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