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.
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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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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).
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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 void jni_exit(oop obj, Thread* THREAD);
69
70 // Handle all interpreter, compiler and jni cases
71 static int wait(Handle obj, jlong millis, TRAPS);
72 static void notify(Handle obj, TRAPS);
73 static void notifyall(Handle obj, TRAPS);
74
75 // Special internal-use-only method for use by JVM infrastructure
76 // that needs to wait() on a java-level object but that can't risk
77 // throwing unexpected InterruptedExecutionExceptions.
78 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD);
79
80 // used by classloading to free classloader object lock,
81 // wait on an internal lock, and reclaim original lock
82 // with original recursion count
83 static intptr_t complete_exit(Handle obj, TRAPS);
84 static void reenter (Handle obj, intptr_t recursion, TRAPS);
85
86 // thread-specific and global objectMonitor free list accessors
87 static void verifyInUse(Thread * Self);
88 static ObjectMonitor * omAlloc(Thread * Self);
89 static void omRelease(Thread * Self, ObjectMonitor * m,
90 bool FromPerThreadAlloc);
91 static void omFlush(Thread * Self);
92
93 // Inflate light weight monitor to heavy weight monitor
94 static ObjectMonitor* inflate(Thread * Self, oop obj);
95 // This version is only for internal use
96 static ObjectMonitor* inflate_helper(oop obj);
97
98 // Returns the identity hash value for an oop
99 // NOTE: It may cause monitor inflation
100 static intptr_t identity_hash_value_for(Handle obj);
101 static intptr_t FastHashCode(Thread * Self, oop obj);
102
103 // java.lang.Thread support
104 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
105 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
106
107 static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
108
109 // JNI detach support
110 static void release_monitors_owned_by_thread(TRAPS);
111 static void monitors_iterate(MonitorClosure* m);
112
113 // GC: we current use aggressive monitor deflation policy
114 // Basically we deflate all monitors that are not busy.
115 // An adaptive profile-based deflation policy could be used if needed
116 static void deflate_idle_monitors();
117 static int walk_monitor_list(ObjectMonitor** listheadp,
118 ObjectMonitor** freeHeadp,
119 ObjectMonitor** freeTailp);
120 static bool deflate_monitor(ObjectMonitor* mid, oop obj,
121 ObjectMonitor** freeHeadp,
122 ObjectMonitor** freeTailp);
123 static void oops_do(OopClosure* f);
124
125 // debugging
126 static void sanity_checks(const bool verbose,
127 const unsigned int cache_line_size,
128 int *error_cnt_ptr, int *warning_cnt_ptr);
129 static void verify() PRODUCT_RETURN;
130 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
131
132 static void RegisterSpinCallback(int(*)(intptr_t, int), intptr_t);
133
134 private:
135 enum { _BLOCKSIZE = 128 };
136 // gBlockList is really PaddedEnd<ObjectMonitor> *, but we don't
137 // want to expose the PaddedEnd template more than necessary.
138 static ObjectMonitor* gBlockList;
139 static ObjectMonitor * volatile gFreeList;
140 // global monitor in use list, for moribund threads,
141 // monitors they inflated need to be scanned for deflation
142 static ObjectMonitor * volatile gOmInUseList;
143 // count of entries in gOmInUseList
144 static int gOmInUseCount;
145
146 };
147
148 // ObjectLocker enforced balanced locking and can never thrown an
149 // IllegalMonitorStateException. However, a pending exception may
150 // have to pass through, and we must also be able to deal with
151 // asynchronous exceptions. The caller is responsible for checking
152 // the threads pending exception if needed.
153 // doLock was added to support classloading with UnsyncloadClass which
154 // requires flag based choice of locking the classloader lock.
155 class ObjectLocker : public StackObj {
156 private:
157 Thread* _thread;
158 Handle _obj;
159 BasicLock _lock;
160 bool _dolock; // default true
161 public:
162 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
163 ~ObjectLocker();
164
165 // Monitor behavior
166 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
167 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
168 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); }
169 // complete_exit gives up lock completely, returning recursion count
170 // reenter reclaims lock with original recursion count
171 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
172 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
173 };
174
175 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP