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 "_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 }; 193 194 // Several instances of this class run in parallel as workers for a gang. 195 class AbstractGangWorker: public WorkerThread { 196 public: 197 AbstractGangWorker(AbstractWorkGang* gang, uint id); 198 199 // The only real method: run a task for the gang. 200 virtual void run(); 201 // Predicate for Thread 202 virtual bool is_GC_task_thread() const; 203 virtual bool is_ConcurrentGC_thread() const; 204 // Printing 205 void print_on(outputStream* st) const; 206 virtual void print() const { print_on(tty); } 207 208 protected: 209 AbstractWorkGang* _gang; 210 211 virtual void initialize(); 212 virtual void loop() = 0; 213 214 AbstractWorkGang* gang() const { return _gang; } 215 }; 216 217 class GangWorker: public AbstractGangWorker { 218 public: 219 GangWorker(WorkGang* gang, uint id) : AbstractGangWorker(gang, id) {} 220 221 protected: 222 virtual void loop(); 223 224 private: 225 WorkData wait_for_task(); 226 void run_task(WorkData work); 227 void signal_task_done(); 228 229 void print_task_started(WorkData data); 230 void print_task_done(WorkData data); 231 232 WorkGang* gang() const { return (WorkGang*)_gang; } 233 }; 234 235 // A class that acts as a synchronisation barrier. Workers enter 236 // the barrier and must wait until all other workers have entered 237 // before any of them may leave. 238 239 class WorkGangBarrierSync : public StackObj { 240 protected: 241 Monitor _monitor; 242 uint _n_workers; 243 uint _n_completed; 244 bool _should_reset; 245 bool _aborted; 246 247 Monitor* monitor() { return &_monitor; } 248 uint n_workers() { return _n_workers; } 249 uint n_completed() { return _n_completed; } 250 bool should_reset() { return _should_reset; } 251 bool aborted() { return _aborted; } 252 253 void zero_completed() { _n_completed = 0; } 254 void inc_completed() { _n_completed++; } 255 void set_aborted() { _aborted = true; } 256 void set_should_reset(bool v) { _should_reset = v; } 257 258 public: 259 WorkGangBarrierSync(); 260 WorkGangBarrierSync(uint n_workers, const char* name); 261 262 // Set the number of workers that will use the barrier. 263 // Must be called before any of the workers start running. 264 void set_n_workers(uint n_workers); 265 266 // Enter the barrier. A worker that enters the barrier will 267 // not be allowed to leave until all other threads have 268 // also entered the barrier or the barrier is aborted. 269 // Returns false if the barrier was aborted. 270 bool enter(); 271 272 // Aborts the barrier and wakes up any threads waiting for 273 // the barrier to complete. The barrier will remain in the 274 // aborted state until the next call to set_n_workers(). 275 void abort(); 276 }; 277 278 // A class to manage claiming of subtasks within a group of tasks. The 279 // subtasks will be identified by integer indices, usually elements of an 280 // enumeration type. 281 282 class SubTasksDone: public CHeapObj<mtInternal> { 283 uint* _tasks; 284 uint _n_tasks; 285 uint _threads_completed; 286 #ifdef ASSERT 287 volatile uint _claimed; 288 #endif 289 290 // Set all tasks to unclaimed. 291 void clear(); 292 293 public: 294 // Initializes "this" to a state in which there are "n" tasks to be 295 // processed, none of the which are originally claimed. The number of 296 // threads doing the tasks is initialized 1. 297 SubTasksDone(uint n); 298 299 // True iff the object is in a valid state. 300 bool valid(); 301 302 // Returns "false" if the task "t" is unclaimed, and ensures that task is 303 // claimed. The task "t" is required to be within the range of "this". 304 bool is_task_claimed(uint t); 305 306 // The calling thread asserts that it has attempted to claim all the 307 // tasks that it will try to claim. Every thread in the parallel task 308 // must execute this. (When the last thread does so, the task array is 309 // cleared.) 310 // 311 // n_threads - Number of threads executing the sub-tasks. 312 void all_tasks_completed(uint n_threads); 313 314 // Destructor. 315 ~SubTasksDone(); 316 }; 317 318 // As above, but for sequential tasks, i.e. instead of claiming 319 // sub-tasks from a set (possibly an enumeration), claim sub-tasks 320 // in sequential order. This is ideal for claiming dynamically 321 // partitioned tasks (like striding in the parallel remembered 322 // set scanning). Note that unlike the above class this is 323 // a stack object - is there any reason for it not to be? 324 325 class SequentialSubTasksDone : public StackObj { 326 protected: 327 uint _n_tasks; // Total number of tasks available. 328 uint _n_claimed; // Number of tasks claimed. 329 // _n_threads is used to determine when a sub task is done. 330 // See comments on SubTasksDone::_n_threads 331 uint _n_threads; // Total number of parallel threads. 332 uint _n_completed; // Number of completed threads. 333 334 void clear(); 335 336 public: 337 SequentialSubTasksDone() { 338 clear(); 339 } 340 ~SequentialSubTasksDone() {} 341 342 // True iff the object is in a valid state. 343 bool valid(); 344 345 // number of tasks 346 uint n_tasks() const { return _n_tasks; } 347 348 // Get/set the number of parallel threads doing the tasks to t. 349 // Should be called before the task starts but it is safe 350 // to call this once a task is running provided that all 351 // threads agree on the number of threads. 352 uint n_threads() { return _n_threads; } 353 void set_n_threads(uint t) { _n_threads = t; } 354 355 // Set the number of tasks to be claimed to t. As above, 356 // should be called before the tasks start but it is safe 357 // to call this once a task is running provided all threads 358 // agree on the number of tasks. 359 void set_n_tasks(uint t) { _n_tasks = t; } 360 361 // Returns false if the next task in the sequence is unclaimed, 362 // and ensures that it is claimed. Will set t to be the index 363 // of the claimed task in the sequence. Will return true if 364 // the task cannot be claimed and there are none left to claim. 365 bool is_task_claimed(uint& t); 366 367 // The calling thread asserts that it has attempted to claim 368 // all the tasks it possibly can in the sequence. Every thread 369 // claiming tasks must promise call this. Returns true if this 370 // is the last thread to complete so that the thread can perform 371 // cleanup if necessary. 372 bool all_tasks_completed(); 373 }; 374 375 // Represents a set of free small integer ids. 376 class FreeIdSet : public CHeapObj<mtInternal> { 377 enum { 378 end_of_list = -1, 379 claimed = -2 380 }; 381 382 int _sz; 383 Monitor* _mon; 384 385 int* _ids; 386 int _hd; 387 int _waiters; 388 int _claimed; 389 390 static bool _safepoint; 391 typedef FreeIdSet* FreeIdSetPtr; 392 static const int NSets = 10; 393 static FreeIdSetPtr _sets[NSets]; 394 static bool _stat_init; 395 int _index; 396 397 public: 398 FreeIdSet(int sz, Monitor* mon); 399 ~FreeIdSet(); 400 401 static void set_safepoint(bool b); 402 403 // Attempt to claim the given id permanently. Returns "true" iff 404 // successful. 405 bool claim_perm_id(int i); 406 407 // Returns an unclaimed parallel id (waiting for one to be released if 408 // necessary). Returns "-1" if a GC wakes up a wait for an id. 409 int claim_par_id(); 410 411 void release_par_id(int id); 412 }; 413 414 #endif // SHARE_VM_GC_SHARED_WORKGROUP_HPP