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
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.
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23 */
24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP
27
28 #ifndef SERIALGC
29 #include "runtime/thread.hpp"
30 #endif
31
32 class VoidClosure;
33
34 // A SuspendibleThreadSet is (obviously) a set of threads that can be
35 // suspended. A thread can join and later leave the set, and periodically
36 // yield. If some thread (not in the set) requests, via suspend_all, that
37 // the threads be suspended, then the requesting thread is blocked until
38 // all the threads in the set have yielded or left the set. (Threads may
39 // not enter the set when an attempted suspension is in progress.) The
40 // suspending thread later calls resume_all, allowing the suspended threads
41 // to continue.
42
43 class SuspendibleThreadSet {
44 Monitor* _m;
45 int _async;
46 bool _async_stop;
47 int _async_stopped;
48 bool _initialized;
49 double _suspend_all_start;
50
51 void initialize_work();
52
53 public:
54 SuspendibleThreadSet() : _initialized(false) {}
55
56 // Add the current thread to the set. May block if a suspension
57 // is in progress.
58 void join();
59 // Removes the current thread from the set.
60 void leave();
61 // Returns "true" iff an suspension is in progress.
62 bool should_yield() { return _async_stop; }
63 // Suspends the current thread if a suspension is in progress (for
64 // the duration of the suspension.)
65 void yield(const char* id);
66 // Return when all threads in the set are suspended.
67 void suspend_all();
68 // Allow suspended threads to resume.
69 void resume_all();
70 // Redundant initializations okay.
71 void initialize() {
72 // Double-check dirty read idiom.
73 if (!_initialized) initialize_work();
74 }
75 };
76
77
78 class ConcurrentGCThread: public NamedThread {
79 friend class VMStructs;
80
81 protected:
82 bool _should_terminate;
83 bool _has_terminated;
84
85 enum CGC_flag_type {
86 CGC_nil = 0x0,
87 CGC_dont_suspend = 0x1,
88 CGC_CGC_safepoint = 0x2,
89 CGC_VM_safepoint = 0x4
90 };
91
92 static int _CGC_flag;
93
94 static bool CGC_flag_is_set(int b) { return (_CGC_flag & b) != 0; }
95 static int set_CGC_flag(int b) { return _CGC_flag |= b; }
96 static int reset_CGC_flag(int b) { return _CGC_flag &= ~b; }
97
98 void stopWorldAndDo(VoidClosure* op);
99
100 // All instances share this one set.
101 static SuspendibleThreadSet _sts;
102
103 // Create and start the thread (setting it's priority high.)
104 void create_and_start();
105
106 // Do initialization steps in the thread: record stack base and size,
107 // init thread local storage, set JNI handle block.
108 void initialize_in_thread();
109
110 // Wait until Universe::is_fully_initialized();
111 void wait_for_universe_init();
112
113 // Record that the current thread is terminating, and will do more
114 // concurrent work.
115 void terminate();
116
117 public:
118 // Constructor
119
120 ConcurrentGCThread();
121 ~ConcurrentGCThread() {} // Exists to call NamedThread destructor.
122
123 // Tester
124 bool is_ConcurrentGC_thread() const { return true; }
125
126 static void safepoint_synchronize();
127 static void safepoint_desynchronize();
128
129 // All overridings should probably do _sts::yield, but we allow
130 // overriding for distinguished debugging messages. Default is to do
131 // nothing.
132 virtual void yield() {}
133
134 bool should_yield() { return _sts.should_yield(); }
135
136 // they are prefixed by sts since there are already yield() and
137 // should_yield() (non-static) methods in this class and it was an
138 // easy way to differentiate them.
139 static void stsYield(const char* id);
140 static bool stsShouldYield();
141 static void stsJoin();
142 static void stsLeave();
143
144 };
145
146 // The SurrogateLockerThread is used by concurrent GC threads for
147 // manipulating Java monitors, in particular, currently for
148 // manipulating the pending_list_lock. XXX
149 class SurrogateLockerThread: public JavaThread {
150 friend class VMStructs;
151 public:
152 enum SLT_msg_type {
153 empty = 0, // no message
154 acquirePLL, // acquire pending list lock
155 releaseAndNotifyPLL // notify and release pending list lock
156 };
157 private:
158 // the following are shared with the CMSThread
159 SLT_msg_type _buffer; // communication buffer
160 Monitor _monitor; // monitor controlling buffer
161 BasicLock _basicLock; // used for PLL locking
162
163 public:
164 static SurrogateLockerThread* make(TRAPS);
165
166 SurrogateLockerThread();
167
168 bool is_hidden_from_external_view() const { return true; }
169
170 void loop(); // main method
171
172 void manipulatePLL(SLT_msg_type msg);
173
174 };
175
176 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_CONCURRENTGCTHREAD_HPP