1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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7 * published by the Free Software Foundation.
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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).
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24
25 #ifndef SHARE_RUNTIME_MUTEXLOCKER_HPP
26 #define SHARE_RUNTIME_MUTEXLOCKER_HPP
27
28 #include "memory/allocation.hpp"
29 #include "runtime/flags/flagSetting.hpp"
30 #include "runtime/mutex.hpp"
31
32 class Thread;
33
34 // Mutexes used in the VM.
35
36 extern Mutex* NMethodState_lock; // a lock used to guard a compiled method state
37 extern Monitor* SystemDictionary_lock; // a lock on the system dictionary
38 extern Mutex* InvokeMethodTypeTable_lock;
39 extern Monitor* InvokeMethodIntrinsicTable_lock;
40 extern Mutex* SharedDictionary_lock; // a lock on the CDS shared dictionary
41 extern Monitor* ClassInitError_lock; // a lock on the class initialization error table
42 extern Mutex* Module_lock; // a lock on module and package related data structures
43 extern Mutex* CompiledIC_lock; // a lock used to guard compiled IC patching and access
44 extern Mutex* VMStatistic_lock; // a lock used to guard statistics count increment
45 extern Mutex* JmethodIdCreation_lock; // a lock on creating JNI method identifiers
46 extern Mutex* JfieldIdCreation_lock; // a lock on creating JNI static field identifiers
47 extern Monitor* JNICritical_lock; // a lock used while synchronizing with threads entering/leaving JNI critical regions
48 extern Mutex* JvmtiThreadState_lock; // a lock on modification of JVMTI thread data
49 extern Monitor* EscapeBarrier_lock; // a lock to sync reallocating and relocking objects because of JVMTI access
50 extern Monitor* JvmtiVTMSTransition_lock; // a lock for Virtual Thread Mount State transition (VTMS transition) management
51 extern Mutex* JvmtiVThreadSuspend_lock; // a lock for virtual threads suspension
52 extern Monitor* Heap_lock; // a lock on the heap
53 #if INCLUDE_PARALLELGC
54 extern Mutex* PSOldGenExpand_lock; // a lock on expanding the heap
55 #endif
56 extern Mutex* AdapterHandlerLibrary_lock; // a lock on the AdapterHandlerLibrary
57 extern Mutex* SignatureHandlerLibrary_lock; // a lock on the SignatureHandlerLibrary
58 extern Mutex* VtableStubs_lock; // a lock on the VtableStubs
59 extern Mutex* SymbolArena_lock; // a lock on the symbol table arena
60 extern Monitor* StringDedup_lock; // a lock on the string deduplication facility
61 extern Mutex* StringDedupIntern_lock; // a lock on StringTable notification of StringDedup
62 extern Monitor* CodeCache_lock; // a lock on the CodeCache
63 extern Mutex* TouchedMethodLog_lock; // a lock on allocation of LogExecutedMethods info
64 extern Mutex* RetData_lock; // a lock on installation of RetData inside method data
65 extern Monitor* VMOperation_lock; // a lock on queue of vm_operations waiting to execute
66 extern Monitor* ThreadsLockThrottle_lock; // used by Thread start/exit to reduce competition for Threads_lock,
67 // so a VM thread calling a safepoint is prioritized
68 extern Monitor* Threads_lock; // a lock on the Threads table of active Java threads
69 // (also used by Safepoints too to block threads creation/destruction)
70 extern Mutex* NonJavaThreadsList_lock; // a lock on the NonJavaThreads list
71 extern Mutex* NonJavaThreadsListSync_lock; // a lock for NonJavaThreads list synchronization
72 extern Monitor* STS_lock; // used for joining/leaving SuspendibleThreadSet.
73 extern Mutex* MonitoringSupport_lock; // Protects updates to the serviceability memory pools and allocated memory high water mark.
