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
  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 "memory/allocation.hpp"
  29 #include "gc_implementation/g1/ptrQueue.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   template <class HeapType>
  53   void filter_impl();
  54 
  55 public:
  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   // Process queue entries and free resources.
  65   void flush();
  66 
  67   // Apply cl to the active part of the buffer.
  68   // Prerequisite: Must be at a safepoint.
  69   void apply_closure_and_empty(SATBBufferClosure* cl);
  70 
  71   // Overrides PtrQueue::should_enqueue_buffer(). See the method's
  72   // definition for more information.
  73   virtual bool should_enqueue_buffer();
  74 
  75 #ifndef PRODUCT
  76   // Helpful for debugging
  77   void print(const char* name);
  78   static void print(const char* name, void** buf, size_t index, size_t sz);
  79 #endif // PRODUCT
  80 };
  81 
  82 class SATBMarkQueueSet: public PtrQueueSet {
  83   ObjPtrQueue _shared_satb_queue;
  84 
  85 #ifdef ASSERT
  86   void dump_active_states(bool expected_active);
  87   void verify_active_states(bool expected_active);
  88 #endif // ASSERT
  89 
  90 public:
  91   SATBMarkQueueSet();
  92 
  93   void initialize(Monitor* cbl_mon, Mutex* fl_lock,
  94                   int process_completed_threshold,
  95                   Mutex* lock);
  96 
  97   static void handle_zero_index_for_thread(JavaThread* t);
  98 
  99   // Apply "set_active(active)" to all SATB queues in the set. It should be
 100   // called only with the world stopped. The method will assert that the
 101   // SATB queues of all threads it visits, as well as the SATB queue
 102   // set itself, has an active value same as expected_active.
 103   void set_active_all_threads(bool active, bool expected_active);
 104 
 105   // Filter all the currently-active SATB buffers.
 106   void filter_thread_buffers();
 107 
 108   // If there exists some completed buffer, pop and process it, and
 109   // return true.  Otherwise return false.  Processing a buffer
 110   // consists of applying the closure to the buffer range starting
 111   // with the first non-NULL entry to the end of the buffer; the
 112   // leading entries may be NULL due to filtering.
 113   bool apply_closure_to_completed_buffer(SATBBufferClosure* cl);
 114 
 115 #ifndef PRODUCT
 116   // Helpful for debugging
 117   void print_all(const char* msg);
 118 #endif // PRODUCT
 119 
 120   ObjPtrQueue* shared_satb_queue() { return &_shared_satb_queue; }
 121 
 122   // If a marking is being abandoned, reset any unprocessed log buffers.
 123   void abandon_partial_marking();
 124 };
 125 
 126 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_SATBQUEUE_HPP