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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

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 *

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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

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#ifndef SHARE_VM_GC_SHARED_WORKGROUP_HPP

#define SHARE_VM_GC_SHARED_WORKGROUP_HPP

#include "runtime/thread.inline.hpp"

// Task class hierarchy:

//   AbstractGangTask

//

// Gang/Group class hierarchy:

//   AbstractWorkGang

//     WorkGang

//

// Worker class hierarchy:

//     YieldingFlexibleGangWorker   (defined in another file)

// Forward declarations of classes defined here

class GangWorker;

class WorkData;

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

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

class AbstractGangTask VALUE_OBJ_CLASS_SPEC {

  // The abstract work method.

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

  virtual void work(uint worker_id) = 0;

  // Debugging accessor for the name.

};

  // Initialize only instance data.

  const bool _are_GC_task_threads;

  const bool _are_ConcurrentGC_threads;

  // The monitor which protects these data,

  // and notifies of changes in it.

  Monitor*  _monitor;

  // The task for this gang.

  AbstractGangTask* _task;

  // A sequence number for the current task.

  int _sequence_number;

  // The number of started workers.

  uint _started_workers;

  // The number of finished workers.

  uint _finished_workers;

public:

  // Accessors for fields

  Monitor* monitor() const {

    return _monitor;

  }

  AbstractGangTask* task() const {

    return _task;

  }

  int sequence_number() const {

    return _sequence_number;

  }

  uint started_workers() const {

    return _started_workers;

  }

  uint finished_workers() const {

    return _finished_workers;

  }

  // Predicates.

  bool is_idle() const {

    return (task() == NULL);

  }

  // Return the Ith gang worker.

  GangWorker* gang_worker(uint i) const;

protected:

  friend class GangWorker;

  // Note activation and deactivation of workers.

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

  void internal_worker_poll(WorkData* data) const;

  void internal_note_start();

  void internal_note_finish();

};

class WorkData: public StackObj {

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

private:

  AbstractGangTask* _task;

  int               _sequence_number;

public:

  // Constructor and destructor

  WorkData() {

    _task            = NULL;

    _sequence_number = 0;

  }

  ~WorkData() {

  }

  AbstractGangTask* task()               const { return _task; }

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

  int sequence_number()                  const { return _sequence_number; }

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

};

public:

  // Constructors and destructor.

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

  virtual void run();

  // Predicate for Thread

  virtual bool is_GC_task_thread() const;

  virtual bool is_ConcurrentGC_thread() const;

  // Printing

  void print_on(outputStream* st) const;

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

protected:

  AbstractWorkGang* _gang;

  virtual void initialize();

  virtual void loop();

};

// Dynamic number of worker threads

//

// This type of work gang is used to run different numbers of

// worker threads at different times.  The

// number of workers run for a task is "_active_workers"

// instead of "_total_workers" in a WorkGang.  The method

// "needs_more_workers()" returns true until "_active_workers"

// have been started and returns false afterwards.  The

// implementation of "needs_more_workers()" in WorkGang always

// returns true so that all workers are started.  The method

// "loop()" in GangWorker was modified to ask "needs_more_workers()"

// in its loop to decide if it should start working on a task.

// A worker in "loop()" waits for notification on the WorkGang

// monitor and execution of each worker as it checks for work

// is serialized via the same monitor.  The "needs_more_workers()"

// call is serialized and additionally the calculation for the

// "part" (effectively the worker id for executing the task) is

// serialized to give each worker a unique "part".  Workers that

// are not needed for this tasks (i.e., "_active_workers" have

// been started before it, continue to wait for work.

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

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

// before any of them may leave.

class WorkGangBarrierSync : public StackObj {

protected:

  Monitor _monitor;

  uint    _n_workers;

  uint    _n_completed;

  bool    _should_reset;

  bool    _aborted;

  Monitor* monitor()        { return &_monitor; }

  uint     n_workers()      { return _n_workers; }

  uint     n_completed()    { return _n_completed; }

  bool     should_reset()   { return _should_reset; }

  bool     aborted()        { return _aborted; }

  void     zero_completed() { _n_completed = 0; }

  void     inc_completed()  { _n_completed++; }

  void     set_aborted()    { _aborted = true; }

  void     set_should_reset(bool v) { _should_reset = v; }

public:

  WorkGangBarrierSync();

  WorkGangBarrierSync(uint n_workers, const char* name);

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

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

  void set_n_workers(uint n_workers);

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

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

  // also entered the barrier or the barrier is aborted.

  // Returns false if the barrier was aborted.

  bool enter();

  // Aborts the barrier and wakes up any threads waiting for

  // the barrier to complete. The barrier will remain in the

  // aborted state until the next call to set_n_workers().

  void abort();

};

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

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

// enumeration type.

class SubTasksDone: public CHeapObj<mtInternal> {

  uint* _tasks;

  uint _n_tasks;

  uint _threads_completed;

#ifdef ASSERT

  volatile uint _claimed;

#endif

  // Set all tasks to unclaimed.

  void clear();

public:

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

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

  // threads doing the tasks is initialized 1.

  SubTasksDone(uint n);

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

  bool valid();

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

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

  bool is_task_claimed(uint t);

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

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

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

  // cleared.)

  //

  // n_threads - Number of threads executing the sub-tasks.

  void all_tasks_completed(uint n_threads);

  // Destructor.

  ~SubTasksDone();

};

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

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

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

// partitioned tasks (like striding in the parallel remembered

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

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

class SequentialSubTasksDone : public StackObj {

protected:

  uint _n_tasks;     // Total number of tasks available.

  uint _n_claimed;   // Number of tasks claimed.

  // _n_threads is used to determine when a sub task is done.

  // See comments on SubTasksDone::_n_threads

  uint _n_threads;   // Total number of parallel threads.

  uint _n_completed; // Number of completed threads.

  void clear();

public:

  SequentialSubTasksDone() {

    clear();

  }

  ~SequentialSubTasksDone() {}

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

  bool valid();

  // number of tasks

  uint n_tasks() const { return _n_tasks; }

  // Get/set the number of parallel threads doing the tasks to t.

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

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

  // threads agree on the number of threads.

  uint n_threads() { return _n_threads; }

  void set_n_threads(uint t) { _n_threads = t; }

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

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

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

  // agree on the number of tasks.

  void set_n_tasks(uint t) { _n_tasks = t; }

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

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

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

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

  bool is_task_claimed(uint& t);

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

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

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

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

  // cleanup if necessary.

  bool all_tasks_completed();

};

// Represents a set of free small integer ids.

class FreeIdSet : public CHeapObj<mtInternal> {

  enum {

    end_of_list = -1,

    claimed = -2

  };

  int _sz;

  Monitor* _mon;

  int* _ids;

  int _hd;

  int _waiters;

  int _claimed;

  static bool _safepoint;

  typedef FreeIdSet* FreeIdSetPtr;

  static const int NSets = 10;

  static FreeIdSetPtr _sets[NSets];

  static bool _stat_init;

  int _index;

public:

  FreeIdSet(int sz, Monitor* mon);

  ~FreeIdSet();

  static void set_safepoint(bool b);

  // Attempt to claim the given id permanently.  Returns "true" iff

  // successful.

  bool claim_perm_id(int i);

  // Returns an unclaimed parallel id (waiting for one to be released if

  // necessary).  Returns "-1" if a GC wakes up a wait for an id.

  int claim_par_id();

  void release_par_id(int id);

};

#endif // SHARE_VM_GC_SHARED_WORKGROUP_HPP