1 /*
2 * Copyright (c) 1998, 2018, 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 synchornized.
53 //
54 // attempt_rebias flag is used by UseBiasedLocking implementation
55 static void fast_enter (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);
56 static void fast_exit (oop obj, BasicLock* lock, Thread* THREAD);
57
58 // WARNING: They are ONLY used to handle the slow cases. They should
59 // only be used when the fast cases failed. Use of these functions
60 // without previous fast case check may cause fatal error.
61 static void slow_enter (Handle obj, BasicLock* lock, TRAPS);
62 static void slow_exit (oop obj, BasicLock* lock, Thread* THREAD);
63
64 // Used only to handle jni locks or other unmatched monitor enter/exit
65 // Internally they will use heavy weight monitor.
66 static void jni_enter (Handle obj, TRAPS);
67 static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
68 static void jni_exit (oop obj, Thread* THREAD);
69
70 // Handle all interpreter, compiler and jni cases
71 static void 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) ; too slow for general assert/debug
88 static ObjectMonitor * omAlloc (Thread * Self) ;
89 static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ;
90 static void omFlush (Thread * Self) ;
91
92 // Inflate light weight monitor to heavy weight monitor
93 static ObjectMonitor* inflate(Thread * Self, oop obj);
94 // This version is only for internal use
95 static ObjectMonitor* inflate_helper(oop obj);
96
97 // Returns the identity hash value for an oop
98 // NOTE: It may cause monitor inflation
99 static intptr_t identity_hash_value_for(Handle obj);
100 static intptr_t FastHashCode (Thread * Self, oop obj) ;
101
102 // java.lang.Thread support
103 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
104 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
105
106 static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
107
108 // JNI detach support
109 static void release_monitors_owned_by_thread(TRAPS);
110 static void monitors_iterate(MonitorClosure* m);
111
112 // GC: we current use aggressive monitor deflation policy
113 // Basically we deflate all monitors that are not busy.
114 // An adaptive profile-based deflation policy could be used if needed
115 static void deflate_idle_monitors();
116 static int walk_monitor_list(ObjectMonitor** listheadp,
117 ObjectMonitor** FreeHeadp,
118 ObjectMonitor** FreeTailp);
119 static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp,
120 ObjectMonitor** FreeTailp);
121 static void oops_do(OopClosure* f);
122
123 // debugging
124 static void sanity_checks(const bool verbose,
125 const unsigned int cache_line_size,
126 int *error_cnt_ptr, int *warning_cnt_ptr);
127 static void verify() PRODUCT_RETURN;
128 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
129
130 static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ;
131
132 private:
133 enum { _BLOCKSIZE = 128 };
134 static ObjectMonitor* gBlockList;
135 static ObjectMonitor * volatile gFreeList;
136 static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned
137 static int gOmInUseCount;
138
139 };
140
141 // ObjectLocker enforced balanced locking and can never thrown an
142 // IllegalMonitorStateException. However, a pending exception may
143 // have to pass through, and we must also be able to deal with
144 // asynchronous exceptions. The caller is responsible for checking
145 // the threads pending exception if needed.
146 // doLock was added to support classloading with UnsyncloadClass which
147 // requires flag based choice of locking the classloader lock.
148 class ObjectLocker : public StackObj {
149 private:
150 Thread* _thread;
151 Handle _obj;
152 BasicLock _lock;
153 bool _dolock; // default true
154 public:
155 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
156 ~ObjectLocker();
157
158 // Monitor behavior
159 void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever
160 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
161 void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);}
162 // complete_exit gives up lock completely, returning recursion count
163 // reenter reclaims lock with original recursion count
164 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
165 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
166 };
167
168 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP