Mercurial > jdk8-mips64-public > hotspot / file revision

 /*

  * Copyright 2001-2009 Sun Microsystems, Inc.  All Rights Reserved.

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

  *

  * This code is free software; you can redistribute it and/or modify it

  * under the terms of the GNU General Public License version 2 only, as

  * published by the Free Software Foundation.

  *

  * This code is distributed in the hope that it will be useful, but WITHOUT

  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

  * 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.

  *

  * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

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

  * have any questions.

  *

  */

 // There are various techniques that require threads to be able to log

 // addresses.  For example, a generational write barrier might log

 // the addresses of modified old-generation objects.  This type supports

 // this operation.

 class PtrQueueSet;

 class PtrQueue VALUE_OBJ_CLASS_SPEC {

 protected:

   // The ptr queue set to which this queue belongs.

   PtrQueueSet* _qset;

   // Whether updates should be logged.

   bool _active;

   // The buffer.

   void** _buf;

   // The index at which an object was last enqueued.  Starts at "_sz"

   // (indicating an empty buffer) and goes towards zero.

   size_t _index;

   // The size of the buffer.

   size_t _sz;

   // If true, the queue is permanent, and doesn't need to deallocate

   // its buffer in the destructor (since that obtains a lock which may not

   // be legally locked by then.

   bool _perm;

   // If there is a lock associated with this buffer, this is that lock.

   Mutex* _lock;

   PtrQueueSet* qset() { return _qset; }

 public:

   // Initialize this queue to contain a null buffer, and be part of the

   // given PtrQueueSet.

   PtrQueue(PtrQueueSet*, bool perm = false);

   // Release any contained resources.

   void flush();

   // Calls flush() when destroyed.

   ~PtrQueue() { flush(); }

   // Associate a lock with a ptr queue.

   void set_lock(Mutex* lock) { _lock = lock; }

   void reset() { if (_buf != NULL) _index = _sz; }

   // Enqueues the given "obj".

   void enqueue(void* ptr) {

     if (!_active) return;

     else enqueue_known_active(ptr);

   }

   inline void handle_zero_index();

   void locking_enqueue_completed_buffer(void** buf);

   void enqueue_known_active(void* ptr);

   size_t size() {

     assert(_sz >= _index, "Invariant.");

     return _buf == NULL ? 0 : _sz - _index;

   }

   // Set the "active" property of the queue to "b".  An enqueue to an

   // inactive thread is a no-op.  Setting a queue to inactive resets its

   // log to the empty state.

   void set_active(bool b) {

     _active = b;

     if (!b && _buf != NULL) {

       _index = _sz;

     } else if (b && _buf != NULL) {

       assert(_index == _sz, "invariant: queues are empty when activated.");

     }

   }

   static int byte_index_to_index(int ind) {

     assert((ind % oopSize) == 0, "Invariant.");

     return ind / oopSize;

   }

   static int index_to_byte_index(int byte_ind) {

     return byte_ind * oopSize;

   }

   // To support compiler.

   static ByteSize byte_offset_of_index() {

     return byte_offset_of(PtrQueue, _index);

   }

   static ByteSize byte_width_of_index() { return in_ByteSize(sizeof(size_t)); }

   static ByteSize byte_offset_of_buf() {

     return byte_offset_of(PtrQueue, _buf);

   }

   static ByteSize byte_width_of_buf() { return in_ByteSize(sizeof(void*)); }

   static ByteSize byte_offset_of_active() {

     return byte_offset_of(PtrQueue, _active);

   }

   static ByteSize byte_width_of_active() { return in_ByteSize(sizeof(bool)); }

 };

 // A PtrQueueSet represents resources common to a set of pointer queues.

 // In particular, the individual queues allocate buffers from this shared

 // set, and return completed buffers to the set.

 // All these variables are are protected by the TLOQ_CBL_mon. XXX ???

 class PtrQueueSet VALUE_OBJ_CLASS_SPEC {

 protected:

   class CompletedBufferNode: public CHeapObj {

   public:

     void** buf;

     size_t index;

     CompletedBufferNode* next;

     CompletedBufferNode() : buf(NULL),

       index(0), next(NULL){ }

   };

   Monitor* _cbl_mon;  // Protects the fields below.

   CompletedBufferNode* _completed_buffers_head;

   CompletedBufferNode* _completed_buffers_tail;

   size_t _n_completed_buffers;

   size_t _process_completed_threshold;

   volatile bool _process_completed;

   // This (and the interpretation of the first element as a "next"

   // pointer) are protected by the TLOQ_FL_lock.

   Mutex* _fl_lock;

   void** _buf_free_list;

   size_t _buf_free_list_sz;

   // Queue set can share a freelist. The _fl_owner variable

   // specifies the owner. It is set to "this" by default.

   PtrQueueSet* _fl_owner;

   // The size of all buffers in the set.

   size_t _sz;

   bool _all_active;

   // If true, notify_all on _cbl_mon when the threshold is reached.

   bool _notify_when_complete;

   // Maximum number of elements allowed on completed queue: after that,

   // enqueuer does the work itself.  Zero indicates no maximum.

   int _max_completed_queue;

   int completed_buffers_list_length();

   void assert_completed_buffer_list_len_correct_locked();

   void assert_completed_buffer_list_len_correct();

 protected:

   // A mutator thread does the the work of processing a buffer.

   // Returns "true" iff the work is complete (and the buffer may be

   // deallocated).

   virtual bool mut_process_buffer(void** buf) {

     ShouldNotReachHere();

     return false;

   }

 public:

   // Create an empty ptr queue set.

   PtrQueueSet(bool notify_when_complete = false);

   // Because of init-order concerns, we can't pass these as constructor

   // arguments.

   void initialize(Monitor* cbl_mon, Mutex* fl_lock,

                   int max_completed_queue = 0,

                   PtrQueueSet *fl_owner = NULL) {

     _max_completed_queue = max_completed_queue;

     assert(cbl_mon != NULL && fl_lock != NULL, "Init order issue?");

     _cbl_mon = cbl_mon;

     _fl_lock = fl_lock;

     _fl_owner = (fl_owner != NULL) ? fl_owner : this;

   }

   // Return an empty oop array of size _sz (required to be non-zero).

   void** allocate_buffer();

   // Return an empty buffer to the free list.  The "buf" argument is

   // required to be a pointer to the head of an array of length "_sz".

   void deallocate_buffer(void** buf);

   // Declares that "buf" is a complete buffer.

   void enqueue_complete_buffer(void** buf, size_t index = 0,

                                bool ignore_max_completed = false);

   bool completed_buffers_exist_dirty() {

     return _n_completed_buffers > 0;

   }

   bool process_completed_buffers() { return _process_completed; }

   bool active() { return _all_active; }

   // Set the buffer size.  Should be called before any "enqueue" operation

   // can be called.  And should only be called once.

   void set_buffer_size(size_t sz);

   // Get the buffer size.

   size_t buffer_size() { return _sz; }

   // Set the number of completed buffers that triggers log processing.

   void set_process_completed_threshold(size_t sz);

   // Must only be called at a safe point.  Indicates that the buffer free

   // list size may be reduced, if that is deemed desirable.

   void reduce_free_list();

   size_t completed_buffers_num() { return _n_completed_buffers; }

   void merge_bufferlists(PtrQueueSet* src);

   void merge_freelists(PtrQueueSet* src);

 };