1 /*
2 * Copyright (c) 1998, 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_RUNTIME_SYNCHRONIZER_HPP
26 #define SHARE_VM_RUNTIME_SYNCHRONIZER_HPP
27
28 #include "oops/markOop.hpp"
29 #include "runtime/handles.hpp"
30 #include "runtime/perfData.hpp"
31 #include "utilities/top.hpp"
32
33 class BasicLock VALUE_OBJ_CLASS_SPEC {
34 friend class VMStructs;
35 private:
36 volatile markOop _displaced_header;
37 public:
38 markOop displaced_header() const { return _displaced_header; }
39 void set_displaced_header(markOop header) { _displaced_header = header; }
40
41 void print_on(outputStream* st) const;
42
43 // move a basic lock (used during deoptimization
44 void move_to(oop obj, BasicLock* dest);
45
46 static int displaced_header_offset_in_bytes() { return offset_of(BasicLock, _displaced_header); }
47 };
48
49 // A BasicObjectLock associates a specific Java object with a BasicLock.
50 // It is currently embedded in an interpreter frame.
51
52 // Because some machines have alignment restrictions on the control stack,
53 // the actual space allocated by the interpreter may include padding words
54 // after the end of the BasicObjectLock. Also, in order to guarantee
55 // alignment of the embedded BasicLock objects on such machines, we
56 // put the embedded BasicLock at the beginning of the struct.
57
58 class BasicObjectLock VALUE_OBJ_CLASS_SPEC {
59 friend class VMStructs;
60 private:
61 BasicLock _lock; // the lock, must be double word aligned
62 oop _obj; // object holds the lock;
63
64 public:
65 // Manipulation
66 oop obj() const { return _obj; }
67 void set_obj(oop obj) { _obj = obj; }
68 BasicLock* lock() { return &_lock; }
69
70 // Note: Use frame::interpreter_frame_monitor_size() for the size of BasicObjectLocks
71 // in interpreter activation frames since it includes machine-specific padding.
72 static int size() { return sizeof(BasicObjectLock)/wordSize; }
73
74 // GC support
75 void oops_do(OopClosure* f) { f->do_oop(&_obj); }
76
77 static int obj_offset_in_bytes() { return offset_of(BasicObjectLock, _obj); }
78 static int lock_offset_in_bytes() { return offset_of(BasicObjectLock, _lock); }
79 };
80
81 class ObjectMonitor;
82
83 class ObjectSynchronizer : AllStatic {
84 friend class VMStructs;
85 public:
86 typedef enum {
87 owner_self,
88 owner_none,
89 owner_other
90 } LockOwnership;
91 // exit must be implemented non-blocking, since the compiler cannot easily handle
92 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
93
94 // This is full version of monitor enter and exit. I choose not
95 // to use enter() and exit() in order to make sure user be ware
96 // of the performance and semantics difference. They are normally
97 // used by ObjectLocker etc. The interpreter and compiler use
98 // assembly copies of these routines. Please keep them synchornized.
99 //
100 // attempt_rebias flag is used by UseBiasedLocking implementation
101 static void fast_enter (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);
102 static void fast_exit (oop obj, BasicLock* lock, Thread* THREAD);
103
104 // WARNING: They are ONLY used to handle the slow cases. They should
105 // only be used when the fast cases failed. Use of these functions
106 // without previous fast case check may cause fatal error.
107 static void slow_enter (Handle obj, BasicLock* lock, TRAPS);
108 static void slow_exit (oop obj, BasicLock* lock, Thread* THREAD);
109
110 // Used only to handle jni locks or other unmatched monitor enter/exit
111 // Internally they will use heavy weight monitor.
112 static void jni_enter (Handle obj, TRAPS);
113 static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
114 static void jni_exit (oop obj, Thread* THREAD);
115
116 // Handle all interpreter, compiler and jni cases
117 static void wait (Handle obj, jlong millis, TRAPS);
118 static void notify (Handle obj, TRAPS);
119 static void notifyall (Handle obj, TRAPS);
120
121 // Special internal-use-only method for use by JVM infrastructure
122 // that needs to wait() on a java-level object but that can't risk
123 // throwing unexpected InterruptedExecutionExceptions.
