J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 1 | /* |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 2 | * Copyright (c) 2001, 2011, Oracle and/or its affiliates. All rights reserved. |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 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 | * |
Erik Trimble | ba7c173 | 2010-05-27 19:08:38 -0700 | [diff] [blame] | 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. |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 22 | * |
| 23 | */ |
| 24 | |
Stefan Karlsson | 8006fe8 | 2010-11-23 13:22:55 -0800 | [diff] [blame] | 25 | #ifndef SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP |
| 26 | #define SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP |
| 27 | |
| 28 | #include "memory/referencePolicy.hpp" |
| 29 | #include "oops/instanceRefKlass.hpp" |
| 30 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 31 | // ReferenceProcessor class encapsulates the per-"collector" processing |
Y. Srinivas Ramakrishna | 7d7cf3f | 2008-11-20 16:56:09 -0800 | [diff] [blame] | 32 | // of java.lang.Reference objects for GC. The interface is useful for supporting |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 33 | // a generational abstraction, in particular when there are multiple |
| 34 | // generations that are being independently collected -- possibly |
| 35 | // concurrently and/or incrementally. Note, however, that the |
| 36 | // ReferenceProcessor class abstracts away from a generational setting |
| 37 | // by using only a heap interval (called "span" below), thus allowing |
| 38 | // its use in a straightforward manner in a general, non-generational |
| 39 | // setting. |
| 40 | // |
| 41 | // The basic idea is that each ReferenceProcessor object concerns |
| 42 | // itself with ("weak") reference processing in a specific "span" |
| 43 | // of the heap of interest to a specific collector. Currently, |
| 44 | // the span is a convex interval of the heap, but, efficiency |
| 45 | // apart, there seems to be no reason it couldn't be extended |
| 46 | // (with appropriate modifications) to any "non-convex interval". |
| 47 | |
| 48 | // forward references |
| 49 | class ReferencePolicy; |
| 50 | class AbstractRefProcTaskExecutor; |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 51 | |
| 52 | // List of discovered references. |
| 53 | class DiscoveredList { |
| 54 | public: |
| 55 | DiscoveredList() : _len(0), _compressed_head(0), _oop_head(NULL) { } |
| 56 | oop head() const { |
| 57 | return UseCompressedOops ? oopDesc::decode_heap_oop(_compressed_head) : |
| 58 | _oop_head; |
| 59 | } |
| 60 | HeapWord* adr_head() { |
| 61 | return UseCompressedOops ? (HeapWord*)&_compressed_head : |
| 62 | (HeapWord*)&_oop_head; |
| 63 | } |
| 64 | void set_head(oop o) { |
| 65 | if (UseCompressedOops) { |
| 66 | // Must compress the head ptr. |
| 67 | _compressed_head = oopDesc::encode_heap_oop(o); |
| 68 | } else { |
| 69 | _oop_head = o; |
| 70 | } |
| 71 | } |
| 72 | bool is_empty() const { return head() == NULL; } |
| 73 | size_t length() { return _len; } |
| 74 | void set_length(size_t len) { _len = len; } |
| 75 | void inc_length(size_t inc) { _len += inc; assert(_len > 0, "Error"); } |
| 76 | void dec_length(size_t dec) { _len -= dec; } |
| 77 | private: |
| 78 | // Set value depending on UseCompressedOops. This could be a template class |
| 79 | // but then we have to fix all the instantiations and declarations that use this class. |
| 80 | oop _oop_head; |
| 81 | narrowOop _compressed_head; |
| 82 | size_t _len; |
| 83 | }; |
| 84 | |
| 85 | // Iterator for the list of discovered references. |
| 86 | class DiscoveredListIterator { |
| 87 | private: |
| 88 | DiscoveredList& _refs_list; |
| 89 | HeapWord* _prev_next; |
| 90 | oop _prev; |
| 91 | oop _ref; |
| 92 | HeapWord* _discovered_addr; |
| 93 | oop _next; |
| 94 | HeapWord* _referent_addr; |
| 95 | oop _referent; |
| 96 | OopClosure* _keep_alive; |
| 97 | BoolObjectClosure* _is_alive; |
| 98 | |
| 99 | DEBUG_ONLY( |
| 100 | oop _first_seen; // cyclic linked list check |
| 101 | ) |
| 102 | |
| 103 | NOT_PRODUCT( |
| 104 | size_t _processed; |
| 105 | size_t _removed; |
| 106 | ) |
| 107 | |
| 108 | public: |
| 109 | inline DiscoveredListIterator(DiscoveredList& refs_list, |
| 110 | OopClosure* keep_alive, |
| 111 | BoolObjectClosure* is_alive): |
| 112 | _refs_list(refs_list), |
| 113 | _prev_next(refs_list.adr_head()), |
| 114 | _prev(NULL), |
| 115 | _ref(refs_list.head()), |
| 116 | #ifdef ASSERT |
| 117 | _first_seen(refs_list.head()), |
| 118 | #endif |
| 119 | #ifndef PRODUCT |
| 120 | _processed(0), |
| 121 | _removed(0), |
| 122 | #endif |
| 123 | _next(NULL), |
| 124 | _keep_alive(keep_alive), |
| 125 | _is_alive(is_alive) |
| 126 | { } |
| 127 | |
| 128 | // End Of List. |
| 129 | inline bool has_next() const { return _ref != NULL; } |
| 130 | |
| 131 | // Get oop to the Reference object. |
| 132 | inline oop obj() const { return _ref; } |
| 133 | |
| 134 | // Get oop to the referent object. |
| 135 | inline oop referent() const { return _referent; } |
| 136 | |
| 137 | // Returns true if referent is alive. |
| 138 | inline bool is_referent_alive() const { |
| 139 | return _is_alive->do_object_b(_referent); |
| 140 | } |
| 141 | |
| 142 | // Loads data for the current reference. |
| 143 | // The "allow_null_referent" argument tells us to allow for the possibility |
| 144 | // of a NULL referent in the discovered Reference object. This typically |
| 145 | // happens in the case of concurrent collectors that may have done the |
| 146 | // discovery concurrently, or interleaved, with mutator execution. |
| 147 | void load_ptrs(DEBUG_ONLY(bool allow_null_referent)); |
| 148 | |
| 149 | // Move to the next discovered reference. |
| 150 | inline void next() { |
| 151 | _prev_next = _discovered_addr; |
| 152 | _prev = _ref; |
| 153 | move_to_next(); |
| 154 | } |
| 155 | |
| 156 | // Remove the current reference from the list |
| 157 | void remove(); |
| 158 | |
| 159 | // Make the Reference object active again. |
| 160 | void make_active(); |
| 161 | |
| 162 | // Make the referent alive. |
| 163 | inline void make_referent_alive() { |
| 164 | if (UseCompressedOops) { |
| 165 | _keep_alive->do_oop((narrowOop*)_referent_addr); |
| 166 | } else { |
| 167 | _keep_alive->do_oop((oop*)_referent_addr); |
| 168 | } |
| 169 | } |
| 170 | |
| 171 | // Update the discovered field. |
| 172 | inline void update_discovered() { |
| 173 | // First _prev_next ref actually points into DiscoveredList (gross). |
| 174 | if (UseCompressedOops) { |
| 175 | if (!oopDesc::is_null(*(narrowOop*)_prev_next)) { |
| 176 | _keep_alive->do_oop((narrowOop*)_prev_next); |
| 177 | } |
| 178 | } else { |
| 179 | if (!oopDesc::is_null(*(oop*)_prev_next)) { |
| 180 | _keep_alive->do_oop((oop*)_prev_next); |
| 181 | } |
| 182 | } |
| 183 | } |
| 184 | |
| 185 | // NULL out referent pointer. |
| 186 | void clear_referent(); |
| 187 | |
| 188 | // Statistics |
| 189 | NOT_PRODUCT( |
| 190 | inline size_t processed() const { return _processed; } |
| 191 | inline size_t removed() const { return _removed; } |
| 192 | ) |
| 193 | |
| 194 | inline void move_to_next() { |
| 195 | if (_ref == _next) { |
| 196 | // End of the list. |
| 197 | _ref = NULL; |
| 198 | } else { |
| 199 | _ref = _next; |
| 200 | } |
| 201 | assert(_ref != _first_seen, "cyclic ref_list found"); |
| 202 | NOT_PRODUCT(_processed++); |
| 203 | } |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 204 | }; |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 205 | |
Zhengyu Gu | a39b176 | 2012-06-28 17:03:16 -0400 | [diff] [blame^] | 206 | class ReferenceProcessor : public CHeapObj<mtGC> { |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 207 | protected: |
Y. Srinivas Ramakrishna | ed72e31 | 2011-09-07 13:55:42 -0700 | [diff] [blame] | 208 | // Compatibility with pre-4965777 JDK's |
| 209 | static bool _pending_list_uses_discovered_field; |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 210 | |
John Cuthbertson | 4738ed8 | 2011-10-12 10:25:51 -0700 | [diff] [blame] | 211 | // The SoftReference master timestamp clock |
| 212 | static jlong _soft_ref_timestamp_clock; |
| 213 | |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 214 | MemRegion _span; // (right-open) interval of heap |
| 215 | // subject to wkref discovery |
| 216 | |
| 217 | bool _discovering_refs; // true when discovery enabled |
| 218 | bool _discovery_is_atomic; // if discovery is atomic wrt |
| 219 | // other collectors in configuration |
| 220 | bool _discovery_is_mt; // true if reference discovery is MT. |
| 221 | |
Y. Srinivas Ramakrishna | 18f3386 | 2008-06-05 15:57:56 -0700 | [diff] [blame] | 222 | // If true, setting "next" field of a discovered refs list requires |
| 223 | // write barrier(s). (Must be true if used in a collector in which |
| 224 | // elements of a discovered list may be moved during discovery: for |
| 225 | // example, a collector like Garbage-First that moves objects during a |
| 226 | // long-term concurrent marking phase that does weak reference |
| 227 | // discovery.) |
| 228 | bool _discovered_list_needs_barrier; |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 229 | |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 230 | BarrierSet* _bs; // Cached copy of BarrierSet. |
| 231 | bool _enqueuing_is_done; // true if all weak references enqueued |
| 232 | bool _processing_is_mt; // true during phases when |
| 233 | // reference processing is MT. |
Jon Masamitsu | 0ebc10b | 2011-12-14 13:34:57 -0800 | [diff] [blame] | 234 | uint _next_id; // round-robin mod _num_q counter in |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 235 | // support of work distribution |
| 236 | |
| 237 | // For collectors that do not keep GC liveness information |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 238 | // in the object header, this field holds a closure that |
| 239 | // helps the reference processor determine the reachability |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 240 | // of an oop. It is currently initialized to NULL for all |
| 241 | // collectors except for CMS and G1. |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 242 | BoolObjectClosure* _is_alive_non_header; |
| 243 | |
Y. Srinivas Ramakrishna | 7d7cf3f | 2008-11-20 16:56:09 -0800 | [diff] [blame] | 244 | // Soft ref clearing policies |
| 245 | // . the default policy |
| 246 | static ReferencePolicy* _default_soft_ref_policy; |
| 247 | // . the "clear all" policy |
| 248 | static ReferencePolicy* _always_clear_soft_ref_policy; |
| 249 | // . the current policy below is either one of the above |
| 250 | ReferencePolicy* _current_soft_ref_policy; |
| 251 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 252 | // The discovered ref lists themselves |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 253 | |
Jon Masamitsu | 28e56b8 | 2010-09-20 14:38:38 -0700 | [diff] [blame] | 254 | // The active MT'ness degree of the queues below |
Jon Masamitsu | 0ebc10b | 2011-12-14 13:34:57 -0800 | [diff] [blame] | 255 | uint _num_q; |
Jon Masamitsu | 28e56b8 | 2010-09-20 14:38:38 -0700 | [diff] [blame] | 256 | // The maximum MT'ness degree of the queues below |
Jon Masamitsu | 0ebc10b | 2011-12-14 13:34:57 -0800 | [diff] [blame] | 257 | uint _max_num_q; |
John Cuthbertson | cab4072 | 2011-10-17 09:57:41 -0700 | [diff] [blame] | 258 | |
| 259 | // Master array of discovered oops |
| 260 | DiscoveredList* _discovered_refs; |
| 261 | |
| 262 | // Arrays of lists of oops, one per thread (pointers into master array above) |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 263 | DiscoveredList* _discoveredSoftRefs; |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 264 | DiscoveredList* _discoveredWeakRefs; |
| 265 | DiscoveredList* _discoveredFinalRefs; |
| 266 | DiscoveredList* _discoveredPhantomRefs; |
| 267 | |
| 268 | public: |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 269 | static int number_of_subclasses_of_ref() { return (REF_PHANTOM - REF_OTHER); } |
| 270 | |
Jon Masamitsu | 0ebc10b | 2011-12-14 13:34:57 -0800 | [diff] [blame] | 271 | uint num_q() { return _num_q; } |
| 272 | uint max_num_q() { return _max_num_q; } |
| 273 | void set_active_mt_degree(uint v) { _num_q = v; } |
John Cuthbertson | cab4072 | 2011-10-17 09:57:41 -0700 | [diff] [blame] | 274 | |
| 275 | DiscoveredList* discovered_refs() { return _discovered_refs; } |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 276 | |
Y. Srinivas Ramakrishna | 16aa57c | 2008-12-01 23:25:24 -0800 | [diff] [blame] | 277 | ReferencePolicy* setup_policy(bool always_clear) { |
Y. Srinivas Ramakrishna | 7d7cf3f | 2008-11-20 16:56:09 -0800 | [diff] [blame] | 278 | _current_soft_ref_policy = always_clear ? |
| 279 | _always_clear_soft_ref_policy : _default_soft_ref_policy; |
Y. Srinivas Ramakrishna | 16aa57c | 2008-12-01 23:25:24 -0800 | [diff] [blame] | 280 | _current_soft_ref_policy->setup(); // snapshot the policy threshold |
Y. Srinivas Ramakrishna | 7d7cf3f | 2008-11-20 16:56:09 -0800 | [diff] [blame] | 281 | return _current_soft_ref_policy; |
| 282 | } |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 283 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 284 | // Process references with a certain reachability level. |
| 285 | void process_discovered_reflist(DiscoveredList refs_lists[], |
| 286 | ReferencePolicy* policy, |
| 287 | bool clear_referent, |
| 288 | BoolObjectClosure* is_alive, |
| 289 | OopClosure* keep_alive, |
| 290 | VoidClosure* complete_gc, |
| 291 | AbstractRefProcTaskExecutor* task_executor); |
| 292 | |
| 293 | void process_phaseJNI(BoolObjectClosure* is_alive, |
| 294 | OopClosure* keep_alive, |
| 295 | VoidClosure* complete_gc); |
| 296 | |
| 297 | // Work methods used by the method process_discovered_reflist |
| 298 | // Phase1: keep alive all those referents that are otherwise |
| 299 | // dead but which must be kept alive by policy (and their closure). |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 300 | void process_phase1(DiscoveredList& refs_list, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 301 | ReferencePolicy* policy, |
| 302 | BoolObjectClosure* is_alive, |
| 303 | OopClosure* keep_alive, |
| 304 | VoidClosure* complete_gc); |
| 305 | // Phase2: remove all those references whose referents are |
| 306 | // reachable. |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 307 | inline void process_phase2(DiscoveredList& refs_list, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 308 | BoolObjectClosure* is_alive, |
| 309 | OopClosure* keep_alive, |
| 310 | VoidClosure* complete_gc) { |
| 311 | if (discovery_is_atomic()) { |
| 312 | // complete_gc is ignored in this case for this phase |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 313 | pp2_work(refs_list, is_alive, keep_alive); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 314 | } else { |
| 315 | assert(complete_gc != NULL, "Error"); |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 316 | pp2_work_concurrent_discovery(refs_list, is_alive, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 317 | keep_alive, complete_gc); |
| 318 | } |
| 319 | } |
| 320 | // Work methods in support of process_phase2 |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 321 | void pp2_work(DiscoveredList& refs_list, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 322 | BoolObjectClosure* is_alive, |
| 323 | OopClosure* keep_alive); |
| 324 | void pp2_work_concurrent_discovery( |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 325 | DiscoveredList& refs_list, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 326 | BoolObjectClosure* is_alive, |
| 327 | OopClosure* keep_alive, |
| 328 | VoidClosure* complete_gc); |
| 329 | // Phase3: process the referents by either clearing them |
| 330 | // or keeping them alive (and their closure) |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 331 | void process_phase3(DiscoveredList& refs_list, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 332 | bool clear_referent, |
| 333 | BoolObjectClosure* is_alive, |
| 334 | OopClosure* keep_alive, |
| 335 | VoidClosure* complete_gc); |
| 336 | |
| 337 | // Enqueue references with a certain reachability level |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 338 | void enqueue_discovered_reflist(DiscoveredList& refs_list, HeapWord* pending_list_addr); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 339 | |
| 340 | // "Preclean" all the discovered reference lists |
| 341 | // by removing references with strongly reachable referents. |
| 342 | // The first argument is a predicate on an oop that indicates |
| 343 | // its (strong) reachability and the second is a closure that |
| 344 | // may be used to incrementalize or abort the precleaning process. |
| 345 | // The caller is responsible for taking care of potential |
| 346 | // interference with concurrent operations on these lists |
| 347 | // (or predicates involved) by other threads. Currently |
Jon Masamitsu | b2ed547 | 2010-01-21 11:33:32 -0800 | [diff] [blame] | 348 | // only used by the CMS collector. should_unload_classes is |
| 349 | // used to aid assertion checking when classes are collected. |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 350 | void preclean_discovered_references(BoolObjectClosure* is_alive, |
| 351 | OopClosure* keep_alive, |
| 352 | VoidClosure* complete_gc, |
Jon Masamitsu | b2ed547 | 2010-01-21 11:33:32 -0800 | [diff] [blame] | 353 | YieldClosure* yield, |
| 354 | bool should_unload_classes); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 355 | |
| 356 | // Delete entries in the discovered lists that have |
| 357 | // either a null referent or are not active. Such |
| 358 | // Reference objects can result from the clearing |
| 359 | // or enqueueing of Reference objects concurrent |
| 360 | // with their discovery by a (concurrent) collector. |
| 361 | // For a definition of "active" see java.lang.ref.Reference; |
| 362 | // Refs are born active, become inactive when enqueued, |
| 363 | // and never become active again. The state of being |
| 364 | // active is encoded as follows: A Ref is active |
| 365 | // if and only if its "next" field is NULL. |
| 366 | void clean_up_discovered_references(); |
| 367 | void clean_up_discovered_reflist(DiscoveredList& refs_list); |
| 368 | |
| 369 | // Returns the name of the discovered reference list |
| 370 | // occupying the i / _num_q slot. |
Jon Masamitsu | 0ebc10b | 2011-12-14 13:34:57 -0800 | [diff] [blame] | 371 | const char* list_name(uint i); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 372 | |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 373 | void enqueue_discovered_reflists(HeapWord* pending_list_addr, AbstractRefProcTaskExecutor* task_executor); |
| 374 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 375 | protected: |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 376 | // Set the 'discovered' field of the given reference to |
| 377 | // the given value - emitting barriers depending upon |
| 378 | // the value of _discovered_list_needs_barrier. |
| 379 | void set_discovered(oop ref, oop value); |
| 380 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 381 | // "Preclean" the given discovered reference list |
| 382 | // by removing references with strongly reachable referents. |
| 383 | // Currently used in support of CMS only. |
| 384 | void preclean_discovered_reflist(DiscoveredList& refs_list, |
| 385 | BoolObjectClosure* is_alive, |
| 386 | OopClosure* keep_alive, |
| 387 | VoidClosure* complete_gc, |
| 388 | YieldClosure* yield); |
| 389 | |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 390 | // round-robin mod _num_q (not: _not_ mode _max_num_q) |
Jon Masamitsu | 0ebc10b | 2011-12-14 13:34:57 -0800 | [diff] [blame] | 391 | uint next_id() { |
| 392 | uint id = _next_id; |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 393 | if (++_next_id == _num_q) { |
| 394 | _next_id = 0; |
| 395 | } |
| 396 | return id; |
| 397 | } |
| 398 | DiscoveredList* get_discovered_list(ReferenceType rt); |
| 399 | inline void add_to_discovered_list_mt(DiscoveredList& refs_list, oop obj, |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 400 | HeapWord* discovered_addr); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 401 | void verify_ok_to_handle_reflists() PRODUCT_RETURN; |
| 402 | |
Stefan Karlsson | 5b6ba4e | 2011-09-01 16:18:17 +0200 | [diff] [blame] | 403 | void clear_discovered_references(DiscoveredList& refs_list); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 404 | void abandon_partial_discovered_list(DiscoveredList& refs_list); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 405 | |
| 406 | // Calculate the number of jni handles. |
| 407 | unsigned int count_jni_refs(); |
| 408 | |
| 409 | // Balances reference queues. |
| 410 | void balance_queues(DiscoveredList ref_lists[]); |
| 411 | |
| 412 | // Update (advance) the soft ref master clock field. |
| 413 | void update_soft_ref_master_clock(); |
| 414 | |
| 415 | public: |
| 416 | // constructor |
| 417 | ReferenceProcessor(): |
| 418 | _span((HeapWord*)NULL, (HeapWord*)NULL), |
John Cuthbertson | cab4072 | 2011-10-17 09:57:41 -0700 | [diff] [blame] | 419 | _discovered_refs(NULL), |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 420 | _discoveredSoftRefs(NULL), _discoveredWeakRefs(NULL), |
| 421 | _discoveredFinalRefs(NULL), _discoveredPhantomRefs(NULL), |
| 422 | _discovering_refs(false), |
| 423 | _discovery_is_atomic(true), |
| 424 | _enqueuing_is_done(false), |
| 425 | _discovery_is_mt(false), |
Y. Srinivas Ramakrishna | 18f3386 | 2008-06-05 15:57:56 -0700 | [diff] [blame] | 426 | _discovered_list_needs_barrier(false), |
| 427 | _bs(NULL), |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 428 | _is_alive_non_header(NULL), |
| 429 | _num_q(0), |
Jon Masamitsu | 28e56b8 | 2010-09-20 14:38:38 -0700 | [diff] [blame] | 430 | _max_num_q(0), |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 431 | _processing_is_mt(false), |
| 432 | _next_id(0) |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 433 | { } |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 434 | |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 435 | // Default parameters give you a vanilla reference processor. |
| 436 | ReferenceProcessor(MemRegion span, |
Jon Masamitsu | 0ebc10b | 2011-12-14 13:34:57 -0800 | [diff] [blame] | 437 | bool mt_processing = false, uint mt_processing_degree = 1, |
| 438 | bool mt_discovery = false, uint mt_discovery_degree = 1, |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 439 | bool atomic_discovery = true, |
| 440 | BoolObjectClosure* is_alive_non_header = NULL, |
Y. Srinivas Ramakrishna | 18f3386 | 2008-06-05 15:57:56 -0700 | [diff] [blame] | 441 | bool discovered_list_needs_barrier = false); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 442 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 443 | // RefDiscoveryPolicy values |
John Cuthbertson | b34027a | 2010-01-29 14:51:38 -0800 | [diff] [blame] | 444 | enum DiscoveryPolicy { |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 445 | ReferenceBasedDiscovery = 0, |
John Cuthbertson | b34027a | 2010-01-29 14:51:38 -0800 | [diff] [blame] | 446 | ReferentBasedDiscovery = 1, |
| 447 | DiscoveryPolicyMin = ReferenceBasedDiscovery, |
| 448 | DiscoveryPolicyMax = ReferentBasedDiscovery |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 449 | }; |
| 450 | |
| 451 | static void init_statics(); |
| 452 | |
| 453 | public: |
| 454 | // get and set "is_alive_non_header" field |
| 455 | BoolObjectClosure* is_alive_non_header() { |
| 456 | return _is_alive_non_header; |
| 457 | } |
| 458 | void set_is_alive_non_header(BoolObjectClosure* is_alive_non_header) { |
| 459 | _is_alive_non_header = is_alive_non_header; |
| 460 | } |
| 461 | |
| 462 | // get and set span |
| 463 | MemRegion span() { return _span; } |
| 464 | void set_span(MemRegion span) { _span = span; } |
| 465 | |
| 466 | // start and stop weak ref discovery |
John Cuthbertson | 4738ed8 | 2011-10-12 10:25:51 -0700 | [diff] [blame] | 467 | void enable_discovery(bool verify_disabled, bool check_no_refs); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 468 | void disable_discovery() { _discovering_refs = false; } |
| 469 | bool discovery_enabled() { return _discovering_refs; } |
| 470 | |
| 471 | // whether discovery is atomic wrt other collectors |
| 472 | bool discovery_is_atomic() const { return _discovery_is_atomic; } |
| 473 | void set_atomic_discovery(bool atomic) { _discovery_is_atomic = atomic; } |
| 474 | |
Y. Srinivas Ramakrishna | ed72e31 | 2011-09-07 13:55:42 -0700 | [diff] [blame] | 475 | // whether the JDK in which we are embedded is a pre-4965777 JDK, |
| 476 | // and thus whether or not it uses the discovered field to chain |
| 477 | // the entries in the pending list. |
| 478 | static bool pending_list_uses_discovered_field() { |
| 479 | return _pending_list_uses_discovered_field; |
| 480 | } |
| 481 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 482 | // whether discovery is done by multiple threads same-old-timeously |
| 483 | bool discovery_is_mt() const { return _discovery_is_mt; } |
| 484 | void set_mt_discovery(bool mt) { _discovery_is_mt = mt; } |
| 485 | |
| 486 | // Whether we are in a phase when _processing_ is MT. |
| 487 | bool processing_is_mt() const { return _processing_is_mt; } |
| 488 | void set_mt_processing(bool mt) { _processing_is_mt = mt; } |
| 489 | |
| 490 | // whether all enqueuing of weak references is complete |
| 491 | bool enqueuing_is_done() { return _enqueuing_is_done; } |
| 492 | void set_enqueuing_is_done(bool v) { _enqueuing_is_done = v; } |
| 493 | |
| 494 | // iterate over oops |
| 495 | void weak_oops_do(OopClosure* f); // weak roots |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 496 | |
Jon Masamitsu | 28e56b8 | 2010-09-20 14:38:38 -0700 | [diff] [blame] | 497 | // Balance each of the discovered lists. |
| 498 | void balance_all_queues(); |
| 499 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 500 | // Discover a Reference object, using appropriate discovery criteria |
| 501 | bool discover_reference(oop obj, ReferenceType rt); |
| 502 | |
| 503 | // Process references found during GC (called by the garbage collector) |
Y. Srinivas Ramakrishna | 7d7cf3f | 2008-11-20 16:56:09 -0800 | [diff] [blame] | 504 | void process_discovered_references(BoolObjectClosure* is_alive, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 505 | OopClosure* keep_alive, |
| 506 | VoidClosure* complete_gc, |
| 507 | AbstractRefProcTaskExecutor* task_executor); |
| 508 | |
| 509 | public: |
| 510 | // Enqueue references at end of GC (called by the garbage collector) |
| 511 | bool enqueue_discovered_references(AbstractRefProcTaskExecutor* task_executor = NULL); |
| 512 | |
Y. Srinivas Ramakrishna | 18f3386 | 2008-06-05 15:57:56 -0700 | [diff] [blame] | 513 | // If a discovery is in process that is being superceded, abandon it: all |
| 514 | // the discovered lists will be empty, and all the objects on them will |
| 515 | // have NULL discovered fields. Must be called only at a safepoint. |
| 516 | void abandon_partial_discovery(); |
| 517 | |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 518 | // debugging |
| 519 | void verify_no_references_recorded() PRODUCT_RETURN; |
Y. Srinivas Ramakrishna | 8baafdf | 2010-12-09 09:22:57 -0800 | [diff] [blame] | 520 | void verify_referent(oop obj) PRODUCT_RETURN; |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 521 | |
| 522 | // clear the discovered lists (unlinking each entry). |
| 523 | void clear_discovered_references() PRODUCT_RETURN; |
| 524 | }; |
| 525 | |
| 526 | // A utility class to disable reference discovery in |
| 527 | // the scope which contains it, for given ReferenceProcessor. |
| 528 | class NoRefDiscovery: StackObj { |
| 529 | private: |
| 530 | ReferenceProcessor* _rp; |
| 531 | bool _was_discovering_refs; |
| 532 | public: |
| 533 | NoRefDiscovery(ReferenceProcessor* rp) : _rp(rp) { |
Pavel Tisnovsky | af25487 | 2010-09-09 05:24:11 -0700 | [diff] [blame] | 534 | _was_discovering_refs = _rp->discovery_enabled(); |
| 535 | if (_was_discovering_refs) { |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 536 | _rp->disable_discovery(); |
| 537 | } |
| 538 | } |
| 539 | |
| 540 | ~NoRefDiscovery() { |
| 541 | if (_was_discovering_refs) { |
John Cuthbertson | 1b62d10 | 2011-09-22 10:57:37 -0700 | [diff] [blame] | 542 | _rp->enable_discovery(true /*verify_disabled*/, false /*check_no_refs*/); |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 543 | } |
| 544 | } |
| 545 | }; |
| 546 | |
| 547 | |
| 548 | // A utility class to temporarily mutate the span of the |
| 549 | // given ReferenceProcessor in the scope that contains it. |
| 550 | class ReferenceProcessorSpanMutator: StackObj { |
| 551 | private: |
| 552 | ReferenceProcessor* _rp; |
| 553 | MemRegion _saved_span; |
| 554 | |
| 555 | public: |
| 556 | ReferenceProcessorSpanMutator(ReferenceProcessor* rp, |
| 557 | MemRegion span): |
| 558 | _rp(rp) { |
| 559 | _saved_span = _rp->span(); |
| 560 | _rp->set_span(span); |
| 561 | } |
| 562 | |
| 563 | ~ReferenceProcessorSpanMutator() { |
| 564 | _rp->set_span(_saved_span); |
| 565 | } |
| 566 | }; |
| 567 | |
| 568 | // A utility class to temporarily change the MT'ness of |
| 569 | // reference discovery for the given ReferenceProcessor |
| 570 | // in the scope that contains it. |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 571 | class ReferenceProcessorMTDiscoveryMutator: StackObj { |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 572 | private: |
| 573 | ReferenceProcessor* _rp; |
| 574 | bool _saved_mt; |
| 575 | |
| 576 | public: |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 577 | ReferenceProcessorMTDiscoveryMutator(ReferenceProcessor* rp, |
| 578 | bool mt): |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 579 | _rp(rp) { |
| 580 | _saved_mt = _rp->discovery_is_mt(); |
| 581 | _rp->set_mt_discovery(mt); |
| 582 | } |
| 583 | |
Y. Srinivas Ramakrishna | b4b287e | 2011-03-17 10:32:46 -0700 | [diff] [blame] | 584 | ~ReferenceProcessorMTDiscoveryMutator() { |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 585 | _rp->set_mt_discovery(_saved_mt); |
| 586 | } |
| 587 | }; |
| 588 | |
| 589 | |
| 590 | // A utility class to temporarily change the disposition |
| 591 | // of the "is_alive_non_header" closure field of the |
| 592 | // given ReferenceProcessor in the scope that contains it. |
| 593 | class ReferenceProcessorIsAliveMutator: StackObj { |
| 594 | private: |
| 595 | ReferenceProcessor* _rp; |
| 596 | BoolObjectClosure* _saved_cl; |
| 597 | |
| 598 | public: |
| 599 | ReferenceProcessorIsAliveMutator(ReferenceProcessor* rp, |
| 600 | BoolObjectClosure* cl): |
| 601 | _rp(rp) { |
| 602 | _saved_cl = _rp->is_alive_non_header(); |
| 603 | _rp->set_is_alive_non_header(cl); |
| 604 | } |
| 605 | |
| 606 | ~ReferenceProcessorIsAliveMutator() { |
| 607 | _rp->set_is_alive_non_header(_saved_cl); |
| 608 | } |
| 609 | }; |
| 610 | |
| 611 | // A utility class to temporarily change the disposition |
| 612 | // of the "discovery_is_atomic" field of the |
| 613 | // given ReferenceProcessor in the scope that contains it. |
| 614 | class ReferenceProcessorAtomicMutator: StackObj { |
| 615 | private: |
| 616 | ReferenceProcessor* _rp; |
| 617 | bool _saved_atomic_discovery; |
| 618 | |
| 619 | public: |
| 620 | ReferenceProcessorAtomicMutator(ReferenceProcessor* rp, |
| 621 | bool atomic): |
| 622 | _rp(rp) { |
| 623 | _saved_atomic_discovery = _rp->discovery_is_atomic(); |
| 624 | _rp->set_atomic_discovery(atomic); |
| 625 | } |
| 626 | |
| 627 | ~ReferenceProcessorAtomicMutator() { |
| 628 | _rp->set_atomic_discovery(_saved_atomic_discovery); |
| 629 | } |
| 630 | }; |
| 631 | |
| 632 | |
| 633 | // A utility class to temporarily change the MT processing |
| 634 | // disposition of the given ReferenceProcessor instance |
| 635 | // in the scope that contains it. |
| 636 | class ReferenceProcessorMTProcMutator: StackObj { |
| 637 | private: |
| 638 | ReferenceProcessor* _rp; |
| 639 | bool _saved_mt; |
| 640 | |
| 641 | public: |
| 642 | ReferenceProcessorMTProcMutator(ReferenceProcessor* rp, |
| 643 | bool mt): |
| 644 | _rp(rp) { |
| 645 | _saved_mt = _rp->processing_is_mt(); |
| 646 | _rp->set_mt_processing(mt); |
| 647 | } |
| 648 | |
| 649 | ~ReferenceProcessorMTProcMutator() { |
| 650 | _rp->set_mt_processing(_saved_mt); |
| 651 | } |
| 652 | }; |
| 653 | |
| 654 | |
| 655 | // This class is an interface used to implement task execution for the |
| 656 | // reference processing. |
| 657 | class AbstractRefProcTaskExecutor { |
| 658 | public: |
| 659 | |
| 660 | // Abstract tasks to execute. |
| 661 | class ProcessTask; |
| 662 | class EnqueueTask; |
| 663 | |
| 664 | // Executes a task using worker threads. |
| 665 | virtual void execute(ProcessTask& task) = 0; |
| 666 | virtual void execute(EnqueueTask& task) = 0; |
| 667 | |
| 668 | // Switch to single threaded mode. |
| 669 | virtual void set_single_threaded_mode() { }; |
| 670 | }; |
| 671 | |
| 672 | // Abstract reference processing task to execute. |
| 673 | class AbstractRefProcTaskExecutor::ProcessTask { |
| 674 | protected: |
| 675 | ProcessTask(ReferenceProcessor& ref_processor, |
| 676 | DiscoveredList refs_lists[], |
| 677 | bool marks_oops_alive) |
| 678 | : _ref_processor(ref_processor), |
| 679 | _refs_lists(refs_lists), |
| 680 | _marks_oops_alive(marks_oops_alive) |
| 681 | { } |
| 682 | |
| 683 | public: |
| 684 | virtual void work(unsigned int work_id, BoolObjectClosure& is_alive, |
| 685 | OopClosure& keep_alive, |
| 686 | VoidClosure& complete_gc) = 0; |
| 687 | |
| 688 | // Returns true if a task marks some oops as alive. |
| 689 | bool marks_oops_alive() const |
| 690 | { return _marks_oops_alive; } |
| 691 | |
| 692 | protected: |
| 693 | ReferenceProcessor& _ref_processor; |
| 694 | DiscoveredList* _refs_lists; |
| 695 | const bool _marks_oops_alive; |
| 696 | }; |
| 697 | |
| 698 | // Abstract reference processing task to execute. |
| 699 | class AbstractRefProcTaskExecutor::EnqueueTask { |
| 700 | protected: |
| 701 | EnqueueTask(ReferenceProcessor& ref_processor, |
| 702 | DiscoveredList refs_lists[], |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 703 | HeapWord* pending_list_addr, |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 704 | int n_queues) |
| 705 | : _ref_processor(ref_processor), |
| 706 | _refs_lists(refs_lists), |
| 707 | _pending_list_addr(pending_list_addr), |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 708 | _n_queues(n_queues) |
| 709 | { } |
| 710 | |
| 711 | public: |
| 712 | virtual void work(unsigned int work_id) = 0; |
| 713 | |
| 714 | protected: |
| 715 | ReferenceProcessor& _ref_processor; |
| 716 | DiscoveredList* _refs_lists; |
Coleen Phillimore | 4a831d4 | 2008-04-13 17:43:42 -0400 | [diff] [blame] | 717 | HeapWord* _pending_list_addr; |
J. Duke | 8153779 | 2007-12-01 00:00:00 +0000 | [diff] [blame] | 718 | int _n_queues; |
| 719 | }; |
Stefan Karlsson | 8006fe8 | 2010-11-23 13:22:55 -0800 | [diff] [blame] | 720 | |
| 721 | #endif // SHARE_VM_MEMORY_REFERENCEPROCESSOR_HPP |