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_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