1 /*
   2  * Copyright (c) 2002, 2010, 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_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