74 extern Monitor* ConcurrentGCBreakpoints_lock; // Protects concurrent GC breakpoint management
75 extern Mutex* Compile_lock; // a lock held when Compilation is updating code (used to block CodeCache traversal, CHA updates, etc)
76 extern Monitor* MethodCompileQueue_lock; // a lock held when method compilations are enqueued, dequeued
77 extern Monitor* CompileThread_lock; // a lock held by compile threads during compilation system initialization
78 extern Monitor* Compilation_lock; // a lock used to pause compilation
79 extern Mutex* TrainingData_lock; // a lock used when accessing training records
80 extern Monitor* TrainingReplayQueue_lock; // a lock held when class are added/removed to the training replay queue
81 extern Monitor* CompileTaskWait_lock; // a lock held when CompileTasks are waited/notified
82 extern Mutex* CompileStatistics_lock; // a lock held when updating compilation statistics
83 extern Mutex* DirectivesStack_lock; // a lock held when mutating the dirstack and ref counting directives
84 extern Monitor* Terminator_lock; // a lock used to guard termination of the vm
85 extern Monitor* InitCompleted_lock; // a lock used to signal threads waiting on init completed
86 extern Monitor* BeforeExit_lock; // a lock used to guard cleanups and shutdown hooks
87 extern Monitor* Notify_lock; // a lock used to synchronize the start-up of the vm
88 extern Mutex* ExceptionCache_lock; // a lock used to synchronize exception cache updates
89
90 #ifndef PRODUCT
91 extern Mutex* FullGCALot_lock; // a lock to make FullGCALot MT safe
92 #endif // PRODUCT
93
94 #if INCLUDE_G1GC
95 extern Monitor* G1CGC_lock; // used for coordination between fore- & background G1 concurrent GC threads.
96 extern Mutex* G1FreeList_lock; // protects the G1 free region list during safepoints
97 extern Mutex* G1MarkStackChunkList_lock; // Protects access to the G1 global mark stack chunk list.
98 extern Mutex* G1MarkStackFreeList_lock; // Protects access to the G1 global mark stack free list.
99 extern Monitor* G1OldGCCount_lock; // in support of "concurrent" full gc
100 extern Mutex* G1OldSets_lock; // protects the G1 old region sets
101 extern Mutex* G1RareEvent_lock; // Synchronizes (rare) parallel GC operations.
102 extern Mutex* G1ReviseYoungLength_lock; // Protects access to young gen length revising operations.
103 extern Monitor* G1RootRegionScan_lock; // used to notify that the G1 CM threads have finished scanning the root regions
104 extern Mutex* G1Uncommit_lock; // protects the G1 uncommit list when not at safepoints
105 #endif
106
107 extern Mutex* RawMonitor_lock;
108 extern Mutex* PerfDataMemAlloc_lock; // a lock on the allocator for PerfData memory for performance data
109 extern Mutex* PerfDataManager_lock; // a long on access to PerfDataManager resources
110
111 extern Mutex* Management_lock; // a lock used to serialize JVM management
112 extern Monitor* MonitorDeflation_lock; // a lock used for monitor deflation thread operation
113 extern Monitor* Service_lock; // a lock used for service thread operation
114 extern Monitor* Notification_lock; // a lock used for notification thread operation
115 extern Monitor* PeriodicTask_lock; // protects the periodic task structure
116 extern Monitor* RedefineClasses_lock; // locks classes from parallel redefinition
117 extern Mutex* Verify_lock; // synchronize initialization of verify library
118 extern Monitor* ThreadsSMRDelete_lock; // Used by ThreadsSMRSupport to take pressure off the Threads_lock
119 extern Mutex* ThreadIdTableCreate_lock; // Used by ThreadIdTable to lazily create the thread id table
120 extern Mutex* SharedDecoder_lock; // serializes access to the decoder during normal (not error reporting) use
121 extern Mutex* DCmdFactory_lock; // serialize access to DCmdFactory information
122 extern Mutex* NMTQuery_lock; // serialize NMT Dcmd queries
123 extern Mutex* NMTCompilationCostHistory_lock; // guards NMT compilation cost history
124 extern Mutex* NmtVirtualMemory_lock; // guards NMT virtual memory updates
125 #if INCLUDE_CDS
126 #if INCLUDE_JVMTI
127 extern Mutex* CDSClassFileStream_lock; // FileMapInfo::open_stream_for_jvmti
128 #endif
129 extern Mutex* DumpTimeTable_lock; // SystemDictionaryShared::_dumptime_table
130 extern Mutex* CDSLambda_lock; // LambdaProxyClassDictionary::find_lambda_proxy_class
131 extern Mutex* DumpRegion_lock; // Symbol::operator new(size_t sz, int len)
132 extern Mutex* ClassListFile_lock; // ClassListWriter()
133 extern Mutex* UnregisteredClassesTable_lock; // UnregisteredClassesTableTable
134 extern Mutex* LambdaFormInvokers_lock; // Protecting LambdaFormInvokers::_lambdaform_lines
135 extern Mutex* ScratchObjects_lock; // Protecting _scratch_xxx_table in heapShared.cpp
136 extern Mutex* FinalImageRecipes_lock; // Protecting the tables used by FinalImageRecipes.
137 #endif // INCLUDE_CDS
138 #if INCLUDE_JFR
139 extern Mutex* JfrStacktrace_lock; // used to guard access to the JFR stacktrace table
140 extern Monitor* JfrMsg_lock; // protects JFR messaging
141 extern Mutex* JfrBuffer_lock; // protects JFR buffer operations
142 #endif
143
144 extern Mutex* Metaspace_lock; // protects Metaspace virtualspace and chunk expansions
145 extern Monitor* MetaspaceCritical_lock; // synchronizes failed metaspace allocations that risk throwing metaspace OOM
146 extern Mutex* ClassLoaderDataGraph_lock; // protects CLDG list, needed for concurrent unloading
147
148
149 extern Mutex* CodeHeapStateAnalytics_lock; // lock print functions against concurrent analyze functions.
150 // Only used locally in PrintCodeCacheLayout processing.
151
152 extern Mutex* ExternalsRecorder_lock; // used to guard access to the external addresses table
153
154 extern Mutex* AOTCodeCStrings_lock; // used to guard access to the AOT code C strings table
155
156 extern Monitor* ContinuationRelativize_lock;
157
158 #if INCLUDE_JVMCI
159 extern Monitor* JVMCI_lock; // protects global JVMCI critical sections
160 extern Monitor* JVMCIRuntime_lock; // protects critical sections for a specific JVMCIRuntime object
161 #endif
162
163 extern Mutex* Bootclasspath_lock;
164
165 extern Mutex* tty_lock; // lock to synchronize output.
166
167 // A MutexLocker provides mutual exclusion with respect to a given mutex
168 // for the scope which contains the locker. The lock is an OS lock, not
169 // an object lock, and the two do not interoperate. Do not use Mutex-based
170 // locks to lock on Java objects, because they will not be respected if a
171 // that object is locked using the Java locking mechanism.
172 //
173 // NOTE WELL!!
174 //
175 // See orderAccess.hpp. We assume throughout the VM that MutexLocker's
176 // and friends constructors do a fence, a lock and an acquire *in that
177 // order*. And that their destructors do a release and unlock, in *that*
178 // order. If their implementations change such that these assumptions
179 // are violated, a whole lot of code will break.
180
181 // for debugging: check that we're already owning this lock (or are at a safepoint / handshake)
182 #ifdef ASSERT
183 void assert_locked_or_safepoint(const Mutex* lock);
184 void assert_lock_strong(const Mutex* lock);
185 #else
186 #define assert_locked_or_safepoint(lock)
187 #define assert_lock_strong(lock)
188 #endif
189
190 // Internal implementation. Skips on null Mutex.
191 // Subclasses enforce stronger invariants.
192 class MutexLockerImpl: public StackObj {
193 protected:
194 Mutex* _mutex;
195
196 MutexLockerImpl(Mutex* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
197 _mutex(mutex) {
198 bool no_safepoint_check = flag == Mutex::_no_safepoint_check_flag;
199 if (_mutex != nullptr) {
200 if (no_safepoint_check) {
201 _mutex->lock_without_safepoint_check();
202 } else {
203 _mutex->lock();
204 }
205 }
206 }
207
208 MutexLockerImpl(Thread* thread, Mutex* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
209 _mutex(mutex) {
210 bool no_safepoint_check = flag == Mutex::_no_safepoint_check_flag;
211 if (_mutex != nullptr) {
212 if (no_safepoint_check) {
213 _mutex->lock_without_safepoint_check(thread);
214 } else {
215 _mutex->lock(thread);
216 }
217 }
218 }
219
220 ~MutexLockerImpl() {
221 if (_mutex != nullptr) {
222 assert_lock_strong(_mutex);
223 _mutex->unlock();
224 }
225 }
226
227 public:
228 static void post_initialize();
229 };
230
231 // Simplest mutex locker.
232 // Does not allow null mutexes.
