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.
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.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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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/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
46 typedef enum {
47 inflate_cause_vm_internal = 0,
48 inflate_cause_monitor_enter = 1,
49 inflate_cause_wait = 2,
50 inflate_cause_notify = 3,
51 inflate_cause_hash_code = 4,
52 inflate_cause_jni_enter = 5,
53 inflate_cause_jni_exit = 6,
54 inflate_cause_nof = 7 // Number of causes
55 } InflateCause;
56
57 // exit must be implemented non-blocking, since the compiler cannot easily handle
58 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
59
60 // This is full version of monitor enter and exit. I choose not
61 // to use enter() and exit() in order to make sure user be ware
62 // of the performance and semantics difference. They are normally
63 // used by ObjectLocker etc. The interpreter and compiler use
64 // assembly copies of these routines. Please keep them synchornized.
65 //
66 // attempt_rebias flag is used by UseBiasedLocking implementation
67 static void fast_enter (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);
68 static void fast_exit (oop obj, BasicLock* lock, Thread* THREAD);
69
70 // WARNING: They are ONLY used to handle the slow cases. They should
71 // only be used when the fast cases failed. Use of these functions
72 // without previous fast case check may cause fatal error.
73 static void slow_enter (Handle obj, BasicLock* lock, TRAPS);
74 static void slow_exit (oop obj, BasicLock* lock, Thread* THREAD);
75
76 // Used only to handle jni locks or other unmatched monitor enter/exit
77 // Internally they will use heavy weight monitor.
78 static void jni_enter (Handle obj, TRAPS);
79 static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
80 static void jni_exit (oop obj, Thread* THREAD);
81
82 // Handle all interpreter, compiler and jni cases
83 static void wait (Handle obj, jlong millis, TRAPS);
84 static void notify (Handle obj, TRAPS);
85 static void notifyall (Handle obj, TRAPS);
86
87 // Special internal-use-only method for use by JVM infrastructure
88 // that needs to wait() on a java-level object but that can't risk
89 // throwing unexpected InterruptedExecutionExceptions.
90 static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ;
91
92 // used by classloading to free classloader object lock,
93 // wait on an internal lock, and reclaim original lock
94 // with original recursion count
95 static intptr_t complete_exit (Handle obj, TRAPS);
96 static void reenter (Handle obj, intptr_t recursion, TRAPS);
97
98 // thread-specific and global objectMonitor free list accessors
99 // static void verifyInUse (Thread * Self) ; too slow for general assert/debug
100 static ObjectMonitor * omAlloc (Thread * Self) ;
101 static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ;
102 static void omFlush (Thread * Self) ;
103
104 // Inflate light weight monitor to heavy weight monitor
105 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause);
106 // This version is only for internal use
107 static ObjectMonitor* inflate_helper(oop obj);
108 static const char* inflate_cause_name(const InflateCause cause);
109
110 // Returns the identity hash value for an oop
111 // NOTE: It may cause monitor inflation
112 static intptr_t identity_hash_value_for(Handle obj);
113 static intptr_t FastHashCode (Thread * Self, oop obj) ;
114
115 // java.lang.Thread support
116 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
117 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
118
119 static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
120
121 // JNI detach support
122 static void release_monitors_owned_by_thread(TRAPS);
123 static void monitors_iterate(MonitorClosure* m);
124
125 // GC: we current use aggressive monitor deflation policy
126 // Basically we deflate all monitors that are not busy.
127 // An adaptive profile-based deflation policy could be used if needed
128 static void deflate_idle_monitors();
129 static int walk_monitor_list(ObjectMonitor** listheadp,
130 ObjectMonitor** FreeHeadp,
131 ObjectMonitor** FreeTailp);
132 static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp,
133 ObjectMonitor** FreeTailp);
134 static void oops_do(OopClosure* f);
135
136 // debugging
137 static void sanity_checks(const bool verbose,
138 const unsigned int cache_line_size,
139 int *error_cnt_ptr, int *warning_cnt_ptr);
140 static void verify() PRODUCT_RETURN;
141 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
142
143 static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ;
144
145 private:
146 enum { _BLOCKSIZE = 128 };
147 static ObjectMonitor * volatile gBlockList;
148 static ObjectMonitor * volatile gFreeList;
149 static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned
150 static int gOmInUseCount;
151
152 };
153
154 // ObjectLocker enforced balanced locking and can never thrown an
155 // IllegalMonitorStateException. However, a pending exception may
156 // have to pass through, and we must also be able to deal with
157 // asynchronous exceptions. The caller is responsible for checking
158 // the threads pending exception if needed.
159 // doLock was added to support classloading with UnsyncloadClass which
160 // requires flag based choice of locking the classloader lock.
161 class ObjectLocker : public StackObj {
162 private:
163 Thread* _thread;
164 Handle _obj;
165 BasicLock _lock;
166 bool _dolock; // default true
167 public:
168 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
169 ~ObjectLocker();
170
171 // Monitor behavior
172 void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever
173 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
174 void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);}
175 // complete_exit gives up lock completely, returning recursion count
176 // reenter reclaims lock with original recursion count
177 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
178 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
179 };
180
181 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP