87 // and then to set it to 0 after that task has completed. A value of
88 // 0 is a "special" value in set_n_threads() which translates to
89 // setting _n_threads to 1.
90 //
91 // Some code uses _n_termination to decide if work should be done in
92 // parallel. The notorious possibly_parallel_oops_do() in threads.cpp
93 // is an example of such code. Look for variable "is_par" for other
94 // examples.
95 //
96 // The active_workers is not reset to 0 after a parallel phase. It's
97 // value may be used in later phases and in one instance at least
98 // (the parallel remark) it has to be used (the parallel remark depends
99 // on the partitioning done in the previous parallel scavenge).
100
101 class SharedHeap : public CollectedHeap {
102 friend class VMStructs;
103
104 friend class VM_GC_Operation;
105 friend class VM_CGC_Operation;
106
107 private:
108 // For claiming strong_roots tasks.
109 SubTasksDone* _process_strong_tasks;
110
111 protected:
112 // There should be only a single instance of "SharedHeap" in a program.
113 // This is enforced with the protected constructor below, which will also
114 // set the static pointer "_sh" to that instance.
115 static SharedHeap* _sh;
116
117 // A gc policy, controls global gc resource issues
118 CollectorPolicy *_collector_policy;
119
120 // See the discussion below, in the specification of the reader function
121 // for this variable.
122 int _strong_roots_parity;
123
124 // If we're doing parallel GC, use this gang of threads.
125 FlexibleWorkGang* _workers;
126
127 // Full initialization is done in a concrete subtype's "initialize"
128 // function.
129 SharedHeap(CollectorPolicy* policy_);
130
131 // Returns true if the calling thread holds the heap lock,
132 // or the calling thread is a par gc thread and the heap_lock is held
133 // by the vm thread doing a gc operation.
134 bool heap_lock_held_for_gc();
135 // True if the heap_lock is held by the a non-gc thread invoking a gc
136 // operation.
137 bool _thread_holds_heap_lock_for_gc;
138
139 public:
140 static SharedHeap* heap() { return _sh; }
141
142 void set_barrier_set(BarrierSet* bs);
143 SubTasksDone* process_strong_tasks() { return _process_strong_tasks; }
144
145 // Does operations required after initialization has been done.
146 virtual void post_initialize();
147
148 // Initialization of ("weak") reference processing support
149 virtual void ref_processing_init();
150
151 // Iteration functions.
152 void oop_iterate(ExtendedOopClosure* cl) = 0;
153
154 // Iterate over all spaces in use in the heap, in an undefined order.
155 virtual void space_iterate(SpaceClosure* cl) = 0;
156
157 // A SharedHeap will contain some number of spaces. This finds the
158 // space whose reserved area contains the given address, or else returns
159 // NULL.
160 virtual Space* space_containing(const void* addr) const = 0;
161
162 bool no_gc_in_progress() { return !is_gc_active(); }
163
176 // The idea is that objects representing fine-grained tasks, such as
177 // threads, will contain a "parity" field. A task will is claimed in the
178 // current "process_roots" call only if its parity field is the
179 // same as the "strong_roots_parity"; task claiming is accomplished by
180 // updating the parity field to the strong_roots_parity with a CAS.
181 //
182 // If the client meats this spec, then strong_roots_parity() will have
183 // the following properties:
184 // a) to return a different value than was returned before the last
185 // call to change_strong_roots_parity, and
186 // c) to never return a distinguished value (zero) with which such
187 // task-claiming variables may be initialized, to indicate "never
188 // claimed".
189 public:
190 int strong_roots_parity() { return _strong_roots_parity; }
191
192 // Call these in sequential code around process_roots.
193 // strong_roots_prologue calls change_strong_roots_parity, if
194 // parallel tasks are enabled.
195 class StrongRootsScope : public MarkingCodeBlobClosure::MarkScope {
196 // Used to implement the Thread work barrier.
197 static Monitor* _lock;
198
199 SharedHeap* _sh;
200 volatile jint _n_workers_done_with_threads;
201
202 public:
203 StrongRootsScope(SharedHeap* heap, bool activate = true);
204 ~StrongRootsScope();
205
206 // Mark that this thread is done with the Threads work.
207 void mark_worker_done_with_threads(uint n_workers);
208 // Wait until all n_workers are done with the Threads work.
209 void wait_until_all_workers_done_with_threads(uint n_workers);
210 };
211 friend class StrongRootsScope;
212
213 // The current active StrongRootScope
214 StrongRootsScope* _strong_roots_scope;
215
216 StrongRootsScope* active_strong_roots_scope() const;
217
218 private:
219 void register_strong_roots_scope(StrongRootsScope* scope);
220 void unregister_strong_roots_scope(StrongRootsScope* scope);
221 void change_strong_roots_parity();
222
223 public:
224 enum ScanningOption {
225 SO_None = 0x0,
226 SO_AllCodeCache = 0x8,
227 SO_ScavengeCodeCache = 0x10
228 };
229
230 FlexibleWorkGang* workers() const { return _workers; }
231
232 // Invoke the "do_oop" method the closure "roots" on all root locations.
233 // The "so" argument determines which roots the closure is applied to:
234 // "SO_None" does none;
235 // "SO_AllCodeCache" applies the closure to all elements of the CodeCache.
236 // "SO_ScavengeCodeCache" applies the closure to elements on the scavenge root list in the CodeCache.
237 void process_roots(bool activate_scope,
238 ScanningOption so,
239 OopClosure* strong_roots,
240 OopClosure* weak_roots,
241 CLDClosure* strong_cld_closure,
242 CLDClosure* weak_cld_closure,
243 CodeBlobClosure* code_roots);
244 void process_all_roots(bool activate_scope,
245 ScanningOption so,
246 OopClosure* roots,
247 CLDClosure* cld_closure,
248 CodeBlobClosure* code_roots);
249 void process_strong_roots(bool activate_scope,
250 ScanningOption so,
251 OopClosure* roots,
252 CLDClosure* cld_closure,
253 CodeBlobClosure* code_roots);
254
255
256 // Apply "root_closure" to the JNI weak roots..
257 void process_weak_roots(OopClosure* root_closure);
258
259 // The functions below are helper functions that a subclass of
260 // "SharedHeap" can use in the implementation of its virtual
261 // functions.
262
263 public:
264
265 // Do anything common to GC's.
266 virtual void gc_prologue(bool full) = 0;
267 virtual void gc_epilogue(bool full) = 0;
268
269 // Sets the number of parallel threads that will be doing tasks
270 // (such as process roots) subsequently.
271 virtual void set_par_threads(uint t);
272
273 int n_termination();
274 void set_n_termination(int t);
275
276 //
277 // New methods from CollectedHeap
278 //
279
280 // Some utilities.
281 void print_size_transition(outputStream* out,
282 size_t bytes_before,
283 size_t bytes_after,
284 size_t capacity);
285 };
286
287 inline SharedHeap::ScanningOption operator|(SharedHeap::ScanningOption so0, SharedHeap::ScanningOption so1) {
288 return static_cast<SharedHeap::ScanningOption>(static_cast<int>(so0) | static_cast<int>(so1));
289 }
290
291 #endif // SHARE_VM_MEMORY_SHAREDHEAP_HPP
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87 // and then to set it to 0 after that task has completed. A value of
88 // 0 is a "special" value in set_n_threads() which translates to
89 // setting _n_threads to 1.
90 //
91 // Some code uses _n_termination to decide if work should be done in
92 // parallel. The notorious possibly_parallel_oops_do() in threads.cpp
93 // is an example of such code. Look for variable "is_par" for other
94 // examples.
95 //
96 // The active_workers is not reset to 0 after a parallel phase. It's
97 // value may be used in later phases and in one instance at least
98 // (the parallel remark) it has to be used (the parallel remark depends
99 // on the partitioning done in the previous parallel scavenge).
100
101 class SharedHeap : public CollectedHeap {
102 friend class VMStructs;
103
104 friend class VM_GC_Operation;
105 friend class VM_CGC_Operation;
106
107 protected:
108 // There should be only a single instance of "SharedHeap" in a program.
109 // This is enforced with the protected constructor below, which will also
110 // set the static pointer "_sh" to that instance.
111 static SharedHeap* _sh;
112
113 // A gc policy, controls global gc resource issues
114 CollectorPolicy *_collector_policy;
115
116 // See the discussion below, in the specification of the reader function
117 // for this variable.
118 int _strong_roots_parity;
119
120 // If we're doing parallel GC, use this gang of threads.
121 FlexibleWorkGang* _workers;
122
123 // Full initialization is done in a concrete subtype's "initialize"
124 // function.
125 SharedHeap(CollectorPolicy* policy_);
126
127 // Returns true if the calling thread holds the heap lock,
128 // or the calling thread is a par gc thread and the heap_lock is held
129 // by the vm thread doing a gc operation.
130 bool heap_lock_held_for_gc();
131 // True if the heap_lock is held by the a non-gc thread invoking a gc
132 // operation.
133 bool _thread_holds_heap_lock_for_gc;
134
135 public:
136 static SharedHeap* heap() { return _sh; }
137
138 void set_barrier_set(BarrierSet* bs);
139
140 // Does operations required after initialization has been done.
141 virtual void post_initialize();
142
143 // Initialization of ("weak") reference processing support
144 virtual void ref_processing_init();
145
146 // Iteration functions.
147 void oop_iterate(ExtendedOopClosure* cl) = 0;
148
149 // Iterate over all spaces in use in the heap, in an undefined order.
150 virtual void space_iterate(SpaceClosure* cl) = 0;
151
152 // A SharedHeap will contain some number of spaces. This finds the
153 // space whose reserved area contains the given address, or else returns
154 // NULL.
155 virtual Space* space_containing(const void* addr) const = 0;
156
157 bool no_gc_in_progress() { return !is_gc_active(); }
158
171 // The idea is that objects representing fine-grained tasks, such as
172 // threads, will contain a "parity" field. A task will is claimed in the
173 // current "process_roots" call only if its parity field is the
174 // same as the "strong_roots_parity"; task claiming is accomplished by
175 // updating the parity field to the strong_roots_parity with a CAS.
176 //
177 // If the client meats this spec, then strong_roots_parity() will have
178 // the following properties:
179 // a) to return a different value than was returned before the last
180 // call to change_strong_roots_parity, and
181 // c) to never return a distinguished value (zero) with which such
182 // task-claiming variables may be initialized, to indicate "never
183 // claimed".
184 public:
185 int strong_roots_parity() { return _strong_roots_parity; }
186
187 // Call these in sequential code around process_roots.
188 // strong_roots_prologue calls change_strong_roots_parity, if
189 // parallel tasks are enabled.
190 class StrongRootsScope : public MarkingCodeBlobClosure::MarkScope {
191 SharedHeap* _sh;
192
193 public:
194 StrongRootsScope(SharedHeap* heap, bool activate = true);
195 };
196 friend class StrongRootsScope;
197
198 private:
199 void change_strong_roots_parity();
200
201 public:
202 FlexibleWorkGang* workers() const { return _workers; }
203
204 // The functions below are helper functions that a subclass of
205 // "SharedHeap" can use in the implementation of its virtual
206 // functions.
207
208 public:
209
210 // Do anything common to GC's.
211 virtual void gc_prologue(bool full) = 0;
212 virtual void gc_epilogue(bool full) = 0;
213
214 // Sets the number of parallel threads that will be doing tasks
215 // (such as process roots) subsequently.
216 virtual void set_par_threads(uint t);
217
218 //
219 // New methods from CollectedHeap
220 //
221
222 // Some utilities.
223 void print_size_transition(outputStream* out,
224 size_t bytes_before,
225 size_t bytes_after,
226 size_t capacity);
227 };
228
229 #endif // SHARE_VM_MEMORY_SHAREDHEAP_HPP
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