1 /*
   2  * Copyright (c) 2001, 2018, 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/g1/dirtyCardQueue.hpp"
  27 #include "gc/g1/g1CollectedHeap.inline.hpp"
  28 #include "gc/g1/g1RemSet.hpp"
  29 #include "gc/g1/g1ThreadLocalData.hpp"
  30 #include "gc/g1/heapRegionRemSet.hpp"
  31 #include "gc/shared/suspendibleThreadSet.hpp"
  32 #include "gc/shared/workgroup.hpp"
  33 #include "runtime/atomic.hpp"
  34 #include "runtime/mutexLocker.hpp"
  35 #include "runtime/safepoint.hpp"
  36 #include "runtime/thread.inline.hpp"
  37 #include "runtime/threadSMR.hpp"
  38 
  39 // Closure used for updating remembered sets and recording references that
  40 // point into the collection set while the mutator is running.
  41 // Assumed to be only executed concurrently with the mutator. Yields via
  42 // SuspendibleThreadSet after every card.
  43 class G1RefineCardConcurrentlyClosure: public CardTableEntryClosure {
  44 public:
  45   bool do_card_ptr(jbyte* card_ptr, uint worker_i) {
  46     G1CollectedHeap::heap()->g1_rem_set()->refine_card_concurrently(card_ptr, worker_i);
  47 
  48     if (SuspendibleThreadSet::should_yield()) {
  49       // Caller will actually yield.
  50       return false;
  51     }
  52     // Otherwise, we finished successfully; return true.
  53     return true;
  54   }
  55 };
  56 
  57 // Represents a set of free small integer ids.
  58 class FreeIdSet : public CHeapObj<mtGC> {
  59   enum {
  60     end_of_list = UINT_MAX,
  61     claimed = UINT_MAX - 1
  62   };
  63 
  64   uint _size;
  65   Monitor* _mon;
  66 
  67   uint* _ids;
  68   uint _hd;
  69   uint _waiters;
  70   uint _claimed;
  71 
  72 public:
  73   FreeIdSet(uint size, Monitor* mon);
  74   ~FreeIdSet();
  75 
  76   // Returns an unclaimed parallel id (waiting for one to be released if
  77   // necessary).
  78   uint claim_par_id();
  79 
  80   void release_par_id(uint id);
  81 };
  82 
  83 FreeIdSet::FreeIdSet(uint size, Monitor* mon) :
  84   _size(size), _mon(mon), _hd(0), _waiters(0), _claimed(0)
  85 {
  86   guarantee(size != 0, "must be");
  87   _ids = NEW_C_HEAP_ARRAY(uint, size, mtGC);
  88   for (uint i = 0; i < size - 1; i++) {
  89     _ids[i] = i+1;
  90   }
  91   _ids[size-1] = end_of_list; // end of list.
  92 }
  93 
  94 FreeIdSet::~FreeIdSet() {
  95   FREE_C_HEAP_ARRAY(uint, _ids);
  96 }
  97 
  98 uint FreeIdSet::claim_par_id() {
  99   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
 100   while (_hd == end_of_list) {
 101     _waiters++;
 102     _mon->wait(Mutex::_no_safepoint_check_flag);
 103     _waiters--;
 104   }
 105   uint res = _hd;
 106   _hd = _ids[res];
 107   _ids[res] = claimed;  // For debugging.
 108   _claimed++;
 109   return res;
 110 }
 111 
 112 void FreeIdSet::release_par_id(uint id) {
 113   MutexLockerEx x(_mon, Mutex::_no_safepoint_check_flag);
 114   assert(_ids[id] == claimed, "Precondition.");
 115   _ids[id] = _hd;
 116   _hd = id;
 117   _claimed--;
 118   if (_waiters > 0) {
 119     _mon->notify_all();
 120   }
 121 }
 122 
 123 DirtyCardQueue::DirtyCardQueue(DirtyCardQueueSet* qset, bool permanent) :
 124   // Dirty card queues are always active, so we create them with their
 125   // active field set to true.
 126   PtrQueue(qset, permanent, true /* active */)
 127 { }
 128 
 129 DirtyCardQueue::~DirtyCardQueue() {
 130   if (!is_permanent()) {
 131     flush();
 132   }
 133 }
 134 
 135 DirtyCardQueueSet::DirtyCardQueueSet(bool notify_when_complete) :
 136   PtrQueueSet(notify_when_complete),
 137   _shared_dirty_card_queue(this, true /* permanent */),
 138   _free_ids(NULL),
 139   _processed_buffers_mut(0), _processed_buffers_rs_thread(0)
 140 {
 141   _all_active = true;
 142 }
 143 
 144 // Determines how many mutator threads can process the buffers in parallel.
