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comparison src/share/vm/runtime/objectMonitor.hpp @ 0:a61af66fc99e jdk7-b24

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author duke
date Sat, 01 Dec 2007 00:00:00 +0000
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1 /*
2 * Copyright 1998-2007 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 */
24
25 // WARNING:
26 // This is a very sensitive and fragile class. DO NOT make any
27 // change unless you are fully aware of the underlying semantics.
28
29 // This class can not inherit from any other class, because I have
30 // to let the displaced header be the very first word. Otherwise I
31 // have to let markOop include this file, which would export the
32 // monitor data structure to everywhere.
33 //
34 // The ObjectMonitor class is used to implement JavaMonitors which have
35 // transformed from the lightweight structure of the thread stack to a
36 // heavy weight lock due to contention
37
38 // It is also used as RawMonitor by the JVMTI
39
40
41 class ObjectWaiter;
42
43 class ObjectMonitor {
44 public:
45 enum {
46 OM_OK, // no error
47 OM_SYSTEM_ERROR, // operating system error
48 OM_ILLEGAL_MONITOR_STATE, // IllegalMonitorStateException
49 OM_INTERRUPTED, // Thread.interrupt()
50 OM_TIMED_OUT // Object.wait() timed out
51 };
52
53 public:
54 // TODO-FIXME: the "offset" routines should return a type of off_t instead of int ...
55 // ByteSize would also be an appropriate type.
56 static int header_offset_in_bytes() { return offset_of(ObjectMonitor, _header); }
57 static int object_offset_in_bytes() { return offset_of(ObjectMonitor, _object); }
58 static int owner_offset_in_bytes() { return offset_of(ObjectMonitor, _owner); }
59 static int count_offset_in_bytes() { return offset_of(ObjectMonitor, _count); }
60 static int recursions_offset_in_bytes() { return offset_of(ObjectMonitor, _recursions); }
61 static int cxq_offset_in_bytes() { return offset_of(ObjectMonitor, _cxq) ; }
62 static int succ_offset_in_bytes() { return offset_of(ObjectMonitor, _succ) ; }
63 static int EntryList_offset_in_bytes() { return offset_of(ObjectMonitor, _EntryList); }
64 static int FreeNext_offset_in_bytes() { return offset_of(ObjectMonitor, FreeNext); }
65 static int WaitSet_offset_in_bytes() { return offset_of(ObjectMonitor, _WaitSet) ; }
66 static int Responsible_offset_in_bytes() { return offset_of(ObjectMonitor, _Responsible);}
67 static int Spinner_offset_in_bytes() { return offset_of(ObjectMonitor, _Spinner); }
68
69 public:
70 // Eventaully we'll make provisions for multiple callbacks, but
71 // now one will suffice.
72 static int (*SpinCallbackFunction)(intptr_t, int) ;
73 static intptr_t SpinCallbackArgument ;
74
75
76 public:
77 ObjectMonitor();
78 ~ObjectMonitor();
79
80 markOop header() const;
81 void set_header(markOop hdr);
82
83 intptr_t is_busy() const;
84 intptr_t is_entered(Thread* current) const;
85
86 void* owner() const;
87 void set_owner(void* owner);
88
89 intptr_t waiters() const;
90
91 intptr_t count() const;
92 void set_count(intptr_t count);
93 intptr_t contentions() const ;
94
95 // JVM/DI GetMonitorInfo() needs this
96 Thread * thread_of_waiter (ObjectWaiter *) ;
97 ObjectWaiter * first_waiter () ;
98 ObjectWaiter * next_waiter(ObjectWaiter* o);
99
100 intptr_t recursions() const { return _recursions; }
101
102 void* object() const;
103 void* object_addr();
104 void set_object(void* obj);
105
106 bool check(TRAPS); // true if the thread owns the monitor.
107 void check_slow(TRAPS);
108 void clear();
109 #ifndef PRODUCT
110 void verify();
111 void print();
112 #endif
113
114 bool try_enter (TRAPS) ;
115 void enter(TRAPS);
116 void exit(TRAPS);
117 void wait(jlong millis, bool interruptable, TRAPS);
118 void notify(TRAPS);
119 void notifyAll(TRAPS);
120
121 // Use the following at your own risk
122 intptr_t complete_exit(TRAPS);
123 void reenter(intptr_t recursions, TRAPS);
124
125 int raw_enter(TRAPS);
126 int raw_exit(TRAPS);
127 int raw_wait(jlong millis, bool interruptable, TRAPS);
128 int raw_notify(TRAPS);
129 int raw_notifyAll(TRAPS);
130
131 private:
132 // JVMTI support -- remove ASAP
133 int SimpleEnter (Thread * Self) ;
134 int SimpleExit (Thread * Self) ;
135 int SimpleWait (Thread * Self, jlong millis) ;
136 int SimpleNotify (Thread * Self, bool All) ;
137
138 private:
139 void Recycle () ;
140 void AddWaiter (ObjectWaiter * waiter) ;
141
142 ObjectWaiter * DequeueWaiter () ;
143 void DequeueSpecificWaiter (ObjectWaiter * waiter) ;
144 void EnterI (TRAPS) ;
145 void ReenterI (Thread * Self, ObjectWaiter * SelfNode) ;
146 void UnlinkAfterAcquire (Thread * Self, ObjectWaiter * SelfNode) ;
147 int TryLock (Thread * Self) ;
148 int NotRunnable (Thread * Self, Thread * Owner) ;
149 int TrySpin_Fixed (Thread * Self) ;
150 int TrySpin_VaryFrequency (Thread * Self) ;
151 int TrySpin_VaryDuration (Thread * Self) ;
152 void ctAsserts () ;
153 void ExitEpilog (Thread * Self, ObjectWaiter * Wakee) ;
154 bool ExitSuspendEquivalent (JavaThread * Self) ;
155
156 private:
157 friend class ObjectSynchronizer;
158 friend class ObjectWaiter;
159 friend class VMStructs;
160
161 // WARNING: this must be the very first word of ObjectMonitor
162 // This means this class can't use any virtual member functions.
163 // TODO-FIXME: assert that offsetof(_header) is 0 or get rid of the
164 // implicit 0 offset in emitted code.
165
166 volatile markOop _header; // displaced object header word - mark
167 void* volatile _object; // backward object pointer - strong root
168
169 double SharingPad [1] ; // temp to reduce false sharing
170
171 // All the following fields must be machine word aligned
172 // The VM assumes write ordering wrt these fields, which can be
173 // read from other threads.
174
175 void * volatile _owner; // pointer to owning thread OR BasicLock
176 volatile intptr_t _recursions; // recursion count, 0 for first entry
177 int OwnerIsThread ; // _owner is (Thread *) vs SP/BasicLock
178 ObjectWaiter * volatile _cxq ; // LL of recently-arrived threads blocked on entry.
179 // The list is actually composed of WaitNodes, acting
180 // as proxies for Threads.
181 ObjectWaiter * volatile _EntryList ; // Threads blocked on entry or reentry.
182 Thread * volatile _succ ; // Heir presumptive thread - used for futile wakeup throttling
183 Thread * volatile _Responsible ;
184 int _PromptDrain ; // rqst to drain cxq into EntryList ASAP
185
186 volatile int _Spinner ; // for exit->spinner handoff optimization
187 volatile int _SpinFreq ; // Spin 1-out-of-N attempts: success rate
188 volatile int _SpinClock ;
189 volatile int _SpinDuration ;
190 volatile intptr_t _SpinState ; // MCS/CLH list of spinners
191
192 // TODO-FIXME: _count, _waiters and _recursions should be of
193 // type int, or int32_t but not intptr_t. There's no reason
194 // to use 64-bit fields for these variables on a 64-bit JVM.
195
196 volatile intptr_t _count; // reference count to prevent reclaimation/deflation
197 // at stop-the-world time. See deflate_idle_monitors().
198 // _count is approximately |_WaitSet| + |_EntryList|
199 volatile intptr_t _waiters; // number of waiting threads
200 ObjectWaiter * volatile _WaitSet; // LL of threads wait()ing on the monitor
201 volatile int _WaitSetLock; // protects Wait Queue - simple spinlock
202
203 public:
204 int _QMix ; // Mixed prepend queue discipline
205 ObjectMonitor * FreeNext ; // Free list linkage
206 intptr_t StatA, StatsB ;
207
208 };