1 /*
2 * Copyright (c) 1998, 2023, 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.
18 *
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
21 * questions.
22 *
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 "utilities/resourceHash.hpp"
33
34 template <typename T> class GrowableArray;
35 class LogStream;
36 class ObjectMonitor;
37 class ThreadsList;
38
39 class MonitorList {
40 friend class VMStructs;
41
42 private:
43 ObjectMonitor* volatile _head;
44 volatile size_t _count;
45 volatile size_t _max;
46
47 public:
48 void add(ObjectMonitor* monitor);
49 size_t unlink_deflated(Thread* current, LogStream* ls, elapsedTimer* timer_p,
50 size_t deflated_count,
51 GrowableArray<ObjectMonitor*>* unlinked_list);
52 size_t count() const;
53 size_t max() const;
54
55 class Iterator;
56 Iterator iterator() const;
57 };
58
59 class MonitorList::Iterator {
60 ObjectMonitor* _current;
61
62 public:
63 Iterator(ObjectMonitor* head) : _current(head) {}
64 bool has_next() const { return _current != nullptr; }
65 ObjectMonitor* next();
66 };
67
68 class ObjectSynchronizer : AllStatic {
69 friend class VMStructs;
70
71 public:
72 typedef enum {
73 inflate_cause_vm_internal = 0,
74 inflate_cause_monitor_enter = 1,
75 inflate_cause_wait = 2,
76 inflate_cause_notify = 3,
77 inflate_cause_hash_code = 4,
78 inflate_cause_jni_enter = 5,
79 inflate_cause_jni_exit = 6,
80 inflate_cause_nof = 7 // Number of causes
81 } InflateCause;
82
83 typedef enum {
84 NOT_ENABLED = 0,
85 FATAL_EXIT = 1,
86 LOG_WARNING = 2
87 } SyncDiagnosticOption;
88
89 // exit must be implemented non-blocking, since the compiler cannot easily handle
90 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
91
92 // This is the "slow path" version of monitor enter and exit.
93 static void enter(Handle obj, BasicLock* lock, JavaThread* current);
94 static void exit(oop obj, BasicLock* lock, JavaThread* current);
95
96 // Used only to handle jni locks or other unmatched monitor enter/exit
97 // Internally they will use heavy weight monitor.
98 static void jni_enter(Handle obj, JavaThread* current);
99 static void jni_exit(oop obj, TRAPS);
100
101 // Handle all interpreter, compiler and jni cases
102 static int wait(Handle obj, jlong millis, TRAPS);
103 static void notify(Handle obj, TRAPS);
104 static void notifyall(Handle obj, TRAPS);
105
106 static bool quick_notify(oopDesc* obj, JavaThread* current, bool All);
107 static bool quick_enter(oop obj, JavaThread* current, BasicLock* Lock);
108
109 // Special internal-use-only method for use by JVM infrastructure
110 // that needs to wait() on a java-level object but that can't risk
111 // throwing unexpected InterruptedExecutionExceptions.
112 static void waitUninterruptibly(Handle obj, jlong Millis, TRAPS);
113
114 // Inflate light weight monitor to heavy weight monitor
115 static ObjectMonitor* inflate(Thread* current, oop obj, const InflateCause cause);
116 // This version is only for internal use
117 static void inflate_helper(oop obj);
118 static const char* inflate_cause_name(const InflateCause cause);
119
120 // Returns the identity hash value for an oop
121 // NOTE: It may cause monitor inflation
122 static intptr_t FastHashCode(Thread* current, oop obj);
123
124 // java.lang.Thread support
125 static bool current_thread_holds_lock(JavaThread* current, Handle h_obj);
126
127 static JavaThread* get_lock_owner(ThreadsList * t_list, Handle h_obj);
128
129 // JNI detach support
130 static void release_monitors_owned_by_thread(JavaThread* current);
131
132 // Iterate over all ObjectMonitors.
133 template <typename Function>
134 static void monitors_iterate(Function function);
135
136 // Iterate ObjectMonitors owned by any thread and where the owner `filter`
137 // returns true.
138 template <typename OwnerFilter>
139 static void owned_monitors_iterate_filtered(MonitorClosure* closure, OwnerFilter filter);
140
141 // Iterate ObjectMonitors where the owner == thread; this does NOT include
142 // ObjectMonitors where owner is set to a stack lock address in thread.
143 static void owned_monitors_iterate(MonitorClosure* m, JavaThread* thread);
144
145 // Iterate ObjectMonitors owned by any thread.
146 static void owned_monitors_iterate(MonitorClosure* closure);
147
148 // Initialize the gInflationLocks
149 static void initialize();
150
151 // We currently use aggressive monitor deflation policy;
152 // basically we try to deflate all monitors that are not busy.
153 static size_t deflate_idle_monitors();
154
155 // Deflate idle monitors:
156 static void chk_for_block_req(JavaThread* current, const char* op_name,
157 const char* cnt_name, size_t cnt, LogStream* ls,
158 elapsedTimer* timer_p);
159 static size_t deflate_monitor_list(Thread* current, LogStream* ls, elapsedTimer* timer_p);
160 static size_t in_use_list_ceiling();
161 static void dec_in_use_list_ceiling();
162 static void inc_in_use_list_ceiling();
163 static void set_in_use_list_ceiling(size_t new_value);
164 static bool is_async_deflation_needed();
165 static bool is_async_deflation_requested() { return _is_async_deflation_requested; }
166 static bool is_final_audit() { return _is_final_audit; }
167 static void set_is_final_audit() { _is_final_audit = true; }
168 static jlong last_async_deflation_time_ns() { return _last_async_deflation_time_ns; }
169 static void request_deflate_idle_monitors();
170 static bool request_deflate_idle_monitors_from_wb(); // for whitebox test support
171 static void set_is_async_deflation_requested(bool new_value) { _is_async_deflation_requested = new_value; }
172 static jlong time_since_last_async_deflation_ms();
173
174 // debugging
175 static void audit_and_print_stats(bool on_exit);
176 static void chk_in_use_list(outputStream* out, int* error_cnt_p);
177 static void chk_in_use_entry(ObjectMonitor* n, outputStream* out,
178 int* error_cnt_p);
179 static void do_final_audit_and_print_stats();
180 static void log_in_use_monitor_details(outputStream* out, bool log_all);
181
182 private:
183 friend class SynchronizerTest;
184
185 static MonitorList _in_use_list;
186 static volatile bool _is_async_deflation_requested;
187 static volatile bool _is_final_audit;
188 static jlong _last_async_deflation_time_ns;
189
190 // Support for SynchronizerTest access to GVars fields:
191 static u_char* get_gvars_addr();
192 static u_char* get_gvars_hc_sequence_addr();
193 static size_t get_gvars_size();
194 static u_char* get_gvars_stw_random_addr();
195
196 static void handle_sync_on_value_based_class(Handle obj, JavaThread* current);
197 };
198
199 // ObjectLocker enforces balanced locking and can never throw an
200 // IllegalMonitorStateException. However, a pending exception may
201 // have to pass through, and we must also be able to deal with
202 // asynchronous exceptions. The caller is responsible for checking
203 // the thread's pending exception if needed.
204 class ObjectLocker : public StackObj {
205 private:
206 JavaThread* _thread;
207 Handle _obj;
208 BasicLock _lock;
209 public:
210 ObjectLocker(Handle obj, JavaThread* current);
211 ~ObjectLocker();
212
213 // Monitor behavior
214 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
215 void wait_uninterruptibly(TRAPS) { ObjectSynchronizer::waitUninterruptibly(_obj, 0, CHECK); } // wait forever
216 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
217 };
218
219 // Interface to visit monitors
220 class ObjectMonitorsView {
221 public:
222 // Visit monitors that belong to the given thread
223 virtual void visit(MonitorClosure* closure, JavaThread* thread) = 0;
224 };
225
226 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP