54 protected:
55 // End of list marker
56 static oop _sentinelRef;
57 MemRegion _span; // (right-open) interval of heap
58 // subject to wkref discovery
59 bool _discovering_refs; // true when discovery enabled
60 bool _discovery_is_atomic; // if discovery is atomic wrt
61 // other collectors in configuration
62 bool _discovery_is_mt; // true if reference discovery is MT.
63 // If true, setting "next" field of a discovered refs list requires
64 // write barrier(s). (Must be true if used in a collector in which
65 // elements of a discovered list may be moved during discovery: for
66 // example, a collector like Garbage-First that moves objects during a
67 // long-term concurrent marking phase that does weak reference
68 // discovery.)
69 bool _discovered_list_needs_barrier;
70 BarrierSet* _bs; // Cached copy of BarrierSet.
71 bool _enqueuing_is_done; // true if all weak references enqueued
72 bool _processing_is_mt; // true during phases when
73 // reference processing is MT.
74 int _next_id; // round-robin counter in
75 // support of work distribution
76
77 // For collectors that do not keep GC marking information
78 // in the object header, this field holds a closure that
79 // helps the reference processor determine the reachability
80 // of an oop (the field is currently initialized to NULL for
81 // all collectors but the CMS collector).
82 BoolObjectClosure* _is_alive_non_header;
83
84 // Soft ref clearing policies
85 // . the default policy
86 static ReferencePolicy* _default_soft_ref_policy;
87 // . the "clear all" policy
88 static ReferencePolicy* _always_clear_soft_ref_policy;
89 // . the current policy below is either one of the above
90 ReferencePolicy* _current_soft_ref_policy;
91
92 // The discovered ref lists themselves
93
94 // The active MT'ness degree of the queues below
95 int _num_q;
96 // The maximum MT'ness degree of the queues below
97 int _max_num_q;
98 // Arrays of lists of oops, one per thread
99 DiscoveredList* _discoveredSoftRefs;
100 DiscoveredList* _discoveredWeakRefs;
101 DiscoveredList* _discoveredFinalRefs;
102 DiscoveredList* _discoveredPhantomRefs;
103
104 public:
105 int num_q() { return _num_q; }
106 void set_mt_degree(int v) { _num_q = v; }
107 DiscoveredList* discovered_soft_refs() { return _discoveredSoftRefs; }
108 static oop sentinel_ref() { return _sentinelRef; }
109 static oop* adr_sentinel_ref() { return &_sentinelRef; }
110 ReferencePolicy* setup_policy(bool always_clear) {
111 _current_soft_ref_policy = always_clear ?
112 _always_clear_soft_ref_policy : _default_soft_ref_policy;
113 _current_soft_ref_policy->setup(); // snapshot the policy threshold
114 return _current_soft_ref_policy;
115 }
116
117 public:
118 // Process references with a certain reachability level.
119 void process_discovered_reflist(DiscoveredList refs_lists[],
120 ReferencePolicy* policy,
121 bool clear_referent,
122 BoolObjectClosure* is_alive,
123 OopClosure* keep_alive,
124 VoidClosure* complete_gc,
125 AbstractRefProcTaskExecutor* task_executor);
126
199 // if and only if its "next" field is NULL.
200 void clean_up_discovered_references();
201 void clean_up_discovered_reflist(DiscoveredList& refs_list);
202
203 // Returns the name of the discovered reference list
204 // occupying the i / _num_q slot.
205 const char* list_name(int i);
206
207 void enqueue_discovered_reflists(HeapWord* pending_list_addr, AbstractRefProcTaskExecutor* task_executor);
208
209 protected:
210 // "Preclean" the given discovered reference list
211 // by removing references with strongly reachable referents.
212 // Currently used in support of CMS only.
213 void preclean_discovered_reflist(DiscoveredList& refs_list,
214 BoolObjectClosure* is_alive,
215 OopClosure* keep_alive,
216 VoidClosure* complete_gc,
217 YieldClosure* yield);
218
219 int next_id() {
220 int id = _next_id;
221 if (++_next_id == _num_q) {
222 _next_id = 0;
223 }
224 return id;
225 }
226 DiscoveredList* get_discovered_list(ReferenceType rt);
227 inline void add_to_discovered_list_mt(DiscoveredList& refs_list, oop obj,
228 HeapWord* discovered_addr);
229 void verify_ok_to_handle_reflists() PRODUCT_RETURN;
230
231 void abandon_partial_discovered_list(DiscoveredList& refs_list);
232
233 // Calculate the number of jni handles.