 145 uint DirtyCardQueueSet::num_par_ids() {
 146   return (uint)os::initial_active_processor_count();
 147 }
 148 
 149 void DirtyCardQueueSet::initialize(Monitor* cbl_mon,
 150                                    BufferNode::Allocator* allocator,
 151                                    Mutex* lock,
 152                                    bool init_free_ids) {
 153   PtrQueueSet::initialize(cbl_mon, allocator);
 154   _shared_dirty_card_queue.set_lock(lock);
 155   if (init_free_ids) {
 156     _free_ids = new FreeIdSet(num_par_ids(), _cbl_mon);
 157   }
 158 }
 159 
 160 void DirtyCardQueueSet::handle_zero_index_for_thread(JavaThread* t) {
 161   G1ThreadLocalData::dirty_card_queue(t).handle_zero_index();
 162 }
 163 
 164 bool DirtyCardQueueSet::apply_closure_to_buffer(CardTableEntryClosure* cl,
 165                                                 BufferNode* node,
 166                                                 bool consume,
 167                                                 uint worker_i) {
 168   if (cl == NULL) return true;
 169   bool result = true;
 170   void** buf = BufferNode::make_buffer_from_node(node);
 171   size_t i = node->index();
 172   size_t limit = buffer_size();
 173   for ( ; i < limit; ++i) {
 174     jbyte* card_ptr = static_cast<jbyte*>(buf[i]);
 175     assert(card_ptr != NULL, "invariant");
 176     if (!cl->do_card_ptr(card_ptr, worker_i)) {
 177       result = false;           // Incomplete processing.
 178       break;
 179     }
 180   }
 181   if (consume) {
 182     assert(i <= buffer_size(), "invariant");
 183     node->set_index(i);
 184   }
 185   return result;
 186 }
 187 
 188 #ifndef ASSERT
 189 #define assert_fully_consumed(node, buffer_size)
 190 #else
 191 #define assert_fully_consumed(node, buffer_size)                \
 192   do {                                                          \
 193     size_t _afc_index = (node)->index();                        \
 194     size_t _afc_size = (buffer_size);                           \
 195     assert(_afc_index == _afc_size,                             \
 196            "Buffer was not fully consumed as claimed: index: "  \
 197            SIZE_FORMAT ", size: " SIZE_FORMAT,                  \
 198             _afc_index, _afc_size);                             \
 199   } while (0)
 200 #endif // ASSERT
 201 
 202 bool DirtyCardQueueSet::mut_process_buffer(BufferNode* node) {
 203   guarantee(_free_ids != NULL, "must be");
 204 
 205   uint worker_i = _free_ids->claim_par_id(); // temporarily claim an id
 206   G1RefineCardConcurrentlyClosure cl;
 207   bool result = apply_closure_to_buffer(&cl, node, true, worker_i);
 208   _free_ids->release_par_id(worker_i); // release the id
 209 
 210   if (result) {
 211     assert_fully_consumed(node, buffer_size());
 212     Atomic::inc(&_processed_buffers_mut);
 213   }
 214   return result;
 215 }
 216 
 217 
 218 BufferNode* DirtyCardQueueSet::get_completed_buffer(size_t stop_at) {
 219   MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
 220 
 221   if (_n_completed_buffers <= stop_at) {
 222     return NULL;
 223   }
 224 
 225   assert(_n_completed_buffers > 0, "invariant");
 226   assert(_completed_buffers_head != NULL, "invariant");
 227   assert(_completed_buffers_tail != NULL, "invariant");
 228 
 229   BufferNode* nd = _completed_buffers_head;
 230   _completed_buffers_head = nd->next();
 231   _n_completed_buffers--;
 232   if (_completed_buffers_head == NULL) {
 233     assert(_n_completed_buffers == 0, "Invariant");
 234     _completed_buffers_tail = NULL;
 235   }
 236   DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
 237   return nd;
 238 }
 239 
 240 bool DirtyCardQueueSet::refine_completed_buffer_concurrently(uint worker_i, size_t stop_at) {
 241   G1RefineCardConcurrentlyClosure cl;
 242   return apply_closure_to_completed_buffer(&cl, worker_i, stop_at, false);
 243 }
 244 
 245 bool DirtyCardQueueSet::apply_closure_during_gc(CardTableEntryClosure* cl, uint worker_i) {
 246   assert_at_safepoint();
 247   return apply_closure_to_completed_buffer(cl, worker_i, 0, true);
 248 }
 249 
 250 bool DirtyCardQueueSet::apply_closure_to_completed_buffer(CardTableEntryClosure* cl,
 251                                                           uint worker_i,
 252                                                           size_t stop_at,
 253                                                           bool during_pause) {
 254   assert(!during_pause || stop_at == 0, "Should not leave any completed buffers during a pause");
 255   BufferNode* nd = get_completed_buffer(stop_at);
 256   if (nd == NULL) {
 257     return false;
 258   } else {
 259     if (apply_closure_to_buffer(cl, nd, true, worker_i)) {
 260       assert_fully_consumed(nd, buffer_size());
 261       // Done with fully processed buffer.
 262       deallocate_buffer(nd);
 263       Atomic::inc(&_processed_buffers_rs_thread);
 264     } else {
 265       // Return partially processed buffer to the queue.
 266       guarantee(!during_pause, "Should never stop early");
 267       enqueue_complete_buffer(nd);
 268     }
 269     return true;
 270   }
 271 }
 272 
 273 void DirtyCardQueueSet::par_apply_closure_to_all_completed_buffers(CardTableEntryClosure* cl) {
 274   BufferNode* nd = _cur_par_buffer_node;
 275   while (nd != NULL) {
 276     BufferNode* next = nd->next();
 277     BufferNode* actual = Atomic::cmpxchg(next, &_cur_par_buffer_node, nd);
 278     if (actual == nd) {
 279       bool b = apply_closure_to_buffer(cl, nd, false);
 280       guarantee(b, "Should not stop early.");
 281       nd = next;
 282     } else {
 283       nd = actual;
 284     }
 285   }
 286 }
 287 
 288 // Deallocates any completed log buffers
 289 void DirtyCardQueueSet::clear() {
 290   BufferNode* buffers_to_delete = NULL;
 291   {
 292     MutexLockerEx x(_cbl_mon, Mutex::_no_safepoint_check_flag);
 293     while (_completed_buffers_head != NULL) {
 294       BufferNode* nd = _completed_buffers_head;
 295       _completed_buffers_head = nd->next();
 296       nd->set_next(buffers_to_delete);
 297       buffers_to_delete = nd;
 298     }
 299     _n_completed_buffers = 0;
 300     _completed_buffers_tail = NULL;
 301     DEBUG_ONLY(assert_completed_buffer_list_len_correct_locked());
 302   }
 303   while (buffers_to_delete != NULL) {
 304     BufferNode* nd = buffers_to_delete;
 305     buffers_to_delete = nd->next();
 306     deallocate_buffer(nd);
 307   }
 308 
 309 }
 310 
 311 void DirtyCardQueueSet::abandon_logs() {
 312   assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
 313   clear();
 314   // Since abandon is done only at safepoints, we can safely manipulate
 315   // these queues.
 316   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
 317     G1ThreadLocalData::dirty_card_queue(t).reset();
 318   }
 319   shared_dirty_card_queue()->reset();
 320 }
 321 
 322 void DirtyCardQueueSet::concatenate_log(DirtyCardQueue& dcq) {
 323   if (!dcq.is_empty()) {
 324     dcq.flush();
 325   }
 326 }
 327 
 328 void DirtyCardQueueSet::concatenate_logs() {
 329   // Iterate over all the threads, if we find a partial log add it to
 330   // the global list of logs.  Temporarily turn off the limit on the number
 331   // of outstanding buffers.
 332   assert(SafepointSynchronize::is_at_safepoint(), "Must be at safepoint.");
 333   size_t save_max_completed_buffers = _max_completed_buffers;
 334   _max_completed_buffers = _max_completed_buffers_unlimited;
 335   for (JavaThreadIteratorWithHandle jtiwh; JavaThread *t = jtiwh.next(); ) {
 336     concatenate_log(G1ThreadLocalData::dirty_card_queue(t));
 337   }
 338   concatenate_log(_shared_dirty_card_queue);
 339   // Restore the completed buffer limit.
 340   _max_completed_buffers = save_max_completed_buffers;
 341 }