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 /*

  * Copyright (c) 2001, 2011, 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

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  */

 #include "precompiled.hpp"

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

 #include "gc_implementation/g1/heapRegionSeq.hpp"

 #include "memory/allocation.hpp"

 // Local to this file.

 static int orderRegions(HeapRegion** hr1p, HeapRegion** hr2p) {

   if ((*hr1p)->end() <= (*hr2p)->bottom()) return -1;

   else if ((*hr2p)->end() <= (*hr1p)->bottom()) return 1;

   else if (*hr1p == *hr2p) return 0;

   else {

     assert(false, "We should never compare distinct overlapping regions.");

   }

   return 0;

 }

 HeapRegionSeq::HeapRegionSeq(const size_t max_size) :

   _alloc_search_start(0),

   // The line below is the worst bit of C++ hackery I've ever written

   // (Detlefs, 11/23).  You should think of it as equivalent to

   // "_regions(100, true)": initialize the growable array and inform it

   // that it should allocate its elem array(s) on the C heap.

   //

   // The first argument, however, is actually a comma expression

   // (set_allocation_type(this, C_HEAP), 100). The purpose of the

   // set_allocation_type() call is to replace the default allocation

   // type for embedded objects STACK_OR_EMBEDDED with C_HEAP. It will

   // allow to pass the assert in GenericGrowableArray() which checks

   // that a growable array object must be on C heap if elements are.

   //

   // Note: containing object is allocated on C heap since it is CHeapObj.

   //

   _regions((ResourceObj::set_allocation_type((address)&_regions,

                                              ResourceObj::C_HEAP),

             (int)max_size),

            true),

   _next_rr_candidate(0),

   _seq_bottom(NULL)

 {}

 // Private methods.

 void HeapRegionSeq::print_empty_runs() {

   int empty_run = 0;

   int n_empty = 0;

   int empty_run_start;

   for (int i = 0; i < _regions.length(); i++) {

     HeapRegion* r = _regions.at(i);

     if (r->continuesHumongous()) continue;

     if (r->is_empty()) {

       assert(!r->isHumongous(), "H regions should not be empty.");

       if (empty_run == 0) empty_run_start = i;

       empty_run++;

       n_empty++;

     } else {

       if (empty_run > 0) {

         gclog_or_tty->print("  %d:%d", empty_run_start, empty_run);

         empty_run = 0;

       }

     }

   }

   if (empty_run > 0) {

     gclog_or_tty->print(" %d:%d", empty_run_start, empty_run);

   }

   gclog_or_tty->print_cr(" [tot = %d]", n_empty);

 }

 int HeapRegionSeq::find(HeapRegion* hr) {

   // FIXME: optimized for adjacent regions of fixed size.

   int ind = hr->hrs_index();

   if (ind != -1) {

     assert(_regions.at(ind) == hr, "Mismatch");

   }

   return ind;

 }

 // Public methods.

 void HeapRegionSeq::insert(HeapRegion* hr) {

   assert(!_regions.is_full(), "Too many elements in HeapRegionSeq");

   if (_regions.length() == 0

       || _regions.top()->end() <= hr->bottom()) {

     hr->set_hrs_index(_regions.length());

     _regions.append(hr);

   } else {

     _regions.append(hr);

     _regions.sort(orderRegions);

     for (int i = 0; i < _regions.length(); i++) {

       _regions.at(i)->set_hrs_index(i);

     }

   }

   char* bot = (char*)_regions.at(0)->bottom();

   if (_seq_bottom == NULL || bot < _seq_bottom) _seq_bottom = bot;

 }

 size_t HeapRegionSeq::length() {

   return _regions.length();

 }

 size_t HeapRegionSeq::free_suffix() {

   size_t res = 0;

   int first = _regions.length() - 1;

   int cur = first;

   while (cur >= 0 &&

          (_regions.at(cur)->is_empty()

           && (first == cur

               || (_regions.at(cur+1)->bottom() ==

                   _regions.at(cur)->end())))) {

       res++;

       cur--;

   }

   return res;

 }

 int HeapRegionSeq::find_contiguous_from(int from, size_t num) {

   assert(num > 1, "pre-condition");

   assert(0 <= from && from <= _regions.length(),

          err_msg("from: %d should be valid and <= than %d",

                  from, _regions.length()));

   int curr = from;

   int first = -1;

   size_t num_so_far = 0;

   while (curr < _regions.length() && num_so_far < num) {

     HeapRegion* curr_hr = _regions.at(curr);

     if (curr_hr->is_empty()) {

       if (first == -1) {

         first = curr;

         num_so_far = 1;

       } else {

         num_so_far += 1;

