1 /*

     2  * Copyright 2002-2007 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    24 

    25 // Forward declarations of classes defined here

    26 

    27 class WorkGang;

    28 class GangWorker;

    29 class YieldingFlexibleGangWorker;

    30 class YieldingFlexibleGangTask;

    31 class WorkData;

    32 

    33 // An abstract task to be worked on by a gang.

    34 // You subclass this to supply your own work() method

    35 class AbstractGangTask: public CHeapObj {

    36 public:

    37   // The abstract work method.

    38   // The argument tells you which member of the gang you are.

    39   virtual void work(int i) = 0;

    40 

    41   // Debugging accessor for the name.

    42   const char* name() const PRODUCT_RETURN_(return NULL;);

    43   int counter() { return _counter; }

    44   void set_counter(int value) { _counter = value; }

    45   int *address_of_counter() { return &_counter; }

    46 

    47   // RTTI

    48   NOT_PRODUCT(virtual bool is_YieldingFlexibleGang_task() const {

    49     return false;

    50   })

    51 

    52 private:

    53   NOT_PRODUCT(const char* _name;)

    54   // ??? Should a task have a priority associated with it?

    55   // ??? Or can the run method adjust priority as needed?

    56   int _counter;

    57 

    58 protected:

    59   // Constructor and desctructor: only construct subclasses.

    60   AbstractGangTask(const char* name) {

    61     NOT_PRODUCT(_name = name);

    62     _counter = 0;

    63   }

    64   virtual ~AbstractGangTask() { }

    65 };

    66 

    67 

    68 // Class AbstractWorkGang:

    69 // An abstract class representing a gang of workers.

    70 // You subclass this to supply an implementation of run_task().

    71 class AbstractWorkGang: public CHeapObj {

    72   // Here's the public interface to this class.

    73 public:

    74   // Constructor and destructor.

    75   AbstractWorkGang(const char* name, bool are_GC_threads);

    76   ~AbstractWorkGang();

    77   // Run a task, returns when the task is done (or terminated).

    78   virtual void run_task(AbstractGangTask* task) = 0;

    79   // Stop and terminate all workers.

    80   virtual void stop();

    81 public:

    82   // Debugging.

    83   const char* name() const;

    84 protected:

    85   // Initialize only instance data.

    86   const bool _are_GC_threads;

    87   // Printing support.

    88   const char* _name;

    89   // The monitor which protects these data,

    90   // and notifies of changes in it.

    91   Monitor*  _monitor;

    92   // The count of the number of workers in the gang.

    93   int _total_workers;

    94   // Whether the workers should terminate.

    95   bool _terminate;

    96   // The array of worker threads for this gang.

    97   // This is only needed for cleaning up.

    98   GangWorker** _gang_workers;

    99   // The task for this gang.

   100   AbstractGangTask* _task;

   101   // A sequence number for the current task.

   102   int _sequence_number;

   103   // The number of started workers.

   104   int _started_workers;

   105   // The number of finished workers.

   106   int _finished_workers;

   107 public:

   108   // Accessors for fields

   109   Monitor* monitor() const {

   110     return _monitor;

   111   }

   112   int total_workers() const {

   113     return _total_workers;

   114   }

   115   bool terminate() const {

   116     return _terminate;

   117   }

   118   GangWorker** gang_workers() const {

   119     return _gang_workers;

   120   }

   121   AbstractGangTask* task() const {

   122     return _task;

   123   }

   124   int sequence_number() const {

   125     return _sequence_number;

   126   }

   127   int started_workers() const {

   128     return _started_workers;

   129   }

   130   int finished_workers() const {

   131     return _finished_workers;

   132   }

   133   bool are_GC_threads() const {

   134     return _are_GC_threads;

   135   }

   136   // Predicates.

   137   bool is_idle() const {

   138     return (task() == NULL);

   139   }

   140   // Return the Ith gang worker.

   141   GangWorker* gang_worker(int i) const;

   142 

   143   void threads_do(ThreadClosure* tc) const;

   144 

   145   // Printing

   146   void print_worker_threads_on(outputStream *st) const;

   147   void print_worker_threads() const {

   148     print_worker_threads_on(tty);

   149   }

   150 

   151 protected:

   152   friend class GangWorker;

   153   friend class YieldingFlexibleGangWorker;

   154   // Note activation and deactivation of workers.

   155   // These methods should only be called with the mutex held.

   156   void internal_worker_poll(WorkData* data) const;

   157   void internal_note_start();

   158   void internal_note_finish();

   159 };

   160 

   161 class WorkData: public StackObj {

   162   // This would be a struct, but I want accessor methods.

   163 private:

   164   bool              _terminate;

   165   AbstractGangTask* _task;

   166   int               _sequence_number;

   167 public:

   168   // Constructor and destructor

   169   WorkData() {

   170     _terminate       = false;

   171     _task            = NULL;

   172     _sequence_number = 0;

   173   }

   174   ~WorkData() {

   175   }

   176   // Accessors and modifiers

   177   bool terminate()                       const { return _terminate;  }

   178   void set_terminate(bool value)               { _terminate = value; }

   179   AbstractGangTask* task()               const { return _task; }

   180   void set_task(AbstractGangTask* value)       { _task = value; }

   181   int sequence_number()                  const { return _sequence_number; }

   182   void set_sequence_number(int value)          { _sequence_number = value; }

   183 

   184   YieldingFlexibleGangTask* yf_task()    const {

   185     return (YieldingFlexibleGangTask*)_task;

   186   }

   187 };

   188 

   189 // Class WorkGang:

   190 class WorkGang: public AbstractWorkGang {

   191 public:

   192   // Constructor

   193   WorkGang(const char* name, int workers, bool are_GC_threads);

   194   // Run a task, returns when the task is done (or terminated).

   195   virtual void run_task(AbstractGangTask* task);

   196 };

   197 

   198 // Class GangWorker:

   199 //   Several instances of this class run in parallel as workers for a gang.

   200 class GangWorker: public WorkerThread {

   201 public:

   202   // Constructors and destructor.

   203   GangWorker(AbstractWorkGang* gang, uint id);

   204 

   205   // The only real method: run a task for the gang.

   206   virtual void run();

   207   // Predicate for Thread

   208   virtual bool is_GC_task_thread() const;

   209   // Printing

   210   void print_on(outputStream* st) const;

   211   virtual void print() const { print_on(tty); }

   212 protected:

   213   AbstractWorkGang* _gang;

   214 

   215   virtual void initialize();

   216   virtual void loop();

   217 

   218 public:

   219   AbstractWorkGang* gang() const { return _gang; }

   220 };

   221 

   222 // A class that acts as a synchronisation barrier. Workers enter

   223 // the barrier and must wait until all other workers have entered

   224 // before any of them may leave.

   225 

   226 class WorkGangBarrierSync : public StackObj {

   227 protected:

   228   Monitor _monitor;

   229   int     _n_workers;

   230   int     _n_completed;

   231 

   232   Monitor* monitor()       { return &_monitor; }

   233   int      n_workers()     { return _n_workers; }

   234   int      n_completed()   { return _n_completed; }

   235 

   236   void     inc_completed() { _n_completed++; }

   237 

   238 public:

   239   WorkGangBarrierSync();

   240   WorkGangBarrierSync(int n_workers, const char* name);

   241 

   242   // Set the number of workers that will use the barrier.

   243   // Must be called before any of the workers start running.

   244   void set_n_workers(int n_workers);

   245 

   246   // Enter the barrier. A worker that enters the barrier will

   247   // not be allowed to leave until all other threads have

   248   // also entered the barrier.

   249   void enter();

   250 };

   251 

   252 // A class to manage claiming of subtasks within a group of tasks.  The

   253 // subtasks will be identified by integer indices, usually elements of an

   254 // enumeration type.

   255 

   256 class SubTasksDone: public CHeapObj {

   257   jint* _tasks;

   258   int _n_tasks;

   259   int _n_threads;

   260   jint _threads_completed;

   261 #ifdef ASSERT

   262   jint _claimed;

   263 #endif

   264 

   265   // Set all tasks to unclaimed.

   266   void clear();

   267 

   268 public:

   269   // Initializes "this" to a state in which there are "n" tasks to be

   270   // processed, none of the which are originally claimed.  The number of

   271   // threads doing the tasks is initialized 1.

   272   SubTasksDone(int n);

   273 

   274   // True iff the object is in a valid state.

   275   bool valid();

   276 

   277   // Set the number of parallel threads doing the tasks to "t".  Can only

   278   // be called before tasks start or after they are complete.

   279   void set_par_threads(int t);

   280 

   281   // Returns "false" if the task "t" is unclaimed, and ensures that task is

   282   // claimed.  The task "t" is required to be within the range of "this".

   283   bool is_task_claimed(int t);

   284 

   285   // The calling thread asserts that it has attempted to claim all the

   286   // tasks that it will try to claim.  Every thread in the parallel task

   287   // must execute this.  (When the last thread does so, the task array is

   288   // cleared.)

   289   void all_tasks_completed();

   290 

   291   // Destructor.

   292   ~SubTasksDone();

   293 };

   294 

   295 // As above, but for sequential tasks, i.e. instead of claiming

   296 // sub-tasks from a set (possibly an enumeration), claim sub-tasks

   297 // in sequential order. This is ideal for claiming dynamically

   298 // partitioned tasks (like striding in the parallel remembered

   299 // set scanning). Note that unlike the above class this is

   300 // a stack object - is there any reason for it not to be?

   301 

   302 class SequentialSubTasksDone : public StackObj {

   303 protected:

   304   jint _n_tasks;     // Total number of tasks available.

   305   jint _n_claimed;   // Number of tasks claimed.

   306   jint _n_threads;   // Total number of parallel threads.

   307   jint _n_completed; // Number of completed threads.

   308 

   309   void clear();

   310 

   311 public:

   312   SequentialSubTasksDone() { clear(); }

   313   ~SequentialSubTasksDone() {}

   314 

   315   // True iff the object is in a valid state.

   316   bool valid();

   317 

   318   // number of tasks

   319   jint n_tasks() const { return _n_tasks; }

   320 

   321   // Set the number of parallel threads doing the tasks to t.

   322   // Should be called before the task starts but it is safe

   323   // to call this once a task is running provided that all

   324   // threads agree on the number of threads.

   325   void set_par_threads(int t) { _n_threads = t; }

   326 

   327   // Set the number of tasks to be claimed to t. As above,

   328   // should be called before the tasks start but it is safe

   329   // to call this once a task is running provided all threads

   330   // agree on the number of tasks.

   331   void set_n_tasks(int t) { _n_tasks = t; }

   332 

   333   // Returns false if the next task in the sequence is unclaimed,

   334   // and ensures that it is claimed. Will set t to be the index

   335   // of the claimed task in the sequence. Will return true if

   336   // the task cannot be claimed and there are none left to claim.

   337   bool is_task_claimed(int& t);

   338 

   339   // The calling thread asserts that it has attempted to claim

   340   // all the tasks it possibly can in the sequence. Every thread

   341   // claiming tasks must promise call this. Returns true if this

   342   // is the last thread to complete so that the thread can perform

   343   // cleanup if necessary.

   344   bool all_tasks_completed();

   345 };