124 static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ;
125
126 // used by classloading to free classloader object lock,
127 // wait on an internal lock, and reclaim original lock
128 // with original recursion count
129 static intptr_t complete_exit (Handle obj, TRAPS);
130 static void reenter (Handle obj, intptr_t recursion, TRAPS);
131
132 // thread-specific and global objectMonitor free list accessors
133 // static void verifyInUse (Thread * Self) ; too slow for general assert/debug
134 static ObjectMonitor * omAlloc (Thread * Self) ;
135 static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ;
136 static void omFlush (Thread * Self) ;
137
138 // Inflate light weight monitor to heavy weight monitor
139 static ObjectMonitor* inflate(Thread * Self, oop obj);
140 // This version is only for internal use
141 static ObjectMonitor* inflate_helper(oop obj);
142
143 // Returns the identity hash value for an oop
144 // NOTE: It may cause monitor inflation
145 static intptr_t identity_hash_value_for(Handle obj);
146 static intptr_t FastHashCode (Thread * Self, oop obj) ;
147
148 // java.lang.Thread support
149 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
150 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
151
152 static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
153
154 // JNI detach support
155 static void release_monitors_owned_by_thread(TRAPS);
156 static void monitors_iterate(MonitorClosure* m);
157
158 // GC: we current use aggressive monitor deflation policy
159 // Basically we deflate all monitors that are not busy.
160 // An adaptive profile-based deflation policy could be used if needed
161 static void deflate_idle_monitors();
162 static int walk_monitor_list(ObjectMonitor** listheadp,
163 ObjectMonitor** FreeHeadp,
164 ObjectMonitor** FreeTailp);
165 static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp,
166 ObjectMonitor** FreeTailp);
167 static void oops_do(OopClosure* f);
168
169 // debugging
170 static void trace_locking(Handle obj, bool is_compiled, bool is_method, bool is_locking) PRODUCT_RETURN;
171 static void verify() PRODUCT_RETURN;
172 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
173
174 private:
175 enum { _BLOCKSIZE = 128 };
176 static ObjectMonitor* gBlockList;
177 static ObjectMonitor * volatile gFreeList;
178 static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned
179 static int gOmInUseCount;
180
181 public:
182 static void Initialize () ;
183 static PerfCounter * _sync_ContendedLockAttempts ;
184 static PerfCounter * _sync_FutileWakeups ;
185 static PerfCounter * _sync_Parks ;
186 static PerfCounter * _sync_EmptyNotifications ;
187 static PerfCounter * _sync_Notifications ;
188 static PerfCounter * _sync_SlowEnter ;
189 static PerfCounter * _sync_SlowExit ;
190 static PerfCounter * _sync_SlowNotify ;
191 static PerfCounter * _sync_SlowNotifyAll ;
192 static PerfCounter * _sync_FailedSpins ;
193 static PerfCounter * _sync_SuccessfulSpins ;
194 static PerfCounter * _sync_PrivateA ;
195 static PerfCounter * _sync_PrivateB ;
196 static PerfCounter * _sync_MonInCirculation ;
197 static PerfCounter * _sync_MonScavenged ;
198 static PerfCounter * _sync_Inflations ;
199 static PerfCounter * _sync_Deflations ;
200 static PerfLongVariable * _sync_MonExtant ;
201
202 public:
203 static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ;
204
205 };
206
207 // ObjectLocker enforced balanced locking and can never thrown an
208 // IllegalMonitorStateException. However, a pending exception may
209 // have to pass through, and we must also be able to deal with
210 // asynchronous exceptions. The caller is responsible for checking
211 // the threads pending exception if needed.
212 // doLock was added to support classloading with UnsyncloadClass which
213 // requires flag based choice of locking the classloader lock.
214 class ObjectLocker : public StackObj {
215 private:
216 Thread* _thread;
217 Handle _obj;
218 BasicLock _lock;
219 bool _dolock; // default true
220 public:
221 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
222 ~ObjectLocker();
223
224 // Monitor behavior
225 void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever
226 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
227 void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);}
228 // complete_exit gives up lock completely, returning recursion count
229 // reenter reclaims lock with original recursion count
230 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, CHECK_0); }
231 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
232 };
233
234 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP