1 /*
2 * Copyright (c) 1998, 2014, 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.
22 *
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/basicLock.hpp"
30 #include "runtime/handles.hpp"
31 #include "runtime/perfData.hpp"
32 #include "utilities/top.hpp"
33
34
35 class ObjectMonitor;
36
37 class ObjectSynchronizer : AllStatic {
38 friend class VMStructs;
39 public:
40 typedef enum {
41 owner_self,
42 owner_none,
43 owner_other
44 } LockOwnership;
45 // exit must be implemented non-blocking, since the compiler cannot easily handle
46 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
47
48 // This is full version of monitor enter and exit. I choose not
49 // to use enter() and exit() in order to make sure user be ware
50 // of the performance and semantics difference. They are normally
51 // used by ObjectLocker etc. The interpreter and compiler use
52 // assembly copies of these routines. Please keep them synchronized.
53 //
54 // attempt_rebias flag is used by UseBiasedLocking implementation
55 static void fast_enter(Handle obj, BasicLock* lock, bool attempt_rebias,
56 TRAPS);
57 static void fast_exit(oop obj, BasicLock* lock, Thread* THREAD);
58
59 // WARNING: They are ONLY used to handle the slow cases. They should
60 // only be used when the fast cases failed. Use of these functions
61 // without previous fast case check may cause fatal error.
62 static void slow_enter(Handle obj, BasicLock* lock, TRAPS);
63 static void slow_exit(oop obj, BasicLock* lock, Thread* THREAD);
64
65 // Used only to handle jni locks or other unmatched monitor enter/exit
66 // Internally they will use heavy weight monitor.
67 static void jni_enter(Handle obj, TRAPS);
68 static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
69 static void jni_exit(oop obj, Thread* THREAD);
70
71 // Handle all interpreter, compiler and jni cases
72 static int wait(Handle obj, jlong millis, TRAPS);
73 static void notify(Handle obj, TRAPS);
74 static void notifyall(Handle obj, TRAPS);
75
76 // Special internal-use-only method for use by JVM infrastructure
77 // that needs to wait() on a java-level object but that can't risk
78 // throwing unexpected InterruptedExecutionExceptions.
79 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD);
80
81 // used by classloading to free classloader object lock,
82 // wait on an internal lock, and reclaim original lock
83 // with original recursion count
84 static intptr_t complete_exit(Handle obj, TRAPS);
85 static void reenter (Handle obj, intptr_t recursion, TRAPS);
86
87 // thread-specific and global objectMonitor free list accessors
88 static void verifyInUse(Thread * Self);
89 static ObjectMonitor * omAlloc(Thread * Self);
90 static void omRelease(Thread * Self, ObjectMonitor * m,
91 bool FromPerThreadAlloc);
92 static void omFlush(Thread * Self);
93
94 // Inflate light weight monitor to heavy weight monitor
95 static ObjectMonitor* inflate(Thread * Self, oop obj);
96 // This version is only for internal use
97 static ObjectMonitor* inflate_helper(oop obj);
98
99 // Returns the identity hash value for an oop
100 // NOTE: It may cause monitor inflation
101 static intptr_t identity_hash_value_for(Handle obj);
102 static intptr_t FastHashCode(Thread * Self, oop obj);
103
104 // java.lang.Thread support
105 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
106 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
107
108 static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
109
110 // JNI detach support
111 static void release_monitors_owned_by_thread(TRAPS);
112 static void monitors_iterate(MonitorClosure* m);
113
114 // GC: we current use aggressive monitor deflation policy
115 // Basically we deflate all monitors that are not busy.
116 // An adaptive profile-based deflation policy could be used if needed
117 static void deflate_idle_monitors();
118 static int walk_monitor_list(ObjectMonitor** listheadp,
119 ObjectMonitor** freeHeadp,
120 ObjectMonitor** freeTailp);
121 static bool deflate_monitor(ObjectMonitor* mid, oop obj,
122 ObjectMonitor** freeHeadp,
123 ObjectMonitor** freeTailp);
124 static void oops_do(OopClosure* f);
125
126 // debugging
127 static void sanity_checks(const bool verbose,
128 const unsigned int cache_line_size,
129 int *error_cnt_ptr, int *warning_cnt_ptr);
130 static void verify() PRODUCT_RETURN;
131 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
132
133 static void RegisterSpinCallback(int(*)(intptr_t, int), intptr_t);
134
135 private:
136 enum { _BLOCKSIZE = 128 };
137 // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't
138 // want to expose the PaddedEnd template more than necessary.
139 static ObjectMonitor* gBlockList;
140 static ObjectMonitor * volatile gFreeList;
141 // global monitor in use list, for moribund threads,
142 // monitors they inflated need to be scanned for deflation
143 static ObjectMonitor * volatile gOmInUseList;
144 // count of entries in gOmInUseList
145 static int gOmInUseCount;
146
147 };
148
149 // ObjectLocker enforced balanced locking and can never thrown an
150 // IllegalMonitorStateException. However, a pending exception may
151 // have to pass through, and we must also be able to deal with
152 // asynchronous exceptions. The caller is responsible for checking
153 // the threads pending exception if needed.
154 // doLock was added to support classloading with UnsyncloadClass which
155 // requires flag based choice of locking the classloader lock.
156 class ObjectLocker : public StackObj {
157 private:
158 Thread* _thread;
159 Handle _obj;
160 BasicLock _lock;
161 bool _dolock; // default true
162 public:
163 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
164 ~ObjectLocker();
165
166 // Monitor behavior
167 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
168 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
169 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); }
170 // complete_exit gives up lock completely, returning recursion count
171 // reenter reclaims lock with original recursion count
172 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
173 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
174 };
175
176 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP