src/share/vm/memory/referenceProcessor.hpp

Wed, 11 Sep 2013 00:38:18 -0400

author
dholmes
date
Wed, 11 Sep 2013 00:38:18 -0400
changeset 5689
de88570fabfc
parent 5237
f2110083203d
child 6395
a258f8cb530f
permissions
-rw-r--r--

8024256: Minimal VM build is broken with PCH disabled
Reviewed-by: coleenp, twisti

duke@435 1 /*
sla@5237 2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
duke@435 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
duke@435 4 *
duke@435 5 * This code is free software; you can redistribute it and/or modify it
duke@435 6 * under the terms of the GNU General Public License version 2 only, as
duke@435 7 * published by the Free Software Foundation.
duke@435 8 *
duke@435 9 * This code is distributed in the hope that it will be useful, but WITHOUT
duke@435 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
duke@435 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
duke@435 12 * version 2 for more details (a copy is included in the LICENSE file that
duke@435 13 * accompanied this code).
duke@435 14 *
duke@435 15 * You should have received a copy of the GNU General Public License version
duke@435 16 * 2 along with this work; if not, write to the Free Software Foundation,
duke@435 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
duke@435 18 *
trims@1907 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
trims@1907 20 * or visit www.oracle.com if you need additional information or have any
trims@1907 21 * questions.
duke@435 22 *
duke@435 23 */
duke@435 24
stefank@2314 25 #ifndef SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP
stefank@2314 26 #define SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP
stefank@2314 27
stefank@2314 28 #include "memory/referencePolicy.hpp"
sla@5237 29 #include "memory/referenceProcessorStats.hpp"
sla@5237 30 #include "memory/referenceType.hpp"
stefank@2314 31 #include "oops/instanceRefKlass.hpp"
stefank@2314 32
sla@5237 33 class GCTimer;
sla@5237 34
duke@435 35 // ReferenceProcessor class encapsulates the per-"collector" processing
ysr@888 36 // of java.lang.Reference objects for GC. The interface is useful for supporting
duke@435 37 // a generational abstraction, in particular when there are multiple
duke@435 38 // generations that are being independently collected -- possibly
duke@435 39 // concurrently and/or incrementally. Note, however, that the
duke@435 40 // ReferenceProcessor class abstracts away from a generational setting
duke@435 41 // by using only a heap interval (called "span" below), thus allowing
duke@435 42 // its use in a straightforward manner in a general, non-generational
duke@435 43 // setting.
duke@435 44 //
duke@435 45 // The basic idea is that each ReferenceProcessor object concerns
duke@435 46 // itself with ("weak") reference processing in a specific "span"
duke@435 47 // of the heap of interest to a specific collector. Currently,
duke@435 48 // the span is a convex interval of the heap, but, efficiency
duke@435 49 // apart, there seems to be no reason it couldn't be extended
duke@435 50 // (with appropriate modifications) to any "non-convex interval".
duke@435 51
duke@435 52 // forward references
duke@435 53 class ReferencePolicy;
duke@435 54 class AbstractRefProcTaskExecutor;
johnc@3175 55
johnc@3175 56 // List of discovered references.
johnc@3175 57 class DiscoveredList {
johnc@3175 58 public:
johnc@3175 59 DiscoveredList() : _len(0), _compressed_head(0), _oop_head(NULL) { }
johnc@3175 60 oop head() const {
johnc@3175 61 return UseCompressedOops ? oopDesc::decode_heap_oop(_compressed_head) :
johnc@3175 62 _oop_head;
johnc@3175 63 }
johnc@3175 64 HeapWord* adr_head() {
johnc@3175 65 return UseCompressedOops ? (HeapWord*)&_compressed_head :
johnc@3175 66 (HeapWord*)&_oop_head;
johnc@3175 67 }
johnc@3175 68 void set_head(oop o) {
johnc@3175 69 if (UseCompressedOops) {
johnc@3175 70 // Must compress the head ptr.
johnc@3175 71 _compressed_head = oopDesc::encode_heap_oop(o);
johnc@3175 72 } else {
johnc@3175 73 _oop_head = o;
johnc@3175 74 }
johnc@3175 75 }
johnc@3175 76 bool is_empty() const { return head() == NULL; }
johnc@3175 77 size_t length() { return _len; }
johnc@3175 78 void set_length(size_t len) { _len = len; }
johnc@3175 79 void inc_length(size_t inc) { _len += inc; assert(_len > 0, "Error"); }
johnc@3175 80 void dec_length(size_t dec) { _len -= dec; }
johnc@3175 81 private:
johnc@3175 82 // Set value depending on UseCompressedOops. This could be a template class
johnc@3175 83 // but then we have to fix all the instantiations and declarations that use this class.
johnc@3175 84 oop _oop_head;
johnc@3175 85 narrowOop _compressed_head;
johnc@3175 86 size_t _len;
johnc@3175 87 };
johnc@3175 88
johnc@3175 89 // Iterator for the list of discovered references.
johnc@3175 90 class DiscoveredListIterator {
johnc@3175 91 private:
johnc@3175 92 DiscoveredList& _refs_list;
johnc@3175 93 HeapWord* _prev_next;
johnc@3175 94 oop _prev;
johnc@3175 95 oop _ref;
johnc@3175 96 HeapWord* _discovered_addr;
johnc@3175 97 oop _next;
johnc@3175 98 HeapWord* _referent_addr;
johnc@3175 99 oop _referent;
johnc@3175 100 OopClosure* _keep_alive;
johnc@3175 101 BoolObjectClosure* _is_alive;
johnc@3175 102
johnc@3175 103 DEBUG_ONLY(
johnc@3175 104 oop _first_seen; // cyclic linked list check
johnc@3175 105 )
johnc@3175 106
johnc@3175 107 NOT_PRODUCT(
johnc@3175 108 size_t _processed;
johnc@3175 109 size_t _removed;
johnc@3175 110 )
johnc@3175 111
johnc@3175 112 public:
johnc@3175 113 inline DiscoveredListIterator(DiscoveredList& refs_list,
johnc@3175 114 OopClosure* keep_alive,
johnc@3175 115 BoolObjectClosure* is_alive):
johnc@3175 116 _refs_list(refs_list),
johnc@3175 117 _prev_next(refs_list.adr_head()),
johnc@3175 118 _prev(NULL),
johnc@3175 119 _ref(refs_list.head()),
johnc@3175 120 #ifdef ASSERT
johnc@3175 121 _first_seen(refs_list.head()),
johnc@3175 122 #endif
johnc@3175 123 #ifndef PRODUCT
johnc@3175 124 _processed(0),
johnc@3175 125 _removed(0),
johnc@3175 126 #endif
johnc@3175 127 _next(NULL),
johnc@3175 128 _keep_alive(keep_alive),
johnc@3175 129 _is_alive(is_alive)
johnc@3175 130 { }
johnc@3175 131
johnc@3175 132 // End Of List.
johnc@3175 133 inline bool has_next() const { return _ref != NULL; }
johnc@3175 134
johnc@3175 135 // Get oop to the Reference object.
johnc@3175 136 inline oop obj() const { return _ref; }
johnc@3175 137
johnc@3175 138 // Get oop to the referent object.
johnc@3175 139 inline oop referent() const { return _referent; }
johnc@3175 140
johnc@3175 141 // Returns true if referent is alive.
johnc@3175 142 inline bool is_referent_alive() const {
johnc@3175 143 return _is_alive->do_object_b(_referent);
johnc@3175 144 }
johnc@3175 145
johnc@3175 146 // Loads data for the current reference.
johnc@3175 147 // The "allow_null_referent" argument tells us to allow for the possibility
johnc@3175 148 // of a NULL referent in the discovered Reference object. This typically
johnc@3175 149 // happens in the case of concurrent collectors that may have done the
johnc@3175 150 // discovery concurrently, or interleaved, with mutator execution.
johnc@3175 151 void load_ptrs(DEBUG_ONLY(bool allow_null_referent));
johnc@3175 152
johnc@3175 153 // Move to the next discovered reference.
johnc@3175 154 inline void next() {
johnc@3175 155 _prev_next = _discovered_addr;
johnc@3175 156 _prev = _ref;
johnc@3175 157 move_to_next();
johnc@3175 158 }
johnc@3175 159
johnc@3175 160 // Remove the current reference from the list
johnc@3175 161 void remove();
johnc@3175 162
johnc@3175 163 // Make the Reference object active again.
johnc@3175 164 void make_active();
johnc@3175 165
johnc@3175 166 // Make the referent alive.
johnc@3175 167 inline void make_referent_alive() {
johnc@3175 168 if (UseCompressedOops) {
johnc@3175 169 _keep_alive->do_oop((narrowOop*)_referent_addr);
johnc@3175 170 } else {
johnc@3175 171 _keep_alive->do_oop((oop*)_referent_addr);
johnc@3175 172 }
johnc@3175 173 }
johnc@3175 174
johnc@3175 175 // Update the discovered field.
johnc@3175 176 inline void update_discovered() {
johnc@3175 177 // First _prev_next ref actually points into DiscoveredList (gross).
johnc@3175 178 if (UseCompressedOops) {
johnc@3175 179 if (!oopDesc::is_null(*(narrowOop*)_prev_next)) {
johnc@3175 180 _keep_alive->do_oop((narrowOop*)_prev_next);
johnc@3175 181 }
johnc@3175 182 } else {
johnc@3175 183 if (!oopDesc::is_null(*(oop*)_prev_next)) {
johnc@3175 184 _keep_alive->do_oop((oop*)_prev_next);
johnc@3175 185 }
johnc@3175 186 }
johnc@3175 187 }
johnc@3175 188
johnc@3175 189 // NULL out referent pointer.
johnc@3175 190 void clear_referent();
johnc@3175 191
johnc@3175 192 // Statistics
johnc@3175 193 NOT_PRODUCT(
johnc@3175 194 inline size_t processed() const { return _processed; }
johnc@3175 195 inline size_t removed() const { return _removed; }
johnc@3175 196 )
johnc@3175 197
johnc@3175 198 inline void move_to_next() {
johnc@3175 199 if (_ref == _next) {
johnc@3175 200 // End of the list.
johnc@3175 201 _ref = NULL;
johnc@3175 202 } else {
johnc@3175 203 _ref = _next;
johnc@3175 204 }
johnc@3175 205 assert(_ref != _first_seen, "cyclic ref_list found");
johnc@3175 206 NOT_PRODUCT(_processed++);
johnc@3175 207 }
johnc@3175 208 };
duke@435 209
zgu@3900 210 class ReferenceProcessor : public CHeapObj<mtGC> {
sla@5237 211
sla@5237 212 private:
sla@5237 213 size_t total_count(DiscoveredList lists[]);
sla@5237 214
duke@435 215 protected:
ysr@3117 216 // Compatibility with pre-4965777 JDK's
ysr@3117 217 static bool _pending_list_uses_discovered_field;
johnc@3175 218
johnc@3188 219 // The SoftReference master timestamp clock
johnc@3188 220 static jlong _soft_ref_timestamp_clock;
johnc@3188 221
johnc@3175 222 MemRegion _span; // (right-open) interval of heap
johnc@3175 223 // subject to wkref discovery
johnc@3175 224
johnc@3175 225 bool _discovering_refs; // true when discovery enabled
johnc@3175 226 bool _discovery_is_atomic; // if discovery is atomic wrt
johnc@3175 227 // other collectors in configuration
johnc@3175 228 bool _discovery_is_mt; // true if reference discovery is MT.
johnc@3175 229
ysr@777 230 // If true, setting "next" field of a discovered refs list requires
ysr@777 231 // write barrier(s). (Must be true if used in a collector in which
ysr@777 232 // elements of a discovered list may be moved during discovery: for
ysr@777 233 // example, a collector like Garbage-First that moves objects during a
ysr@777 234 // long-term concurrent marking phase that does weak reference
ysr@777 235 // discovery.)
ysr@777 236 bool _discovered_list_needs_barrier;
duke@435 237
johnc@3175 238 BarrierSet* _bs; // Cached copy of BarrierSet.
johnc@3175 239 bool _enqueuing_is_done; // true if all weak references enqueued
johnc@3175 240 bool _processing_is_mt; // true during phases when
johnc@3175 241 // reference processing is MT.
jmasa@3357 242 uint _next_id; // round-robin mod _num_q counter in
johnc@3175 243 // support of work distribution
johnc@3175 244
johnc@3175 245 // For collectors that do not keep GC liveness information
duke@435 246 // in the object header, this field holds a closure that
duke@435 247 // helps the reference processor determine the reachability
johnc@3175 248 // of an oop. It is currently initialized to NULL for all
johnc@3175 249 // collectors except for CMS and G1.
duke@435 250 BoolObjectClosure* _is_alive_non_header;
duke@435 251
ysr@888 252 // Soft ref clearing policies
ysr@888 253 // . the default policy
ysr@888 254 static ReferencePolicy* _default_soft_ref_policy;
ysr@888 255 // . the "clear all" policy
ysr@888 256 static ReferencePolicy* _always_clear_soft_ref_policy;
ysr@888 257 // . the current policy below is either one of the above
ysr@888 258 ReferencePolicy* _current_soft_ref_policy;
ysr@888 259
duke@435 260 // The discovered ref lists themselves
coleenp@548 261
jmasa@2188 262 // The active MT'ness degree of the queues below
jmasa@3357 263 uint _num_q;
jmasa@2188 264 // The maximum MT'ness degree of the queues below
jmasa@3357 265 uint _max_num_q;
johnc@3210 266
johnc@3210 267 // Master array of discovered oops
johnc@3210 268 DiscoveredList* _discovered_refs;
johnc@3210 269
johnc@3210 270 // Arrays of lists of oops, one per thread (pointers into master array above)
coleenp@548 271 DiscoveredList* _discoveredSoftRefs;
duke@435 272 DiscoveredList* _discoveredWeakRefs;
duke@435 273 DiscoveredList* _discoveredFinalRefs;
duke@435 274 DiscoveredList* _discoveredPhantomRefs;
duke@435 275
duke@435 276 public:
johnc@3175 277 static int number_of_subclasses_of_ref() { return (REF_PHANTOM - REF_OTHER); }
johnc@3175 278
jmasa@3357 279 uint num_q() { return _num_q; }
jmasa@3357 280 uint max_num_q() { return _max_num_q; }
jmasa@3357 281 void set_active_mt_degree(uint v) { _num_q = v; }
johnc@3210 282
johnc@3210 283 DiscoveredList* discovered_refs() { return _discovered_refs; }
johnc@3175 284
ysr@892 285 ReferencePolicy* setup_policy(bool always_clear) {
ysr@888 286 _current_soft_ref_policy = always_clear ?
ysr@888 287 _always_clear_soft_ref_policy : _default_soft_ref_policy;
ysr@892 288 _current_soft_ref_policy->setup(); // snapshot the policy threshold
ysr@888 289 return _current_soft_ref_policy;
ysr@888 290 }
duke@435 291
duke@435 292 // Process references with a certain reachability level.
sla@5237 293 size_t process_discovered_reflist(DiscoveredList refs_lists[],
sla@5237 294 ReferencePolicy* policy,
sla@5237 295 bool clear_referent,
sla@5237 296 BoolObjectClosure* is_alive,
sla@5237 297 OopClosure* keep_alive,
sla@5237 298 VoidClosure* complete_gc,
sla@5237 299 AbstractRefProcTaskExecutor* task_executor);
duke@435 300
duke@435 301 void process_phaseJNI(BoolObjectClosure* is_alive,
duke@435 302 OopClosure* keep_alive,
duke@435 303 VoidClosure* complete_gc);
duke@435 304
duke@435 305 // Work methods used by the method process_discovered_reflist
duke@435 306 // Phase1: keep alive all those referents that are otherwise
duke@435 307 // dead but which must be kept alive by policy (and their closure).
coleenp@548 308 void process_phase1(DiscoveredList& refs_list,
duke@435 309 ReferencePolicy* policy,
duke@435 310 BoolObjectClosure* is_alive,
duke@435 311 OopClosure* keep_alive,
duke@435 312 VoidClosure* complete_gc);
duke@435 313 // Phase2: remove all those references whose referents are
duke@435 314 // reachable.
coleenp@548 315 inline void process_phase2(DiscoveredList& refs_list,
duke@435 316 BoolObjectClosure* is_alive,
duke@435 317 OopClosure* keep_alive,
duke@435 318 VoidClosure* complete_gc) {
duke@435 319 if (discovery_is_atomic()) {
duke@435 320 // complete_gc is ignored in this case for this phase
coleenp@548 321 pp2_work(refs_list, is_alive, keep_alive);
duke@435 322 } else {
duke@435 323 assert(complete_gc != NULL, "Error");
coleenp@548 324 pp2_work_concurrent_discovery(refs_list, is_alive,
duke@435 325 keep_alive, complete_gc);
duke@435 326 }
duke@435 327 }
duke@435 328 // Work methods in support of process_phase2
coleenp@548 329 void pp2_work(DiscoveredList& refs_list,
duke@435 330 BoolObjectClosure* is_alive,
duke@435 331 OopClosure* keep_alive);
duke@435 332 void pp2_work_concurrent_discovery(
coleenp@548 333 DiscoveredList& refs_list,
duke@435 334 BoolObjectClosure* is_alive,
duke@435 335 OopClosure* keep_alive,
duke@435 336 VoidClosure* complete_gc);
duke@435 337 // Phase3: process the referents by either clearing them
duke@435 338 // or keeping them alive (and their closure)
coleenp@548 339 void process_phase3(DiscoveredList& refs_list,
duke@435 340 bool clear_referent,
duke@435 341 BoolObjectClosure* is_alive,
duke@435 342 OopClosure* keep_alive,
duke@435 343 VoidClosure* complete_gc);
duke@435 344
duke@435 345 // Enqueue references with a certain reachability level
coleenp@548 346 void enqueue_discovered_reflist(DiscoveredList& refs_list, HeapWord* pending_list_addr);
duke@435 347
duke@435 348 // "Preclean" all the discovered reference lists
duke@435 349 // by removing references with strongly reachable referents.
duke@435 350 // The first argument is a predicate on an oop that indicates
duke@435 351 // its (strong) reachability and the second is a closure that
duke@435 352 // may be used to incrementalize or abort the precleaning process.
duke@435 353 // The caller is responsible for taking care of potential
duke@435 354 // interference with concurrent operations on these lists
duke@435 355 // (or predicates involved) by other threads. Currently
coleenp@4037 356 // only used by the CMS collector.
duke@435 357 void preclean_discovered_references(BoolObjectClosure* is_alive,
duke@435 358 OopClosure* keep_alive,
duke@435 359 VoidClosure* complete_gc,
sla@5237 360 YieldClosure* yield,
sla@5237 361 GCTimer* gc_timer);
duke@435 362
duke@435 363 // Delete entries in the discovered lists that have
duke@435 364 // either a null referent or are not active. Such
duke@435 365 // Reference objects can result from the clearing
duke@435 366 // or enqueueing of Reference objects concurrent
duke@435 367 // with their discovery by a (concurrent) collector.
duke@435 368 // For a definition of "active" see java.lang.ref.Reference;
duke@435 369 // Refs are born active, become inactive when enqueued,
duke@435 370 // and never become active again. The state of being
duke@435 371 // active is encoded as follows: A Ref is active
duke@435 372 // if and only if its "next" field is NULL.
duke@435 373 void clean_up_discovered_references();
duke@435 374 void clean_up_discovered_reflist(DiscoveredList& refs_list);
duke@435 375
duke@435 376 // Returns the name of the discovered reference list
duke@435 377 // occupying the i / _num_q slot.
jmasa@3357 378 const char* list_name(uint i);
duke@435 379
coleenp@548 380 void enqueue_discovered_reflists(HeapWord* pending_list_addr, AbstractRefProcTaskExecutor* task_executor);
coleenp@548 381
duke@435 382 protected:
johnc@3175 383 // Set the 'discovered' field of the given reference to
johnc@3175 384 // the given value - emitting barriers depending upon
johnc@3175 385 // the value of _discovered_list_needs_barrier.
johnc@3175 386 void set_discovered(oop ref, oop value);
johnc@3175 387
duke@435 388 // "Preclean" the given discovered reference list
duke@435 389 // by removing references with strongly reachable referents.
duke@435 390 // Currently used in support of CMS only.
duke@435 391 void preclean_discovered_reflist(DiscoveredList& refs_list,
duke@435 392 BoolObjectClosure* is_alive,
duke@435 393 OopClosure* keep_alive,
duke@435 394 VoidClosure* complete_gc,
duke@435 395 YieldClosure* yield);
duke@435 396
ysr@2651 397 // round-robin mod _num_q (not: _not_ mode _max_num_q)
jmasa@3357 398 uint next_id() {
jmasa@3357 399 uint id = _next_id;
duke@435 400 if (++_next_id == _num_q) {
duke@435 401 _next_id = 0;
duke@435 402 }
duke@435 403 return id;
duke@435 404 }
duke@435 405 DiscoveredList* get_discovered_list(ReferenceType rt);
duke@435 406 inline void add_to_discovered_list_mt(DiscoveredList& refs_list, oop obj,
coleenp@548 407 HeapWord* discovered_addr);
duke@435 408 void verify_ok_to_handle_reflists() PRODUCT_RETURN;
duke@435 409
stefank@3115 410 void clear_discovered_references(DiscoveredList& refs_list);
duke@435 411 void abandon_partial_discovered_list(DiscoveredList& refs_list);
duke@435 412
duke@435 413 // Calculate the number of jni handles.
duke@435 414 unsigned int count_jni_refs();
duke@435 415
duke@435 416 // Balances reference queues.
duke@435 417 void balance_queues(DiscoveredList ref_lists[]);
duke@435 418
duke@435 419 // Update (advance) the soft ref master clock field.
duke@435 420 void update_soft_ref_master_clock();
duke@435 421
duke@435 422 public:
duke@435 423 // constructor
duke@435 424 ReferenceProcessor():
duke@435 425 _span((HeapWord*)NULL, (HeapWord*)NULL),
johnc@3210 426 _discovered_refs(NULL),
duke@435 427 _discoveredSoftRefs(NULL), _discoveredWeakRefs(NULL),
duke@435 428 _discoveredFinalRefs(NULL), _discoveredPhantomRefs(NULL),
duke@435 429 _discovering_refs(false),
duke@435 430 _discovery_is_atomic(true),
duke@435 431 _enqueuing_is_done(false),
duke@435 432 _discovery_is_mt(false),
ysr@777 433 _discovered_list_needs_barrier(false),
ysr@777 434 _bs(NULL),
duke@435 435 _is_alive_non_header(NULL),
duke@435 436 _num_q(0),
jmasa@2188 437 _max_num_q(0),
duke@435 438 _processing_is_mt(false),
duke@435 439 _next_id(0)
ysr@2651 440 { }
duke@435 441
ysr@2651 442 // Default parameters give you a vanilla reference processor.
ysr@2651 443 ReferenceProcessor(MemRegion span,
jmasa@3357 444 bool mt_processing = false, uint mt_processing_degree = 1,
jmasa@3357 445 bool mt_discovery = false, uint mt_discovery_degree = 1,
ysr@2651 446 bool atomic_discovery = true,
ysr@2651 447 BoolObjectClosure* is_alive_non_header = NULL,
ysr@777 448 bool discovered_list_needs_barrier = false);
duke@435 449
duke@435 450 // RefDiscoveryPolicy values
johnc@1679 451 enum DiscoveryPolicy {
duke@435 452 ReferenceBasedDiscovery = 0,
johnc@1679 453 ReferentBasedDiscovery = 1,
johnc@1679 454 DiscoveryPolicyMin = ReferenceBasedDiscovery,
johnc@1679 455 DiscoveryPolicyMax = ReferentBasedDiscovery
duke@435 456 };
duke@435 457
duke@435 458 static void init_statics();
duke@435 459
duke@435 460 public:
duke@435 461 // get and set "is_alive_non_header" field
duke@435 462 BoolObjectClosure* is_alive_non_header() {
duke@435 463 return _is_alive_non_header;
duke@435 464 }
duke@435 465 void set_is_alive_non_header(BoolObjectClosure* is_alive_non_header) {
duke@435 466 _is_alive_non_header = is_alive_non_header;
duke@435 467 }
duke@435 468
duke@435 469 // get and set span
duke@435 470 MemRegion span() { return _span; }
duke@435 471 void set_span(MemRegion span) { _span = span; }
duke@435 472
duke@435 473 // start and stop weak ref discovery
johnc@3188 474 void enable_discovery(bool verify_disabled, bool check_no_refs);
duke@435 475 void disable_discovery() { _discovering_refs = false; }
duke@435 476 bool discovery_enabled() { return _discovering_refs; }
duke@435 477
duke@435 478 // whether discovery is atomic wrt other collectors
duke@435 479 bool discovery_is_atomic() const { return _discovery_is_atomic; }
duke@435 480 void set_atomic_discovery(bool atomic) { _discovery_is_atomic = atomic; }
duke@435 481
ysr@3117 482 // whether the JDK in which we are embedded is a pre-4965777 JDK,
ysr@3117 483 // and thus whether or not it uses the discovered field to chain
ysr@3117 484 // the entries in the pending list.
ysr@3117 485 static bool pending_list_uses_discovered_field() {
ysr@3117 486 return _pending_list_uses_discovered_field;
ysr@3117 487 }
ysr@3117 488
duke@435 489 // whether discovery is done by multiple threads same-old-timeously
duke@435 490 bool discovery_is_mt() const { return _discovery_is_mt; }
duke@435 491 void set_mt_discovery(bool mt) { _discovery_is_mt = mt; }
duke@435 492
duke@435 493 // Whether we are in a phase when _processing_ is MT.
duke@435 494 bool processing_is_mt() const { return _processing_is_mt; }
duke@435 495 void set_mt_processing(bool mt) { _processing_is_mt = mt; }
duke@435 496
duke@435 497 // whether all enqueuing of weak references is complete
duke@435 498 bool enqueuing_is_done() { return _enqueuing_is_done; }
duke@435 499 void set_enqueuing_is_done(bool v) { _enqueuing_is_done = v; }
duke@435 500
duke@435 501 // iterate over oops
duke@435 502 void weak_oops_do(OopClosure* f); // weak roots
duke@435 503
jmasa@2188 504 // Balance each of the discovered lists.
jmasa@2188 505 void balance_all_queues();
coleenp@4037 506 void verify_list(DiscoveredList& ref_list);
jmasa@2188 507
duke@435 508 // Discover a Reference object, using appropriate discovery criteria
duke@435 509 bool discover_reference(oop obj, ReferenceType rt);
duke@435 510
duke@435 511 // Process references found during GC (called by the garbage collector)
sla@5237 512 ReferenceProcessorStats
sla@5237 513 process_discovered_references(BoolObjectClosure* is_alive,
sla@5237 514 OopClosure* keep_alive,
sla@5237 515 VoidClosure* complete_gc,
sla@5237 516 AbstractRefProcTaskExecutor* task_executor,
sla@5237 517 GCTimer *gc_timer);
duke@435 518
duke@435 519 // Enqueue references at end of GC (called by the garbage collector)
duke@435 520 bool enqueue_discovered_references(AbstractRefProcTaskExecutor* task_executor = NULL);
duke@435 521
ysr@777 522 // If a discovery is in process that is being superceded, abandon it: all
ysr@777 523 // the discovered lists will be empty, and all the objects on them will
ysr@777 524 // have NULL discovered fields. Must be called only at a safepoint.
ysr@777 525 void abandon_partial_discovery();
ysr@777 526
duke@435 527 // debugging
duke@435 528 void verify_no_references_recorded() PRODUCT_RETURN;
ysr@2337 529 void verify_referent(oop obj) PRODUCT_RETURN;
duke@435 530
duke@435 531 // clear the discovered lists (unlinking each entry).
duke@435 532 void clear_discovered_references() PRODUCT_RETURN;
duke@435 533 };
duke@435 534
duke@435 535 // A utility class to disable reference discovery in
duke@435 536 // the scope which contains it, for given ReferenceProcessor.
duke@435 537 class NoRefDiscovery: StackObj {
duke@435 538 private:
duke@435 539 ReferenceProcessor* _rp;
duke@435 540 bool _was_discovering_refs;
duke@435 541 public:
duke@435 542 NoRefDiscovery(ReferenceProcessor* rp) : _rp(rp) {
twisti@2144 543 _was_discovering_refs = _rp->discovery_enabled();
twisti@2144 544 if (_was_discovering_refs) {
duke@435 545 _rp->disable_discovery();
duke@435 546 }
duke@435 547 }
duke@435 548
duke@435 549 ~NoRefDiscovery() {
duke@435 550 if (_was_discovering_refs) {
johnc@3175 551 _rp->enable_discovery(true /*verify_disabled*/, false /*check_no_refs*/);
duke@435 552 }
duke@435 553 }
duke@435 554 };
duke@435 555
duke@435 556
duke@435 557 // A utility class to temporarily mutate the span of the
duke@435 558 // given ReferenceProcessor in the scope that contains it.
duke@435 559 class ReferenceProcessorSpanMutator: StackObj {
duke@435 560 private:
duke@435 561 ReferenceProcessor* _rp;
duke@435 562 MemRegion _saved_span;
duke@435 563
duke@435 564 public:
duke@435 565 ReferenceProcessorSpanMutator(ReferenceProcessor* rp,
duke@435 566 MemRegion span):
duke@435 567 _rp(rp) {
duke@435 568 _saved_span = _rp->span();
duke@435 569 _rp->set_span(span);
duke@435 570 }
duke@435 571
duke@435 572 ~ReferenceProcessorSpanMutator() {
duke@435 573 _rp->set_span(_saved_span);
duke@435 574 }
duke@435 575 };
duke@435 576
duke@435 577 // A utility class to temporarily change the MT'ness of
duke@435 578 // reference discovery for the given ReferenceProcessor
duke@435 579 // in the scope that contains it.
ysr@2651 580 class ReferenceProcessorMTDiscoveryMutator: StackObj {
duke@435 581 private:
duke@435 582 ReferenceProcessor* _rp;
duke@435 583 bool _saved_mt;
duke@435 584
duke@435 585 public:
ysr@2651 586 ReferenceProcessorMTDiscoveryMutator(ReferenceProcessor* rp,
ysr@2651 587 bool mt):
duke@435 588 _rp(rp) {
duke@435 589 _saved_mt = _rp->discovery_is_mt();
duke@435 590 _rp->set_mt_discovery(mt);
duke@435 591 }
duke@435 592
ysr@2651 593 ~ReferenceProcessorMTDiscoveryMutator() {
duke@435 594 _rp->set_mt_discovery(_saved_mt);
duke@435 595 }
duke@435 596 };
duke@435 597
duke@435 598
duke@435 599 // A utility class to temporarily change the disposition
duke@435 600 // of the "is_alive_non_header" closure field of the
duke@435 601 // given ReferenceProcessor in the scope that contains it.
duke@435 602 class ReferenceProcessorIsAliveMutator: StackObj {
duke@435 603 private:
duke@435 604 ReferenceProcessor* _rp;
duke@435 605 BoolObjectClosure* _saved_cl;
duke@435 606
duke@435 607 public:
duke@435 608 ReferenceProcessorIsAliveMutator(ReferenceProcessor* rp,
duke@435 609 BoolObjectClosure* cl):
duke@435 610 _rp(rp) {
duke@435 611 _saved_cl = _rp->is_alive_non_header();
duke@435 612 _rp->set_is_alive_non_header(cl);
duke@435 613 }
duke@435 614
duke@435 615 ~ReferenceProcessorIsAliveMutator() {
duke@435 616 _rp->set_is_alive_non_header(_saved_cl);
duke@435 617 }
duke@435 618 };
duke@435 619
duke@435 620 // A utility class to temporarily change the disposition
duke@435 621 // of the "discovery_is_atomic" field of the
duke@435 622 // given ReferenceProcessor in the scope that contains it.
duke@435 623 class ReferenceProcessorAtomicMutator: StackObj {
duke@435 624 private:
duke@435 625 ReferenceProcessor* _rp;
duke@435 626 bool _saved_atomic_discovery;
duke@435 627
duke@435 628 public:
duke@435 629 ReferenceProcessorAtomicMutator(ReferenceProcessor* rp,
duke@435 630 bool atomic):
duke@435 631 _rp(rp) {
duke@435 632 _saved_atomic_discovery = _rp->discovery_is_atomic();
duke@435 633 _rp->set_atomic_discovery(atomic);
duke@435 634 }
duke@435 635
duke@435 636 ~ReferenceProcessorAtomicMutator() {
duke@435 637 _rp->set_atomic_discovery(_saved_atomic_discovery);
duke@435 638 }
duke@435 639 };
duke@435 640
duke@435 641
duke@435 642 // A utility class to temporarily change the MT processing
duke@435 643 // disposition of the given ReferenceProcessor instance
duke@435 644 // in the scope that contains it.
duke@435 645 class ReferenceProcessorMTProcMutator: StackObj {
duke@435 646 private:
duke@435 647 ReferenceProcessor* _rp;
duke@435 648 bool _saved_mt;
duke@435 649
duke@435 650 public:
duke@435 651 ReferenceProcessorMTProcMutator(ReferenceProcessor* rp,
duke@435 652 bool mt):
duke@435 653 _rp(rp) {
duke@435 654 _saved_mt = _rp->processing_is_mt();
duke@435 655 _rp->set_mt_processing(mt);
duke@435 656 }
duke@435 657
duke@435 658 ~ReferenceProcessorMTProcMutator() {
duke@435 659 _rp->set_mt_processing(_saved_mt);
duke@435 660 }
duke@435 661 };
duke@435 662
duke@435 663
duke@435 664 // This class is an interface used to implement task execution for the
duke@435 665 // reference processing.
duke@435 666 class AbstractRefProcTaskExecutor {
duke@435 667 public:
duke@435 668
duke@435 669 // Abstract tasks to execute.
duke@435 670 class ProcessTask;
duke@435 671 class EnqueueTask;
duke@435 672
duke@435 673 // Executes a task using worker threads.
duke@435 674 virtual void execute(ProcessTask& task) = 0;
duke@435 675 virtual void execute(EnqueueTask& task) = 0;
duke@435 676
duke@435 677 // Switch to single threaded mode.
duke@435 678 virtual void set_single_threaded_mode() { };
duke@435 679 };
duke@435 680
duke@435 681 // Abstract reference processing task to execute.
duke@435 682 class AbstractRefProcTaskExecutor::ProcessTask {
duke@435 683 protected:
duke@435 684 ProcessTask(ReferenceProcessor& ref_processor,
duke@435 685 DiscoveredList refs_lists[],
duke@435 686 bool marks_oops_alive)
duke@435 687 : _ref_processor(ref_processor),
duke@435 688 _refs_lists(refs_lists),
duke@435 689 _marks_oops_alive(marks_oops_alive)
duke@435 690 { }
duke@435 691
duke@435 692 public:
duke@435 693 virtual void work(unsigned int work_id, BoolObjectClosure& is_alive,
duke@435 694 OopClosure& keep_alive,
duke@435 695 VoidClosure& complete_gc) = 0;
duke@435 696
duke@435 697 // Returns true if a task marks some oops as alive.
duke@435 698 bool marks_oops_alive() const
duke@435 699 { return _marks_oops_alive; }
duke@435 700
duke@435 701 protected:
duke@435 702 ReferenceProcessor& _ref_processor;
duke@435 703 DiscoveredList* _refs_lists;
duke@435 704 const bool _marks_oops_alive;
duke@435 705 };
duke@435 706
duke@435 707 // Abstract reference processing task to execute.
duke@435 708 class AbstractRefProcTaskExecutor::EnqueueTask {
duke@435 709 protected:
duke@435 710 EnqueueTask(ReferenceProcessor& ref_processor,
duke@435 711 DiscoveredList refs_lists[],
coleenp@548 712 HeapWord* pending_list_addr,
duke@435 713 int n_queues)
duke@435 714 : _ref_processor(ref_processor),
duke@435 715 _refs_lists(refs_lists),
duke@435 716 _pending_list_addr(pending_list_addr),
duke@435 717 _n_queues(n_queues)
duke@435 718 { }
duke@435 719
duke@435 720 public:
duke@435 721 virtual void work(unsigned int work_id) = 0;
duke@435 722
duke@435 723 protected:
duke@435 724 ReferenceProcessor& _ref_processor;
duke@435 725 DiscoveredList* _refs_lists;
coleenp@548 726 HeapWord* _pending_list_addr;
duke@435 727 int _n_queues;
duke@435 728 };
stefank@2314 729
stefank@2314 730 #endif // SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP

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