1 /*
2 * Copyright (c) 2002, 2011, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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24
25 #ifndef SHARE_VM_UTILITIES_WORKGROUP_HPP
26 #define SHARE_VM_UTILITIES_WORKGROUP_HPP
27
28 #include "utilities/taskqueue.hpp"
29 #ifdef TARGET_OS_FAMILY_linux
30 # include "thread_linux.inline.hpp"
31 #endif
32 #ifdef TARGET_OS_FAMILY_solaris
33 # include "thread_solaris.inline.hpp"
34 #endif
35 #ifdef TARGET_OS_FAMILY_windows
36 # include "thread_windows.inline.hpp"
37 #endif
38
39 // Task class hierarchy:
40 // AbstractGangTask
41 // AbstractGangTaskWOopQueues
42 //
43 // Gang/Group class hierarchy:
44 // AbstractWorkGang
45 // WorkGang
46 // FlexibleWorkGang
47 // YieldingFlexibleWorkGang (defined in another file)
48 //
49 // Worker class hierarchy:
50 // GangWorker (subclass of WorkerThread)
51 // YieldingFlexibleGangWorker (defined in another file)
52
53 // Forward declarations of classes defined here
54
55 class WorkGang;
56 class GangWorker;
57 class YieldingFlexibleGangWorker;
58 class YieldingFlexibleGangTask;
59 class WorkData;
60 class AbstractWorkGang;
61
62 // An abstract task to be worked on by a gang.
63 // You subclass this to supply your own work() method
64 class AbstractGangTask VALUE_OBJ_CLASS_SPEC {
65 public:
66 // The abstract work method.
67 // The argument tells you which member of the gang you are.
68 virtual void work(int i) = 0;
69
70 // This method configures the task for proper termination.
71 // Some tasks do not have any requirements on termination
72 // and may inherit this method that does nothing. Some
73 // tasks do some coordination on termination and override
74 // this method to implement that coordination.
75 virtual void set_for_termination(int active_workers) {};
76
77 // Debugging accessor for the name.
78 const char* name() const PRODUCT_RETURN_(return NULL;);
79 int counter() { return _counter; }
80 void set_counter(int value) { _counter = value; }
81 int *address_of_counter() { return &_counter; }
82
83 // RTTI
84 NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {
85 return false;
86 })
87
88 private:
89 NOT_PRODUCT(const char* _name;)
90 // ??? Should a task have a priority associated with it?
91 // ??? Or can the run method adjust priority as needed?
92 int _counter;
93
94 protected:
95 // Constructor and desctructor: only construct subclasses.
96 AbstractGangTask(const char* name) {
97 NOT_PRODUCT(_name = name);
98 _counter = 0;
99 }
100 virtual ~AbstractGangTask() { }
101 };
102
103 class AbstractGangTaskWOopQueues : public AbstractGangTask {
104 OopTaskQueueSet* _queues;
105 ParallelTaskTerminator _terminator;
106 public:
107 AbstractGangTaskWOopQueues(const char* name, OopTaskQueueSet* queues) :
108 AbstractGangTask(name), _queues(queues), _terminator(0, _queues) {}
109 ParallelTaskTerminator* terminator() { return &_terminator; }
110 virtual void set_for_termination(int active_workers) {
111 terminator()->reset_for_reuse(active_workers);
112 }
113 OopTaskQueueSet* queues() { return _queues; }
114 };
115
116 // Class AbstractWorkGang:
117 // An abstract class representing a gang of workers.
118 // You subclass this to supply an implementation of run_task().
119 class AbstractWorkGang: public CHeapObj {
120 // Here's the public interface to this class.
121 public:
122 // Constructor and destructor.
123 AbstractWorkGang(const char* name, bool are_GC_task_threads,
124 bool are_ConcurrentGC_threads);
125 ~AbstractWorkGang();
126 // Run a task, returns when the task is done (or terminated).
127 virtual void run_task(AbstractGangTask* task) = 0;
128 // Stop and terminate all workers.
129 virtual void stop();
130 public:
131 // Debugging.
132 const char* name() const;
133 protected:
134 // Initialize only instance data.
135 const bool _are_GC_task_threads;
136 const bool _are_ConcurrentGC_threads;
137 // Printing support.
138 const char* _name;
139 // The monitor which protects these data,
140 // and notifies of changes in it.
141 Monitor* _monitor;
142 // The count of the number of workers in the gang.
143 int _total_workers;
144 // Whether the workers should terminate.
145 bool _terminate;
146 // The array of worker threads for this gang.
147 // This is only needed for cleaning up.
148 GangWorker** _gang_workers;
149 // The task for this gang.
150 AbstractGangTask* _task;
151 // A sequence number for the current task.
152 int _sequence_number;
153 // The number of started workers.
154 int _started_workers;
155 // The number of finished workers.
156 int _finished_workers;
157 public:
158 // Accessors for fields
159 Monitor* monitor() const {
160 return _monitor;
161 }
162 int total_workers() const {
163 return _total_workers;
164 }
165 virtual int active_workers() const {
166 return _total_workers;
167 }
168 bool terminate() const {
169 return _terminate;
170 }
171 GangWorker** gang_workers() const {
172 return _gang_workers;
173 }
174 AbstractGangTask* task() const {
175 return _task;
176 }
177 int sequence_number() const {
178 return _sequence_number;
179 }
180 int started_workers() const {
181 return _started_workers;
182 }
183 int finished_workers() const {
184 return _finished_workers;
185 }
186 bool are_GC_task_threads() const {
187 return _are_GC_task_threads;
188 }
189 bool are_ConcurrentGC_threads() const {
190 return _are_ConcurrentGC_threads;
191 }
192 // Predicates.
193 bool is_idle() const {
194 return (task() == NULL);
195 }
196 // Return the Ith gang worker.
197 GangWorker* gang_worker(int i) const;
198
199 void threads_do(ThreadClosure* tc) const;
200
201 // Printing
202 void print_worker_threads_on(outputStream *st) const;
203 void print_worker_threads() const {
204 print_worker_threads_on(tty);
205 }
206
207 protected:
208 friend class GangWorker;
209 friend class YieldingFlexibleGangWorker;
210 // Note activation and deactivation of workers.
211 // These methods should only be called with the mutex held.
212 void internal_worker_poll(WorkData* data) const;
213 void internal_note_start();
214 void internal_note_finish();
215 };
216
217 class WorkData: public StackObj {
218 // This would be a struct, but I want accessor methods.
219 private:
220 bool _terminate;
221 AbstractGangTask* _task;
222 int _sequence_number;
223 public:
224 // Constructor and destructor
225 WorkData() {
226 _terminate = false;
227 _task = NULL;
228 _sequence_number = 0;
229 }
230 ~WorkData() {
231 }
232 // Accessors and modifiers
233 bool terminate() const { return _terminate; }
234 void set_terminate(bool value) { _terminate = value; }
235 AbstractGangTask* task() const { return _task; }
236 void set_task(AbstractGangTask* value) { _task = value; }
237 int sequence_number() const { return _sequence_number; }
238 void set_sequence_number(int value) { _sequence_number = value; }
239
240 YieldingFlexibleGangTask* yf_task() const {
241 return (YieldingFlexibleGangTask*)_task;
242 }
243 };
244
245 // Class WorkGang:
246 class WorkGang: public AbstractWorkGang {
247 public:
248 // Constructor
249 WorkGang(const char* name, int workers,
250 bool are_GC_task_threads, bool are_ConcurrentGC_threads);
251 // Run a task, returns when the task is done (or terminated).
252 virtual void run_task(AbstractGangTask* task);
253 void run_task(AbstractGangTask* task, uint no_of_parallel_workers);
254 // Allocate a worker and return a pointer to it.
255 virtual GangWorker* allocate_worker(int which);
256 // Initialize workers in the gang. Return true if initialization
257 // succeeded. The type of the worker can be overridden in a derived
258 // class with the appropriate implementation of allocate_worker().
259 bool initialize_workers();
260 };
261
262 // Class GangWorker:
263 // Several instances of this class run in parallel as workers for a gang.
264 class GangWorker: public WorkerThread {
265 public:
266 // Constructors and destructor.
267 GangWorker(AbstractWorkGang* gang, uint id);
268
269 // The only real method: run a task for the gang.
270 virtual void run();
271 // Predicate for Thread
272 virtual bool is_GC_task_thread() const;
273 virtual bool is_ConcurrentGC_thread() const;
274 // Printing
275 void print_on(outputStream* st) const;
276 virtual void print() const { print_on(tty); }
277 protected:
278 AbstractWorkGang* _gang;
279
280 virtual void initialize();
281 virtual void loop();
282
283 public:
284 AbstractWorkGang* gang() const { return _gang; }
285 };
286
287 class FlexibleWorkGang: public WorkGang {
288 protected:
289 int _active_workers;
290 public:
291 // Constructor and destructor.
292 FlexibleWorkGang(const char* name, int workers,
293 bool are_GC_task_threads,
294 bool are_ConcurrentGC_threads) :
295 WorkGang(name, workers, are_GC_task_threads, are_ConcurrentGC_threads) {
296 _active_workers = ParallelGCThreads;
297 };
298 // Accessors for fields
299 virtual int active_workers() const { return _active_workers; }
300 void set_active_workers(int v) { _active_workers = v; }
301 };
302
303 // Work gangs in garbage collectors: 2009-06-10
304 //
305 // SharedHeap - work gang for stop-the-world parallel collection.
306 // Used by
307 // ParNewGeneration
308 // CMSParRemarkTask
309 // CMSRefProcTaskExecutor
310 // G1CollectedHeap
311 // G1ParFinalCountTask
312 // ConcurrentMark
313 // CMSCollector
314
315 // A class that acts as a synchronisation barrier. Workers enter
316 // the barrier and must wait until all other workers have entered
317 // before any of them may leave.
318
319 class WorkGangBarrierSync : public StackObj {
320 protected:
321 Monitor _monitor;
322 int _n_workers;
323 int _n_completed;
324 bool _should_reset;
325
326 Monitor* monitor() { return &_monitor; }
327 int n_workers() { return _n_workers; }
328 int n_completed() { return _n_completed; }
329 bool should_reset() { return _should_reset; }
330
331 void zero_completed() { _n_completed = 0; }
332 void inc_completed() { _n_completed++; }
333
334 void set_should_reset(bool v) { _should_reset = v; }
335
336 public:
337 WorkGangBarrierSync();
338 WorkGangBarrierSync(int n_workers, const char* name);
339
340 // Set the number of workers that will use the barrier.
341 // Must be called before any of the workers start running.
342 void set_n_workers(int n_workers);
343
344 // Enter the barrier. A worker that enters the barrier will
345 // not be allowed to leave until all other threads have
346 // also entered the barrier.
347 void enter();
348 };
349
350 // A class to manage claiming of subtasks within a group of tasks. The
351 // subtasks will be identified by integer indices, usually elements of an
352 // enumeration type.
353
354 class SubTasksDone: public CHeapObj {
355 jint* _tasks;
356 int _n_tasks;
357 int _n_threads;
358 jint _threads_completed;
359 #ifdef ASSERT
360 volatile jint _claimed;
361 #endif
362
363 // Set all tasks to unclaimed.
364 void clear();
365
366 public:
367 // Initializes "this" to a state in which there are "n" tasks to be
368 // processed, none of the which are originally claimed. The number of
369 // threads doing the tasks is initialized 1.
370 SubTasksDone(int n);
371
372 // True iff the object is in a valid state.
373 bool valid();
374
375 // Get/set the number of parallel threads doing the tasks to "t". Can only
376 // be called before tasks start or after they are complete.
377 int n_threads() { return _n_threads; }
378 void set_n_threads(int t);
379
380 // Returns "false" if the task "t" is unclaimed, and ensures that task is
381 // claimed. The task "t" is required to be within the range of "this".
382 bool is_task_claimed(int t);
383
384 // The calling thread asserts that it has attempted to claim all the
385 // tasks that it will try to claim. Every thread in the parallel task
386 // must execute this. (When the last thread does so, the task array is
387 // cleared.)
388 void all_tasks_completed();
389
390 // Destructor.
391 ~SubTasksDone();
392 };
393
394 // As above, but for sequential tasks, i.e. instead of claiming
395 // sub-tasks from a set (possibly an enumeration), claim sub-tasks
396 // in sequential order. This is ideal for claiming dynamically
397 // partitioned tasks (like striding in the parallel remembered
398 // set scanning). Note that unlike the above class this is
399 // a stack object - is there any reason for it not to be?
400
401 class SequentialSubTasksDone : public StackObj {
402 protected:
403 jint _n_tasks; // Total number of tasks available.
404 jint _n_claimed; // Number of tasks claimed.
405 // _n_threads is used to determine when a sub task is done.
406 // See comments on SubTasksDone::_n_threads
407 jint _n_threads; // Total number of parallel threads.
408 jint _n_completed; // Number of completed threads.
409
410 void clear();
411
412 public:
413 SequentialSubTasksDone() {
414 clear();
415 }
416 ~SequentialSubTasksDone() {}
417
418 // True iff the object is in a valid state.
419 bool valid();
420
421 // number of tasks
422 jint n_tasks() const { return _n_tasks; }
423
424 // Get/set the number of parallel threads doing the tasks to t.
425 // Should be called before the task starts but it is safe
426 // to call this once a task is running provided that all
427 // threads agree on the number of threads.
428 int n_threads() { return _n_threads; }
429 void set_n_threads(int t) { _n_threads = t; }
430
431 // Set the number of tasks to be claimed to t. As above,
432 // should be called before the tasks start but it is safe
433 // to call this once a task is running provided all threads
434 // agree on the number of tasks.
435 void set_n_tasks(int t) { _n_tasks = t; }
436
437 // Returns false if the next task in the sequence is unclaimed,
438 // and ensures that it is claimed. Will set t to be the index
439 // of the claimed task in the sequence. Will return true if
440 // the task cannot be claimed and there are none left to claim.
441 bool is_task_claimed(int& t);
442
443 // The calling thread asserts that it has attempted to claim
444 // all the tasks it possibly can in the sequence. Every thread
445 // claiming tasks must promise call this. Returns true if this
446 // is the last thread to complete so that the thread can perform
447 // cleanup if necessary.
448 bool all_tasks_completed();
449 };
450
451 // Represents a set of free small integer ids.
452 class FreeIdSet {
453 enum {
454 end_of_list = -1,
455 claimed = -2
456 };
457
458 int _sz;
459 Monitor* _mon;
460
461 int* _ids;
462 int _hd;
463 int _waiters;
464 int _claimed;
465
466 static bool _safepoint;
467 typedef FreeIdSet* FreeIdSetPtr;
468 static const int NSets = 10;
469 static FreeIdSetPtr _sets[NSets];
470 static bool _stat_init;
471 int _index;
472
473 public:
474 FreeIdSet(int sz, Monitor* mon);
475 ~FreeIdSet();
476
477 static void set_safepoint(bool b);
478
479 // Attempt to claim the given id permanently. Returns "true" iff
480 // successful.
481 bool claim_perm_id(int i);
482
483 // Returns an unclaimed parallel id (waiting for one to be released if
484 // necessary). Returns "-1" if a GC wakes up a wait for an id.
485 int claim_par_id();
486
487 void release_par_id(int id);
488 };
489
490 #endif // SHARE_VM_UTILITIES_WORKGROUP_HPP