--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/heapRegionManager.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,510 @@
+/*
+ * 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.
+ *
+ */
+
+#include "precompiled.hpp"
+#include "gc/g1/concurrentG1Refine.hpp"
+#include "gc/g1/g1CollectedHeap.inline.hpp"
+#include "gc/g1/heapRegion.hpp"
+#include "gc/g1/heapRegionManager.inline.hpp"
+#include "gc/g1/heapRegionSet.inline.hpp"
+#include "memory/allocation.hpp"
+
+void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,
+                               G1RegionToSpaceMapper* prev_bitmap,
+                               G1RegionToSpaceMapper* next_bitmap,
+                               G1RegionToSpaceMapper* bot,
+                               G1RegionToSpaceMapper* cardtable,
+                               G1RegionToSpaceMapper* card_counts) {
+  _allocated_heapregions_length = 0;
+
+  _heap_mapper = heap_storage;
+
+  _prev_bitmap_mapper = prev_bitmap;
+  _next_bitmap_mapper = next_bitmap;
+
+  _bot_mapper = bot;
+  _cardtable_mapper = cardtable;
+
+  _card_counts_mapper = card_counts;
+
+  MemRegion reserved = heap_storage->reserved();
+  _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
+
+  _available_map.initialize(_regions.length());
+}
+
+bool HeapRegionManager::is_available(uint region) const {
+  return _available_map.at(region);
+}
+
+#ifdef ASSERT
+bool HeapRegionManager::is_free(HeapRegion* hr) const {
+  return _free_list.contains(hr);
+}
+#endif
+
+HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
+  G1CollectedHeap* g1h = G1CollectedHeap::heap();
+  HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
+  MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
+  assert(reserved().contains(mr), "invariant");
+  return g1h->new_heap_region(hrm_index, mr);
+}
+
+void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) {
+  guarantee(num_regions > 0, "Must commit more than zero regions");
+  guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
+
+  _num_committed += (uint)num_regions;
+
+  _heap_mapper->commit_regions(index, num_regions, pretouch_gang);
+
+  // Also commit auxiliary data
+  _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
+  _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
+
+  _bot_mapper->commit_regions(index, num_regions, pretouch_gang);
+  _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang);
+
+  _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang);
+}
+
+void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
+  guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start);
+  guarantee(_num_committed >= num_regions, "pre-condition");
+
+  // Print before uncommitting.
+  if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
+    for (uint i = start; i < start + num_regions; i++) {
+      HeapRegion* hr = at(i);
+      G1CollectedHeap::heap()->hr_printer()->uncommit(hr);
+    }
+  }
+
+  _num_committed -= (uint)num_regions;
+
+  _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
+  _heap_mapper->uncommit_regions(start, num_regions);
+
+  // Also uncommit auxiliary data
+  _prev_bitmap_mapper->uncommit_regions(start, num_regions);
+  _next_bitmap_mapper->uncommit_regions(start, num_regions);
+
+  _bot_mapper->uncommit_regions(start, num_regions);
+  _cardtable_mapper->uncommit_regions(start, num_regions);
+
+  _card_counts_mapper->uncommit_regions(start, num_regions);
+}
+
+void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) {
+  guarantee(num_regions > 0, "No point in calling this for zero regions");
+  commit_regions(start, num_regions, pretouch_gang);
+  for (uint i = start; i < start + num_regions; i++) {
+    if (_regions.get_by_index(i) == NULL) {
+      HeapRegion* new_hr = new_heap_region(i);
+      OrderAccess::storestore();
+      _regions.set_by_index(i, new_hr);
+      _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
+    }
+  }
+
+  _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
+
+  for (uint i = start; i < start + num_regions; i++) {
+    assert(is_available(i), "Just made region %u available but is apparently not.", i);
+    HeapRegion* hr = at(i);
+    if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
+      G1CollectedHeap::heap()->hr_printer()->commit(hr);
+    }
+    HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
+    MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
+
+    hr->initialize(mr);
+    insert_into_free_list(at(i));
+  }
+}
+
+MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {
+  size_t used_sz =
+    _prev_bitmap_mapper->committed_size() +
+    _next_bitmap_mapper->committed_size() +
+    _bot_mapper->committed_size() +
+    _cardtable_mapper->committed_size() +
+    _card_counts_mapper->committed_size();
+
+  size_t committed_sz =
+    _prev_bitmap_mapper->reserved_size() +
+    _next_bitmap_mapper->reserved_size() +
+    _bot_mapper->reserved_size() +
+    _cardtable_mapper->reserved_size() +
+    _card_counts_mapper->reserved_size();
+
+  return MemoryUsage(0, used_sz, committed_sz, committed_sz);
+}
+
+uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) {
+  return expand_at(0, num_regions, pretouch_workers);
+}
+
+uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) {
+  if (num_regions == 0) {
+    return 0;
+  }
+
+  uint cur = start;
+  uint idx_last_found = 0;
+  uint num_last_found = 0;
+
+  uint expanded = 0;
+
+  while (expanded < num_regions &&
+         (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
+    uint to_expand = MIN2(num_regions - expanded, num_last_found);
+    make_regions_available(idx_last_found, to_expand, pretouch_workers);
+    expanded += to_expand;
+    cur = idx_last_found + num_last_found + 1;
+  }
+
+  verify_optional();
+  return expanded;
+}
+
+uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
+  uint found = 0;
+  size_t length_found = 0;
+  uint cur = 0;
+
+  while (length_found < num && cur < max_length()) {
+    HeapRegion* hr = _regions.get_by_index(cur);
+    if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
+      // This region is a potential candidate for allocation into.
