--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/hotspot/share/gc/g1/heapRegionSet.cpp	Tue Sep 12 19:03:39 2017 +0200
@@ -0,0 +1,372 @@
+/*
+ * Copyright (c) 2011, 2016, 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/g1CollectedHeap.inline.hpp"
+#include "gc/g1/heapRegionRemSet.hpp"
+#include "gc/g1/heapRegionSet.inline.hpp"
+
+uint FreeRegionList::_unrealistically_long_length = 0;
+
+#ifndef PRODUCT
+void HeapRegionSetBase::verify_region(HeapRegion* hr) {
+  assert(hr->containing_set() == this, "Inconsistent containing set for %u", hr->hrm_index());
+  assert(!hr->is_young(), "Adding young region %u", hr->hrm_index()); // currently we don't use these sets for young regions
+  assert(hr->is_humongous() == regions_humongous(), "Wrong humongous state for region %u and set %s", hr->hrm_index(), name());
+  assert(hr->is_free() == regions_free(), "Wrong free state for region %u and set %s", hr->hrm_index(), name());
+  assert(!hr->is_free() || hr->is_empty(), "Free region %u is not empty for set %s", hr->hrm_index(), name());
+  assert(!hr->is_empty() || hr->is_free() || hr->is_archive(),
+         "Empty region %u is not free or archive for set %s", hr->hrm_index(), name());
+}
+#endif
+
+void HeapRegionSetBase::verify() {
+  // It's important that we also observe the MT safety protocol even
+  // for the verification calls. If we do verification without the
+  // appropriate locks and the set changes underneath our feet
+  // verification might fail and send us on a wild goose chase.
+  check_mt_safety();
+
+  guarantee_heap_region_set(( is_empty() && length() == 0) ||
+                            (!is_empty() && length() > 0),
+                            "invariant");
+}
+
+void HeapRegionSetBase::verify_start() {
+  // See comment in verify() about MT safety and verification.
+  check_mt_safety();
+  assert_heap_region_set(!_verify_in_progress, "verification should not be in progress");
+
+  // Do the basic verification first before we do the checks over the regions.
+  HeapRegionSetBase::verify();
+
+  _verify_in_progress = true;
+}
+
+void HeapRegionSetBase::verify_end() {
+  // See comment in verify() about MT safety and verification.
+  check_mt_safety();
+  assert_heap_region_set(_verify_in_progress, "verification should be in progress");
+
+  _verify_in_progress = false;
+}
+
+void HeapRegionSetBase::print_on(outputStream* out, bool print_contents) {
+  out->cr();
+  out->print_cr("Set: %s (" PTR_FORMAT ")", name(), p2i(this));
+  out->print_cr("  Region Assumptions");
+  out->print_cr("    humongous         : %s", BOOL_TO_STR(regions_humongous()));
+  out->print_cr("    free              : %s", BOOL_TO_STR(regions_free()));
+  out->print_cr("  Attributes");
+  out->print_cr("    length            : %14u", length());
+}
+
+HeapRegionSetBase::HeapRegionSetBase(const char* name, bool humongous, bool free, HRSMtSafeChecker* mt_safety_checker)
+  : _name(name), _verify_in_progress(false),
+    _is_humongous(humongous), _is_free(free), _mt_safety_checker(mt_safety_checker),
+    _length(0)
+{ }
+
+void FreeRegionList::set_unrealistically_long_length(uint len) {
+  guarantee(_unrealistically_long_length == 0, "should only be set once");
+  _unrealistically_long_length = len;
+}
+
+void FreeRegionList::remove_all() {
+  check_mt_safety();
+  verify_optional();
+
+  HeapRegion* curr = _head;
+  while (curr != NULL) {
+    verify_region(curr);
+
+    HeapRegion* next = curr->next();
+    curr->set_next(NULL);
+    curr->set_prev(NULL);
+    curr->set_containing_set(NULL);
+    curr = next;
+  }
+  clear();
+
+  verify_optional();
+}
+
+void FreeRegionList::add_ordered(FreeRegionList* from_list) {
+  check_mt_safety();
+  from_list->check_mt_safety();
+
+  verify_optional();
+  from_list->verify_optional();
+
+  if (from_list->is_empty()) {
+    return;
+  }
+
+  #ifdef ASSERT
+  FreeRegionListIterator iter(from_list);
+  while (iter.more_available()) {
+    HeapRegion* hr = iter.get_next();
+    // In set_containing_set() we check that we either set the value
+    // from NULL to non-NULL or vice versa to catch bugs. So, we have
+    // to NULL it first before setting it to the value.
+    hr->set_containing_set(NULL);
+    hr->set_containing_set(this);
+  }
+  #endif // ASSERT
+
+  if (is_empty()) {
+    assert_free_region_list(length() == 0 && _tail == NULL, "invariant");
+    _head = from_list->_head;
+    _tail = from_list->_tail;
+  } else {
+    HeapRegion* curr_to = _head;
+    HeapRegion* curr_from = from_list->_head;
+
+    while (curr_from != NULL) {
+      while (curr_to != NULL && curr_to->hrm_index() < curr_from->hrm_index()) {
+        curr_to = curr_to->next();
+      }
+
+      if (curr_to == NULL) {
+        // The rest of the from list should be added as tail
+        _tail->set_next(curr_from);
+        curr_from->set_prev(_tail);
+        curr_from = NULL;
+      } else {
+        HeapRegion* next_from = curr_from->next();
+
+        curr_from->set_next(curr_to);
+        curr_from->set_prev(curr_to->prev());
+        if (curr_to->prev() == NULL) {
+          _head = curr_from;
+        } else {
+          curr_to->prev()->set_next(curr_from);
+        }
+        curr_to->set_prev(curr_from);
+
+        curr_from = next_from;
+      }
+    }
+
+    if (_tail->hrm_index() < from_list->_tail->hrm_index()) {
+      _tail = from_list->_tail;
+    }
+  }
+
+  _length += from_list->length();
+  from_list->clear();
+
+  verify_optional();
+  from_list->verify_optional();
+}
+
+void FreeRegionList::remove_starting_at(HeapRegion* first, uint num_regions) {
+  check_mt_safety();
+  assert_free_region_list(num_regions >= 1, "pre-condition");
+  assert_free_region_list(!is_empty(), "pre-condition");
+
+  verify_optional();
+  DEBUG_ONLY(uint old_length = length();)
+
+  HeapRegion* curr = first;
+  uint count = 0;
+  while (count < num_regions) {
+    verify_region(curr);
+    HeapRegion* next = curr->next();
+    HeapRegion* prev = curr->prev();
+
+    assert(count < num_regions,
+           "[%s] should not come across more regions "
+           "pending for removal than num_regions: %u",
+           name(), num_regions);
+
+    if (prev == NULL) {
+      assert_free_region_list(_head == curr, "invariant");
+      _head = next;
+    } else {
+      assert_free_region_list(_head != curr, "invariant");
+      prev->set_next(next);
+    }
+    if (next == NULL) {
+      assert_free_region_list(_tail == curr, "invariant");
+      _tail = prev;
+    } else {
+      assert_free_region_list(_tail != curr, "invariant");
+      next->set_prev(prev);
+    }
+    if (_last == curr) {
+      _last = NULL;
+    }
+
+    curr->set_next(NULL);
+    curr->set_prev(NULL);
+    remove(curr);
+
+    count++;
+    curr = next;
+  }
+
+  assert(count == num_regions,
+         "[%s] count: %u should be == num_regions: %u",
+         name(), count, num_regions);
+  assert(length() + num_regions == old_length,
+         "[%s] new length should be consistent "
+         "new length: %u old length: %u num_regions: %u",
+         name(), length(), old_length, num_regions);
+
+  verify_optional();
+}
+
+void FreeRegionList::verify() {
+  // See comment in HeapRegionSetBase::verify() about MT safety and
+  // verification.
+  check_mt_safety();
+
+  // This will also do the basic verification too.
+  verify_start();
+
+  verify_list();
+
+  verify_end();
+}
+
+void FreeRegionList::clear() {
+  _length = 0;
+  _head = NULL;
+  _tail = NULL;
+  _last = NULL;
+}
+
+void FreeRegionList::verify_list() {
+  HeapRegion* curr = _head;
+  HeapRegion* prev1 = NULL;
+  HeapRegion* prev0 = NULL;
+  uint count = 0;
+  size_t capacity = 0;
+  uint last_index = 0;
+
+  guarantee(_head == NULL || _head->prev() == NULL, "_head should not have a prev");
+  while (curr != NULL) {
+    verify_region(curr);
+
+    count++;
+    guarantee(count < _unrealistically_long_length,
+              "[%s] the calculated length: %u seems very long, is there maybe a cycle? curr: " PTR_FORMAT " prev0: " PTR_FORMAT " " "prev1: " PTR_FORMAT " length: %u",
+              name(), count, p2i(curr), p2i(prev0), p2i(prev1), length());
+
+    if (curr->next() != NULL) {
+      guarantee(curr->next()->prev() == curr, "Next or prev pointers messed up");
+    }
+    guarantee(curr->hrm_index() == 0 || curr->hrm_index() > last_index, "List should be sorted");
+    last_index = curr->hrm_index();
+
+    capacity += curr->capacity();
+
+    prev1 = prev0;
+    prev0 = curr;
+    curr = curr->next();
+  }
+
+  guarantee(_tail == prev0, "Expected %s to end with %u but it ended with %u.", name(), _tail->hrm_index(), prev0->hrm_index());
+  guarantee(_tail == NULL || _tail->next() == NULL, "_tail should not have a next");
+  guarantee(length() == count, "%s count mismatch. Expected %u, actual %u.", name(), length(), count);
+}
+
+// Note on the check_mt_safety() methods below:
+//
+// Verification of the "master" heap region sets / lists that are
+// maintained by G1CollectedHeap is always done during a STW pause and
+// by the VM thread at the start / end of the pause. The standard
+// verification methods all assert check_mt_safety(). This is
+// important as it ensures that verification is done without
+// concurrent updates taking place at the same time. It follows, that,
+// for the "master" heap region sets / lists, the check_mt_safety()
+// method should include the VM thread / STW case.
+
+void MasterFreeRegionListMtSafeChecker::check() {
+  // Master Free List MT safety protocol:
+  // (a) If we're at a safepoint, operations on the master free list
+  // should be invoked by either the VM thread (which will serialize
+  // them) or by the GC workers while holding the
+  // FreeList_lock.
+  // (b) If we're not at a safepoint, operations on the master free
+  // list should be invoked while holding the Heap_lock.
+
+  if (SafepointSynchronize::is_at_safepoint()) {
+    guarantee(Thread::current()->is_VM_thread() ||
+              FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
+  } else {
+    guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
+  }
+}
+
+void SecondaryFreeRegionListMtSafeChecker::check() {
+  // Secondary Free List MT safety protocol:
+  // Operations on the secondary free list should always be invoked
+  // while holding the SecondaryFreeList_lock.
+
+  guarantee(SecondaryFreeList_lock->owned_by_self(), "secondary free list MT safety protocol");
+}
+
+void OldRegionSetMtSafeChecker::check() {
+  // Master Old Set MT safety protocol:
+  // (a) If we're at a safepoint, operations on the master old set
+  // should be invoked:
+  // - by the VM thread (which will serialize them), or
+  // - by the GC workers while holding the FreeList_lock, if we're
+  //   at a safepoint for an evacuation pause (this lock is taken
+  //   anyway when an GC alloc region is retired so that a new one
+  //   is allocated from the free list), or
+  // - by the GC workers while holding the OldSets_lock, if we're at a
+  //   safepoint for a cleanup pause.
+  // (b) If we're not at a safepoint, operations on the master old set
+  // should be invoked while holding the Heap_lock.
+
+  if (SafepointSynchronize::is_at_safepoint()) {
+    guarantee(Thread::current()->is_VM_thread()
+        || FreeList_lock->owned_by_self() || OldSets_lock->owned_by_self(),
+        "master old set MT safety protocol at a safepoint");
+  } else {
+    guarantee(Heap_lock->owned_by_self(), "master old set MT safety protocol outside a safepoint");
+  }
+}
+
+void HumongousRegionSetMtSafeChecker::check() {
+  // Humongous Set MT safety protocol:
+  // (a) If we're at a safepoint, operations on the master humongous
+  // set should be invoked by either the VM thread (which will
+  // serialize them) or by the GC workers while holding the
+  // OldSets_lock.
+  // (b) If we're not at a safepoint, operations on the master
+  // humongous set should be invoked while holding the Heap_lock.
+
+  if (SafepointSynchronize::is_at_safepoint()) {
+    guarantee(Thread::current()->is_VM_thread() ||
+              OldSets_lock->owned_by_self(),
+              "master humongous set MT safety protocol at a safepoint");
+  } else {
+    guarantee(Heap_lock->owned_by_self(),
+              "master humongous set MT safety protocol outside a safepoint");
+  }
+}