1 /*
   2  * Copyright (c) 1997, 2017, 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/serial/genMarkSweep.hpp"
  27 #include "gc/shared/blockOffsetTable.inline.hpp"
  28 #include "gc/shared/cardTableRS.hpp"
  29 #include "gc/shared/collectedHeap.inline.hpp"
  30 #include "gc/shared/gcLocker.hpp"
  31 #include "gc/shared/gcTimer.hpp"
  32 #include "gc/shared/gcTrace.hpp"
  33 #include "gc/shared/genCollectedHeap.hpp"
  34 #include "gc/shared/genOopClosures.hpp"
  35 #include "gc/shared/genOopClosures.inline.hpp"
  36 #include "gc/shared/generation.hpp"
  37 #include "gc/shared/space.inline.hpp"
  38 #include "gc/shared/spaceDecorator.hpp"
  39 #include "logging/log.hpp"
  40 #include "memory/allocation.inline.hpp"
  41 #include "oops/oop.inline.hpp"
  42 #include "runtime/java.hpp"
  43 #include "utilities/copy.hpp"
  44 #include "utilities/events.hpp"
  45 
  46 Generation::Generation(ReservedSpace rs, size_t initial_size) :
  47   _ref_processor(NULL),
  48   _gc_manager(NULL) {
  49   if (!_virtual_space.initialize(rs, initial_size)) {
  50     vm_exit_during_initialization("Could not reserve enough space for "
  51                     "object heap");
  52   }
  53   // Mangle all of the the initial generation.
  54   if (ZapUnusedHeapArea) {
  55     MemRegion mangle_region((HeapWord*)_virtual_space.low(),
  56       (HeapWord*)_virtual_space.high());
  57     SpaceMangler::mangle_region(mangle_region);
  58   }
  59   _reserved = MemRegion((HeapWord*)_virtual_space.low_boundary(),
  60           (HeapWord*)_virtual_space.high_boundary());
  61 }
  62 
  63 size_t Generation::initial_size() {
  64   GenCollectedHeap* gch = GenCollectedHeap::heap();
  65   if (gch->is_young_gen(this)) {
  66     return gch->young_gen_spec()->init_size();
  67   }
  68   return gch->old_gen_spec()->init_size();
  69 }
  70 
  71 size_t Generation::max_capacity() const {
  72   return reserved().byte_size();
  73 }
  74 
  75 // By default we get a single threaded default reference processor;
  76 // generations needing multi-threaded refs processing or discovery override this method.
  77 void Generation::ref_processor_init() {
  78   assert(_ref_processor == NULL, "a reference processor already exists");
  79   assert(!_reserved.is_empty(), "empty generation?");
  80   _ref_processor = new ReferenceProcessor(_reserved);    // a vanilla reference processor
  81   if (_ref_processor == NULL) {
  82     vm_exit_during_initialization("Could not allocate ReferenceProcessor object");
  83   }
  84 }
  85 
  86 void Generation::print() const { print_on(tty); }
  87 
  88 void Generation::print_on(outputStream* st)  const {
  89   st->print(" %-20s", name());
  90   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
  91              capacity()/K, used()/K);
  92   st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
  93               p2i(_virtual_space.low_boundary()),
  94               p2i(_virtual_space.high()),
  95               p2i(_virtual_space.high_boundary()));
  96 }
  97 
  98 void Generation::print_summary_info_on(outputStream* st) {
  99   StatRecord* sr = stat_record();
 100   double time = sr->accumulated_time.seconds();
 101   st->print_cr("Accumulated %s generation GC time %3.7f secs, "
 102                "%u GC's, avg GC time %3.7f",
 103                GenCollectedHeap::heap()->is_young_gen(this) ? "young" : "old" ,
 104                time,
 105                sr->invocations,
 106                sr->invocations > 0 ? time / sr->invocations : 0.0);
 107 }
 108 
 109 // Utility iterator classes
 110 
 111 class GenerationIsInReservedClosure : public SpaceClosure {
 112  public:
 113   const void* _p;
 114   Space* sp;
 115   virtual void do_space(Space* s) {
 116     if (sp == NULL) {
 117       if (s->is_in_reserved(_p)) sp = s;
 118     }
 119   }
 120   GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {}
 121 };
 122 
 123 class GenerationIsInClosure : public SpaceClosure {
 124  public:
 125   const void* _p;
 126   Space* sp;
 127   virtual void do_space(Space* s) {
 128     if (sp == NULL) {
 129       if (s->is_in(_p)) sp = s;
 130     }
 131   }
 132   GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {}
 133 };
 134 
 135 bool Generation::is_in(const void* p) const {
 136   GenerationIsInClosure blk(p);
 137   ((Generation*)this)->space_iterate(&blk);
 138   return blk.sp != NULL;
 139 }
 140 
 141 size_t Generation::max_contiguous_available() const {
 142   // The largest number of contiguous free words in this or any higher generation.
 143   size_t avail = contiguous_available();
 144   size_t old_avail = 0;
 145   if (GenCollectedHeap::heap()->is_young_gen(this)) {
 146     old_avail = GenCollectedHeap::heap()->old_gen()->contiguous_available();
 147   }
 148   return MAX2(avail, old_avail);
 149 }
 150 
 151 bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
 152   size_t available = max_contiguous_available();
 153   bool   res = (available >= max_promotion_in_bytes);
 154   log_trace(gc)("Generation: promo attempt is%s safe: available(" SIZE_FORMAT ") %s max_promo(" SIZE_FORMAT ")",
 155                 res? "":" not", available, res? ">=":"<", max_promotion_in_bytes);
 156   return res;
 157 }
 158 
 159 // Ignores "ref" and calls allocate().
 160 oop Generation::promote(oop obj, size_t obj_size) {
 161   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
 162 
 163 #ifndef PRODUCT
 164   if (GenCollectedHeap::heap()->promotion_should_fail()) {
 165     return NULL;
 166   }
 167 #endif  // #ifndef PRODUCT
 168 
 169   HeapWord* result = allocate(obj_size, false);
 170   if (result != NULL) {
 171     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
 172     return oop(result);
 173   } else {
 174     GenCollectedHeap* gch = GenCollectedHeap::heap();
 175     return gch->handle_failed_promotion(this, obj, obj_size);
 176   }
 177 }
 178 
 179 oop Generation::par_promote(int thread_num,
 180                             oop obj, markOop m, size_t word_sz) {
 181   // Could do a bad general impl here that gets a lock.  But no.
 182   ShouldNotCallThis();
 183   return NULL;
 184 }
 185 
 186 Space* Generation::space_containing(const void* p) const {
 187   GenerationIsInReservedClosure blk(p);
 188   // Cast away const
 189   ((Generation*)this)->space_iterate(&blk);
 190   return blk.sp;
 191 }
 192 
 193 // Some of these are mediocre general implementations.  Should be
 194 // overridden to get better performance.
