1 /*
   2  * Copyright (c) 2001, 2016, 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.
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  23  */
  24 
  25 #ifndef SHARE_VM_GC_G1_SATBMARKQUEUE_HPP
  26 #define SHARE_VM_GC_G1_SATBMARKQUEUE_HPP
  27 
  28 #include "gc/g1/ptrQueue.hpp"
  29 #include "memory/allocation.hpp"
  30 
  31 class JavaThread;
  32 class SATBMarkQueueSet;
  33 
  34 // Base class for processing the contents of a SATB buffer.
  35 class SATBBufferClosure : public StackObj {
  36 protected:
  37   ~SATBBufferClosure() { }
  38 
  39 public:
  40   // Process the SATB entries in the designated buffer range.
  41   virtual void do_buffer(void** buffer, size_t size) = 0;
  42 };
  43 
  44 // A PtrQueue whose elements are (possibly stale) pointers to object heads.
  45 class SATBMarkQueue: public PtrQueue {
  46   friend class SATBMarkQueueSet;
  47 
  48 private:
  49   // Filter out unwanted entries from the buffer.
  50   void filter();
  51 
  52 public:
  53   SATBMarkQueue(SATBMarkQueueSet* qset, bool permanent = false);
  54 
  55   // Process queue entries and free resources.
  56   void flush();
  57 
  58   // Apply cl to the active part of the buffer.
  59   // Prerequisite: Must be at a safepoint.
  60   void apply_closure_and_empty(SATBBufferClosure* cl);
  61 
  62   // Overrides PtrQueue::should_enqueue_buffer(). See the method's
  63   // definition for more information.
  64   virtual bool should_enqueue_buffer();
  65 
  66 #ifndef PRODUCT
  67   // Helpful for debugging
  68   void print(const char* name);
  69 #endif // PRODUCT
  70 
  71   // Compiler support.
  72   static ByteSize byte_offset_of_index() {
  73     return PtrQueue::byte_offset_of_index<SATBMarkQueue>();
  74   }
  75   using PtrQueue::byte_width_of_index;
  76 
  77   static ByteSize byte_offset_of_buf() {
  78     return PtrQueue::byte_offset_of_buf<SATBMarkQueue>();
  79   }
  80   using PtrQueue::byte_width_of_buf;
  81 
  82   static ByteSize byte_offset_of_active() {
  83     return PtrQueue::byte_offset_of_active<SATBMarkQueue>();
  84   }
  85   using PtrQueue::byte_width_of_active;
  86 
  87 };
  88 
  89 class SATBMarkQueueSet: public PtrQueueSet {
  90   SATBMarkQueue _shared_satb_queue;
  91 
  92 #ifdef ASSERT
  93   void dump_active_states(bool expected_active);
  94   void verify_active_states(bool expected_active);
  95 #endif // ASSERT
  96 
  97 public:
  98   SATBMarkQueueSet();
  99 
 100   void initialize(Monitor* cbl_mon, Mutex* fl_lock,
 101                   int process_completed_threshold,
 102                   Mutex* lock);
 103 
 104   static void handle_zero_index_for_thread(JavaThread* t);
 105 
 106   // Apply "set_active(active)" to all SATB queues in the set. It should be
 107   // called only with the world stopped. The method will assert that the
 108   // SATB queues of all threads it visits, as well as the SATB queue
 109   // set itself, has an active value same as expected_active.
 110   void set_active_all_threads(bool active, bool expected_active);
 111 
 112   // Filter all the currently-active SATB buffers.
 113   void filter_thread_buffers();
 114 
 115   // If there exists some completed buffer, pop and process it, and
 116   // return true.  Otherwise return false.  Processing a buffer
 117   // consists of applying the closure to the active range of the
 118   // buffer; the leading entries may be excluded due to filtering.
 119   bool apply_closure_to_completed_buffer(SATBBufferClosure* cl);
 120 
 121 #ifndef PRODUCT
 122   // Helpful for debugging
 123   void print_all(const char* msg);
 124 #endif // PRODUCT
 125 
 126   SATBMarkQueue* shared_satb_queue() { return &_shared_satb_queue; }
 127 
 128   // If a marking is being abandoned, reset any unprocessed log buffers.
 129   void abandon_partial_marking();
 130 };
 131 
 132 #endif // SHARE_VM_GC_G1_SATBMARKQUEUE_HPP