1 /* 2 * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved. 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 * 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. 22 * 23 */ 24 25 #ifndef SHARE_VM_GC_SHARED_WORKGROUP_HPP 26 #define SHARE_VM_GC_SHARED_WORKGROUP_HPP 27 28 #include "runtime/thread.inline.hpp" 29 30 // Task class hierarchy: 31 // AbstractGangTask 32 // 33 // Gang/Group class hierarchy: 34 // AbstractWorkGang 35 // WorkGang 36 // YieldingFlexibleWorkGang (defined in another file) 37 // 38 // Worker class hierarchy: 39 // AbstractGangWorker (subclass of WorkerThread) 40 // GangWorker 41 // YieldingFlexibleGangWorker (defined in another file) 42 43 // Forward declarations of classes defined here 44 45 class AbstractGangWorker; 46 class GangWorker; 47 class WorkData; 48 49 // An abstract task to be worked on by a gang. 50 // You subclass this to supply your own work() method 51 class AbstractGangTask VALUE_OBJ_CLASS_SPEC { 52 const char* _name; 53 54 public: 55 AbstractGangTask(const char* name) : _name(name) {} 56 57 // The abstract work method. 58 // The argument tells you which member of the gang you are. 59 virtual void work(uint worker_id) = 0; 60 61 // Debugging accessor for the name. 62 const char* name() const { return _name; } 63 }; 64 65 66 // The work gang is the collection of workers to execute tasks. 67 // The number of workers run for a task is "_active_workers" 68 // while "_total_workers" is the number of available of workers. 69 class AbstractWorkGang : public CHeapObj<mtInternal> { 70 protected: 71 // The array of worker threads for this gang. 72 AbstractGangWorker** _workers; 73 // The count of the number of workers in the gang. 74 uint _total_workers; 75 // The currently active workers in this gang. 76 uint _active_workers; 77 // Printing support. 78 const char* _name; 79 80 private: 81 // Initialize only instance data. 82 const bool _are_GC_task_threads; 83 const bool _are_ConcurrentGC_threads; 84 85 public: 86 AbstractWorkGang(const char* name, uint workers, bool are_GC_task_threads, bool are_ConcurrentGC_threads) : 87 _name(name), 88 _total_workers(workers), 89 _active_workers(UseDynamicNumberOfGCThreads ? 1U : workers), 90 _are_GC_task_threads(are_GC_task_threads), 91 _are_ConcurrentGC_threads(are_ConcurrentGC_threads) 92 { } 93 94 virtual AbstractGangWorker* allocate_worker(uint which) = 0; 95 96 // Initialize workers in the gang. Return true if initialization succeeded. 97 bool initialize_workers(); 98 99 bool are_GC_task_threads() const { return _are_GC_task_threads; } 100 bool are_ConcurrentGC_threads() const { return _are_ConcurrentGC_threads; } 101 102 uint total_workers() const { return _total_workers; } 103 104 virtual uint active_workers() const { 105 assert(_active_workers <= _total_workers, 106 err_msg("_active_workers: %u > _total_workers: %u", _active_workers, _total_workers)); 107 assert(UseDynamicNumberOfGCThreads || _active_workers == _total_workers, 108 "Unless dynamic should use total workers"); 109 return _active_workers; 110 } 111 void set_active_workers(uint v) { 112 assert(v <= _total_workers, 113 "Trying to set more workers active than there are"); 114 _active_workers = MIN2(v, _total_workers); 115 assert(v != 0, "Trying to set active workers to 0"); 116 _active_workers = MAX2(1U, _active_workers); 117 assert(UseDynamicNumberOfGCThreads || _active_workers == _total_workers, 118 "Unless dynamic should use total workers"); 119 } 120 121 // Return the Ith worker. 122 AbstractGangWorker* worker(uint i) const; 123 124 void threads_do(ThreadClosure* tc) const; 125 126 // Debugging. 127 const char* name() const { return _name; } 128 129 // Printing 130 void print_worker_threads_on(outputStream *st) const; 131 void print_worker_threads() const { 132 print_worker_threads_on(tty); 133 } 134 }; 135 136 // An class representing a gang of workers. 137 class WorkGang: public AbstractWorkGang { 138 private: 139 // Never deleted. 140 ~WorkGang(); 141 public: 142 WorkGang(const char* name, 143 uint workers, 144 bool are_GC_task_threads, 145 bool are_ConcurrentGC_threads); 146 147 // Run a task, returns when the task is done. 148 virtual void run_task(AbstractGangTask* task); 149 void run_task(AbstractGangTask* task, uint no_of_parallel_workers); 150 151 // Return true if more workers should be applied to the task. 152 virtual bool needs_more_workers() const { 153 return _started_workers < _active_workers; 154 } 155 156 protected: 157 // The monitor which protects these data, 158 // and notifies of changes in it. 159 Monitor* _monitor; 160 // The task for this gang. 161 AbstractGangTask* _task; 162 // A sequence number for the current task. 163 int _sequence_number; 164 // The number of started workers. 165 uint _started_workers; 166 // The number of finished workers. 167 uint _finished_workers; 168 169 public: 170 virtual AbstractGangWorker* allocate_worker(uint which); 171 172 // Accessors for fields 173 Monitor* monitor() const { 174 return _monitor; 175 } 176 AbstractGangTask* task() const { 177 return _task; 178 } 179 int sequence_number() const { 180 return _sequence_number; 181 } 182 uint started_workers() const { 183 return _started_workers; 184 } 185 uint finished_workers() const { 186 return _finished_workers; 187 } 188 // Predicates. 189 bool is_idle() const { 190 return (task() == NULL); 191 } 192 // Return the Ith gang worker. 193 GangWorker* gang_worker(uint i) const; 194 195 protected: 196 friend class GangWorker; 197 // Note activation and deactivation of workers. 198 // These methods should only be called with the mutex held. 199 void internal_worker_poll(WorkData* data) const; 200 void internal_note_start(); 201 void internal_note_finish(); 202 }; 203 204 class WorkData: public StackObj { 205 // This would be a struct, but I want accessor methods. 206 private: 207 AbstractGangTask* _task; 208 int _sequence_number; 209 public: 210 // Constructor and destructor 211 WorkData() { 212 _task = NULL; 213 _sequence_number = 0; 214 } 215 ~WorkData() { 216 } 217 AbstractGangTask* task() const { return _task; } 218 void set_task(AbstractGangTask* value) { _task = value; } 219 int sequence_number() const { return _sequence_number; } 220 void set_sequence_number(int value) { _sequence_number = value; } 221 }; 222 223 // Several instances of this class run in parallel as workers for a gang. 224 class AbstractGangWorker: public WorkerThread { 225 public: 226 // Constructors and destructor. 227 AbstractGangWorker(AbstractWorkGang* gang, uint id); 228 229 // The only real method: run a task for the gang. 230 virtual void run(); 231 // Predicate for Thread 232 virtual bool is_GC_task_thread() const; 233 virtual bool is_ConcurrentGC_thread() const; 234 // Printing 235 void print_on(outputStream* st) const; 236 virtual void print() const { print_on(tty); } 237 238 protected: 239 AbstractWorkGang* _gang; 240 241 virtual void initialize(); 242 virtual void loop() = 0; 243 244 AbstractWorkGang* gang() const { return _gang; } 245 }; 246 247 class GangWorker: public AbstractGangWorker { 248 public: 249 GangWorker(WorkGang* gang, uint id) : AbstractGangWorker(gang, id) {} 250 251 protected: 252 virtual void loop(); 253 254 private: 255 WorkGang* gang() const { return (WorkGang*)_gang; } 256 }; 257 258 // Dynamic number of worker threads 259 // 260 // This type of work gang is used to run different numbers of 261 // worker threads at different times. The 262 // number of workers run for a task is "_active_workers" 263 // instead of "_total_workers" in a WorkGang. The method 264 // "needs_more_workers()" returns true until "_active_workers" 265 // have been started and returns false afterwards. The 266 // implementation of "needs_more_workers()" in WorkGang always 267 // returns true so that all workers are started. The method 268 // "loop()" in GangWorker was modified to ask "needs_more_workers()" 269 // in its loop to decide if it should start working on a task. 270 // A worker in "loop()" waits for notification on the WorkGang 271 // monitor and execution of each worker as it checks for work 272 // is serialized via the same monitor. The "needs_more_workers()" 273 // call is serialized and additionally the calculation for the 274 // "part" (effectively the worker id for executing the task) is 275 // serialized to give each worker a unique "part". Workers that 276 // are not needed for this tasks (i.e., "_active_workers" have 277 // been started before it, continue to wait for work. 278 279 // A class that acts as a synchronisation barrier. Workers enter 280 // the barrier and must wait until all other workers have entered 281 // before any of them may leave. 282 283 class WorkGangBarrierSync : public StackObj { 284 protected: 285 Monitor _monitor; 286 uint _n_workers; 287 uint _n_completed; 288 bool _should_reset; 289 bool _aborted; 290 291 Monitor* monitor() { return &_monitor; } 292 uint n_workers() { return _n_workers; } 293 uint n_completed() { return _n_completed; } 294 bool should_reset() { return _should_reset; } 295 bool aborted() { return _aborted; } 296 297 void zero_completed() { _n_completed = 0; } 298 void inc_completed() { _n_completed++; } 299 void set_aborted() { _aborted = true; } 300 void set_should_reset(bool v) { _should_reset = v; } 301 302 public: 303 WorkGangBarrierSync(); 304 WorkGangBarrierSync(uint n_workers, const char* name); 305 306 // Set the number of workers that will use the barrier. 307 // Must be called before any of the workers start running. 308 void set_n_workers(uint n_workers); 309 310 // Enter the barrier. A worker that enters the barrier will 311 // not be allowed to leave until all other threads have 312 // also entered the barrier or the barrier is aborted. 313 // Returns false if the barrier was aborted. 314 bool enter(); 315 316 // Aborts the barrier and wakes up any threads waiting for 317 // the barrier to complete. The barrier will remain in the 318 // aborted state until the next call to set_n_workers(). 319 void abort(); 320 }; 321 322 // A class to manage claiming of subtasks within a group of tasks. The 323 // subtasks will be identified by integer indices, usually elements of an 324 // enumeration type. 325 326 class SubTasksDone: public CHeapObj<mtInternal> { 327 uint* _tasks; 328 uint _n_tasks; 329 uint _threads_completed; 330 #ifdef ASSERT 331 volatile uint _claimed; 332 #endif 333 334 // Set all tasks to unclaimed. 335 void clear(); 336 337 public: 338 // Initializes "this" to a state in which there are "n" tasks to be 339 // processed, none of the which are originally claimed. The number of 340 // threads doing the tasks is initialized 1. 341 SubTasksDone(uint n); 342 343 // True iff the object is in a valid state. 344 bool valid(); 345 346 // Returns "false" if the task "t" is unclaimed, and ensures that task is 347 // claimed. The task "t" is required to be within the range of "this". 348 bool is_task_claimed(uint t); 349 350 // The calling thread asserts that it has attempted to claim all the 351 // tasks that it will try to claim. Every thread in the parallel task 352 // must execute this. (When the last thread does so, the task array is 353 // cleared.) 354 // 355 // n_threads - Number of threads executing the sub-tasks. 356 void all_tasks_completed(uint n_threads); 357 358 // Destructor. 359 ~SubTasksDone(); 360 }; 361 362 // As above, but for sequential tasks, i.e. instead of claiming 363 // sub-tasks from a set (possibly an enumeration), claim sub-tasks 364 // in sequential order. This is ideal for claiming dynamically 365 // partitioned tasks (like striding in the parallel remembered 366 // set scanning). Note that unlike the above class this is 367 // a stack object - is there any reason for it not to be? 368 369 class SequentialSubTasksDone : public StackObj { 370 protected: 371 uint _n_tasks; // Total number of tasks available. 372 uint _n_claimed; // Number of tasks claimed. 373 // _n_threads is used to determine when a sub task is done. 374 // See comments on SubTasksDone::_n_threads 375 uint _n_threads; // Total number of parallel threads. 376 uint _n_completed; // Number of completed threads. 377 378 void clear(); 379 380 public: 381 SequentialSubTasksDone() { 382 clear(); 383 } 384 ~SequentialSubTasksDone() {} 385 386 // True iff the object is in a valid state. 387 bool valid(); 388 389 // number of tasks 390 uint n_tasks() const { return _n_tasks; } 391 392 // Get/set the number of parallel threads doing the tasks to t. 393 // Should be called before the task starts but it is safe 394 // to call this once a task is running provided that all 395 // threads agree on the number of threads. 396 uint n_threads() { return _n_threads; } 397 void set_n_threads(uint t) { _n_threads = t; } 398 399 // Set the number of tasks to be claimed to t. As above, 400 // should be called before the tasks start but it is safe 401 // to call this once a task is running provided all threads 402 // agree on the number of tasks. 403 void set_n_tasks(uint t) { _n_tasks = t; } 404 405 // Returns false if the next task in the sequence is unclaimed, 406 // and ensures that it is claimed. Will set t to be the index 407 // of the claimed task in the sequence. Will return true if 408 // the task cannot be claimed and there are none left to claim. 409 bool is_task_claimed(uint& t); 410 411 // The calling thread asserts that it has attempted to claim 412 // all the tasks it possibly can in the sequence. Every thread 413 // claiming tasks must promise call this. Returns true if this 414 // is the last thread to complete so that the thread can perform 415 // cleanup if necessary. 416 bool all_tasks_completed(); 417 }; 418 419 // Represents a set of free small integer ids. 420 class FreeIdSet : public CHeapObj<mtInternal> { 421 enum { 422 end_of_list = -1, 423 claimed = -2 424 }; 425 426 int _sz; 427 Monitor* _mon; 428 429 int* _ids; 430 int _hd; 431 int _waiters; 432 int _claimed; 433 434 static bool _safepoint; 435 typedef FreeIdSet* FreeIdSetPtr; 436 static const int NSets = 10; 437 static FreeIdSetPtr _sets[NSets]; 438 static bool _stat_init; 439 int _index; 440 441 public: 442 FreeIdSet(int sz, Monitor* mon); 443 ~FreeIdSet(); 444 445 static void set_safepoint(bool b); 446 447 // Attempt to claim the given id permanently. Returns "true" iff 448 // successful. 449 bool claim_perm_id(int i); 450 451 // Returns an unclaimed parallel id (waiting for one to be released if 452 // necessary). Returns "-1" if a GC wakes up a wait for an id. 453 int claim_par_id(); 454 455 void release_par_id(int id); 456 }; 457 458 #endif // SHARE_VM_GC_SHARED_WORKGROUP_HPP