233 class MutexLocker: public MutexLockerImpl {
234 public:
235 MutexLocker(Mutex* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
236 MutexLockerImpl(mutex, flag) {
237 assert(mutex != nullptr, "null mutex not allowed");
238 }
239
240 MutexLocker(Thread* thread, Mutex* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
241 MutexLockerImpl(thread, mutex, flag) {
242 assert(mutex != nullptr, "null mutex not allowed");
243 }
244 };
245
246 // Conditional mutex locker.
247 // Like MutexLocker above, but only locks when condition is true.
248 class ConditionalMutexLocker: public MutexLockerImpl {
249 public:
250 ConditionalMutexLocker(Mutex* mutex, bool condition, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
251 MutexLockerImpl(condition ? mutex : nullptr, flag) {
252 assert(!condition || mutex != nullptr, "null mutex not allowed when locking");
253 }
254
255 ConditionalMutexLocker(Thread* thread, Mutex* mutex, bool condition, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
256 MutexLockerImpl(thread, condition ? mutex : nullptr, flag) {
257 assert(!condition || mutex != nullptr, "null mutex not allowed when locking");
258 }
259 };
260
261 // A MonitorLocker is like a MutexLocker above, except it allows
262 // wait/notify as well which are delegated to the underlying Monitor.
263 // It also disallows null.
264 class MonitorLocker: public MutexLockerImpl {
265 Mutex::SafepointCheckFlag _flag;
266
267 protected:
268 Monitor* as_monitor() const {
269 return static_cast<Monitor*>(_mutex);
270 }
271
272 public:
273 MonitorLocker(Monitor* monitor, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
274 MutexLockerImpl(monitor, flag), _flag(flag) {
275 // Superclass constructor did locking
276 assert(monitor != nullptr, "null monitor not allowed");
277 }
278
279 MonitorLocker(Thread* thread, Monitor* monitor, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
280 MutexLockerImpl(thread, monitor, flag), _flag(flag) {
281 // Superclass constructor did locking
282 assert(monitor != nullptr, "null monitor not allowed");
283 }
284
285 bool wait(int64_t timeout = 0) {
286 return _flag == Mutex::_safepoint_check_flag ?
287 as_monitor()->wait(timeout) : as_monitor()->wait_without_safepoint_check(timeout);
288 }
289
290 void notify_all() {
291 as_monitor()->notify_all();
292 }
293
294 void notify() {
295 as_monitor()->notify();
296 }
297 };
298
299
300 // A GCMutexLocker is usually initialized with a mutex that is
301 // automatically acquired in order to do GC. The function that
302 // synchronizes using a GCMutexLocker may be called both during and between
303 // GC's. Thus, it must acquire the mutex if GC is not in progress, but not
304 // if GC is in progress (since the mutex is already held on its behalf.)
305
306 class GCMutexLocker: public StackObj {
307 private:
308 Mutex* _mutex;
309 bool _locked;
310 public:
311 GCMutexLocker(Mutex* mutex);
312 ~GCMutexLocker() { if (_locked) _mutex->unlock(); }
313 };
314
315 // A MutexUnlocker temporarily exits a previously
316 // entered mutex for the scope which contains the unlocker.
317
318 class MutexUnlocker: StackObj {
319 private:
320 Mutex* _mutex;
321 bool _no_safepoint_check;
322
323 public:
324 MutexUnlocker(Mutex* mutex, Mutex::SafepointCheckFlag flag = Mutex::_safepoint_check_flag) :
325 _mutex(mutex),
326 _no_safepoint_check(flag == Mutex::_no_safepoint_check_flag) {
327 _mutex->unlock();
328 }
329
330 ~MutexUnlocker() {
331 if (_no_safepoint_check) {
332 _mutex->lock_without_safepoint_check();
333 } else {
334 _mutex->lock();
335 }
336 }
337 };
338
339 // Instance of a RecursiveLock that may be held through Java heap allocation, which may include calls to Java,
340 // and JNI event notification for resource exhaustion for metaspace or heap.
341 extern RecursiveMutex* MultiArray_lock;
342
343 // RAII locker for a RecursiveMutex. See comments in mutex.hpp for more information.
344 class RecursiveLocker {
345 RecursiveMutex* _lock;
346 Thread* _thread;
347 public:
348 RecursiveLocker(RecursiveMutex* lock, Thread* current) : _lock(lock), _thread(current) {
349 _lock->lock(_thread);
350 }
351 ~RecursiveLocker() {
352 _lock->unlock(_thread);
353 }
354 };
355
356 #endif // SHARE_RUNTIME_MUTEXLOCKER_HPP