/*

 * 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

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 */

#include "precompiled.hpp"

#include "gc_implementation/g1/heapRegionRemSet.hpp"

#include "gc_implementation/g1/heapRegionSet.inline.hpp"

uint FreeRegionList::_unrealistically_long_length = 0;

void HeapRegionSetBase::fill_in_ext_msg(hrs_ext_msg* msg, const char* message) {

  msg->append("[%s] %s ln: %u cy: "SIZE_FORMAT,

              name(), message, length(), total_capacity_bytes());

  fill_in_ext_msg_extra(msg);

}

#ifndef PRODUCT

void HeapRegionSetBase::verify_region(HeapRegion* hr) {

  assert(hr->containing_set() == this, err_msg("Inconsistent containing set for %u", hr->hrs_index()));

  assert(!hr->is_young(), err_msg("Adding young region %u", hr->hrs_index())); // currently we don't use these sets for young regions

  assert(hr->isHumongous() == regions_humongous(), err_msg("Wrong humongous state for region %u and set %s", hr->hrs_index(), name()));

  assert(hr->is_empty() == regions_empty(), err_msg("Wrong empty state for region %u and set %s", hr->hrs_index(), name()));

  assert(hr->rem_set()->verify_ready_for_par_iteration(), err_msg("Wrong iteration state %u", hr->hrs_index()));

}

#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(( is_empty() && length() == 0 && total_capacity_bytes() == 0) ||

            (!is_empty() && length() >= 0 && total_capacity_bytes() >= 0),

            hrs_ext_msg(this, "invariant"));

}

void HeapRegionSetBase::verify_start() {

  // See comment in verify() about MT safety and verification.

  check_mt_safety();

  assert(!_verify_in_progress,

         hrs_ext_msg(this, "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(_verify_in_progress,

         hrs_ext_msg(this, "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(), this);

  out->print_cr("  Region Assumptions");

  out->print_cr("    humongous         : %s", BOOL_TO_STR(regions_humongous()));

  out->print_cr("    empty             : %s", BOOL_TO_STR(regions_empty()));

  out->print_cr("  Attributes");

  out->print_cr("    length            : %14u", length());

  out->print_cr("    total capacity    : "SIZE_FORMAT_W(14)" bytes",

                total_capacity_bytes());

}

HeapRegionSetBase::HeapRegionSetBase(const char* name, bool humongous, bool empty, HRSMtSafeChecker* mt_safety_checker)

  : _name(name), _verify_in_progress(false),

    _is_humongous(humongous), _is_empty(empty), _mt_safety_checker(mt_safety_checker),

    _count()

{ }

void FreeRegionList::set_unrealistically_long_length(uint len) {

  guarantee(_unrealistically_long_length == 0, "should only be set once");

  _unrealistically_long_length = len;

}

void FreeRegionList::fill_in_ext_msg_extra(hrs_ext_msg* msg) {

  msg->append(" hd: "PTR_FORMAT" tl: "PTR_FORMAT, head(), tail());

}

void FreeRegionList::add_as_head_or_tail(FreeRegionList* from_list, bool as_head) {

  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 (_head == NULL) {

    assert(length() == 0 && _tail == NULL, hrs_ext_msg(this, "invariant"));

    _head = from_list->_head;

    _tail = from_list->_tail;

  } else {

    assert(length() > 0 && _tail != NULL, hrs_ext_msg(this, "invariant"));

    if (as_head) {

      from_list->_tail->set_next(_head);

      _head = from_list->_head;

    } else {

      _tail->set_next(from_list->_head);

      _tail = from_list->_tail;

    }

  }

  _count.increment(from_list->length(), from_list->total_capacity_bytes());

  from_list->clear();

  verify_optional();

  from_list->verify_optional();

}

void FreeRegionList::add_as_head(FreeRegionList* from_list) {

  add_as_head_or_tail(from_list, true /* as_head */);

}

void FreeRegionList::add_as_tail(FreeRegionList* from_list) {

  add_as_head_or_tail(from_list, false /* as_head */);

}

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_containing_set(NULL);

    curr = next;

  }

  clear();

  verify_optional();

}

void FreeRegionList::remove_all_pending(uint target_count) {

  check_mt_safety();

  assert(target_count > 1, hrs_ext_msg(this, "pre-condition"));

  assert(!is_empty(), hrs_ext_msg(this, "pre-condition"));

  verify_optional();

  DEBUG_ONLY(uint old_length = length();)

  HeapRegion* curr = _head;

  uint count = 0;

  while (curr != NULL) {

    verify_region(curr);

    HeapRegion* next = curr->next();

    if (curr->pending_removal()) {

      assert(count < target_count,

             hrs_err_msg("[%s] should not come across more regions "

                         "pending for removal than target_count: %u",

                         name(), target_count));

      if (prev == NULL) {

        assert(_head == curr, hrs_ext_msg(this, "invariant"));

        _head = next;

      } else {

        assert(_head != curr, hrs_ext_msg(this, "invariant"));

        prev->set_next(next);

      }

      if (next == NULL) {

        assert(_tail == curr, hrs_ext_msg(this, "invariant"));

        _tail = prev;

      } else {

        assert(_tail != curr, hrs_ext_msg(this, "invariant"));

      }

      curr->set_next(NULL);

      remove(curr);

      curr->set_pending_removal(false);

      count += 1;

      // If we have come across the target number of regions we can

      // just bail out. However, for debugging purposes, we can just

      // carry on iterating to make sure there are not more regions

      // tagged with pending removal.

      DEBUG_ONLY(if (count == target_count) break;)

    }

    curr = next;

  }

  assert(count == target_count,

         hrs_err_msg("[%s] count: %u should be == target_count: %u",

                     name(), count, target_count));

  assert(length() + target_count == old_length,

         hrs_err_msg("[%s] new length should be consistent "

                     "new length: %u old length: %u target_count: %u",

                     name(), length(), old_length, target_count));

  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() {

  _count = HeapRegionSetCount();

  _head = NULL;

  _tail = NULL;

}

void FreeRegionList::print_on(outputStream* out, bool print_contents) {

  HeapRegionSetBase::print_on(out, print_contents);

  out->print_cr("  Linking");

  out->print_cr("    head              : "PTR_FORMAT, _head);

  out->print_cr("    tail              : "PTR_FORMAT, _tail);

  if (print_contents) {

    out->print_cr("  Contents");

    FreeRegionListIterator iter(this);

    while (iter.more_available()) {

      HeapRegion* hr = iter.get_next();

      hr->print_on(out);

    }

  }

}

void FreeRegionList::verify_list() {

  HeapRegion* curr = head();

  HeapRegion* prev1 = NULL;

  HeapRegion* prev0 = NULL;

  uint count = 0;

  size_t capacity = 0;

  while (curr != NULL) {

    verify_region(curr);

    count++;

    guarantee(count < _unrealistically_long_length,

        hrs_err_msg("[%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, curr, prev0, prev1, length()));

    capacity += curr->capacity();

    prev1 = prev0;

    prev0 = curr;

    curr = curr->next();

  }

  guarantee(tail() == prev0, err_msg("Expected %s to end with %u but it ended with %u.", name(), tail()->hrs_index(), prev0->hrs_index()));

  guarantee(length() == count, err_msg("%s count mismatch. Expected %u, actual %u.", name(), length(), count));

  guarantee(total_capacity_bytes() == capacity, err_msg("%s capacity mismatch. Expected " SIZE_FORMAT ", actual " SIZE_FORMAT,

      name(), total_capacity_bytes(), capacity));

}

// 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");

  }

}