 195 
 196 class GenerationBlockStartClosure : public SpaceClosure {
 197  public:
 198   const void* _p;
 199   HeapWord* _start;
 200   virtual void do_space(Space* s) {
 201     if (_start == NULL && s->is_in_reserved(_p)) {
 202       _start = s->block_start(_p);
 203     }
 204   }
 205   GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; }
 206 };
 207 
 208 HeapWord* Generation::block_start(const void* p) const {
 209   GenerationBlockStartClosure blk(p);
 210   // Cast away const
 211   ((Generation*)this)->space_iterate(&blk);
 212   return blk._start;
 213 }
 214 
 215 class GenerationBlockSizeClosure : public SpaceClosure {
 216  public:
 217   const HeapWord* _p;
 218   size_t size;
 219   virtual void do_space(Space* s) {
 220     if (size == 0 && s->is_in_reserved(_p)) {
 221       size = s->block_size(_p);
 222     }
 223   }
 224   GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; }
 225 };
 226 
 227 size_t Generation::block_size(const HeapWord* p) const {
 228   GenerationBlockSizeClosure blk(p);
 229   // Cast away const
 230   ((Generation*)this)->space_iterate(&blk);
 231   assert(blk.size > 0, "seems reasonable");
 232   return blk.size;
 233 }
 234 
 235 class GenerationBlockIsObjClosure : public SpaceClosure {
 236  public:
 237   const HeapWord* _p;
 238   bool is_obj;
 239   virtual void do_space(Space* s) {
 240     if (!is_obj && s->is_in_reserved(_p)) {
 241       is_obj |= s->block_is_obj(_p);
 242     }
 243   }
 244   GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; }
 245 };
 246 
 247 bool Generation::block_is_obj(const HeapWord* p) const {
 248   GenerationBlockIsObjClosure blk(p);
 249   // Cast away const
 250   ((Generation*)this)->space_iterate(&blk);
 251   return blk.is_obj;
 252 }
 253 
 254 class GenerationOopIterateClosure : public SpaceClosure {
 255  public:
 256   ExtendedOopClosure* _cl;
 257   virtual void do_space(Space* s) {
 258     s->oop_iterate(_cl);
 259   }
 260   GenerationOopIterateClosure(ExtendedOopClosure* cl) :
 261     _cl(cl) {}
 262 };
 263 
 264 void Generation::oop_iterate(ExtendedOopClosure* cl) {
 265   GenerationOopIterateClosure blk(cl);
 266   space_iterate(&blk);
 267 }
 268 
 269 void Generation::younger_refs_in_space_iterate(Space* sp,
 270                                                OopsInGenClosure* cl,
 271                                                uint n_threads) {
 272   CardTableRS* rs = GenCollectedHeap::heap()->rem_set();
 273   rs->younger_refs_in_space_iterate(sp, cl, n_threads);
 274 }
 275 
 276 class GenerationObjIterateClosure : public SpaceClosure {
 277  private:
 278   ObjectClosure* _cl;
 279  public:
 280   virtual void do_space(Space* s) {
 281     s->object_iterate(_cl);
 282   }
 283   GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
 284 };
 285 
 286 void Generation::object_iterate(ObjectClosure* cl) {
 287   GenerationObjIterateClosure blk(cl);
 288   space_iterate(&blk);
 289 }
 290 
 291 class GenerationSafeObjIterateClosure : public SpaceClosure {
 292  private:
 293   ObjectClosure* _cl;
 294  public:
 295   virtual void do_space(Space* s) {
 296     s->safe_object_iterate(_cl);
 297   }
 298   GenerationSafeObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
 299 };
 300 
 301 void Generation::safe_object_iterate(ObjectClosure* cl) {
 302   GenerationSafeObjIterateClosure blk(cl);
 303   space_iterate(&blk);
 304 }
 305 
 306 void Generation::prepare_for_compaction(CompactPoint* cp) {
 307   // Generic implementation, can be specialized
 308   CompactibleSpace* space = first_compaction_space();
 309   while (space != NULL) {
 310     space->prepare_for_compaction(cp);
 311     space = space->next_compaction_space();
 312   }
 313 }
 314 
 315 class AdjustPointersClosure: public SpaceClosure {
 316  public:
 317   void do_space(Space* sp) {
 318     sp->adjust_pointers();
 319   }
 320 };
 321 
 322 void Generation::adjust_pointers() {
 323   // Note that this is done over all spaces, not just the compactible
 324   // ones.
 325   AdjustPointersClosure blk;
 326   space_iterate(&blk, true);
 327 }
 328 
 329 void Generation::compact() {
 330   CompactibleSpace* sp = first_compaction_space();
 331   while (sp != NULL) {
 332     sp->compact();
 333     sp = sp->next_compaction_space();
 334   }
 335 }