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 ObjectMonitorHandle;
36 class ThreadsList;
37
38 #ifndef OM_CACHE_LINE_SIZE
39 // Use DEFAULT_CACHE_LINE_SIZE if not already specified for
40 // the current build platform.
41 #define OM_CACHE_LINE_SIZE DEFAULT_CACHE_LINE_SIZE
42 #endif
43
44 typedef PaddedEnd<ObjectMonitor, OM_CACHE_LINE_SIZE> PaddedObjectMonitor;
45
46 struct DeflateMonitorCounters {
47 volatile int n_in_use; // currently associated with objects
48 volatile int n_in_circulation; // extant
49 volatile int n_scavenged; // reclaimed (global and per-thread)
50 volatile int per_thread_scavenged; // per-thread scavenge total
51 double per_thread_times; // per-thread scavenge times
52 };
53
54 class ObjectSynchronizer : AllStatic {
55 friend class VMStructs;
56 public:
57 typedef enum {
58 owner_self,
59 owner_none,
60 owner_other
61 } LockOwnership;
62
63 typedef enum {
64 inflate_cause_vm_internal = 0,
65 inflate_cause_monitor_enter = 1,
66 inflate_cause_wait = 2,
67 inflate_cause_notify = 3,
68 inflate_cause_hash_code = 4,
69 inflate_cause_jni_enter = 5,
70 inflate_cause_jni_exit = 6,
71 inflate_cause_nof = 7 // Number of causes
72 } InflateCause;
73
74 // exit must be implemented non-blocking, since the compiler cannot easily handle
75 // deoptimization at monitor exit. Hence, it does not take a Handle argument.
76
77 // This is the "slow path" version of monitor enter and exit.
78 static void enter(Handle obj, BasicLock* lock, TRAPS);
79 static void exit(oop obj, BasicLock* lock, Thread* THREAD);
80
81 // Used only to handle jni locks or other unmatched monitor enter/exit
82 // Internally they will use heavy weight monitor.
83 static void jni_enter(Handle obj, TRAPS);
84 static void jni_exit(oop obj, Thread* THREAD);
85
86 // Handle all interpreter, compiler and jni cases
87 static int wait(Handle obj, jlong millis, TRAPS);
88 static void notify(Handle obj, TRAPS);
89 static void notifyall(Handle obj, TRAPS);
90
91 static bool quick_notify(oopDesc* obj, Thread* self, bool All);
92 static bool quick_enter(oop obj, Thread* self, BasicLock* Lock);
93
94 // Special internal-use-only method for use by JVM infrastructure
95 // that needs to wait() on a java-level object but that can't risk
96 // throwing unexpected InterruptedExecutionExceptions.
97 static void wait_uninterruptibly(Handle obj, jlong Millis, Thread* THREAD);
98
99 // used by classloading to free classloader object lock,
100 // wait on an internal lock, and reclaim original lock
101 // with original recursion count
102 static intx complete_exit(Handle obj, TRAPS);
103 static void reenter (Handle obj, intx recursions, TRAPS);
104
105 // thread-specific and global ObjectMonitor free list accessors
106 static ObjectMonitor* om_alloc(Thread* self);
107 static void om_release(Thread* self, ObjectMonitor* m,
108 bool FromPerThreadAlloc);
109 static void om_flush(Thread* self);
110
111 // Inflate light weight monitor to heavy weight monitor
112 static void inflate(ObjectMonitorHandle* omh_p, Thread* self, oop obj,
113 const InflateCause cause);
114 // This version is only for internal use
115 static void inflate_helper(ObjectMonitorHandle* omh_p, oop obj);
116 static const char* inflate_cause_name(const InflateCause cause);
117
118 // Returns the identity hash value for an oop
119 // NOTE: It may cause monitor inflation
120 static intptr_t identity_hash_value_for(Handle obj);
121 static intptr_t FastHashCode(Thread* self, oop obj);
122
123 // java.lang.Thread support
124 static bool current_thread_holds_lock(JavaThread* thread, Handle h_obj);
125 static LockOwnership query_lock_ownership(JavaThread* self, 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(TRAPS);
131 static void monitors_iterate(MonitorClosure* m);
132
133 // GC: we current use aggressive monitor deflation policy
134 // Basically we deflate all monitors that are not busy.
135 // An adaptive profile-based deflation policy could be used if needed
136 static void deflate_idle_monitors(DeflateMonitorCounters* counters);
137 static void deflate_idle_monitors_using_JT();
138 static void deflate_global_idle_monitors_using_JT();
139 static void deflate_per_thread_idle_monitors_using_JT(JavaThread* target);
140 static void deflate_common_idle_monitors_using_JT(bool is_global, JavaThread* target);
141 static void deflate_thread_local_monitors(Thread* thread, DeflateMonitorCounters* counters);
142 static void prepare_deflate_idle_monitors(DeflateMonitorCounters* counters);
143 static void finish_deflate_idle_monitors(DeflateMonitorCounters* counters);
144
145 // For a given monitor list: global or per-thread, deflate idle monitors
146 static int deflate_monitor_list(ObjectMonitor** list_p,
147 int* count_p,
148 ObjectMonitor** free_head_p,
149 ObjectMonitor** free_tail_p);
150 // For a given in-use monitor list: global or per-thread, deflate idle
151 // monitors using a JavaThread.
152 static int deflate_monitor_list_using_JT(ObjectMonitor** list_p,
153 int* count_p,
154 ObjectMonitor** free_head_p,
155 ObjectMonitor** free_tail_p,
156 ObjectMonitor** saved_mid_in_use_p);
157 static bool deflate_monitor(ObjectMonitor* mid, oop obj,
158 ObjectMonitor** free_head_p,
159 ObjectMonitor** free_tail_p);
160 static bool deflate_monitor_using_JT(ObjectMonitor* mid,
161 ObjectMonitor** free_head_p,
162 ObjectMonitor** free_tail_p);
163 static bool is_async_deflation_needed();
164 static bool needs_monitor_scavenge();
165 static bool is_safepoint_deflation_needed();
166 static bool is_async_deflation_requested() { return _is_async_deflation_requested; }
167 static bool is_special_deflation_requested() { return _is_special_deflation_requested; }
168 static void set_is_async_deflation_requested(bool new_value) { _is_async_deflation_requested = new_value; }
169 static void set_is_special_deflation_requested(bool new_value) { _is_special_deflation_requested = new_value; }
170 static jlong time_since_last_async_deflation_ms();
171 static void oops_do(OopClosure* f);
172 // Process oops in thread local used monitors
173 static void thread_local_used_oops_do(Thread* thread, OopClosure* f);
174
175 // debugging
176 static void audit_and_print_stats(bool on_exit);
177 static void chk_free_entry(JavaThread* jt, ObjectMonitor* n,
178 outputStream * out, int *error_cnt_p);
179 static void chk_global_free_list_and_count(outputStream * out,
180 int *error_cnt_p);
181 static void chk_global_wait_list_and_count(outputStream * out,
182 int *error_cnt_p);
183 static void chk_global_in_use_list_and_count(outputStream * out,
184 int *error_cnt_p);
185 static void chk_in_use_entry(JavaThread* jt, ObjectMonitor* n,
186 outputStream * out, int *error_cnt_p);
187 static void chk_per_thread_in_use_list_and_count(JavaThread *jt,
188 outputStream * out,
189 int *error_cnt_p);
190 static void chk_per_thread_free_list_and_count(JavaThread *jt,
191 outputStream * out,
192 int *error_cnt_p);
193 static void log_in_use_monitor_details(outputStream * out);
194 static int log_monitor_list_counts(outputStream * out);
195 static int verify_objmon_isinpool(ObjectMonitor *addr) PRODUCT_RETURN0;
196
197 static void do_safepoint_work(DeflateMonitorCounters* counters);
198
199 private:
200 friend class SynchronizerTest;
201
202 enum { _BLOCKSIZE = 128 };
203 // global list of blocks of monitors
204 static PaddedObjectMonitor* g_block_list;
205 static volatile bool _is_async_deflation_requested;
206 static volatile bool _is_special_deflation_requested;
207 static jlong _last_async_deflation_time_ns;
208
209 // Function to prepend new blocks to the appropriate lists:
210 static void prepend_block_to_lists(PaddedObjectMonitor* new_blk);
211
212 // Process oops in all global used monitors (i.e. moribund thread's monitors)
213 static void global_used_oops_do(OopClosure* f);
214 // Process oops in monitors on the given list
215 static void list_oops_do(ObjectMonitor* list, OopClosure* f);
216
217 // Support for SynchronizerTest access to GVars fields:
218 static u_char* get_gvars_addr();
219 static u_char* get_gvars_hc_sequence_addr();
220 static size_t get_gvars_size();
221 static u_char* get_gvars_stw_random_addr();
222 };
223
224 // ObjectLocker enforces balanced locking and can never throw an
225 // IllegalMonitorStateException. However, a pending exception may
226 // have to pass through, and we must also be able to deal with
227 // asynchronous exceptions. The caller is responsible for checking
228 // the thread's pending exception if needed.
229 class ObjectLocker : public StackObj {
230 private:
231 Thread* _thread;
232 Handle _obj;
233 BasicLock _lock;
234 bool _dolock; // default true
235 public:
236 ObjectLocker(Handle obj, Thread* thread, bool do_lock = true);
237 ~ObjectLocker();
238
239 // Monitor behavior
240 void wait(TRAPS) { ObjectSynchronizer::wait(_obj, 0, CHECK); } // wait forever
241 void notify_all(TRAPS) { ObjectSynchronizer::notifyall(_obj, CHECK); }
242 void wait_uninterruptibly(TRAPS) { ObjectSynchronizer::wait_uninterruptibly(_obj, 0, CHECK); }
243 // complete_exit gives up lock completely, returning recursion count
244 // reenter reclaims lock with original recursion count
245 intx complete_exit(TRAPS) { return ObjectSynchronizer::complete_exit(_obj, THREAD); }
246 void reenter(intx recursions, TRAPS) { ObjectSynchronizer::reenter(_obj, recursions, CHECK); }
247 };
248
249 #endif // SHARE_RUNTIME_SYNCHRONIZER_HPP