1 /*

     2  * Copyright (c) 2001, 2014, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.

     8  *

     9  * This code is distributed in the hope that it will be useful, but WITHOUT

    10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    12  * version 2 for more details (a copy is included in the LICENSE file that

    13  * accompanied this code).

    14  *

    15  * You should have received a copy of the GNU General Public License version

    16  * 2 along with this work; if not, write to the Free Software Foundation,

    17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    18  *

    19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    20  * or visit www.oracle.com if you need additional information or have any

    21  * questions.

    22  *

    23  */

    24 

    25 #include "precompiled.hpp"

    26 #include "gc_implementation/g1/heapRegion.hpp"

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

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

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

    30 #include "gc_implementation/g1/concurrentG1Refine.hpp"

    31 #include "memory/allocation.hpp"

    32 

    33 void HeapRegionSeq::initialize(G1RegionToSpaceMapper* heap_storage,

    34                                G1RegionToSpaceMapper* prev_bitmap,

    35                                G1RegionToSpaceMapper* next_bitmap,

    36                                G1RegionToSpaceMapper* bot,

    37                                G1RegionToSpaceMapper* cardtable,

    38                                G1RegionToSpaceMapper* card_counts) {

    39   _allocated_heapregions_length = 0;

    40 

    41   _heap_mapper = heap_storage;

    42 

    43   _prev_bitmap_mapper = prev_bitmap;

    44   _next_bitmap_mapper = next_bitmap;

    45 

    46   _bot_mapper = bot;

    47   _cardtable_mapper = cardtable;

    48 

    49   _card_counts_mapper = card_counts;

    50 

    51   MemRegion reserved = heap_storage->reserved();

    52   _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);

    53 

    54   _available_map.resize(_regions.length(), false);

    55   _available_map.clear();

    56 }

    57 

    58 bool HeapRegionSeq::is_available(uint region) const {

    59   return _available_map.at(region);

    60 }

    61 

    62 #ifdef ASSERT

    63 bool HeapRegionSeq::is_free(HeapRegion* hr) const {

    64   return _free_list.contains(hr);

    65 }

    66 #endif

    67 

    68 HeapRegion* HeapRegionSeq::new_heap_region(uint hrs_index) {

    69   HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(hrs_index);

    70   MemRegion mr(bottom, bottom + HeapRegion::GrainWords);

    71   assert(reserved().contains(mr), "invariant");

    72   return new HeapRegion(hrs_index, G1CollectedHeap::heap()->bot_shared(), mr);

    73 }

    74 

    75 void HeapRegionSeq::commit_regions(uint index, size_t num_regions) {

    76   guarantee(num_regions > 0, "Must commit more than zero regions");

    77   guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");

    78 

    79   _num_committed += (uint)num_regions;

    80 

    81   _heap_mapper->commit_regions(index, num_regions);

    82 

    83   // Also commit auxiliary data

    84   _prev_bitmap_mapper->commit_regions(index, num_regions);

    85   _next_bitmap_mapper->commit_regions(index, num_regions);

    86 

    87   _bot_mapper->commit_regions(index, num_regions);

    88   _cardtable_mapper->commit_regions(index, num_regions);

    89 

    90   _card_counts_mapper->commit_regions(index, num_regions);

    91 }

    92 

    93 void HeapRegionSeq::uncommit_regions(uint start, size_t num_regions) {

    94   guarantee(num_regions >= 1, err_msg("Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start));

    95   guarantee(_num_committed >= num_regions, "pre-condition");

    96 

    97   // Print before uncommitting.

