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 /*

  * Copyright (c) 2001, 2012, 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_implementation/g1/heapRegion.hpp"

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

 #include "gc_implementation/g1/heapRegionSets.hpp"

 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"

 #include "memory/allocation.hpp"

 // Private

 uint HeapRegionSeq::find_contiguous_from(uint from, uint num) {

   uint len = length();

   assert(num > 1, "use this only for sequences of length 2 or greater");

   assert(from <= len,

          err_msg("from: %u should be valid and <= than %u", from, len));

   uint curr = from;

   uint first = G1_NULL_HRS_INDEX;

   uint num_so_far = 0;

   while (curr < len && num_so_far < num) {

     if (at(curr)->is_empty()) {

       if (first == G1_NULL_HRS_INDEX) {

         first = curr;

         num_so_far = 1;

       } else {

         num_so_far += 1;

       }

     } else {

       first = G1_NULL_HRS_INDEX;

       num_so_far = 0;

     }

     curr += 1;

   }

   assert(num_so_far <= num, "post-condition");

   if (num_so_far == num) {

     // we found enough space for the humongous object

     assert(from <= first && first < len, "post-condition");

     assert(first < curr && (curr - first) == num, "post-condition");

     for (uint i = first; i < first + num; ++i) {

       assert(at(i)->is_empty(), "post-condition");

     }

     return first;

   } else {

     // we failed to find enough space for the humongous object

     return G1_NULL_HRS_INDEX;

   }

 }

 // Public

 void HeapRegionSeq::initialize(HeapWord* bottom, HeapWord* end,

                                uint max_length) {

   assert((uintptr_t) bottom % HeapRegion::GrainBytes == 0,

          "bottom should be heap region aligned");

   assert((uintptr_t) end % HeapRegion::GrainBytes == 0,

          "end should be heap region aligned");

   _length = 0;

   _heap_bottom = bottom;

   _heap_end = end;

   _region_shift = HeapRegion::LogOfHRGrainBytes;

   _next_search_index = 0;

   _allocated_length = 0;

   _max_length = max_length;

   _regions = NEW_C_HEAP_ARRAY(HeapRegion*, max_length, mtGC);

   memset(_regions, 0, (size_t) max_length * sizeof(HeapRegion*));

   _regions_biased = _regions - ((uintx) bottom >> _region_shift);

   assert(&_regions[0] == &_regions_biased[addr_to_index_biased(bottom)],

          "bottom should be included in the region with index 0");

 }

 MemRegion HeapRegionSeq::expand_by(HeapWord* old_end,

                                    HeapWord* new_end,

                                    FreeRegionList* list) {

   assert(old_end < new_end, "don't call it otherwise");

   G1CollectedHeap* g1h = G1CollectedHeap::heap();

   HeapWord* next_bottom = old_end;

   assert(_heap_bottom <= next_bottom, "invariant");

   while (next_bottom < new_end) {

     assert(next_bottom < _heap_end, "invariant");

     uint index = length();

     assert(index < _max_length, "otherwise we cannot expand further");

     if (index == 0) {

       // We have not allocated any regions so far

       assert(next_bottom == _heap_bottom, "invariant");

     } else {

       // next_bottom should match the end of the last/previous region

       assert(next_bottom == at(index - 1)->end(), "invariant");

     }

     if (index == _allocated_length) {

       // We have to allocate a new HeapRegion.

       HeapRegion* new_hr = g1h->new_heap_region(index, next_bottom);

       if (new_hr == NULL) {

         // allocation failed, we bail out and return what we have done so far

         return MemRegion(old_end, next_bottom);

       }

       assert(_regions[index] == NULL, "invariant");

       _regions[index] = new_hr;

       increment_length(&_allocated_length);

     }

     // Have to increment the length first, otherwise we will get an

     // assert failure at(index) below.

     increment_length(&_length);

     HeapRegion* hr = at(index);

     list->add_as_tail(hr);

     next_bottom = hr->end();

   }

   assert(next_bottom == new_end, "post-condition");

   return MemRegion(old_end, next_bottom);

 }

 uint HeapRegionSeq::free_suffix() {

   uint res = 0;

   uint index = length();

   while (index > 0) {

     index -= 1;

     if (!at(index)->is_empty()) {

       break;

     }

     res += 1;

   }

   return res;

 }

 uint HeapRegionSeq::find_contiguous(uint num) {

   assert(num > 1, "use this only for sequences of length 2 or greater");

   assert(_next_search_index <= length(),

          err_msg("_next_search_index: %u should be valid and <= than %u",

                  _next_search_index, length()));

   uint start = _next_search_index;

   uint res = find_contiguous_from(start, num);

   if (res == G1_NULL_HRS_INDEX && start > 0) {

     // Try starting from the beginning. If _next_search_index was 0,

     // no point in doing this again.

     res = find_contiguous_from(0, num);

   }

   if (res != G1_NULL_HRS_INDEX) {

     assert(res < length(), err_msg("res: %u should be valid", res));

     _next_search_index = res + num;

     assert(_next_search_index <= length(),

            err_msg("_next_search_index: %u should be valid and <= than %u",

                    _next_search_index, length()));

   }

   return res;

 }

 void HeapRegionSeq::iterate(HeapRegionClosure* blk) const {

   iterate_from((HeapRegion*) NULL, blk);

 }

 void HeapRegionSeq::iterate_from(HeapRegion* hr, HeapRegionClosure* blk) const {

   uint hr_index = 0;

   if (hr != NULL) {

     hr_index = hr->hrs_index();

   }

   uint len = length();

   for (uint i = hr_index; i < len; i += 1) {

     bool res = blk->doHeapRegion(at(i));

     if (res) {

       blk->incomplete();

       return;

     }

   }

   for (uint i = 0; i < hr_index; i += 1) {

     bool res = blk->doHeapRegion(at(i));

     if (res) {

       blk->incomplete();

       return;

     }

   }

 }

 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,

                                    uint* num_regions_deleted) {

   // Reset this in case it's currently pointing into the regions that

   // we just removed.

   _next_search_index = 0;

   assert(shrink_bytes % os::vm_page_size() == 0, "unaligned");

   assert(shrink_bytes % HeapRegion::GrainBytes == 0, "unaligned");

   assert(length() > 0, "the region sequence should not be empty");

   assert(length() <= _allocated_length, "invariant");

   assert(_allocated_length > 0, "we should have at least one region committed");

   // around the loop, i will be the next region to be removed

   uint i = length() - 1;

   assert(i > 0, "we should never remove all regions");

   // [last_start, end) is the MemRegion that covers the regions we will remove.

   HeapWord* end = at(i)->end();

   HeapWord* last_start = end;

   *num_regions_deleted = 0;

   while (shrink_bytes > 0) {

     HeapRegion* cur = at(i);

     // We should leave the humongous regions where they are.

     if (cur->isHumongous()) break;

     // We should stop shrinking if we come across a non-empty region.

     if (!cur->is_empty()) break;

     i -= 1;

     *num_regions_deleted += 1;

     shrink_bytes -= cur->capacity();

     last_start = cur->bottom();

     decrement_length(&_length);

     // We will reclaim the HeapRegion. _allocated_length should be

     // covering this index. So, even though we removed the region from

     // the active set by decreasing _length, we still have it

     // available in the future if we need to re-use it.

     assert(i > 0, "we should never remove all regions");

     assert(length() > 0, "we should never remove all regions");

   }

   return MemRegion(last_start, end);

 }

 #ifndef PRODUCT

 void HeapRegionSeq::verify_optional() {

   guarantee(_length <= _allocated_length,

             err_msg("invariant: _length: %u _allocated_length: %u",

                     _length, _allocated_length));

   guarantee(_allocated_length <= _max_length,

             err_msg("invariant: _allocated_length: %u _max_length: %u",

                     _allocated_length, _max_length));

   guarantee(_next_search_index <= _length,

             err_msg("invariant: _next_search_index: %u _length: %u",

                     _next_search_index, _length));

   HeapWord* prev_end = _heap_bottom;

   for (uint i = 0; i < _allocated_length; i += 1) {

     HeapRegion* hr = _regions[i];

     guarantee(hr != NULL, err_msg("invariant: i: %u", i));

     guarantee(hr->bottom() == prev_end,

               err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,

                       i, HR_FORMAT_PARAMS(hr), prev_end));

     guarantee(hr->hrs_index() == i,

               err_msg("invariant: i: %u hrs_index(): %u", i, hr->hrs_index()));

     if (i < _length) {

       // Asserts will fire if i is >= _length

       HeapWord* addr = hr->bottom();

       guarantee(addr_to_region(addr) == hr, "sanity");

       guarantee(addr_to_region_unsafe(addr) == hr, "sanity");

     } else {

       guarantee(hr->is_empty(), "sanity");

       guarantee(!hr->isHumongous(), "sanity");

       // using assert instead of guarantee here since containing_set()

       // is only available in non-product builds.

       assert(hr->containing_set() == NULL, "sanity");

     }

     if (hr->startsHumongous()) {

       prev_end = hr->orig_end();

     } else {

       prev_end = hr->end();

     }

   }

   for (uint i = _allocated_length; i < _max_length; i += 1) {

     guarantee(_regions[i] == NULL, err_msg("invariant i: %u", i));

   }

 }

 #endif // PRODUCT