rev 9830 : [mq]: rev.01

   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 #include "precompiled.hpp"
  26 #include "code/codeCache.hpp"
  27 #include "code/nmethod.hpp"
  28 #include "gc/g1/g1CodeCacheRemSet.hpp"
  29 #include "gc/g1/heapRegion.hpp"
  30 #include "memory/heap.hpp"
  31 #include "memory/iterator.hpp"
  32 #include "oops/oop.inline.hpp"
  33 #include "utilities/hashtable.inline.hpp"
  34 #include "utilities/stack.inline.hpp"
  35 
  36 class CodeRootSetTable : public Hashtable<nmethod*, mtGC> {
  37   friend class G1CodeRootSetTest;
  38   typedef HashtableEntry<nmethod*, mtGC> Entry;
  39 
  40   static CodeRootSetTable* volatile _purge_list;
  41 
  42   CodeRootSetTable* _purge_next;
  43 
  44   unsigned int compute_hash(nmethod* nm) {
  45     uintptr_t hash = (uintptr_t)nm;
  46     return hash ^ (hash >> 7); // code heap blocks are 128byte aligned
  47   }
  48 
  49   void remove_entry(Entry* e, Entry* previous);
  50   Entry* new_entry(nmethod* nm);
  51 
  52  public:
  53   CodeRootSetTable(int size) : Hashtable<nmethod*, mtGC>(size, sizeof(Entry)), _purge_next(NULL) {}
  54   ~CodeRootSetTable();
  55 
  56   // Needs to be protected locks
  57   bool add(nmethod* nm);
  58   bool remove(nmethod* nm);
  59 
  60   // Can be called without locking
  61   bool contains(nmethod* nm);
  62 
  63   int entry_size() const { return BasicHashtable<mtGC>::entry_size(); }
  64 
  65   void copy_to(CodeRootSetTable* new_table);
  66   void nmethods_do(CodeBlobClosure* blk);
  67 
  68   template<typename CB>
  69   int remove_if(CB& should_remove);
  70 
  71   static void purge_list_append(CodeRootSetTable* tbl);
  72   static void purge();
  73 
  74   static size_t static_mem_size() {
  75     return sizeof(_purge_list);
  76   }


  77 };
  78 
  79 CodeRootSetTable* volatile CodeRootSetTable::_purge_list = NULL;
  80 




  81 CodeRootSetTable::Entry* CodeRootSetTable::new_entry(nmethod* nm) {
  82   unsigned int hash = compute_hash(nm);
  83   Entry* entry = (Entry*) new_entry_free_list();
  84   if (entry == NULL) {
  85     entry = (Entry*) NEW_C_HEAP_ARRAY2(char, entry_size(), mtGC, CURRENT_PC);
  86   }
  87   entry->set_next(NULL);
  88   entry->set_hash(hash);
  89   entry->set_literal(nm);
  90   return entry;
  91 }
  92 
  93 void CodeRootSetTable::remove_entry(Entry* e, Entry* previous) {
  94   int index = hash_to_index(e->hash());
  95   assert((e == bucket(index)) == (previous == NULL), "if e is the first entry then previous should be null");
  96 
  97   if (previous == NULL) {
  98     set_entry(index, e->next());
  99   } else {
 100     previous->set_next(e->next());
 101   }
 102   free_entry(e);
 103 }
 104 
 105 CodeRootSetTable::~CodeRootSetTable() {
 106   for (int index = 0; index < table_size(); ++index) {
 107     for (Entry* e = bucket(index); e != NULL; ) {
 108       Entry* to_remove = e;
 109       // read next before freeing.
 110       e = e->next();
 111       unlink_entry(to_remove);
 112       FREE_C_HEAP_ARRAY(char, to_remove);
 113     }
 114   }
 115   assert(number_of_entries() == 0, "should have removed all entries");
 116   free_buckets();
 117   for (BasicHashtableEntry<mtGC>* e = new_entry_free_list(); e != NULL; e = new_entry_free_list()) {
 118     FREE_C_HEAP_ARRAY(char, e);
 119   }
 120 }
 121 
 122 bool CodeRootSetTable::add(nmethod* nm) {
 123   if (!contains(nm)) {
 124     Entry* e = new_entry(nm);
 125     int index = hash_to_index(e->hash());
 126     add_entry(index, e);
 127     return true;
 128   }
 129   return false;
 130 }
 131 
 132 bool CodeRootSetTable::contains(nmethod* nm) {
 133   int index = hash_to_index(compute_hash(nm));
 134   for (Entry* e = bucket(index); e != NULL; e = e->next()) {
 135     if (e->literal() == nm) {
 136       return true;
 137     }
 138   }
 139   return false;
 140 }
 141 
 142 bool CodeRootSetTable::remove(nmethod* nm) {
 143   int index = hash_to_index(compute_hash(nm));
 144   Entry* previous = NULL;
 145   for (Entry* e = bucket(index); e != NULL; previous = e, e = e->next()) {
 146     if (e->literal() == nm) {
 147       remove_entry(e, previous);
 148       return true;
 149     }
 150   }
 151   return false;
 152 }
 153 
 154 void CodeRootSetTable::copy_to(CodeRootSetTable* new_table) {
 155   for (int index = 0; index < table_size(); ++index) {
 156     for (Entry* e = bucket(index); e != NULL; e = e->next()) {
 157       new_table->add(e->literal());
 158     }
 159   }
 160   new_table->copy_freelist(this);
 161 }
 162 
 163 void CodeRootSetTable::nmethods_do(CodeBlobClosure* blk) {
 164   for (int index = 0; index < table_size(); ++index) {
 165     for (Entry* e = bucket(index); e != NULL; e = e->next()) {
 166       blk->do_code_blob(e->literal());
 167     }
 168   }
 169 }
 170 
 171 template<typename CB>
 172 int CodeRootSetTable::remove_if(CB& should_remove) {
 173   int num_removed = 0;
 174   for (int index = 0; index < table_size(); ++index) {
 175     Entry* previous = NULL;
 176     Entry* e = bucket(index);
 177     while (e != NULL) {
 178       Entry* next = e->next();
 179       if (should_remove(e->literal())) {
 180         remove_entry(e, previous);
 181         ++num_removed;
 182       } else {
 183         previous = e;
 184       }
 185       e = next;
 186     }
 187   }
 188   return num_removed;
 189 }
 190 
 191 G1CodeRootSet::~G1CodeRootSet() {
 192   delete _table;
 193 }
 194 
 195 CodeRootSetTable* G1CodeRootSet::load_acquire_table() {
 196   return (CodeRootSetTable*) OrderAccess::load_ptr_acquire(&_table);
 197 }
 198 
 199 void G1CodeRootSet::allocate_small_table() {
 200   CodeRootSetTable* temp = new CodeRootSetTable(SmallSize);
 201 
 202   OrderAccess::release_store_ptr(&_table, temp);
 203 }
 204 
 205 void CodeRootSetTable::purge_list_append(CodeRootSetTable* table) {
 206   for (;;) {
 207     table->_purge_next = _purge_list;
 208     CodeRootSetTable* old = (CodeRootSetTable*) Atomic::cmpxchg_ptr(table, &_purge_list, table->_purge_next);
 209     if (old == table->_purge_next) {
 210       break;
 211     }
 212   }
 213 }
 214 
 215 void CodeRootSetTable::purge() {
 216   CodeRootSetTable* table = _purge_list;
 217   _purge_list = NULL;
 218   while (table != NULL) {
 219     CodeRootSetTable* to_purge = table;
 220     table = table->_purge_next;
 221     delete to_purge;
 222   }
 223 }
 224 
 225 void G1CodeRootSet::move_to_large() {
 226   CodeRootSetTable* temp = new CodeRootSetTable(LargeSize);
 227 
 228   _table->copy_to(temp);
 229 
 230   CodeRootSetTable::purge_list_append(_table);
 231 
 232   OrderAccess::release_store_ptr(&_table, temp);
 233 }
 234 
 235 
 236 void G1CodeRootSet::purge() {
 237   CodeRootSetTable::purge();
 238 }
 239 
 240 size_t G1CodeRootSet::static_mem_size() {
 241   return CodeRootSetTable::static_mem_size();
 242 }
 243 
 244 void G1CodeRootSet::add(nmethod* method) {
 245   bool added = false;
 246   if (is_empty()) {
 247     allocate_small_table();
 248   }
 249   added = _table->add(method);

 250   if (_length == Threshold) {
 251     move_to_large();
 252   }
 253   if (added) {
 254     ++_length;
 255   }

 256 }
 257 
 258 bool G1CodeRootSet::remove(nmethod* method) {
 259   bool removed = false;
 260   if (_table != NULL) {
 261     removed = _table->remove(method);
 262   }
 263   if (removed) {
 264     _length--;
 265     if (_length == 0) {
 266       clear();
 267     }
 268   }


 269   return removed;
 270 }
 271 
 272 bool G1CodeRootSet::contains(nmethod* method) {
 273   CodeRootSetTable* table = load_acquire_table();
 274   if (table != NULL) {
 275     return table->contains(method);
 276   }
 277   return false;
 278 }
 279 
 280 void G1CodeRootSet::clear() {
 281   delete _table;
 282   _table = NULL;
 283   _length = 0;
 284 }
 285 
 286 size_t G1CodeRootSet::mem_size() {
 287   return sizeof(*this) +
 288       (_table != NULL ? sizeof(CodeRootSetTable) + _table->entry_size() * _length : 0);
 289 }
 290 
 291 void G1CodeRootSet::nmethods_do(CodeBlobClosure* blk) const {
 292   if (_table != NULL) {
 293     _table->nmethods_do(blk);
 294   }
 295 }
 296 
 297 class CleanCallback : public StackObj {
 298   class PointsIntoHRDetectionClosure : public OopClosure {
 299     HeapRegion* _hr;
 300    public:
 301     bool _points_into;
 302     PointsIntoHRDetectionClosure(HeapRegion* hr) : _hr(hr), _points_into(false) {}
 303 
 304     void do_oop(narrowOop* o) {
 305       do_oop_work(o);
 306     }
 307 
 308     void do_oop(oop* o) {
 309       do_oop_work(o);
 310     }
 311 
 312     template <typename T>
 313     void do_oop_work(T* p) {
 314       if (_hr->is_in(oopDesc::load_decode_heap_oop(p))) {
 315         _points_into = true;
 316       }
 317     }
 318   };
 319 
 320   PointsIntoHRDetectionClosure _detector;
 321   CodeBlobToOopClosure _blobs;
 322 
 323  public:
 324   CleanCallback(HeapRegion* hr) : _detector(hr), _blobs(&_detector, !CodeBlobToOopClosure::FixRelocations) {}
 325 
 326   bool operator() (nmethod* nm) {
 327     _detector._points_into = false;
 328     _blobs.do_code_blob(nm);
 329     return !_detector._points_into;
 330   }
 331 };
 332 
 333 void G1CodeRootSet::clean(HeapRegion* owner) {
 334   CleanCallback should_clean(owner);
 335   if (_table != NULL) {
 336     int removed = _table->remove_if(should_clean);
 337     assert((size_t)removed <= _length, "impossible");
 338     _length -= removed;
 339   }
 340   if (_length == 0) {
 341     clear();
 342   }
 343 }
 344 
 345 #ifndef PRODUCT
 346 
 347 class G1CodeRootSetTest {
 348  public:
 349   static void test() {
 350     {
 351       G1CodeRootSet set1;
 352       assert(set1.is_empty(), "Code root set must be initially empty but is not.");
 353 
 354       assert(G1CodeRootSet::static_mem_size() == sizeof(void*),
 355              "The code root set's static memory usage is incorrect, " SIZE_FORMAT " bytes", G1CodeRootSet::static_mem_size());
 356 
 357       set1.add((nmethod*)1);
 358       assert(set1.length() == 1, "Added exactly one element, but set contains "
 359              SIZE_FORMAT " elements", set1.length());
 360 
 361       const size_t num_to_add = (size_t)G1CodeRootSet::Threshold + 1;
 362 
 363       for (size_t i = 1; i <= num_to_add; i++) {
 364         set1.add((nmethod*)1);
 365       }
 366       assert(set1.length() == 1,
 367              "Duplicate detection should not have increased the set size but "
 368              "is " SIZE_FORMAT, set1.length());
 369 
 370       for (size_t i = 2; i <= num_to_add; i++) {
 371         set1.add((nmethod*)(uintptr_t)(i));
 372       }
 373       assert(set1.length() == num_to_add,
 374              "After adding in total " SIZE_FORMAT " distinct code roots, they "
 375              "need to be in the set, but there are only " SIZE_FORMAT,
 376              num_to_add, set1.length());
 377 
 378       assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
 379 
 380       size_t num_popped = 0;
 381       for (size_t i = 1; i <= num_to_add; i++) {
 382         bool removed = set1.remove((nmethod*)i);
 383         if (removed) {
 384           num_popped += 1;
 385         } else {
 386           break;
 387         }
 388       }
 389       assert(num_popped == num_to_add,
 390              "Managed to pop " SIZE_FORMAT " code roots, but only " SIZE_FORMAT " "
 391              "were added", num_popped, num_to_add);
 392       assert(CodeRootSetTable::_purge_list != NULL, "should have grown to large hashtable");
 393 
 394       G1CodeRootSet::purge();
 395 
 396       assert(CodeRootSetTable::_purge_list == NULL, "should have purged old small tables");
 397 
 398     }
 399 
 400   }
 401 };
 402 
 403 void TestCodeCacheRemSet_test() {
 404   G1CodeRootSetTest::test();
 405 }
 406 
 407 #endif
--- EOF ---