src/share/vm/gc_implementation/g1/dirtyCardQueue.hpp

Thu, 07 Apr 2011 09:53:20 -0700

author
johnc
date
Thu, 07 Apr 2011 09:53:20 -0700
changeset 2781
e1162778c1c8
parent 2314
f95d63e2154a
child 3900
d2a62e0f25eb
permissions
-rw-r--r--

7009266: G1: assert(obj->is_oop_or_null(true )) failed: Error
Summary: A referent object that is only weakly reachable at the start of concurrent marking but is re-attached to the strongly reachable object graph during marking may not be marked as live. This can cause the reference object to be processed prematurely and leave dangling pointers to the referent object. Implement a read barrier for the java.lang.ref.Reference::referent field by intrinsifying the Reference.get() method, and intercepting accesses though JNI, reflection, and Unsafe, so that when a non-null referent object is read it is also logged in an SATB buffer.
Reviewed-by: kvn, iveresov, never, tonyp, dholmes

     1 /*
     2  * Copyright (c) 2001, 2010, 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
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    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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    22  *
    23  */
    25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_DIRTYCARDQUEUE_HPP
    26 #define SHARE_VM_GC_IMPLEMENTATION_G1_DIRTYCARDQUEUE_HPP
    28 #include "gc_implementation/g1/ptrQueue.hpp"
    29 #include "memory/allocation.hpp"
    31 class FreeIdSet;
    33 // A closure class for processing card table entries.  Note that we don't
    34 // require these closure objects to be stack-allocated.
    35 class CardTableEntryClosure: public CHeapObj {
    36 public:
    37   // Process the card whose card table entry is "card_ptr".  If returns
    38   // "false", terminate the iteration early.
    39   virtual bool do_card_ptr(jbyte* card_ptr, int worker_i = 0) = 0;
    40 };
    42 // A ptrQueue whose elements are "oops", pointers to object heads.
    43 class DirtyCardQueue: public PtrQueue {
    44 public:
    45   DirtyCardQueue(PtrQueueSet* qset_, bool perm = false) :
    46     // Dirty card queues are always active, so we create them with their
    47     // active field set to true.
    48     PtrQueue(qset_, perm, true /* active */) { }
    50   // Apply the closure to all elements, and reset the index to make the
    51   // buffer empty.  If a closure application returns "false", return
    52   // "false" immediately, halting the iteration.  If "consume" is true,
    53   // deletes processed entries from logs.
    54   bool apply_closure(CardTableEntryClosure* cl,
    55                      bool consume = true,
    56                      size_t worker_i = 0);
    58   // Apply the closure to all elements of "buf", down to "index"
    59   // (inclusive.)  If returns "false", then a closure application returned
    60   // "false", and we return immediately.  If "consume" is true, entries are
    61   // set to NULL as they are processed, so they will not be processed again
    62   // later.
    63   static bool apply_closure_to_buffer(CardTableEntryClosure* cl,
    64                                       void** buf, size_t index, size_t sz,
    65                                       bool consume = true,
    66                                       int worker_i = 0);
    67   void **get_buf() { return _buf;}
    68   void set_buf(void **buf) {_buf = buf;}
    69   size_t get_index() { return _index;}
    70   void reinitialize() { _buf = 0; _sz = 0; _index = 0;}
    71 };
    75 class DirtyCardQueueSet: public PtrQueueSet {
    76   CardTableEntryClosure* _closure;
    78   DirtyCardQueue _shared_dirty_card_queue;
    80   // Override.
    81   bool mut_process_buffer(void** buf);
    83   // Protected by the _cbl_mon.
    84   FreeIdSet* _free_ids;
    86   // The number of completed buffers processed by mutator and rs thread,
    87   // respectively.
    88   jint _processed_buffers_mut;
    89   jint _processed_buffers_rs_thread;
    91 public:
    92   DirtyCardQueueSet(bool notify_when_complete = true);
    94   void initialize(Monitor* cbl_mon, Mutex* fl_lock,
    95                   int process_completed_threshold,
    96                   int max_completed_queue,
    97                   Mutex* lock, PtrQueueSet* fl_owner = NULL);
    99   // The number of parallel ids that can be claimed to allow collector or
   100   // mutator threads to do card-processing work.
   101   static size_t num_par_ids();
   103   static void handle_zero_index_for_thread(JavaThread* t);
   105   // Register "blk" as "the closure" for all queues.  Only one such closure
   106   // is allowed.  The "apply_closure_to_completed_buffer" method will apply
   107   // this closure to a completed buffer, and "iterate_closure_all_threads"
   108   // applies it to partially-filled buffers (the latter should only be done
   109   // with the world stopped).
   110   void set_closure(CardTableEntryClosure* closure);
   112   // If there is a registered closure for buffers, apply it to all entries
   113   // in all currently-active buffers.  This should only be applied at a
   114   // safepoint.  (Currently must not be called in parallel; this should
   115   // change in the future.)  If "consume" is true, processed entries are
   116   // discarded.
   117   void iterate_closure_all_threads(bool consume = true,
   118                                    size_t worker_i = 0);
   120   // If there exists some completed buffer, pop it, then apply the
   121   // registered closure to all its elements, nulling out those elements
   122   // processed.  If all elements are processed, returns "true".  If no
   123   // completed buffers exist, returns false.  If a completed buffer exists,
   124   // but is only partially completed before a "yield" happens, the
   125   // partially completed buffer (with its processed elements set to NULL)
   126   // is returned to the completed buffer set, and this call returns false.
   127   bool apply_closure_to_completed_buffer(int worker_i = 0,
   128                                          int stop_at = 0,
   129                                          bool during_pause = false);
   131   // If there exists some completed buffer, pop it, then apply the
   132   // specified closure to all its elements, nulling out those elements
   133   // processed.  If all elements are processed, returns "true".  If no
   134   // completed buffers exist, returns false.  If a completed buffer exists,
   135   // but is only partially completed before a "yield" happens, the
   136   // partially completed buffer (with its processed elements set to NULL)
   137   // is returned to the completed buffer set, and this call returns false.
   138   bool apply_closure_to_completed_buffer(CardTableEntryClosure* cl,
   139                                          int worker_i = 0,
   140                                          int stop_at = 0,
   141                                          bool during_pause = false);
   143   // Helper routine for the above.
   144   bool apply_closure_to_completed_buffer_helper(CardTableEntryClosure* cl,
   145                                                 int worker_i,
   146                                                 BufferNode* nd);
   148   BufferNode* get_completed_buffer(int stop_at);
   150   // Applies the current closure to all completed buffers,
   151   // non-consumptively.
   152   void apply_closure_to_all_completed_buffers();
   154   DirtyCardQueue* shared_dirty_card_queue() {
   155     return &_shared_dirty_card_queue;
   156   }
   158   // Deallocate any completed log buffers
   159   void clear();
   161   // If a full collection is happening, reset partial logs, and ignore
   162   // completed ones: the full collection will make them all irrelevant.
   163   void abandon_logs();
   165   // If any threads have partial logs, add them to the global list of logs.
   166   void concatenate_logs();
   167   void clear_n_completed_buffers() { _n_completed_buffers = 0;}
   169   jint processed_buffers_mut() {
   170     return _processed_buffers_mut;
   171   }
   172   jint processed_buffers_rs_thread() {
   173     return _processed_buffers_rs_thread;
   174   }
   176 };
   178 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_DIRTYCARDQUEUE_HPP

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