       }

     } else {

       first = -1;

       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 < _regions.length(), "post-condition");

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

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

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

     }

     return first;

   } else {

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

     return -1;

   }

 }

 int HeapRegionSeq::find_contiguous(size_t num) {

   assert(num > 1, "otherwise we should not be calling this");

   assert(0 <= _alloc_search_start && _alloc_search_start <= _regions.length(),

          err_msg("_alloc_search_start: %d should be valid and <= than %d",

                  _alloc_search_start, _regions.length()));

   int start = _alloc_search_start;

   int res = find_contiguous_from(start, num);

   if (res == -1 && start != 0) {

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

     // no point in doing this again.

     res = find_contiguous_from(0, num);

   }

   if (res != -1) {

     assert(0 <= res && res < _regions.length(),

            err_msg("res: %d should be valid", res));

     _alloc_search_start = res + (int) num;

     assert(0 < _alloc_search_start && _alloc_search_start <= _regions.length(),

            err_msg("_alloc_search_start: %d should be valid",

                    _alloc_search_start));

   }

   return res;

 }

 void HeapRegionSeq::iterate(HeapRegionClosure* blk) {

   iterate_from((HeapRegion*)NULL, blk);

 }

 // The first argument r is the heap region at which iteration begins.

 // This operation runs fastest when r is NULL, or the heap region for

 // which a HeapRegionClosure most recently returned true, or the

 // heap region immediately to its right in the sequence.  In all

 // other cases a linear search is required to find the index of r.

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

   // :::: FIXME ::::

   // Static cache value is bad, especially when we start doing parallel

   // remembered set update. For now just don't cache anything (the

   // code in the def'd out blocks).

 #if 0

   static int cached_j = 0;

 #endif

   int len = _regions.length();

   int j = 0;

   // Find the index of r.

   if (r != NULL) {

 #if 0

     assert(cached_j >= 0, "Invariant.");

     if ((cached_j < len) && (r == _regions.at(cached_j))) {

       j = cached_j;

     } else if ((cached_j + 1 < len) && (r == _regions.at(cached_j + 1))) {

       j = cached_j + 1;

     } else {

       j = find(r);

 #endif

       if (j < 0) {

         j = 0;

       }

 #if 0

     }

 #endif

   }

   int i;

   for (i = j; i < len; i += 1) {

     int res = blk->doHeapRegion(_regions.at(i));

     if (res) {

 #if 0

       cached_j = i;

 #endif

       blk->incomplete();

       return;

     }

   }

   for (i = 0; i < j; i += 1) {

     int res = blk->doHeapRegion(_regions.at(i));

     if (res) {

 #if 0

       cached_j = i;

 #endif

       blk->incomplete();

       return;

     }

   }

 }

 void HeapRegionSeq::iterate_from(int idx, HeapRegionClosure* blk) {

   int len = _regions.length();

   int i;

   for (i = idx; i < len; i++) {

     if (blk->doHeapRegion(_regions.at(i))) {

       blk->incomplete();

       return;

     }

   }

   for (i = 0; i < idx; i++) {

     if (blk->doHeapRegion(_regions.at(i))) {

       blk->incomplete();

       return;

     }

   }

 }

 MemRegion HeapRegionSeq::shrink_by(size_t shrink_bytes,

                                    size_t& num_regions_deleted) {

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

   // we just removed.

   _alloc_search_start = 0;

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

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

   if (_regions.length() == 0) {

     num_regions_deleted = 0;

     return MemRegion();

   }

   int j = _regions.length() - 1;

   HeapWord* end = _regions.at(j)->end();

   HeapWord* last_start = end;

   while (j >= 0 && shrink_bytes > 0) {

     HeapRegion* cur = _regions.at(j);

     // We have to leave humongous regions where they are,

     // and work around them.

     if (cur->isHumongous()) {

       return MemRegion(last_start, end);

     }

     assert(cur == _regions.top(), "Should be top");

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

     shrink_bytes -= cur->capacity();

     num_regions_deleted++;

     _regions.pop();

     last_start = cur->bottom();

     // We need to delete these somehow, but can't currently do so here: if

     // we do, the ZF thread may still access the deleted region.  We'll

     // leave this here as a reminder that we have to do something about

     // this.

     // delete cur;

     j--;

   }

   return MemRegion(last_start, end);

 }

 class PrintHeapRegionClosure : public  HeapRegionClosure {

 public:

   bool doHeapRegion(HeapRegion* r) {

     gclog_or_tty->print(PTR_FORMAT ":", r);

     r->print();

     return false;

   }

 };

 void HeapRegionSeq::print() {

   PrintHeapRegionClosure cl;

   iterate(&cl);

 }