1/*
2 * Copyright (c) 2002, 2015, 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).
14 *
15 * You should have received a copy of the GNU General Public License version
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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    flat_profiler         = 5,
61    system_dictionary     = 6,
62    class_loader_data     = 7,
63    management            = 8,
64    jvmti                 = 9,
65    code_cache            = 10
66  };
67 private:
68  RootType _root_type;
69 public:
70  ScavengeRootsTask(RootType value) : _root_type(value) {}
71
72  char* name() { return (char *)"scavenge-roots-task"; }
73
74  virtual void do_it(GCTaskManager* manager, uint which);
75};
76
77//
78// ThreadRootsTask
79//
80// This task scans the roots of a single thread. This task
81// enables scanning of thread roots in parallel.
82//
83
84class ThreadRootsTask : public GCTask {
85 private:
86  JavaThread* _java_thread;
87  VMThread* _vm_thread;
88 public:
89  ThreadRootsTask(JavaThread* root) : _java_thread(root), _vm_thread(NULL) {}
90  ThreadRootsTask(VMThread* root) : _java_thread(NULL), _vm_thread(root) {}
91
92  char* name() { return (char *)"thread-roots-task"; }
93
94  virtual void do_it(GCTaskManager* manager, uint which);
95};
96
97//
98// StealTask
99//
100// This task is used to distribute work to idle threads.
101//
102
103class StealTask : public GCTask {
104 private:
105   ParallelTaskTerminator* const _terminator;
106 public:
107  char* name() { return (char *)"steal-task"; }
108
109  StealTask(ParallelTaskTerminator* t);
110
111  ParallelTaskTerminator* terminator() { return _terminator; }
112
113  virtual void do_it(GCTaskManager* manager, uint which);
114};
115
116//
117// OldToYoungRootsTask
118//
119// This task is used to scan old to young roots in parallel
120//
121// A GC thread executing this tasks divides the generation (old gen)
122// into slices and takes a stripe in the slice as its part of the
123// work.
124//
125//      +===============+        slice 0
126//      |  stripe 0     |
127//      +---------------+
128//      |  stripe 1     |
129//      +---------------+
130//      |  stripe 2     |
131//      +---------------+
132//      |  stripe 3     |
133//      +===============+        slice 1
134//      |  stripe 0     |
135//      +---------------+
136//      |  stripe 1     |
137//      +---------------+
138//      |  stripe 2     |
139//      +---------------+
140//      |  stripe 3     |
141//      +===============+        slice 2
142//      ...
143//
144// A task is created for each stripe.  In this case there are 4 tasks
145// created.  A GC thread first works on its stripe within slice 0
146// and then moves to its stripe in the next slice until all stripes
147// exceed the top of the generation.  Note that having fewer GC threads
148// than stripes works because all the tasks are executed so all stripes
149// will be covered.  In this example if 4 tasks have been created to cover
150// all the stripes and there are only 3 threads, one of the threads will
151// get the tasks with the 4th stripe.  However, there is a dependence in
152// CardTableExtension::scavenge_contents_parallel() on the number
153// of tasks created.  In scavenge_contents_parallel the distance
154// to the next stripe is calculated based on the number of tasks.
155// If the stripe width is ssize, a task's next stripe is at
156// ssize * number_of_tasks (= slice_stride).  In this case after
157// finishing stripe 0 in slice 0, the thread finds the stripe 0 in slice1
158// by adding slice_stride to the start of stripe 0 in slice 0 to get
159// to the start of stride 0 in slice 1.
160
161class OldToYoungRootsTask : public GCTask {
162 private:
163  PSOldGen* _old_gen;
164  HeapWord* _gen_top;
165  uint _stripe_number;
166  uint _stripe_total;
167
168 public:
169  OldToYoungRootsTask(PSOldGen *old_gen,
170                      HeapWord* gen_top,
171                      uint stripe_number,
172                      uint stripe_total) :
173    _old_gen(old_gen),
174    _gen_top(gen_top),
175    _stripe_number(stripe_number),
176    _stripe_total(stripe_total) { }
177
178  char* name() { return (char *)"old-to-young-roots-task"; }
179
180  virtual void do_it(GCTaskManager* manager, uint which);
181};
182
183#endif // SHARE_VM_GC_PARALLEL_PSTASKS_HPP
184