234 unsigned int count_jni_refs();
235
236 // Balances reference queues.
237 void balance_queues(DiscoveredList ref_lists[]);
238
239 // Update (advance) the soft ref master clock field.
240 void update_soft_ref_master_clock();
241
242 public:
243 // constructor
244 ReferenceProcessor():
245 _span((HeapWord*)NULL, (HeapWord*)NULL),
246 _discoveredSoftRefs(NULL), _discoveredWeakRefs(NULL),
247 _discoveredFinalRefs(NULL), _discoveredPhantomRefs(NULL),
248 _discovering_refs(false),
249 _discovery_is_atomic(true),
250 _enqueuing_is_done(false),
251 _discovery_is_mt(false),
252 _discovered_list_needs_barrier(false),
253 _bs(NULL),
254 _is_alive_non_header(NULL),
255 _num_q(0),
256 _max_num_q(0),
257 _processing_is_mt(false),
258 _next_id(0)
259 {}
260
261 ReferenceProcessor(MemRegion span, bool atomic_discovery,
262 bool mt_discovery,
263 int mt_degree = 1,
264 bool mt_processing = false,
265 bool discovered_list_needs_barrier = false);
266
267 // Allocates and initializes a reference processor.
268 static ReferenceProcessor* create_ref_processor(
269 MemRegion span,
270 bool atomic_discovery,
271 bool mt_discovery,
272 BoolObjectClosure* is_alive_non_header = NULL,
273 int parallel_gc_threads = 1,
274 bool mt_processing = false,
275 bool discovered_list_needs_barrier = false);
276
277 // RefDiscoveryPolicy values
278 enum DiscoveryPolicy {
279 ReferenceBasedDiscovery = 0,
280 ReferentBasedDiscovery = 1,
281 DiscoveryPolicyMin = ReferenceBasedDiscovery,
282 DiscoveryPolicyMax = ReferentBasedDiscovery
283 };
284
285 static void init_statics();
286
287 public:
288 // get and set "is_alive_non_header" field
289 BoolObjectClosure* is_alive_non_header() {
290 return _is_alive_non_header;
291 }
292 void set_is_alive_non_header(BoolObjectClosure* is_alive_non_header) {
293 _is_alive_non_header = is_alive_non_header;
294 }
380 private:
381 ReferenceProcessor* _rp;
382 MemRegion _saved_span;
383
384 public:
385 ReferenceProcessorSpanMutator(ReferenceProcessor* rp,
386 MemRegion span):
387 _rp(rp) {
388 _saved_span = _rp->span();
389 _rp->set_span(span);
390 }
391
392 ~ReferenceProcessorSpanMutator() {
393 _rp->set_span(_saved_span);
394 }
395 };
396
397 // A utility class to temporarily change the MT'ness of
398 // reference discovery for the given ReferenceProcessor
399 // in the scope that contains it.
400 class ReferenceProcessorMTMutator: StackObj {
401 private:
402 ReferenceProcessor* _rp;
403 bool _saved_mt;
404
405 public:
406 ReferenceProcessorMTMutator(ReferenceProcessor* rp,
407 bool mt):
408 _rp(rp) {
409 _saved_mt = _rp->discovery_is_mt();
410 _rp->set_mt_discovery(mt);
411 }
412
413 ~ReferenceProcessorMTMutator() {
414 _rp->set_mt_discovery(_saved_mt);
415 }
416 };
417
418
419 // A utility class to temporarily change the disposition
420 // of the "is_alive_non_header" closure field of the
421 // given ReferenceProcessor in the scope that contains it.
422 class ReferenceProcessorIsAliveMutator: StackObj {
423 private:
424 ReferenceProcessor* _rp;
425 BoolObjectClosure* _saved_cl;
426
427 public:
428 ReferenceProcessorIsAliveMutator(ReferenceProcessor* rp,
429 BoolObjectClosure* cl):
430 _rp(rp) {
431 _saved_cl = _rp->is_alive_non_header();
432 _rp->set_is_alive_non_header(cl);
433 }
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54 protected:
55 // End of list marker
56 static oop _sentinelRef;
57 MemRegion _span; // (right-open) interval of heap
58 // subject to wkref discovery
59 bool _discovering_refs; // true when discovery enabled
60 bool _discovery_is_atomic; // if discovery is atomic wrt
61 // other collectors in configuration
62 bool _discovery_is_mt; // true if reference discovery is MT.
63 // If true, setting "next" field of a discovered refs list requires
64 // write barrier(s). (Must be true if used in a collector in which
65 // elements of a discovered list may be moved during discovery: for
66 // example, a collector like Garbage-First that moves objects during a
67 // long-term concurrent marking phase that does weak reference
68 // discovery.)
69 bool _discovered_list_needs_barrier;
70 BarrierSet* _bs; // Cached copy of BarrierSet.
71 bool _enqueuing_is_done; // true if all weak references enqueued
72 bool _processing_is_mt; // true during phases when
73 // reference processing is MT.
74 int _next_id; // round-robin mod _num_q counter in
75 // support of work distribution
76
77 // For collectors that do not keep GC marking information
78 // in the object header, this field holds a closure that
79 // helps the reference processor determine the reachability
80 // of an oop (the field is currently initialized to NULL for
81 // all collectors but the CMS collector).
82 BoolObjectClosure* _is_alive_non_header;
83
84 // Soft ref clearing policies
85 // . the default policy
86 static ReferencePolicy* _default_soft_ref_policy;
87 // . the "clear all" policy
88 static ReferencePolicy* _always_clear_soft_ref_policy;
89 // . the current policy below is either one of the above
90 ReferencePolicy* _current_soft_ref_policy;
91
92 // The discovered ref lists themselves
93
94 // The active MT'ness degree of the queues below
95 int _num_q;
96 // The maximum MT'ness degree of the queues below
97 int _max_num_q;
98 // Arrays of lists of oops, one per thread
99 DiscoveredList* _discoveredSoftRefs;
100 DiscoveredList* _discoveredWeakRefs;
101 DiscoveredList* _discoveredFinalRefs;
102 DiscoveredList* _discoveredPhantomRefs;
103
104 public:
105 int num_q() { return _num_q; }
106 int max_num_q() { return _max_num_q; }
107 void set_active_mt_degree(int v) { _num_q = v; }
108 DiscoveredList* discovered_soft_refs() { return _discoveredSoftRefs; }
109 static oop sentinel_ref() { return _sentinelRef; }
110 static oop* adr_sentinel_ref() { return &_sentinelRef; }
111 ReferencePolicy* setup_policy(bool always_clear) {
112 _current_soft_ref_policy = always_clear ?
113 _always_clear_soft_ref_policy : _default_soft_ref_policy;
114 _current_soft_ref_policy->setup(); // snapshot the policy threshold
115 return _current_soft_ref_policy;
116 }
117
118 public:
119 // Process references with a certain reachability level.
120 void process_discovered_reflist(DiscoveredList refs_lists[],
121 ReferencePolicy* policy,
122 bool clear_referent,
123 BoolObjectClosure* is_alive,
124 OopClosure* keep_alive,
125 VoidClosure* complete_gc,
126 AbstractRefProcTaskExecutor* task_executor);
127
200 // if and only if its "next" field is NULL.
201 void clean_up_discovered_references();
202 void clean_up_discovered_reflist(DiscoveredList& refs_list);
203
204 // Returns the name of the discovered reference list
205 // occupying the i / _num_q slot.
206 const char* list_name(int i);
207
208 void enqueue_discovered_reflists(HeapWord* pending_list_addr, AbstractRefProcTaskExecutor* task_executor);
209
210 protected:
211 // "Preclean" the given discovered reference list
212 // by removing references with strongly reachable referents.
213 // Currently used in support of CMS only.
214 void preclean_discovered_reflist(DiscoveredList& refs_list,
215 BoolObjectClosure* is_alive,
216 OopClosure* keep_alive,
217 VoidClosure* complete_gc,
218 YieldClosure* yield);
219
220 // round-robin mod _num_q (not: _not_ mode _max_num_q)
221 int next_id() {
222 int id = _next_id;
223 if (++_next_id == _num_q) {
224 _next_id = 0;
225 }
226 return id;
227 }
228 DiscoveredList* get_discovered_list(ReferenceType rt);
229 inline void add_to_discovered_list_mt(DiscoveredList& refs_list, oop obj,
230 HeapWord* discovered_addr);
231 void verify_ok_to_handle_reflists() PRODUCT_RETURN;
232
233 void abandon_partial_discovered_list(DiscoveredList& refs_list);
234
235 // Calculate the number of jni handles.
236 unsigned int count_jni_refs();
237
238 // Balances reference queues.
239 void balance_queues(DiscoveredList ref_lists[]);
240
241 // Update (advance) the soft ref master clock field.
242 void update_soft_ref_master_clock();
243
244 public:
245 // constructor
246 ReferenceProcessor():
247 _span((HeapWord*)NULL, (HeapWord*)NULL),
248 _discoveredSoftRefs(NULL), _discoveredWeakRefs(NULL),
249 _discoveredFinalRefs(NULL), _discoveredPhantomRefs(NULL),
250 _discovering_refs(false),
251 _discovery_is_atomic(true),
252 _enqueuing_is_done(false),
253 _discovery_is_mt(false),
254 _discovered_list_needs_barrier(false),
255 _bs(NULL),
256 _is_alive_non_header(NULL),
257 _num_q(0),
258 _max_num_q(0),
259 _processing_is_mt(false),
260 _next_id(0)
261 { }
262
263 // Default parameters give you a vanilla reference processor.
264 ReferenceProcessor(MemRegion span,
265 bool mt_processing = false, int mt_processing_degree = 1,
266 bool mt_discovery = false, int mt_discovery_degree = 1,
267 bool atomic_discovery = true,
268 BoolObjectClosure* is_alive_non_header = NULL,
269 bool discovered_list_needs_barrier = false);
270
271 // RefDiscoveryPolicy values
272 enum DiscoveryPolicy {
273 ReferenceBasedDiscovery = 0,
274 ReferentBasedDiscovery = 1,
275 DiscoveryPolicyMin = ReferenceBasedDiscovery,
276 DiscoveryPolicyMax = ReferentBasedDiscovery
277 };
278
279 static void init_statics();
280
281 public:
282 // get and set "is_alive_non_header" field
283 BoolObjectClosure* is_alive_non_header() {
284 return _is_alive_non_header;
285 }
286 void set_is_alive_non_header(BoolObjectClosure* is_alive_non_header) {
287 _is_alive_non_header = is_alive_non_header;
288 }
374 private:
375 ReferenceProcessor* _rp;
376 MemRegion _saved_span;
377
378 public:
379 ReferenceProcessorSpanMutator(ReferenceProcessor* rp,
380 MemRegion span):
381 _rp(rp) {
382 _saved_span = _rp->span();
383 _rp->set_span(span);
384 }
385
386 ~ReferenceProcessorSpanMutator() {
387 _rp->set_span(_saved_span);
388 }
389 };
390
391 // A utility class to temporarily change the MT'ness of
392 // reference discovery for the given ReferenceProcessor
393 // in the scope that contains it.
394 class ReferenceProcessorMTDiscoveryMutator: StackObj {
395 private:
396 ReferenceProcessor* _rp;
397 bool _saved_mt;
398
399 public:
400 ReferenceProcessorMTDiscoveryMutator(ReferenceProcessor* rp,
401 bool mt):
402 _rp(rp) {
403 _saved_mt = _rp->discovery_is_mt();
404 _rp->set_mt_discovery(mt);
405 }
406
407 ~ReferenceProcessorMTDiscoveryMutator() {
408 _rp->set_mt_discovery(_saved_mt);
409 }
410 };
411
412
413 // A utility class to temporarily change the disposition
414 // of the "is_alive_non_header" closure field of the
415 // given ReferenceProcessor in the scope that contains it.
416 class ReferenceProcessorIsAliveMutator: StackObj {
417 private:
418 ReferenceProcessor* _rp;
419 BoolObjectClosure* _saved_cl;
420
421 public:
422 ReferenceProcessorIsAliveMutator(ReferenceProcessor* rp,
423 BoolObjectClosure* cl):
424 _rp(rp) {
425 _saved_cl = _rp->is_alive_non_header();
426 _rp->set_is_alive_non_header(cl);
427 }
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