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 /*

  * Copyright (c) 2011, 2014, 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.

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  */

 #include "precompiled.hpp"

 #include "gc_implementation/g1/heapRegionRemSet.hpp"

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

 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC

 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->set_prev(from_list->_tail);

       _head = from_list->_head;

     } else {

       _tail->set_next(from_list->_head);

       from_list->_head->set_prev(_tail);

       _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_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;

   }

   if (is_empty()) {

     add_as_head(from_list);

     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

   HeapRegion* curr_to = _head;

   HeapRegion* curr_from = from_list->_head;

   while (curr_from != NULL) {

     while (curr_to != NULL && curr_to->hrs_index() < curr_from->hrs_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->hrs_index() < from_list->_tail->hrs_index()) {

     _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::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();

     HeapRegion* prev = curr->prev();

     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"));

         next->set_prev(prev);

       }

       if (_last = curr) {

         _last = NULL;

       }

       curr->set_next(NULL);

       curr->set_prev(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;

   _last = 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;

   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,

         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()));

     if (curr->next() != NULL) {

       guarantee(curr->next()->prev() == curr, "Next or prev pointers messed up");

     }

     guarantee(curr->hrs_index() == 0 || curr->hrs_index() > last_index, "List should be sorted");

     last_index = curr->hrs_index();

     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(_tail == NULL || _tail->next() == NULL, "_tail should not have a next");

   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");

   }

 }