jdk8-mips64-public/hotspot: src/share/vm/memory/modRefBarrierSet.hpp@0bfd3fb24150

6858496: Clear all SoftReferences before an out-of-memory due to GC overhead limit.
Summary: Ensure a full GC that clears SoftReferences before throwing an out-of-memory
Reviewed-by: ysr, jcoomes

     1 /*

     2  * Copyright 2000-2008 Sun Microsystems, Inc.  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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,

    20  * CA 95054 USA or visit www.sun.com if you need additional information or

    21  * have any questions.

    22  *

    23  */

    25 // This kind of "BarrierSet" allows a "CollectedHeap" to detect and

    26 // enumerate ref fields that have been modified (since the last

    27 // enumeration), using a card table.

    29 class OopClosure;

    30 class Generation;

    32 class ModRefBarrierSet: public BarrierSet {

    33 public:

    35   ModRefBarrierSet() { _kind = BarrierSet::ModRef; }

    37   bool is_a(BarrierSet::Name bsn) {

    38     return bsn == BarrierSet::ModRef;

    39   }

    41   // Barriers only on ref writes.

    42   bool has_read_ref_barrier() { return false; }

    43   bool has_read_prim_barrier() { return false; }

    44   bool has_write_ref_barrier() { return true; }

    45   bool has_write_prim_barrier() { return false; }

    47   bool read_ref_needs_barrier(void* field) { return false; }

    48   bool read_prim_needs_barrier(HeapWord* field, size_t bytes) { return false; }

    49   virtual bool write_ref_needs_barrier(void* field, oop new_val) = 0;

    50   bool write_prim_needs_barrier(HeapWord* field, size_t bytes,

    51                                 juint val1, juint val2) { return false; }

    53   void write_prim_field(oop obj, size_t offset, size_t bytes,

    54                         juint val1, juint val2) {}

    56   void read_ref_field(void* field) {}

    57   void read_prim_field(HeapWord* field, size_t bytes) {}

    58 protected:

    59   virtual void write_ref_field_work(void* field, oop new_val) = 0;

    60 public:

    61   void write_prim_field(HeapWord* field, size_t bytes,

    62                         juint val1, juint val2) {}

    64   bool has_read_ref_array_opt() { return false; }

    65   bool has_read_prim_array_opt() { return false; }

    66   bool has_write_prim_array_opt() { return false; }

    68   bool has_read_region_opt() { return false; }

    71   // These operations should assert false unless the correponding operation

    72   // above returns true.

    73   void read_ref_array(MemRegion mr) {

    74     assert(false, "can't call");

    75   }

    76   void read_prim_array(MemRegion mr) {

    77     assert(false, "can't call");

    78   }

    79   void write_prim_array(MemRegion mr) {

    80     assert(false, "can't call");

    81   }

    82   void read_region(MemRegion mr) {

    83     assert(false, "can't call");

    84   }

    86   // Invoke "cl->do_oop" on (the address of) every possibly-modifed

    87   // reference field in objects in "sp".  If "clear" is "true", the oops

    88   // are no longer considered possibly modified after application of the

    89   // closure.  If' "before_save_marks" is true, oops in objects allocated

    90   // after the last call to "save_marks" on "sp" will not be considered.

    91   virtual void mod_oop_in_space_iterate(Space* sp, OopClosure* cl,

    92                                         bool clear = false,

    93                                         bool before_save_marks = false) = 0;

    95   // Causes all refs in "mr" to be assumed to be modified.  If "whole_heap"

    96   // is true, the caller asserts that the entire heap is being invalidated,

    97   // which may admit an optimized implementation for some barriers.

    98   virtual void invalidate(MemRegion mr, bool whole_heap = false) = 0;

   100   // The caller guarantees that "mr" contains no references.  (Perhaps it's

   101   // objects have been moved elsewhere.)

   102   virtual void clear(MemRegion mr) = 0;

   104   // Pass along the argument to the superclass.

   105   ModRefBarrierSet(int max_covered_regions) :

   106     BarrierSet(max_covered_regions) {}

   108 #ifndef PRODUCT

   109   // Verifies that the given region contains no modified references.

   110   virtual void verify_clean_region(MemRegion mr) = 0;

   111 #endif

   113 };

Mercurial > jdk8-mips64-public > hotspot / file revision

src/share/vm/memory/modRefBarrierSet.hpp@0bfd3fb24150

src/share/vm/memory/modRefBarrierSet.hpp