+      length_found++;
+    } else {
+      // This region is not a candidate. The next region is the next possible one.
+      found = cur + 1;
+      length_found = 0;
+    }
+    cur++;
+  }
+
+  if (length_found == num) {
+    for (uint i = found; i < (found + num); i++) {
+      HeapRegion* hr = _regions.get_by_index(i);
+      // sanity check
+      guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
+                "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
+                " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr));
+    }
+    return found;
+  } else {
+    return G1_NO_HRM_INDEX;
+  }
+}
+
+HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
+  guarantee(r != NULL, "Start region must be a valid region");
+  guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index());
+  for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
+    HeapRegion* hr = _regions.get_by_index(i);
+    if (is_available(i)) {
+      return hr;
+    }
+  }
+  return NULL;
+}
+
+void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
+  uint len = max_length();
+
+  for (uint i = 0; i < len; i++) {
+    if (!is_available(i)) {
+      continue;
+    }
+    guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i);
+    bool res = blk->doHeapRegion(at(i));
+    if (res) {
+      blk->incomplete();
+      return;
+    }
+  }
+}
+
+uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
+  guarantee(res_idx != NULL, "checking");
+  guarantee(start_idx <= (max_length() + 1), "checking");
+
+  uint num_regions = 0;
+
+  uint cur = start_idx;
+  while (cur < max_length() && is_available(cur)) {
+    cur++;
+  }
+  if (cur == max_length()) {
+    return num_regions;
+  }
+  *res_idx = cur;
+  while (cur < max_length() && !is_available(cur)) {
+    cur++;
+  }
+  num_regions = cur - *res_idx;
+#ifdef ASSERT
+  for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
+    assert(!is_available(i), "just checking");
+  }
+  assert(cur == max_length() || num_regions == 0 || is_available(cur),
+         "The region at the current position %u must be available or at the end of the heap.", cur);
+#endif
+  return num_regions;
+}
+
+uint HeapRegionManager::find_highest_free(bool* expanded) {
+  // Loop downwards from the highest region index, looking for an
+  // entry which is either free or not yet committed.  If not yet
+  // committed, expand_at that index.
+  uint curr = max_length() - 1;
+  while (true) {
+    HeapRegion *hr = _regions.get_by_index(curr);
+    if (hr == NULL) {
+      uint res = expand_at(curr, 1, NULL);
+      if (res == 1) {
+        *expanded = true;
+        return curr;
+      }
+    } else {
+      if (hr->is_free()) {
+        *expanded = false;
+        return curr;
+      }
+    }
+    if (curr == 0) {
+      return G1_NO_HRM_INDEX;
+    }
+    curr--;
+  }
+}
+
+bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) {
+  size_t commits = 0;
+  uint start_index = (uint)_regions.get_index_by_address(range.start());
+  uint last_index = (uint)_regions.get_index_by_address(range.last());
+
+  // Ensure that each G1 region in the range is free, returning false if not.
+  // Commit those that are not yet available, and keep count.
+  for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {
+    if (!is_available(curr_index)) {
+      commits++;
+      expand_at(curr_index, 1, pretouch_workers);
+    }
+    HeapRegion* curr_region  = _regions.get_by_index(curr_index);
+    if (!curr_region->is_free()) {
+      return false;
+    }
+  }
+
+  allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);
+  *commit_count = commits;
+  return true;
+}
+
+void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer) const {
+  const uint start_index = hrclaimer->start_region_for_worker(worker_id);
+
+  // Every worker will actually look at all regions, skipping over regions that
+  // are currently not committed.
+  // This also (potentially) iterates over regions newly allocated during GC. This
+  // is no problem except for some extra work.
+  const uint n_regions = hrclaimer->n_regions();
+  for (uint count = 0; count < n_regions; count++) {
+    const uint index = (start_index + count) % n_regions;
+    assert(index < n_regions, "sanity");
+    // Skip over unavailable regions
+    if (!is_available(index)) {
+      continue;
+    }
+    HeapRegion* r = _regions.get_by_index(index);
+    // We'll ignore regions already claimed.
+    // However, if the iteration is specified as concurrent, the values for
+    // is_starts_humongous and is_continues_humongous can not be trusted,
+    // and we should just blindly iterate over regions regardless of their
+    // humongous status.
+    if (hrclaimer->is_region_claimed(index)) {
+      continue;
+    }
+    // OK, try to claim it
+    if (!hrclaimer->claim_region(index)) {
+      continue;
+    }
+    bool res = blk->doHeapRegion(r);
+    if (res) {
+      return;
+    }
+  }
+}
+
+uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
+  assert(length() > 0, "the region sequence should not be empty");
+  assert(length() <= _allocated_heapregions_length, "invariant");
+  assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
+  assert(num_regions_to_remove < length(), "We should never remove all regions");
+
+  if (num_regions_to_remove == 0) {
+    return 0;
+  }
+
+  uint removed = 0;
+  uint cur = _allocated_heapregions_length - 1;
+  uint idx_last_found = 0;
+  uint num_last_found = 0;
+
+  while ((removed < num_regions_to_remove) &&
+      (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
+    uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
+
+    shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
+
+    cur = idx_last_found;
+    removed += to_remove;
+  }
+
+  verify_optional();
+
+  return removed;
+}
+
+void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
+#ifdef ASSERT
+  for (uint i = index; i < (index + num_regions); i++) {
+    assert(is_available(i), "Expected available region at index %u", i);
+    assert(at(i)->is_empty(), "Expected empty region at index %u", i);
+    assert(at(i)->is_free(), "Expected free region at index %u", i);
+  }
+#endif
+  uncommit_regions(index, num_regions);
+}
+
+uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
+  guarantee(start_idx < _allocated_heapregions_length, "checking");
+  guarantee(res_idx != NULL, "checking");
+
+  uint num_regions_found = 0;
+
+  jlong cur = start_idx;
+  while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
+    cur--;
+  }
+  if (cur == -1) {
+    return num_regions_found;
+  }
+  jlong old_cur = cur;
+  // cur indexes the first empty region
+  while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
+    cur--;
+  }
+  *res_idx = cur + 1;
+  num_regions_found = old_cur - cur;
+
+#ifdef ASSERT
+  for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
+    assert(at(i)->is_empty(), "just checking");
+  }
+#endif
+  return num_regions_found;
+}
+
+void HeapRegionManager::verify() {
+  guarantee(length() <= _allocated_heapregions_length,
+            "invariant: _length: %u _allocated_length: %u",
+            length(), _allocated_heapregions_length);
+  guarantee(_allocated_heapregions_length <= max_length(),
+            "invariant: _allocated_length: %u _max_length: %u",
+            _allocated_heapregions_length, max_length());
+
+  bool prev_committed = true;
+  uint num_committed = 0;
+  HeapWord* prev_end = heap_bottom();
+  for (uint i = 0; i < _allocated_heapregions_length; i++) {
+    if (!is_available(i)) {
+      prev_committed = false;
+      continue;
+    }
+    num_committed++;
+    HeapRegion* hr = _regions.get_by_index(i);
+    guarantee(hr != NULL, "invariant: i: %u", i);
+    guarantee(!prev_committed || hr->bottom() == prev_end,
+              "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT,
+              i, HR_FORMAT_PARAMS(hr), p2i(prev_end));
+    guarantee(hr->hrm_index() == i,
+              "invariant: i: %u hrm_index(): %u", i, hr->hrm_index());
+    // Asserts will fire if i is >= _length
+    HeapWord* addr = hr->bottom();
+    guarantee(addr_to_region(addr) == hr, "sanity");
+    // We cannot check whether the region is part of a particular set: at the time
+    // this method may be called, we have only completed allocation of the regions,
+    // but not put into a region set.
+    prev_committed = true;
+    prev_end = hr->end();
+  }
+  for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
+    guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i);
+  }
+
+  guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed);
+  _free_list.verify();
+}
+
+#ifndef PRODUCT
+void HeapRegionManager::verify_optional() {
+  verify();
+}
+#endif // PRODUCT
+
+HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
+    _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {
+  assert(n_workers > 0, "Need at least one worker.");
+  uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
+  memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions);
+  _claims = new_claims;
+}
+
+HeapRegionClaimer::~HeapRegionClaimer() {
+  if (_claims != NULL) {
+    FREE_C_HEAP_ARRAY(uint, _claims);
+  }
+}
+
+uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {
+  assert(worker_id < _n_workers, "Invalid worker_id.");
+  return _n_regions * worker_id / _n_workers;
+}
+
+bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
+  assert(region_index < _n_regions, "Invalid index.");
+  return _claims[region_index] == Claimed;
+}
+
+bool HeapRegionClaimer::claim_region(uint region_index) {
+  assert(region_index < _n_regions, "Invalid index.");
+  uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
+  return old_val == Unclaimed;
+}