(NULL), _prev_bitmap_mapper(NULL), _bot_mapper(NULL),
+                    _allocated_heapregions_length(0), _available_map(mtGC),
+                    _free_list("Free list", new MasterFreeRegionListMtSafeChecker())
+  { }
+
+  void initialize(G1RegionToSpaceMapper* heap_storage,
+                  G1RegionToSpaceMapper* prev_bitmap,
+                  G1RegionToSpaceMapper* next_bitmap,
+                  G1RegionToSpaceMapper* bot,
+                  G1RegionToSpaceMapper* cardtable,
+                  G1RegionToSpaceMapper* card_counts);
+
+  // Return the "dummy" region used for G1AllocRegion. This is currently a hardwired
+  // new HeapRegion that owns HeapRegion at index 0. Since at the moment we commit
+  // the heap from the lowest address, this region (and its associated data
+  // structures) are available and we do not need to check further.
+  HeapRegion* get_dummy_region() { return new_heap_region(0); }
+
+  // Return the HeapRegion at the given index. Assume that the index
+  // is valid.
+  inline HeapRegion* at(uint index) const;
+
+  // Return the next region (by index) that is part of the same
+  // humongous object that hr is part of.
+  inline HeapRegion* next_region_in_humongous(HeapRegion* hr) const;
+
+  // If addr is within the committed space return its corresponding
+  // HeapRegion, otherwise return NULL.
+  inline HeapRegion* addr_to_region(HeapWord* addr) const;
+
+  // Insert the given region into the free region list.
+  inline void insert_into_free_list(HeapRegion* hr);
+
+  // Insert the given region list into the global free region list.
+  void insert_list_into_free_list(FreeRegionList* list) {
+    _free_list.add_ordered(list);
+  }
+
+  HeapRegion* allocate_free_region(bool is_old) {
+    HeapRegion* hr = _free_list.remove_region(is_old);
+
+    if (hr != NULL) {
+      assert(hr->next() == NULL, "Single region should not have next");
+      assert(is_available(hr->hrm_index()), "Must be committed");
+    }
+    return hr;
+  }
+
+  inline void allocate_free_regions_starting_at(uint first, uint num_regions);
+
+  // Remove all regions from the free list.
+  void remove_all_free_regions() {
+    _free_list.remove_all();
+  }
+
+  // Return the number of committed free regions in the heap.
+  uint num_free_regions() const {
+    return _free_list.length();
+  }
+
+  size_t total_capacity_bytes() const {
+    return num_free_regions() * HeapRegion::GrainBytes;
+  }
+
+  // Return the number of available (uncommitted) regions.
+  uint available() const { return max_length() - length(); }
+
+  // Return the number of regions that have been committed in the heap.
+  uint length() const { return _num_committed; }
+
+  // Return the maximum number of regions in the heap.
+  uint max_length() const { return (uint)_regions.length(); }
+
+  MemoryUsage get_auxiliary_data_memory_usage() const;
+
+  MemRegion reserved() const { return MemRegion(heap_bottom(), heap_end()); }
+
+  // Expand the sequence to reflect that the heap has grown. Either create new
+  // HeapRegions, or re-use existing ones. Returns the number of regions the
+  // sequence was expanded by. If a HeapRegion allocation fails, the resulting
+  // number of regions might be smaller than what's desired.
+  uint expand_by(uint num_regions, WorkGang* pretouch_workers);
+
+  // Makes sure that the regions from start to start+num_regions-1 are available
+  // for allocation. Returns the number of regions that were committed to achieve
+  // this.
+  uint expand_at(uint start, uint num_regions, WorkGang* pretouch_workers);
+
+  // Find a contiguous set of empty regions of length num. Returns the start index of
+  // that set, or G1_NO_HRM_INDEX.
+  uint find_contiguous_only_empty(size_t num) { return find_contiguous(num, true); }
+  // Find a contiguous set of empty or unavailable regions of length num. Returns the
+  // start index of that set, or G1_NO_HRM_INDEX.
+  uint find_contiguous_empty_or_unavailable(size_t num) { return find_contiguous(num, false); }
+
+  HeapRegion* next_region_in_heap(const HeapRegion* r) const;
+
+  // Find the highest free or uncommitted region in the reserved heap,
+  // and if uncommitted, commit it. If none are available, return G1_NO_HRM_INDEX.
+  // Set the 'expanded' boolean true if a new region was committed.
+  uint find_highest_free(bool* expanded);
+
+  // Allocate the regions that contain the address range specified, committing the
+  // regions if necessary. Return false if any of the regions is already committed
+  // and not free, and return the number of regions newly committed in commit_count.
+  bool allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers);
+
+  // Apply blk->doHeapRegion() on all committed regions in address order,
+  // terminating the iteration early if doHeapRegion() returns true.
+  void iterate(HeapRegionClosure* blk) const;
+
+  void par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer) const;
+
+  // Uncommit up to num_regions_to_remove regions that are completely free.
+  // Return the actual number of uncommitted regions.
+  uint shrink_by(uint num_regions_to_remove);
+
+  // Uncommit a number of regions starting at the specified index, which must be available,
+  // empty, and free.
+  void shrink_at(uint index, size_t num_regions);
+
+  void verify();
+
+  // Do some sanity checking.
+  void verify_optional() PRODUCT_RETURN;
+};
+
+// The HeapRegionClaimer is used during parallel iteration over heap regions,
+// allowing workers to claim heap regions, gaining exclusive rights to these regions.
+class HeapRegionClaimer : public StackObj {
+  uint           _n_workers;
+  uint           _n_regions;
+  volatile uint* _claims;
+
+  static const uint Unclaimed = 0;
+  static const uint Claimed   = 1;
+
+ public:
+  HeapRegionClaimer(uint n_workers);
+  ~HeapRegionClaimer();
+
+  inline uint n_regions() const {
+    return _n_regions;
+  }
+
+  // Calculate the starting region for given worker so
+  // that they do not all start from the same region.
+  uint start_region_for_worker(uint worker_id) const;
+
+  // Check if region has been claimed with this HRClaimer.
+  bool is_region_claimed(uint region_index) const;
+
+  // Claim the given region, returns true if successfully claimed.
+  bool claim_region(uint region_index);
+};
+#endif // SHARE_VM_GC_G1_HEAPREGIONMANAGER_HPP