1 /*
2 * Copyright (c) 2002, 2008, 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 class GCTaskManager;
26 class GCTaskQueue;
27 class OopStack;
28 class ReferenceProcessor;
29 class ParallelScavengeHeap;
30 class PSIsAliveClosure;
31 class PSRefProcTaskExecutor;
32
33 class PSScavenge: AllStatic {
34 friend class PSIsAliveClosure;
35 friend class PSKeepAliveClosure;
36 friend class PSPromotionManager;
37
38 enum ScavengeSkippedCause {
39 not_skipped = 0,
40 to_space_not_empty,
41 promoted_too_large,
42 full_follows_scavenge
43 };
44
45 // Saved value of to_space->top(), used to prevent objects in to_space from
46 // being rescanned.
47 static HeapWord* _to_space_top_before_gc;
48
49 // Number of consecutive attempts to scavenge that were skipped
50 static int _consecutive_skipped_scavenges;
51
52
53 protected:
54 // Flags/counters
55 static ReferenceProcessor* _ref_processor; // Reference processor for scavenging.
56 static PSIsAliveClosure _is_alive_closure; // Closure used for reference processing
57 static CardTableExtension* _card_table; // We cache the card table for fast access.
58 static bool _survivor_overflow; // Overflow this collection
59 static int _tenuring_threshold; // tenuring threshold for next scavenge
60 static elapsedTimer _accumulated_time; // total time spent on scavenge
61 static HeapWord* _young_generation_boundary; // The lowest address possible for the young_gen.
62 // This is used to decide if an oop should be scavenged,
63 // cards should be marked, etc.
64 static Stack<markOop> _preserved_mark_stack; // List of marks to be restored after failed promotion
65 static Stack<oop> _preserved_oop_stack; // List of oops that need their mark restored.
66 static CollectorCounters* _counters; // collector performance counters
67 static bool _promotion_failed;
68
69 static void clean_up_failed_promotion();
70
71 static bool should_attempt_scavenge();
72
73 static HeapWord* to_space_top_before_gc() { return _to_space_top_before_gc; }
74 static inline void save_to_space_top_before_gc();
75
76 // Private accessors
77 static CardTableExtension* const card_table() { assert(_card_table != NULL, "Sanity"); return _card_table; }
78
79 public:
80 // Accessors
81 static int tenuring_threshold() { return _tenuring_threshold; }
82 static elapsedTimer* accumulated_time() { return &_accumulated_time; }
83 static bool promotion_failed() { return _promotion_failed; }
84 static int consecutive_skipped_scavenges()
85 { return _consecutive_skipped_scavenges; }
86
87 // Performance Counters
88 static CollectorCounters* counters() { return _counters; }
89
90 // Used by scavenge_contents && psMarkSweep
91 static ReferenceProcessor* const reference_processor() {
92 assert(_ref_processor != NULL, "Sanity");
93 return _ref_processor;
94 }
95 // Used to add tasks
96 static GCTaskManager* const gc_task_manager();
97 // The promotion managers tell us if they encountered overflow
98 static void set_survivor_overflow(bool state) {
99 _survivor_overflow = state;
100 }
101 // Adaptive size policy support. When the young generation/old generation
102 // boundary moves, _young_generation_boundary must be reset
103 static void set_young_generation_boundary(HeapWord* v) {
104 _young_generation_boundary = v;
105 }
106
107 // Called by parallelScavengeHeap to init the tenuring threshold
108 static void initialize();
109
110 // Scavenge entry point
111 static void invoke();
112 // Return true is a collection was done. Return
113 // false if the collection was skipped.
114 static bool invoke_no_policy();
115
116 // If an attempt to promote fails, this method is invoked
117 static void oop_promotion_failed(oop obj, markOop obj_mark);
118
119 template <class T> static inline bool should_scavenge(T* p);
120
121 // These call should_scavenge() above and, if it returns true, also check that
122 // the object was not newly copied into to_space. The version with the bool
123 // argument is a convenience wrapper that fetches the to_space pointer from
124 // the heap and calls the other version (if the arg is true).
125 template <class T> static inline bool should_scavenge(T* p, MutableSpace* to_space);
126 template <class T> static inline bool should_scavenge(T* p, bool check_to_space);
127
128 template <class T> inline static void copy_and_push_safe_barrier(PSPromotionManager* pm, T* p);
129
130 // Is an object in the young generation
131 // This assumes that the HeapWord argument is in the heap,
132 // so it only checks one side of the complete predicate.
133 inline static bool is_obj_in_young(HeapWord* o) {
134 const bool result = (o >= _young_generation_boundary);
135 return result;
136 }
137 };