1 /*
   2  * Copyright (c) 2001, 2007, 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 class ObjectClosure;
  26 class JavaThread;
  27 
  28 // A ptrQueue whose elements are "oops", pointers to object heads.
  29 class ObjPtrQueue: public PtrQueue {
  30 public:
  31   ObjPtrQueue(PtrQueueSet* qset_, bool perm = false) :
  32     // SATB queues are only active during marking cycles. We create
  33     // them with their active field set to false. If a thread is
  34     // created during a cycle and its SATB queue needs to be activated
  35     // before the thread starts running, we'll need to set its active
  36     // field to true. This is done in JavaThread::initialize_queues().
  37     PtrQueue(qset_, perm, false /* active */) { }
  38   // Apply the closure to all elements, and reset the index to make the
  39   // buffer empty.
  40   void apply_closure(ObjectClosure* cl);
  41 
  42   // Apply the closure to all elements of "buf", down to "index" (inclusive.)
  43   static void apply_closure_to_buffer(ObjectClosure* cl,
  44                                       void** buf, size_t index, size_t sz);
  45 
  46   void verify_oops_in_buffer() NOT_DEBUG_RETURN;
  47 };
  48 
  49 
  50 
  51 class SATBMarkQueueSet: public PtrQueueSet {
  52   ObjectClosure* _closure;
  53   ObjectClosure** _par_closures;  // One per ParGCThread.
  54 
  55   ObjPtrQueue _shared_satb_queue;
  56 
  57   // Utility function to support sequential and parallel versions.  If
  58   // "par" is true, then "worker" is the par thread id; if "false", worker
  59   // is ignored.
  60   bool apply_closure_to_completed_buffer_work(bool par, int worker);
  61 
  62 #ifdef ASSERT
  63   void dump_active_values(JavaThread* first, bool expected_active);
  64 #endif // ASSERT
  65 
  66 public:
  67   SATBMarkQueueSet();
  68 
  69   void initialize(Monitor* cbl_mon, Mutex* fl_lock,
  70                   int process_completed_threshold,
  71                   Mutex* lock);
  72 
  73   static void handle_zero_index_for_thread(JavaThread* t);
  74 
  75   // Apply "set_active(b)" to all Java threads' SATB queues. It should be
  76   // called only with the world stopped. The method will assert that the
  77   // SATB queues of all threads it visits, as well as the SATB queue
  78   // set itself, has an active value same as expected_active.
  79   void set_active_all_threads(bool b, bool expected_active);
  80 
  81   // Register "blk" as "the closure" for all queues.  Only one such closure
  82   // is allowed.  The "apply_closure_to_completed_buffer" method will apply
  83   // this closure to a completed buffer, and "iterate_closure_all_threads"
  84   // applies it to partially-filled buffers (the latter should only be done
  85   // with the world stopped).
  86   void set_closure(ObjectClosure* closure);
  87   // Set the parallel closures: pointer is an array of pointers to
  88   // closures, one for each parallel GC thread.
  89   void set_par_closure(int i, ObjectClosure* closure);
  90 
  91   // If there is a registered closure for buffers, apply it to all entries
  92   // in all currently-active buffers.  This should only be applied at a
  93   // safepoint.  (Currently must not be called in parallel; this should
  94   // change in the future.)
  95   void iterate_closure_all_threads();
  96   // Parallel version of the above.
  97   void par_iterate_closure_all_threads(int worker);
  98 
  99   // If there exists some completed buffer, pop it, then apply the
 100   // registered closure to all its elements, and return true.  If no
 101   // completed buffers exist, return false.
 102   bool apply_closure_to_completed_buffer() {
 103     return apply_closure_to_completed_buffer_work(false, 0);
 104   }
 105   // Parallel version of the above.
 106   bool par_apply_closure_to_completed_buffer(int worker) {
 107     return apply_closure_to_completed_buffer_work(true, worker);
 108   }
 109 
 110   ObjPtrQueue* shared_satb_queue() { return &_shared_satb_queue; }
 111 
 112   // If a marking is being abandoned, reset any unprocessed log buffers.
 113   void abandon_partial_marking();
 114 
 115 };