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/shared/blockOffsetTable.inline.hpp"
  27 #include "gc/shared/cardTableRS.hpp"
  28 #include "gc/shared/collectedHeap.inline.hpp"
  29 #include "gc/shared/gcLocker.hpp"
  30 #include "gc/shared/gcTimer.hpp"
  31 #include "gc/shared/gcTrace.hpp"
  32 #include "gc/shared/genCollectedHeap.hpp"
  33 #include "gc/shared/genOopClosures.hpp"
  34 #include "gc/shared/genOopClosures.inline.hpp"
  35 #include "gc/shared/generation.hpp"
  36 #include "gc/shared/generationSpec.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   _gc_manager(NULL),
  48   _ref_processor(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 // This is for CMS. It returns stable monotonic used space size.
  72 // Remove this when CMS is removed.
  73 size_t Generation::used_stable() const {
  74   return used();
  75 }
  76 
  77 size_t Generation::max_capacity() const {
  78   return reserved().byte_size();
  79 }
  80 
  81 // By default we get a single threaded default reference processor;
  82 // generations needing multi-threaded refs processing or discovery override this method.
  83 void Generation::ref_processor_init() {
  84   assert(_ref_processor == NULL, "a reference processor already exists");
  85   assert(!_reserved.is_empty(), "empty generation?");
  86   _span_based_discoverer.set_span(_reserved);
  87   _ref_processor = new ReferenceProcessor(&_span_based_discoverer);    // a vanilla reference processor
  88   if (_ref_processor == NULL) {
  89     vm_exit_during_initialization("Could not allocate ReferenceProcessor object");
  90   }
  91 }
  92 
  93 void Generation::print() const { print_on(tty); }
  94 
  95 void Generation::print_on(outputStream* st)  const {
  96   st->print(" %-20s", name());
  97   st->print(" total " SIZE_FORMAT "K, used " SIZE_FORMAT "K",
  98              capacity()/K, used()/K);
  99   st->print_cr(" [" INTPTR_FORMAT ", " INTPTR_FORMAT ", " INTPTR_FORMAT ")",
 100               p2i(_virtual_space.low_boundary()),
 101               p2i(_virtual_space.high()),
 102               p2i(_virtual_space.high_boundary()));
 103 }
 104 
 105 void Generation::print_summary_info_on(outputStream* st) {
 106   StatRecord* sr = stat_record();
 107   double time = sr->accumulated_time.seconds();
 108   st->print_cr("Accumulated %s generation GC time %3.7f secs, "
 109                "%u GC's, avg GC time %3.7f",
 110                GenCollectedHeap::heap()->is_young_gen(this) ? "young" : "old" ,
 111                time,
 112                sr->invocations,
 113                sr->invocations > 0 ? time / sr->invocations : 0.0);
 114 }
 115 
 116 // Utility iterator classes
 117 
 118 class GenerationIsInReservedClosure : public SpaceClosure {
 119  public:
 120   const void* _p;
 121   Space* sp;
 122   virtual void do_space(Space* s) {
 123     if (sp == NULL) {
 124       if (s->is_in_reserved(_p)) sp = s;
 125     }
 126   }
 127   GenerationIsInReservedClosure(const void* p) : _p(p), sp(NULL) {}
 128 };
 129 
 130 class GenerationIsInClosure : public SpaceClosure {
 131  public:
 132   const void* _p;
 133   Space* sp;
 134   virtual void do_space(Space* s) {
 135     if (sp == NULL) {
 136       if (s->is_in(_p)) sp = s;
 137     }
 138   }
 139   GenerationIsInClosure(const void* p) : _p(p), sp(NULL) {}
 140 };
 141 
 142 bool Generation::is_in(const void* p) const {
 143   GenerationIsInClosure blk(p);
 144   ((Generation*)this)->space_iterate(&blk);
 145   return blk.sp != NULL;
 146 }
 147 
 148 size_t Generation::max_contiguous_available() const {
 149   // The largest number of contiguous free words in this or any higher generation.
 150   size_t avail = contiguous_available();
 151   size_t old_avail = 0;
 152   if (GenCollectedHeap::heap()->is_young_gen(this)) {
 153     old_avail = GenCollectedHeap::heap()->old_gen()->contiguous_available();
 154   }
 155   return MAX2(avail, old_avail);
 156 }
 157 
 158 bool Generation::promotion_attempt_is_safe(size_t max_promotion_in_bytes) const {
 159   size_t available = max_contiguous_available();
 160   bool   res = (available >= max_promotion_in_bytes);
 161   log_trace(gc)("Generation: promo attempt is%s safe: available(" SIZE_FORMAT ") %s max_promo(" SIZE_FORMAT ")",
 162                 res? "":" not", available, res? ">=":"<", max_promotion_in_bytes);
 163   return res;
 164 }
 165 
 166 // Ignores "ref" and calls allocate().
 167 oop Generation::promote(oop obj, size_t obj_size) {
 168   assert(obj_size == (size_t)obj->size(), "bad obj_size passed in");
 169 
 170 #ifndef PRODUCT
 171   if (GenCollectedHeap::heap()->promotion_should_fail()) {
 172     return NULL;
 173   }
 174 #endif  // #ifndef PRODUCT
 175 
 176   HeapWord* result = allocate(obj_size, false);
 177   if (result != NULL) {
 178     Copy::aligned_disjoint_words((HeapWord*)obj, result, obj_size);
 179     return oop(result);
 180   } else {
 181     GenCollectedHeap* gch = GenCollectedHeap::heap();
 182     return gch->handle_failed_promotion(this, obj, obj_size);
 183   }
 184 }
 185 
 186 oop Generation::par_promote(int thread_num,
 187                             oop obj, markOop m, size_t word_sz) {
 188   // Could do a bad general impl here that gets a lock.  But no.
