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
20 * or visit www.oracle.com if you need additional information or have any
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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 #if INCLUDE_ALL_GCS
40 friend class ShenandoahSynchronizerIterator;
41 #endif
42
43 public:
44 typedef enum {
45 owner_self,
46 owner_none,
47 owner_other
48 } LockOwnership;
49
50 typedef enum {
51 inflate_cause_vm_internal = 0,
52 inflate_cause_monitor_enter = 1,
53 inflate_cause_wait = 2,
54 inflate_cause_notify = 3,
55 inflate_cause_hash_code = 4,
56 inflate_cause_jni_enter = 5,
57 inflate_cause_jni_exit = 6,
58 inflate_cause_nof = 7 // Number of causes
59 } InflateCause;
60
61 // exit must be implemented non-blocking, since the compiler cannot easily handle
62 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
63
64 // This is full version of monitor enter and exit. I choose not
65 // to use enter() and exit() in order to make sure user be ware
66 // of the performance and semantics difference. They are normally
67 // used by ObjectLocker etc. The interpreter and compiler use
68 // assembly copies of these routines. Please keep them synchornized.
69 //
70 // attempt_rebias flag is used by UseBiasedLocking implementation
71 static void fast_enter (Handle obj, BasicLock* lock, bool attempt_rebias, TRAPS);
72 static void fast_exit (oop obj, BasicLock* lock, Thread* THREAD);
73
74 // WARNING: They are ONLY used to handle the slow cases. They should
75 // only be used when the fast cases failed. Use of these functions
76 // without previous fast case check may cause fatal error.
77 static void slow_enter (Handle obj, BasicLock* lock, TRAPS);
78 static void slow_exit (oop obj, BasicLock* lock, Thread* THREAD);
79
80 // Used only to handle jni locks or other unmatched monitor enter/exit
81 // Internally they will use heavy weight monitor.
82 static void jni_enter (Handle obj, TRAPS);
83 static bool jni_try_enter(Handle obj, Thread* THREAD); // Implements Unsafe.tryMonitorEnter
84 static void jni_exit (oop obj, Thread* THREAD);
85
86 // Handle all interpreter, compiler and jni cases
87 static void wait (Handle obj, jlong millis, TRAPS);
88 static void notify (Handle obj, TRAPS);
89 static void notifyall (Handle obj, TRAPS);
90
91 // Special internal-use-only method for use by JVM infrastructure
92 // that needs to wait() on a java-level object but that can't risk
93 // throwing unexpected InterruptedExecutionExceptions.
94 static void waitUninterruptibly (Handle obj, jlong Millis, Thread * THREAD) ;
95
96 // used by classloading to free classloader object lock,
97 // wait on an internal lock, and reclaim original lock
98 // with original recursion count
99 static intptr_t complete_exit (Handle obj, TRAPS);
100 static void reenter (Handle obj, intptr_t recursion, TRAPS);
101
102 // thread-specific and global objectMonitor free list accessors
103 // static void verifyInUse (Thread * Self) ; too slow for general assert/debug
104 static ObjectMonitor * omAlloc (Thread * Self) ;
105 static void omRelease (Thread * Self, ObjectMonitor * m, bool FromPerThreadAlloc) ;
106 static void omFlush (Thread * Self) ;
107
108 // Inflate light weight monitor to heavy weight monitor
109 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause);
110 // This version is only for internal use
111 static ObjectMonitor* inflate_helper(oop obj);
112 static const char* inflate_cause_name(const InflateCause cause);
113
114 // Returns the identity hash value for an oop
115 // NOTE: It may cause monitor inflation
116 static intptr_t identity_hash_value_for(Handle obj);
117 static intptr_t FastHashCode (Thread * Self, oop obj) ;
118
119 // java.lang.Thread support
120 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
121 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
122
123 static JavaThread* get_lock_owner(Handle h_obj, bool doLock);
124
125 // JNI detach support
126 static void release_monitors_owned_by_thread(TRAPS);
127 static void monitors_iterate(MonitorClosure* m);
128
129 // GC: we current use aggressive monitor deflation policy
130 // Basically we deflate all monitors that are not busy.
131 // An adaptive profile-based deflation policy could be used if needed
132 static void deflate_idle_monitors();
133 static int walk_monitor_list(ObjectMonitor** listheadp,
134 ObjectMonitor** FreeHeadp,
135 ObjectMonitor** FreeTailp);
136 static bool deflate_monitor(ObjectMonitor* mid, oop obj, ObjectMonitor** FreeHeadp,
137 ObjectMonitor** FreeTailp);
138 static void oops_do(OopClosure* f);
139
140 // debugging
141 static void sanity_checks(const bool verbose,
142 const unsigned int cache_line_size,
143 int *error_cnt_ptr, int *warning_cnt_ptr);
144 static void verify() PRODUCT_RETURN;
145 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
146
147 static void RegisterSpinCallback (int (*)(intptr_t, int), intptr_t) ;
148
149 private:
150 enum { _BLOCKSIZE = 128 };
151 static ObjectMonitor * volatile gBlockList;
152 static ObjectMonitor * volatile gFreeList;
153 static ObjectMonitor * volatile gOmInUseList; // for moribund thread, so monitors they inflated still get scanned
154 static int gOmInUseCount;
155
156 };
157
158 // ObjectLocker enforced balanced locking and can never thrown an
159 // IllegalMonitorStateException. However, a pending exception may
160 // have to pass through, and we must also be able to deal with
161 // asynchronous exceptions. The caller is responsible for checking
162 // the threads pending exception if needed.
163 // doLock was added to support classloading with UnsyncloadClass which
164 // requires flag based choice of locking the classloader lock.
165 class ObjectLocker : public StackObj {
166 private:
167 Thread* _thread;
168 Handle _obj;
169 BasicLock _lock;
170 bool _dolock; // default true
171 public:
172 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
173 ~ObjectLocker();
174
175 // Monitor behavior
176 void wait (TRAPS) { ObjectSynchronizer::wait (_obj, 0, CHECK); } // wait forever
177 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
178 void waitUninterruptibly (TRAPS) { ObjectSynchronizer::waitUninterruptibly (_obj, 0, CHECK);}
179 // complete_exit gives up lock completely, returning recursion count
180 // reenter reclaims lock with original recursion count
181 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
182 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
183 };
184
185 #endif // SHARE_VM_RUNTIME_SYNCHRONIZER_HPP