1/*
2 * Copyright (c) 2002, 2017, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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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.
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23 */
24
25#ifndef SHARE_VM_GC_PARALLEL_PSTASKS_HPP
26#define SHARE_VM_GC_PARALLEL_PSTASKS_HPP
27
28#include "memory/allocation.hpp"
29#include "utilities/growableArray.hpp"
30
31//
32// psTasks.hpp is a collection of GCTasks used by the
33// parallelScavenge collector.
34//
35
36class GCTask;
37class OopClosure;
38class OopStack;
39class ObjectStartArray;
40class ParallelTaskTerminator;
41class MutableSpace;
42class PSOldGen;
43class Thread;
44class VMThread;
45
46//
47// ScavengeRootsTask
48//
49// This task scans all the roots of a given type.
50//
51//
52
53class ScavengeRootsTask : public GCTask {
54 public:
55  enum RootType {
56    universe              = 1,
57    jni_handles           = 2,
58    threads               = 3,
59    object_synchronizer   = 4,
60    system_dictionary     = 5,
61    class_loader_data     = 6,
62    management            = 7,
63    jvmti                 = 8,
64    code_cache            = 9
65  };
66 private:
67  RootType _root_type;
68 public:
69  ScavengeRootsTask(RootType value) : _root_type(value) {}
70
71  char* name() { return (char *)"scavenge-roots-task"; }
72
73  virtual void do_it(GCTaskManager* manager, uint which);
74};
75
76//
77// ThreadRootsTask
78//
79// This task scans the roots of a single thread. This task
80// enables scanning of thread roots in parallel.
81//
82
83class ThreadRootsTask : public GCTask {
84 private:
85  JavaThread* _java_thread;
86  VMThread* _vm_thread;
87 public:
88  ThreadRootsTask(JavaThread* root) : _java_thread(root), _vm_thread(NULL) {}
89  ThreadRootsTask(VMThread* root) : _java_thread(NULL), _vm_thread(root) {}
90
91  char* name() { return (char *)"thread-roots-task"; }
92
93  virtual void do_it(GCTaskManager* manager, uint which);
94};
95
96//
97// StealTask
98//
99// This task is used to distribute work to idle threads.
100//
101
102class StealTask : public GCTask {
103 private:
104   ParallelTaskTerminator* const _terminator;
105 public:
106  char* name() { return (char *)"steal-task"; }
107
108  StealTask(ParallelTaskTerminator* t);
109
110  ParallelTaskTerminator* terminator() { return _terminator; }
111
112  virtual void do_it(GCTaskManager* manager, uint which);
113};
114
115//
116// OldToYoungRootsTask
117//
118// This task is used to scan old to young roots in parallel
119//
120// A GC thread executing this tasks divides the generation (old gen)
121// into slices and takes a stripe in the slice as its part of the
122// work.
123//
124//      +===============+        slice 0
125//      |  stripe 0     |
126//      +---------------+
127//      |  stripe 1     |
128//      +---------------+
129//      |  stripe 2     |
130//      +---------------+
131//      |  stripe 3     |
132//      +===============+        slice 1
133//      |  stripe 0     |
134//      +---------------+
135//      |  stripe 1     |
136//      +---------------+
137//      |  stripe 2     |
138//      +---------------+
139//      |  stripe 3     |
140//      +===============+        slice 2
141//      ...
142//
143// A task is created for each stripe.  In this case there are 4 tasks
144// created.  A GC thread first works on its stripe within slice 0
145// and then moves to its stripe in the next slice until all stripes
146// exceed the top of the generation.  Note that having fewer GC threads
147// than stripes works because all the tasks are executed so all stripes
148// will be covered.  In this example if 4 tasks have been created to cover
149// all the stripes and there are only 3 threads, one of the threads will
150// get the tasks with the 4th stripe.  However, there is a dependence in
151// CardTableExtension::scavenge_contents_parallel() on the number
152// of tasks created.  In scavenge_contents_parallel the distance
153// to the next stripe is calculated based on the number of tasks.
154// If the stripe width is ssize, a task's next stripe is at
155// ssize * number_of_tasks (= slice_stride).  In this case after
156// finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1
157// by adding slice_stride to the start of stripe 0 in slice 0 to get
158// to the start of stride 0 in slice 1.
159
160class OldToYoungRootsTask : public GCTask {
161 private:
162  PSOldGen* _old_gen;
163  HeapWord* _gen_top;
164  uint _stripe_number;
165  uint _stripe_total;
166
167 public:
168  OldToYoungRootsTask(PSOldGen *old_gen,
169                      HeapWord* gen_top,
170                      uint stripe_number,
171                      uint stripe_total) :
172    _old_gen(old_gen),
173    _gen_top(gen_top),
174    _stripe_number(stripe_number),
175    _stripe_total(stripe_total) { }
176
177  char* name() { return (char *)"old-to-young-roots-task"; }
178
179  virtual void do_it(GCTaskManager* manager, uint which);
180};
181
182#endif // SHARE_VM_GC_PARALLEL_PSTASKS_HPP
183