    98   if (G1CollectedHeap::heap()->hr_printer()->is_active()) {

    99     for (uint i = start; i < start + num_regions; i++) {

   100       HeapRegion* hr = at(i);

   101       G1CollectedHeap::heap()->hr_printer()->uncommit(hr->bottom(), hr->end());

   102     }

   103   }

   104 

   105   _num_committed -= (uint)num_regions;

   106 

   107   _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);

   108   _heap_mapper->uncommit_regions(start, num_regions);

   109 

   110   // Also uncommit auxiliary data

   111   _prev_bitmap_mapper->uncommit_regions(start, num_regions);

   112   _next_bitmap_mapper->uncommit_regions(start, num_regions);

   113 

   114   _bot_mapper->uncommit_regions(start, num_regions);

   115   _cardtable_mapper->uncommit_regions(start, num_regions);

   116 

   117   _card_counts_mapper->uncommit_regions(start, num_regions);

   118 }

   119 

   120 void HeapRegionSeq::make_regions_available(uint start, uint num_regions) {

   121   guarantee(num_regions > 0, "No point in calling this for zero regions");

   122   commit_regions(start, num_regions);

   123   for (uint i = start; i < start + num_regions; i++) {

   124     if (_regions.get_by_index(i) == NULL) {

   125       HeapRegion* new_hr = new_heap_region(i);

   126       _regions.set_by_index(i, new_hr);

   127       _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);

   128     }

   129   }

   130 

   131   _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);

   132 

   133   for (uint i = start; i < start + num_regions; i++) {

   134     assert(is_available(i), err_msg("Just made region %u available but is apparently not.", i));

   135     HeapRegion* hr = at(i);

   136     if (G1CollectedHeap::heap()->hr_printer()->is_active()) {

   137       G1CollectedHeap::heap()->hr_printer()->commit(hr->bottom(), hr->end());

   138     }

   139     HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);

   140     MemRegion mr(bottom, bottom + HeapRegion::GrainWords);

   141 

   142     hr->initialize(mr);

   143     insert_into_free_list(at(i));

   144   }

   145 }

   146 

   147 uint HeapRegionSeq::expand_by(uint num_regions) {

   148   return expand_at(0, num_regions);

   149 }

   150 

   151 uint HeapRegionSeq::expand_at(uint start, uint num_regions) {

   152   if (num_regions == 0) {

   153     return 0;

   154   }

   155 

   156   uint cur = start;

   157   uint idx_last_found = 0;

   158   uint num_last_found = 0;

   159 

   160   uint expanded = 0;

   161 

   162   while (expanded < num_regions &&

   163          (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {

   164     uint to_expand = MIN2(num_regions - expanded, num_last_found);

   165     make_regions_available(idx_last_found, to_expand);

   166     expanded += to_expand;

   167     cur = idx_last_found + num_last_found + 1;

   168   }

   169 

   170   verify_optional();

   171   return expanded;

   172 }

   173 

   174 uint HeapRegionSeq::find_contiguous(size_t num, bool empty_only) {

   175   uint found = 0;

   176   size_t length_found = 0;

   177   uint cur = 0;

   178 

   179   while (length_found < num && cur < max_length()) {

   180     HeapRegion* hr = _regions.get_by_index(cur);

   181     if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {

   182       // This region is a potential candidate for allocation into.

   183       length_found++;

   184     } else {

   185       // This region is not a candidate. The next region is the next possible one.

   186       found = cur + 1;

   187       length_found = 0;

   188     }

   189     cur++;

   190   }

   191 

   192   if (length_found == num) {

   193     for (uint i = found; i < (found + num); i++) {

   194       HeapRegion* hr = _regions.get_by_index(i);

   195       // sanity check

   196       guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),

   197                 err_msg("Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT

   198                         " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)));

   199     }

   200     return found;

   201   } else {

   202     return G1_NO_HRS_INDEX;

   203   }

   204 }

   205 

   206 HeapRegion* HeapRegionSeq::next_region_in_heap(const HeapRegion* r) const {

   207   guarantee(r != NULL, "Start region must be a valid region");

   208   guarantee(is_available(r->hrs_index()), err_msg("Trying to iterate starting from region %u which is not in the heap", r->hrs_index()));

   209   for (uint i = r->hrs_index() + 1; i < _allocated_heapregions_length; i++) {

   210     HeapRegion* hr = _regions.get_by_index(i);

   211     if (is_available(i)) {

   212       return hr;

   213     }

   214   }

   215   return NULL;

   216 }

   217 

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

   219   uint len = max_length();

   220 

   221   for (uint i = 0; i < len; i++) {

   222     if (!is_available(i)) {

   223       continue;

   224     }

   225     guarantee(at(i) != NULL, err_msg("Tried to access region %u that has a NULL HeapRegion*", i));

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

   227     if (res) {

   228       blk->incomplete();

   229       return;

   230     }

   231   }

   232 }

   233 

   234 uint HeapRegionSeq::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {

   235   guarantee(res_idx != NULL, "checking");

   236   guarantee(start_idx <= (max_length() + 1), "checking");

   237 

   238   uint num_regions = 0;

   239 

   240   uint cur = start_idx;

   241   while (cur < max_length() && is_available(cur)) {

   242     cur++;

   243   }

   244   if (cur == max_length()) {

   245     return num_regions;

   246   }

   247   *res_idx = cur;

   248   while (cur < max_length() && !is_available(cur)) {

   249     cur++;

   250   }

   251   num_regions = cur - *res_idx;

   252 #ifdef ASSERT

   253   for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {

   254     assert(!is_available(i), "just checking");

   255   }

   256   assert(cur == max_length() || num_regions == 0 || is_available(cur),

   257          err_msg("The region at the current position %u must be available or at the end of the heap.", cur));

   258 #endif

   259   return num_regions;

   260 }

   261 

   262 uint HeapRegionSeq::start_region_for_worker(uint worker_i, uint num_workers, uint num_regions) const {

   263   return num_regions * worker_i / num_workers;

   264 }

   265 

   266 void HeapRegionSeq::par_iterate(HeapRegionClosure* blk, uint worker_id, uint num_workers, jint claim_value) const {

   267   const uint start_index = start_region_for_worker(worker_id, num_workers, _allocated_heapregions_length);

   268 

   269   // Every worker will actually look at all regions, skipping over regions that

   270   // are currently not committed.

   271   // This also (potentially) iterates over regions newly allocated during GC. This

   272   // is no problem except for some extra work.

   273   for (uint count = 0; count < _allocated_heapregions_length; count++) {

   274     const uint index = (start_index + count) % _allocated_heapregions_length;

   275     assert(0 <= index && index < _allocated_heapregions_length, "sanity");

   276     // Skip over unavailable regions

   277     if (!is_available(index)) {

   278       continue;

   279     }

   280     HeapRegion* r = _regions.get_by_index(index);

   281     // We'll ignore "continues humongous" regions (we'll process them

   282     // when we come across their corresponding "start humongous"

   283     // region) and regions already claimed.

   284     if (r->claim_value() == claim_value || r->continuesHumongous()) {

   285       continue;

   286     }

   287     // OK, try to claim it

   288     if (!r->claimHeapRegion(claim_value)) {

   289       continue;

   290     }

   291     // Success!

   292     if (r->startsHumongous()) {

   293       // If the region is "starts humongous" we'll iterate over its

   294       // "continues humongous" first; in fact we'll do them

   295       // first. The order is important. In one case, calling the

   296       // closure on the "starts humongous" region might de-allocate

   297       // and clear all its "continues humongous" regions and, as a

   298       // result, we might end up processing them twice. So, we'll do

   299       // them first (note: most closures will ignore them anyway) and

   300       // then we'll do the "starts humongous" region.

   301       for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {

   302         HeapRegion* chr = _regions.get_by_index(ch_index);

   303 

   304         assert(chr->continuesHumongous(), "Must be humongous region");

   305         assert(chr->humongous_start_region() == r,

   306                err_msg("Must work on humongous continuation of the original start region "

   307                        PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));

   308         assert(chr->claim_value() != claim_value,

   309                "Must not have been claimed yet because claiming of humongous continuation first claims the start region");

   310 

   311         bool claim_result = chr->claimHeapRegion(claim_value);

   312         // We should always be able to claim it; no one else should

   313         // be trying to claim this region.

   314         guarantee(claim_result, "We should always be able to claim the continuesHumongous part of the humongous object");

   315 

   316         bool res2 = blk->doHeapRegion(chr);

   317         if (res2) {

   318           return;

   319         }

   320 

   321         // Right now, this holds (i.e., no closure that actually

   322         // does something with "continues humongous" regions

   323         // clears them). We might have to weaken it in the future,

   324         // but let's leave these two asserts here for extra safety.

   325         assert(chr->continuesHumongous(), "should still be the case");

   326         assert(chr->humongous_start_region() == r, "sanity");

   327       }

   328     }

   329 

   330     bool res = blk->doHeapRegion(r);

   331     if (res) {

   332       return;

   333     }

   334   }

   335 }

   336 

   337 uint HeapRegionSeq::shrink_by(uint num_regions_to_remove) {

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

   339   assert(length() <= _allocated_heapregions_length, "invariant");

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

   341   assert(num_regions_to_remove < length(), "We should never remove all regions");

   342 

   343   if (num_regions_to_remove == 0) {

   344     return 0;

   345   }

   346 

   347   uint removed = 0;

   348   uint cur = _allocated_heapregions_length - 1;

   349   uint idx_last_found = 0;

   350   uint num_last_found = 0;

   351 

   352   while ((removed < num_regions_to_remove) &&

   353       (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {

   354     // Only allow uncommit from the end of the heap.

   355     if ((idx_last_found + num_last_found) != _allocated_heapregions_length) {

   356       return 0;

   357     }

   358     uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);

   359 

   360     uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);

   361 

   362     cur -= num_last_found;

   363     removed += to_remove;

   364   }

   365 

   366   verify_optional();

   367 

   368   return removed;

   369 }

   370 

   371 uint HeapRegionSeq::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {

   372   guarantee(start_idx < _allocated_heapregions_length, "checking");

   373   guarantee(res_idx != NULL, "checking");

   374 

   375   uint num_regions_found = 0;

   376 

   377   jlong cur = start_idx;

   378   while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {

   379     cur--;

   380   }

   381   if (cur == -1) {

   382     return num_regions_found;

   383   }

   384   jlong old_cur = cur;

   385   // cur indexes the first empty region

   386   while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {

   387     cur--;

   388   }

   389   *res_idx = cur + 1;

   390   num_regions_found = old_cur - cur;

   391 

   392 #ifdef ASSERT

   393   for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {

   394     assert(at(i)->is_empty(), "just checking");

   395   }

   396 #endif

   397   return num_regions_found;

   398 }

   399 

   400 void HeapRegionSeq::verify() {

   401   guarantee(length() <= _allocated_heapregions_length,

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

   403                     length(), _allocated_heapregions_length));

   404   guarantee(_allocated_heapregions_length <= max_length(),

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

   406                     _allocated_heapregions_length, max_length()));

   407 

   408   bool prev_committed = true;

   409   uint num_committed = 0;

   410   HeapWord* prev_end = heap_bottom();

   411   for (uint i = 0; i < _allocated_heapregions_length; i++) {

   412     if (!is_available(i)) {

   413       prev_committed = false;

   414       continue;

   415     }

   416     num_committed++;

   417     HeapRegion* hr = _regions.get_by_index(i);

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

   419     guarantee(!prev_committed || hr->bottom() == prev_end,

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

   421                       i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));

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

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

   424     // Asserts will fire if i is >= _length

   425     HeapWord* addr = hr->bottom();

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

   427     // We cannot check whether the region is part of a particular set: at the time

   428     // this method may be called, we have only completed allocation of the regions,

   429     // but not put into a region set.

   430     prev_committed = true;

   431     if (hr->startsHumongous()) {

   432       prev_end = hr->orig_end();

   433     } else {

   434       prev_end = hr->end();

   435     }

   436   }

   437   for (uint i = _allocated_heapregions_length; i < max_length(); i++) {

   438     guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));

   439   }

   440 

   441   guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));

   442   _free_list.verify();

   443 }

   444 

   445 #ifndef PRODUCT

   446 void HeapRegionSeq::verify_optional() {

   447   verify();

   448 }

   449 #endif // PRODUCT

   450