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 /*

  * Copyright (c) 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

  * questions.

  *

  */

 #include "precompiled.hpp"

 #include "gc_implementation/g1/g1AllocRegion.inline.hpp"

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

 G1CollectedHeap* G1AllocRegion::_g1h = NULL;

 HeapRegion* G1AllocRegion::_dummy_region = NULL;

 void G1AllocRegion::setup(G1CollectedHeap* g1h, HeapRegion* dummy_region) {

   assert(_dummy_region == NULL, "should be set once");

   assert(dummy_region != NULL, "pre-condition");

   assert(dummy_region->free() == 0, "pre-condition");

   // Make sure that any allocation attempt on this region will fail

   // and will not trigger any asserts.

   assert(allocate(dummy_region, 1, false) == NULL, "should fail");

   assert(par_allocate(dummy_region, 1, false) == NULL, "should fail");

   assert(allocate(dummy_region, 1, true) == NULL, "should fail");

   assert(par_allocate(dummy_region, 1, true) == NULL, "should fail");

   _g1h = g1h;

   _dummy_region = dummy_region;

 }

 void G1AllocRegion::fill_up_remaining_space(HeapRegion* alloc_region,

                                             bool bot_updates) {

   assert(alloc_region != NULL && alloc_region != _dummy_region,

          "pre-condition");

   // Other threads might still be trying to allocate using a CAS out

   // of the region we are trying to retire, as they can do so without

   // holding the lock. So, we first have to make sure that noone else

   // can allocate out of it by doing a maximal allocation. Even if our

   // CAS attempt fails a few times, we'll succeed sooner or later

   // given that failed CAS attempts mean that the region is getting

   // closed to being full.

   size_t free_word_size = alloc_region->free() / HeapWordSize;

   // This is the minimum free chunk we can turn into a dummy

   // object. If the free space falls below this, then noone can

   // allocate in this region anyway (all allocation requests will be

   // of a size larger than this) so we won't have to perform the dummy

   // allocation.

   size_t min_word_size_to_fill = CollectedHeap::min_fill_size();

   while (free_word_size >= min_word_size_to_fill) {

     HeapWord* dummy = par_allocate(alloc_region, free_word_size, bot_updates);

     if (dummy != NULL) {

       // If the allocation was successful we should fill in the space.

       CollectedHeap::fill_with_object(dummy, free_word_size);

       alloc_region->set_pre_dummy_top(dummy);

       break;

     }

     free_word_size = alloc_region->free() / HeapWordSize;

     // It's also possible that someone else beats us to the

     // allocation and they fill up the region. In that case, we can

     // just get out of the loop.

   }

   assert(alloc_region->free() / HeapWordSize < min_word_size_to_fill,

          "post-condition");

 }

 void G1AllocRegion::retire(bool fill_up) {

   assert(_alloc_region != NULL, ar_ext_msg(this, "not initialized properly"));

   trace("retiring");

   HeapRegion* alloc_region = _alloc_region;

   if (alloc_region != _dummy_region) {

     // We never have to check whether the active region is empty or not,

     // and potentially free it if it is, given that it's guaranteed that

     // it will never be empty.

     assert(!alloc_region->is_empty(),

            ar_ext_msg(this, "the alloc region should never be empty"));

     if (fill_up) {

       fill_up_remaining_space(alloc_region, _bot_updates);

     }

     assert(alloc_region->used() >= _used_bytes_before,

            ar_ext_msg(this, "invariant"));

     size_t allocated_bytes = alloc_region->used() - _used_bytes_before;

     retire_region(alloc_region, allocated_bytes);

     _used_bytes_before = 0;

     _alloc_region = _dummy_region;

   }

   trace("retired");

 }

 HeapWord* G1AllocRegion::new_alloc_region_and_allocate(size_t word_size,

                                                        bool force) {

   assert(_alloc_region == _dummy_region, ar_ext_msg(this, "pre-condition"));

   assert(_used_bytes_before == 0, ar_ext_msg(this, "pre-condition"));

   trace("attempting region allocation");

   HeapRegion* new_alloc_region = allocate_new_region(word_size, force);

   if (new_alloc_region != NULL) {

     new_alloc_region->reset_pre_dummy_top();

     // Need to do this before the allocation

     _used_bytes_before = new_alloc_region->used();

     HeapWord* result = allocate(new_alloc_region, word_size, _bot_updates);

     assert(result != NULL, ar_ext_msg(this, "the allocation should succeeded"));

     OrderAccess::storestore();

     // Note that we first perform the allocation and then we store the

     // region in _alloc_region. This is the reason why an active region

     // can never be empty.

     _alloc_region = new_alloc_region;

     _count += 1;

     trace("region allocation successful");

     return result;

   } else {

     trace("region allocation failed");

     return NULL;

   }

   ShouldNotReachHere();

 }

 void G1AllocRegion::fill_in_ext_msg(ar_ext_msg* msg, const char* message) {

   msg->append("[%s] %s c: "SIZE_FORMAT" b: %s r: "PTR_FORMAT" u: "SIZE_FORMAT,

               _name, message, _count, BOOL_TO_STR(_bot_updates),

               _alloc_region, _used_bytes_before);

 }

 void G1AllocRegion::init() {

   trace("initializing");

   assert(_alloc_region == NULL && _used_bytes_before == 0,

          ar_ext_msg(this, "pre-condition"));

   assert(_dummy_region != NULL, ar_ext_msg(this, "should have been set"));

   _alloc_region = _dummy_region;

   _count = 0;

   trace("initialized");

 }

 void G1AllocRegion::set(HeapRegion* alloc_region) {

   trace("setting");

   // We explicitly check that the region is not empty to make sure we

   // maintain the "the alloc region cannot be empty" invariant.

   assert(alloc_region != NULL && !alloc_region->is_empty(),

          ar_ext_msg(this, "pre-condition"));

   assert(_alloc_region == _dummy_region &&

          _used_bytes_before == 0 && _count == 0,

          ar_ext_msg(this, "pre-condition"));

   _used_bytes_before = alloc_region->used();

   _alloc_region = alloc_region;

   _count += 1;

   trace("set");

 }

 HeapRegion* G1AllocRegion::release() {

   trace("releasing");

   HeapRegion* alloc_region = _alloc_region;

   retire(false /* fill_up */);

   assert(_alloc_region == _dummy_region,

          ar_ext_msg(this, "post-condition of retire()"));

   _alloc_region = NULL;

   trace("released");

   return (alloc_region == _dummy_region) ? NULL : alloc_region;

 }

 #if G1_ALLOC_REGION_TRACING

 void G1AllocRegion::trace(const char* str, size_t word_size, HeapWord* result) {

   // All the calls to trace that set either just the size or the size

   // and the result are considered part of level 2 tracing and are

   // skipped during level 1 tracing.

   if ((word_size == 0 && result == NULL) || (G1_ALLOC_REGION_TRACING > 1)) {

     const size_t buffer_length = 128;

     char hr_buffer[buffer_length];

     char rest_buffer[buffer_length];

     HeapRegion* alloc_region = _alloc_region;

     if (alloc_region == NULL) {

       jio_snprintf(hr_buffer, buffer_length, "NULL");

     } else if (alloc_region == _dummy_region) {

       jio_snprintf(hr_buffer, buffer_length, "DUMMY");

     } else {

       jio_snprintf(hr_buffer, buffer_length,

                    HR_FORMAT, HR_FORMAT_PARAMS(alloc_region));

     }

     if (G1_ALLOC_REGION_TRACING > 1) {

       if (result != NULL) {

         jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT" "PTR_FORMAT,

                      word_size, result);

       } else if (word_size != 0) {

         jio_snprintf(rest_buffer, buffer_length, SIZE_FORMAT, word_size);

       } else {

         jio_snprintf(rest_buffer, buffer_length, "");

       }

     } else {

       jio_snprintf(rest_buffer, buffer_length, "");

     }

     tty->print_cr("[%s] "SIZE_FORMAT" %s : %s %s",

                   _name, _count, hr_buffer, str, rest_buffer);

   }

 }

 #endif // G1_ALLOC_REGION_TRACING

 G1AllocRegion::G1AllocRegion(const char* name,

                              bool bot_updates)

   : _name(name), _bot_updates(bot_updates),

     _alloc_region(NULL), _count(0), _used_bytes_before(0) { }