1 /*
   2  * Copyright (c) 2001, 2015, 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
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  24 
  25 #ifndef SHARE_VM_GC_G1_SATBQUEUE_HPP
  26 #define SHARE_VM_GC_G1_SATBQUEUE_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 "oops", pointers to object heads.
  45 class ObjPtrQueue: public PtrQueue {
  46   friend class SATBMarkQueueSet;
  47 
  48 private:
  49   // Filter out unwanted entries from the buffer.
  50   void filter();
  51 
  52 public:
  53   ObjPtrQueue(PtrQueueSet* qset, bool perm = false) :
  54     // SATB queues are only active during marking cycles. We create
  55     // them with their active field set to false. If a thread is
  56     // created during a cycle and its SATB queue needs to be activated
  57     // before the thread starts running, we'll need to set its active
  58     // field to true. This is done in JavaThread::initialize_queues().
  59     PtrQueue(qset, perm, false /* active */) { }
  60 
  61   // Process queue entries and free resources.
  62   void flush();
  63 
  64   // Apply cl to the active part of the buffer.
  65   // Prerequisite: Must be at a safepoint.
  66   void apply_closure_and_empty(SATBBufferClosure* cl);
  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 
  79 class SATBMarkQueueSet: public PtrQueueSet {
  80   ObjPtrQueue _shared_satb_queue;
  81 
  82 #ifdef ASSERT
  83   void dump_active_states(bool expected_active);
  84   void verify_active_states(bool expected_active);
  85 #endif // ASSERT
  86 
  87 public:
  88   SATBMarkQueueSet();
  89 
  90   void initialize(Monitor* cbl_mon, Mutex* fl_lock,
  91                   int process_completed_threshold,
  92                   Mutex* lock);
  93 
  94   static void handle_zero_index_for_thread(JavaThread* t);
  95 
  96   // Apply "set_active(active)" to all SATB queues in the set. It should be
  97   // called only with the world stopped. The method will assert that the
  98   // SATB queues of all threads it visits, as well as the SATB queue
  99   // set itself, has an active value same as expected_active.
 100   void set_active_all_threads(bool active, bool expected_active);
 101 
 102   // Filter all the currently-active SATB buffers.
 103   void filter_thread_buffers();
 104 
 105   // If there exists some completed buffer, pop and process it, and
 106   // return true.  Otherwise return false.  Processing a buffer
 107   // consists of applying the closure to the buffer range starting
 108   // with the first non-NULL entry to the end of the buffer; the
 109   // leading entries may be NULL due to filtering.
 110   bool apply_closure_to_completed_buffer(SATBBufferClosure* cl);
 111 
 112 #ifndef PRODUCT
 113   // Helpful for debugging
 114   void print_all(const char* msg);
 115 #endif // PRODUCT
 116 
 117   ObjPtrQueue* shared_satb_queue() { return &_shared_satb_queue; }
 118 
 119   // If a marking is being abandoned, reset any unprocessed log buffers.
 120   void abandon_partial_marking();
 121 };
 122 
 123 #endif // SHARE_VM_GC_G1_SATBQUEUE_HPP