1 /*
   2  * Copyright (c) 2014, 2015, 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 #ifndef SHARE_VM_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  26 #define SHARE_VM_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
  27 
  28 #include "gc/g1/g1ParScanThreadState.hpp"
  29 #include "gc/g1/g1RemSet.inline.hpp"
  30 #include "oops/oop.inline.hpp"
  31 
  32 template <class T> void G1ParScanThreadState::do_oop_evac(T* p, HeapRegion* from) {
  33   assert(!oopDesc::is_null(oopDesc::load_decode_heap_oop(p)),
  34          "Reference should not be NULL here as such are never pushed to the task queue.");
  35   oop obj = oopDesc::load_decode_heap_oop_not_null(p);
  36 
  37   // Although we never intentionally push references outside of the collection
  38   // set, due to (benign) races in the claim mechanism during RSet scanning more
  39   // than one thread might claim the same card. So the same card may be
  40   // processed multiple times. So redo this check.
  41   const InCSetState in_cset_state = _g1h->in_cset_state(obj);
  42   if (in_cset_state.is_in_cset()) {
  43     markOop m = obj->mark();
  44     if (m->is_marked()) {
  45       obj = (oop) m->decode_pointer();
  46     } else {
  47       obj = copy_to_survivor_space(in_cset_state, obj, m);
  48     }
  49     oopDesc::encode_store_heap_oop(p, obj);
  50   } else if (in_cset_state.is_humongous()) {
  51     _g1h->set_humongous_is_live(obj);
  52   } else {
  53     assert(in_cset_state.is_default() || in_cset_state.is_ext(),
  54            "In_cset_state must be NotInCSet or Ext here, but is " CSETSTATE_FORMAT, in_cset_state.value());
  55   }
  56 
  57   assert(obj != NULL, "Must be");
  58   update_rs(from, p, obj);
  59 }
  60 
  61 template <class T> inline void G1ParScanThreadState::push_on_queue(T* ref) {
  62   assert(verify_ref(ref), "sanity");
  63   _refs->push(ref);
  64 }
  65 
  66 inline void G1ParScanThreadState::do_oop_partial_array(oop* p) {
  67   assert(has_partial_array_mask(p), "invariant");
  68   oop from_obj = clear_partial_array_mask(p);
  69 
  70   assert(_g1h->is_in_reserved(from_obj), "must be in heap.");
  71   assert(from_obj->is_objArray(), "must be obj array");
  72   objArrayOop from_obj_array = objArrayOop(from_obj);
  73   // The from-space object contains the real length.
  74   int length                 = from_obj_array->length();
  75 
  76   assert(from_obj->is_forwarded(), "must be forwarded");
  77   oop to_obj                 = from_obj->forwardee();
  78   assert(from_obj != to_obj, "should not be chunking self-forwarded objects");
  79   objArrayOop to_obj_array   = objArrayOop(to_obj);
  80   // We keep track of the next start index in the length field of the
  81   // to-space object.
  82   int next_index             = to_obj_array->length();
  83   assert(0 <= next_index && next_index < length,
  84          "invariant, next index: %d, length: %d", next_index, length);
  85 
  86   int start                  = next_index;
  87   int end                    = length;
  88   int remainder              = end - start;
  89   // We'll try not to push a range that's smaller than ParGCArrayScanChunk.
  90   if (remainder > 2 * ParGCArrayScanChunk) {
  91     end = start + ParGCArrayScanChunk;
  92     to_obj_array->set_length(end);
  93     // Push the remainder before we process the range in case another
  94     // worker has run out of things to do and can steal it.
  95     oop* from_obj_p = set_partial_array_mask(from_obj);
  96     push_on_queue(from_obj_p);
  97   } else {
  98     assert(length == end, "sanity");
  99     // We'll process the final range for this object. Restore the length
 100     // so that the heap remains parsable in case of evacuation failure.
 101     to_obj_array->set_length(end);
 102   }
 103   _scanner.set_region(_g1h->heap_region_containing(to_obj));
 104   // Process indexes [start,end). It will also process the header
 105   // along with the first chunk (i.e., the chunk with start == 0).
 106   // Note that at this point the length field of to_obj_array is not
 107   // correct given that we are using it to keep track of the next
 108   // start index. oop_iterate_range() (thankfully!) ignores the length
 109   // field and only relies on the start / end parameters.  It does
 110   // however return the size of the object which will be incorrect. So
 111   // we have to ignore it even if we wanted to use it.
 112   to_obj_array->oop_iterate_range(&_scanner, start, end);
 113 }
 114 
 115 template <class T> inline void G1ParScanThreadState::deal_with_reference(T* ref_to_scan) {
 116   if (!has_partial_array_mask(ref_to_scan)) {
 117     HeapRegion* r = _g1h->heap_region_containing(ref_to_scan);
 118     do_oop_evac(ref_to_scan, r);
 119   } else {
 120     do_oop_partial_array((oop*)ref_to_scan);
 121   }
 122 }
 123 
 124 inline void G1ParScanThreadState::dispatch_reference(StarTask ref) {
 125   assert(verify_task(ref), "sanity");
 126   if (ref.is_narrow()) {
 127     deal_with_reference((narrowOop*)ref);
 128   } else {
 129     deal_with_reference((oop*)ref);
 130   }
 131 }
 132 
 133 void G1ParScanThreadState::steal_and_trim_queue(RefToScanQueueSet *task_queues) {
 134   StarTask stolen_task;
 135   while (task_queues->steal(_worker_id, &_hash_seed, stolen_task)) {
 136     assert(verify_task(stolen_task), "sanity");
 137     dispatch_reference(stolen_task);
 138 
 139     // We've just processed a reference and we might have made
 140     // available new entries on the queues. So we have to make sure
 141     // we drain the queues as necessary.
 142     trim_queue();
 143   }
 144 }
 145 
 146 #endif // SHARE_VM_GC_G1_G1PARSCANTHREADSTATE_INLINE_HPP
 147