 189   ShouldNotCallThis();
 190   return NULL;
 191 }
 192 
 193 Space* Generation::space_containing(const void* p) const {
 194   GenerationIsInReservedClosure blk(p);
 195   // Cast away const
 196   ((Generation*)this)->space_iterate(&blk);
 197   return blk.sp;
 198 }
 199 
 200 // Some of these are mediocre general implementations.  Should be
 201 // overridden to get better performance.
 202 
 203 class GenerationBlockStartClosure : public SpaceClosure {
 204  public:
 205   const void* _p;
 206   HeapWord* _start;
 207   virtual void do_space(Space* s) {
 208     if (_start == NULL && s->is_in_reserved(_p)) {
 209       _start = s->block_start(_p);
 210     }
 211   }
 212   GenerationBlockStartClosure(const void* p) { _p = p; _start = NULL; }
 213 };
 214 
 215 HeapWord* Generation::block_start(const void* p) const {
 216   GenerationBlockStartClosure blk(p);
 217   // Cast away const
 218   ((Generation*)this)->space_iterate(&blk);
 219   return blk._start;
 220 }
 221 
 222 class GenerationBlockSizeClosure : public SpaceClosure {
 223  public:
 224   const HeapWord* _p;
 225   size_t size;
 226   virtual void do_space(Space* s) {
 227     if (size == 0 && s->is_in_reserved(_p)) {
 228       size = s->block_size(_p);
 229     }
 230   }
 231   GenerationBlockSizeClosure(const HeapWord* p) { _p = p; size = 0; }
 232 };
 233 
 234 size_t Generation::block_size(const HeapWord* p) const {
 235   GenerationBlockSizeClosure blk(p);
 236   // Cast away const
 237   ((Generation*)this)->space_iterate(&blk);
 238   assert(blk.size > 0, "seems reasonable");
 239   return blk.size;
 240 }
 241 
 242 class GenerationBlockIsObjClosure : public SpaceClosure {
 243  public:
 244   const HeapWord* _p;
 245   bool is_obj;
 246   virtual void do_space(Space* s) {
 247     if (!is_obj && s->is_in_reserved(_p)) {
 248       is_obj |= s->block_is_obj(_p);
 249     }
 250   }
 251   GenerationBlockIsObjClosure(const HeapWord* p) { _p = p; is_obj = false; }
 252 };
 253 
 254 bool Generation::block_is_obj(const HeapWord* p) const {
 255   GenerationBlockIsObjClosure blk(p);
 256   // Cast away const
 257   ((Generation*)this)->space_iterate(&blk);
 258   return blk.is_obj;
 259 }
 260 
 261 class GenerationOopIterateClosure : public SpaceClosure {
 262  public:
 263   OopIterateClosure* _cl;
 264   virtual void do_space(Space* s) {
 265     s->oop_iterate(_cl);
 266   }
 267   GenerationOopIterateClosure(OopIterateClosure* cl) :
 268     _cl(cl) {}
 269 };
 270 
 271 void Generation::oop_iterate(OopIterateClosure* cl) {
 272   GenerationOopIterateClosure blk(cl);
 273   space_iterate(&blk);
 274 }
 275 
 276 void Generation::younger_refs_in_space_iterate(Space* sp,
 277                                                OopsInGenClosure* cl,
 278                                                uint n_threads) {
 279   CardTableRS* rs = GenCollectedHeap::heap()->rem_set();
 280   rs->younger_refs_in_space_iterate(sp, cl, n_threads);
 281 }
 282 
 283 class GenerationObjIterateClosure : public SpaceClosure {
 284  private:
 285   ObjectClosure* _cl;
 286  public:
 287   virtual void do_space(Space* s) {
 288     s->object_iterate(_cl);
 289   }
 290   GenerationObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
 291 };
 292 
 293 void Generation::object_iterate(ObjectClosure* cl) {
 294   GenerationObjIterateClosure blk(cl);
 295   space_iterate(&blk);
 296 }
 297 
 298 class GenerationSafeObjIterateClosure : public SpaceClosure {
 299  private:
 300   ObjectClosure* _cl;
 301  public:
 302   virtual void do_space(Space* s) {
 303     s->safe_object_iterate(_cl);
 304   }
 305   GenerationSafeObjIterateClosure(ObjectClosure* cl) : _cl(cl) {}
 306 };
 307 
 308 void Generation::safe_object_iterate(ObjectClosure* cl) {
 309   GenerationSafeObjIterateClosure blk(cl);
 310   space_iterate(&blk);
 311 }
 312 
 313 #if INCLUDE_SERIALGC
 314 
 315 void Generation::prepare_for_compaction(CompactPoint* cp) {
 316   // Generic implementation, can be specialized
 317   CompactibleSpace* space = first_compaction_space();
 318   while (space != NULL) {
 319     space->prepare_for_compaction(cp);
 320     space = space->next_compaction_space();
 321   }
 322 }
 323 
 324 class AdjustPointersClosure: public SpaceClosure {
 325  public:
 326   void do_space(Space* sp) {
 327     sp->adjust_pointers();
 328   }
 329 };
 330 
 331 void Generation::adjust_pointers() {
 332   // Note that this is done over all spaces, not just the compactible
 333   // ones.
 334   AdjustPointersClosure blk;
 335   space_iterate(&blk, true);
 336 }
 337 
 338 void Generation::compact() {
 339   CompactibleSpace* sp = first_compaction_space();
 340   while (sp != NULL) {
 341     sp->compact();
 342     sp = sp->next_compaction_space();
 343   }
 344 }
 345 
 346 #endif // INCLUDE_SERIALGC
--- EOF ---