1 /*
   2  * Copyright (c) 2001, 2012, 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_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP
  26 #define SHARE_VM_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP
  27 
  28 #include "gc_implementation/g1/ptrQueue.hpp"
  29 
  30 class ObjectClosure;
  31 class JavaThread;
  32 class SATBMarkQueueSet;
  33 
  34 // A ptrQueue whose elements are "oops", pointers to object heads.
  35 class ObjPtrQueue: public PtrQueue {
  36   friend class Threads;
  37   friend class SATBMarkQueueSet;
  38   friend class G1RemarkThreadsClosure;
  39 
  40 private:
  41   // Filter out unwanted entries from the buffer.
  42   void filter();
  43 
  44   // Apply the closure to all elements.
  45   void apply_closure(ObjectClosure* cl);
  46 
  47   // Apply the closure to all elements and empty the buffer;
  48   void apply_closure_and_empty(ObjectClosure* cl);
  49 
  50   // Apply the closure to all elements of "buf", down to "index" (inclusive.)
  51   static void apply_closure_to_buffer(ObjectClosure* cl,
  52                                       void** buf, size_t index, size_t sz);
  53 
  54 public:
  55   ObjPtrQueue() {}
  56   ObjPtrQueue(PtrQueueSet* qset, bool perm = false) :
  57     // SATB queues are only active during marking cycles. We create
  58     // them with their active field set to false. If a thread is
  59     // created during a cycle and its SATB queue needs to be activated
  60     // before the thread starts running, we'll need to set its active
  61     // field to true. This is done in JavaThread::initialize_queues().
  62     PtrQueue(qset, perm, false /* active */) { }
  63 
  64   // Overrides PtrQueue::flush() so that it can filter the buffer
  65   // before it is flushed.
  66   virtual void flush();
  67 
  68   // Overrides PtrQueue::should_enqueue_buffer(). See the method's
  69   // definition for more information.
  70   virtual bool should_enqueue_buffer();
  71 
  72 #ifndef PRODUCT
  73   // Helpful for debugging
  74   void print(const char* name);
  75   static void print(const char* name, void** buf, size_t index, size_t sz);
  76 #endif // PRODUCT
  77 
  78   void verify_oops_in_buffer() NOT_DEBUG_RETURN;
  79 };
  80 
  81 class SATBMarkQueueSet: public PtrQueueSet {
  82   ObjectClosure** _closures;  // One per ParGCThread.
  83 
  84   ObjPtrQueue _shared_satb_queue;
  85 
  86 #ifdef ASSERT
  87   void dump_active_states(bool expected_active);
  88   void verify_active_states(bool expected_active);
  89 #endif // ASSERT
  90 
  91 public:
  92   SATBMarkQueueSet();
  93 
  94   void initialize(Monitor* cbl_mon, Mutex* fl_lock,
  95                   int process_completed_threshold,
  96                   Mutex* lock);
  97 
  98   static void handle_zero_index_for_thread(JavaThread* t);
  99 
 100   // Apply "set_active(active)" to all SATB queues in the set. It should be
 101   // called only with the world stopped. The method will assert that the
 102   // SATB queues of all threads it visits, as well as the SATB queue
 103   // set itself, has an active value same as expected_active.
 104   void set_active_all_threads(bool active, bool expected_active);
 105 
 106   // Filter all the currently-active SATB buffers.
 107   void filter_thread_buffers();
 108 
 109   // Register closure for the given worker thread. The "apply_closure_to_completed_buffer"
 110   // method will apply this closure to a completed buffer, and "iterate_closure_all_threads"
 111   // applies it to partially-filled buffers (the latter should only be done
 112   // with the world stopped).
 113   void set_closure(uint worker, ObjectClosure* closure);
 114 
 115   // If there exists some completed buffer, pop it, then apply the
 116   // registered closure to all its elements, and return true.  If no
 117   // completed buffers exist, return false.
 118   bool apply_closure_to_completed_buffer(uint worker);
 119 
 120   // Apply the given closure on enqueued and currently-active buffers
 121   // respectively. Both methods are read-only, i.e., they do not
 122   // modify any of the buffers.
 123   void iterate_completed_buffers_read_only(ObjectClosure* cl);
 124   void iterate_thread_buffers_read_only(ObjectClosure* cl);
 125 
 126 #ifndef PRODUCT
 127   // Helpful for debugging
 128   void print_all(const char* msg);
 129 #endif // PRODUCT
 130 
 131   ObjPtrQueue* shared_satb_queue() { return &_shared_satb_queue; }
 132 
 133   // If a marking is being abandoned, reset any unprocessed log buffers.
 134   void abandon_partial_marking();
 135 };
 136 
 137 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP