1 /*
2 * Copyright (c) 1998, 2019, 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_RUNTIME_SYNCHRONIZER_HPP
26 #define SHARE_RUNTIME_SYNCHRONIZER_HPP
27
28 #include "memory/padded.hpp"
29 #include "oops/markWord.hpp"
30 #include "runtime/basicLock.hpp"
31 #include "runtime/handles.hpp"
32 #include "runtime/perfData.hpp"
33
34 class ObjectMonitor;
35 class ThreadsList;
36
37 struct DeflateMonitorCounters {
38 int nInuse; // currently associated with objects
39 int nInCirculation; // extant
40 int nScavenged; // reclaimed (global and per-thread)
41 int perThreadScavenged; // per-thread scavenge total
42 double perThreadTimes; // per-thread scavenge times
43 };
44
45 class ObjectSynchronizer : AllStatic {
46 friend class VMStructs;
47 public:
48 typedef enum {
49 owner_self,
50 owner_none,
51 owner_other
52 } LockOwnership;
53
54 typedef enum {
55 inflate_cause_vm_internal = 0,
56 inflate_cause_monitor_enter = 1,
57 inflate_cause_wait = 2,
58 inflate_cause_notify = 3,
59 inflate_cause_hash_code = 4,
60 inflate_cause_jni_enter = 5,
61 inflate_cause_jni_exit = 6,
62 inflate_cause_nof = 7 // Number of causes
63 } InflateCause;
64
65 // exit must be implemented non-blocking, since the compiler cannot easily handle
66 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
67
68 // This is full version of monitor enter and exit.
69 static void enter(Handle obj, BasicLock* lock, TRAPS);
70 static void exit(oop obj, BasicLock* lock, Thread* THREAD);
71
72 // Used only to handle jni locks or other unmatched monitor enter/exit
73 // Internally they will use heavy weight monitor.
74 static void jni_enter(Handle obj, TRAPS);
75 static void jni_exit(oop obj, Thread* THREAD);
76
77 // Handle all interpreter, compiler and jni cases
78 static int wait(Handle obj, jlong millis, TRAPS);
79 static void notify(Handle obj, TRAPS);
80 static void notifyall(Handle obj, TRAPS);
81
82 static bool quick_notify(oopDesc* obj, Thread* Self, bool All);
83 static bool quick_enter(oop obj, Thread* Self, BasicLock* Lock);
84
85 // Special internal-use-only method for use by JVM infrastructure
86 // that needs to wait() on a java-level object but that can't risk
87 // throwing unexpected InterruptedExecutionExceptions.
88 static void waitUninterruptibly(Handle obj, jlong Millis, Thread * THREAD);
89
90 // used by classloading to free classloader object lock,
91 // wait on an internal lock, and reclaim original lock
92 // with original recursion count
93 static intptr_t complete_exit(Handle obj, TRAPS);
94 static void reenter (Handle obj, intptr_t recursion, TRAPS);
95
96 // thread-specific and global objectMonitor free list accessors
97 static ObjectMonitor * omAlloc(Thread * Self);
98 static void omRelease(Thread * Self, ObjectMonitor * m,
99 bool FromPerThreadAlloc);
100 static void omFlush(Thread * Self);
101
102 // Inflate light weight monitor to heavy weight monitor
103 static ObjectMonitor* inflate(Thread * Self, oop obj, const InflateCause cause);
104 // This version is only for internal use
105 static void inflate_helper(oop obj);
106 static const char* inflate_cause_name(const InflateCause cause);
107
108 // Returns the identity hash value for an oop
109 // NOTE: It may cause monitor inflation
110 static intptr_t identity_hash_value_for(Handle obj);
111 static intptr_t FastHashCode(Thread * Self, oop obj);
112
113 // java.lang.Thread support
114 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
115 static LockOwnership query_lock_ownership(JavaThread * self, Handle h_obj);
116
117 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj);
118
119 // JNI detach support
120 static void release_monitors_owned_by_thread(TRAPS);
121 static void monitors_iterate(MonitorClosure* m);
122
123 // GC: we current use aggressive monitor deflation policy
124 // Basically we deflate all monitors that are not busy.
125 // An adaptive profile-based deflation policy could be used if needed
126 static void deflate_idle_monitors(DeflateMonitorCounters* counters);
127 static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters);
128 static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters);
129 static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters);
130
131 // For a given monitor list: global or per-thread, deflate idle monitors
132 static int deflate_monitor_list(ObjectMonitor** listheadp,
133 ObjectMonitor** freeHeadp,
134 ObjectMonitor** freeTailp);
135 static bool deflate_monitor(ObjectMonitor* mid, oop obj,
136 ObjectMonitor** freeHeadp,
137 ObjectMonitor** freeTailp);
138 static bool is_cleanup_needed();
139 static void oops_do(OopClosure* f);
140 // Process oops in thread local used monitors
141 static void thread_local_used_oops_do(Thread* thread, OopClosure* f);
142
143 // debugging
144 static void audit_and_print_stats(bool on_exit);
145 static void chk_free_entry(JavaThread * jt, ObjectMonitor * n,
146 outputStream * out, int *error_cnt_p);
147 static void chk_global_free_list_and_count(outputStream * out,
148 int *error_cnt_p);
149 static void chk_global_in_use_list_and_count(outputStream * out,
150 int *error_cnt_p);
151 static void chk_in_use_entry(JavaThread * jt, ObjectMonitor * n,
152 outputStream * out, int *error_cnt_p);
153 static void chk_per_thread_in_use_list_and_count(JavaThread *jt,
154 outputStream * out,
155 int *error_cnt_p);
156 static void chk_per_thread_free_list_and_count(JavaThread *jt,
157 outputStream * out,
158 int *error_cnt_p);
159 static void log_in_use_monitor_details(outputStream * out, bool on_exit);
160 static int log_monitor_list_counts(outputStream * out);
161 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
162
163 private:
164 friend class SynchronizerTest;
165
166 enum { _BLOCKSIZE = 128 };
167 // global list of blocks of monitors
168 static PaddedEnd<ObjectMonitor> * volatile gBlockList;
169 // global monitor free list
170 static ObjectMonitor * volatile gFreeList;
171 // global monitor in-use list, for moribund threads,
172 // monitors they inflated need to be scanned for deflation
173 static ObjectMonitor * volatile gOmInUseList;
174 // count of entries in gOmInUseList
175 static int gOmInUseCount;
176
177 // Process oops in all global used monitors (i.e. moribund thread's monitors)
178 static void global_used_oops_do(OopClosure* f);
179 // Process oops in monitors on the given list
180 static void list_oops_do(ObjectMonitor* list, OopClosure* f);
181
182 // Support for SynchronizerTest access to GVars fields:
183 static u_char* get_gvars_addr();
184 static u_char* get_gvars_hcSequence_addr();
185 static size_t get_gvars_size();
186 static u_char* get_gvars_stwRandom_addr();
187 };
188
189 // ObjectLocker enforces balanced locking and can never throw an
190 // IllegalMonitorStateException. However, a pending exception may
191 // have to pass through, and we must also be able to deal with
192 // asynchronous exceptions. The caller is responsible for checking
193 // the thread's pending exception if needed.
194 class ObjectLocker : public StackObj {
195 private:
196 Thread* _thread;
197 Handle _obj;
198 BasicLock _lock;
199 bool _dolock; // default true
200 public:
201 ObjectLocker(Handle obj, Thread* thread, bool doLock = true);
202 ~ObjectLocker();
203
204 // Monitor behavior
205 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
206 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
207 void waitUninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); }
208 // complete_exit gives up lock completely, returning recursion count
209 // reenter reclaims lock with original recursion count
210 intptr_t complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
211 void reenter(intptr_t recursion, TRAPS) { ObjectSynchronizer::reenter(_obj, recursion, CHECK); }
212 };
213
214 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP