1 /*
2 * Copyright (c) 1997, 2025, Oracle and/or its affiliates. All rights reserved.
3 * Copyright (c) 2021, Azul Systems, Inc. All rights reserved.
4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
5 *
6 * This code is free software; you can redistribute it and/or modify it
7 * under the terms of the GNU General Public License version 2 only, as
8 * published by the Free Software Foundation.
9 *
10 * This code is distributed in the hope that it will be useful, but WITHOUT
11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
13 * version 2 for more details (a copy is included in the LICENSE file that
14 * accompanied this code).
15 *
16 * You should have received a copy of the GNU General Public License version
17 * 2 along with this work; if not, write to the Free Software Foundation,
18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
19 *
20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
21 * or visit www.oracle.com if you need additional information or have any
22 * questions.
23 *
24 */
25
26 #ifndef SHARE_RUNTIME_THREAD_HPP
27 #define SHARE_RUNTIME_THREAD_HPP
28
29 #include "gc/shared/gcThreadLocalData.hpp"
30 #include "gc/shared/threadLocalAllocBuffer.hpp"
31 #include "jni.h"
32 #include "memory/allocation.hpp"
33 #include "runtime/atomic.hpp"
34 #include "runtime/globals.hpp"
35 #include "runtime/os.hpp"
36 #include "runtime/safepointMechanism.hpp"
37 #include "runtime/threadHeapSampler.hpp"
38 #include "runtime/threadLocalStorage.hpp"
39 #include "runtime/threadStatisticalInfo.hpp"
40 #include "runtime/unhandledOops.hpp"
41 #include "utilities/globalDefinitions.hpp"
42 #include "utilities/macros.hpp"
43 #if INCLUDE_JFR
44 #include "jfr/support/jfrThreadExtension.hpp"
45 #endif
46
47 class CompilerThread;
48 class HandleArea;
49 class HandleMark;
50 class JvmtiRawMonitor;
51 class NMethodClosure;
52 class Metadata;
53 class OopClosure;
54 class OSThread;
55 class ParkEvent;
56 class ResourceArea;
57 class SafeThreadsListPtr;
58 class ThreadClosure;
59 class ThreadsList;
60 class ThreadsSMRSupport;
61 class VMErrorCallback;
62
63
64 DEBUG_ONLY(class ResourceMark;)
65
66 class WorkerThread;
67
68 class JavaThread;
69
70 // Class hierarchy
71 // - Thread
72 // - JavaThread
73 // - various subclasses eg CompilerThread, ServiceThread
74 // - NonJavaThread
75 // - NamedThread
76 // - VMThread
77 // - ConcurrentGCThread
78 // - WorkerThread
79 // - WatcherThread
80 // - JfrThreadSampler
81 // - LogAsyncWriter
82 //
83 // All Thread subclasses must be either JavaThread or NonJavaThread.
84 // This means !t->is_Java_thread() iff t is a NonJavaThread, or t is
85 // a partially constructed/destroyed Thread.
86
87 // Thread execution sequence and actions:
88 // All threads:
89 // - thread_native_entry // per-OS native entry point
90 // - stack initialization
91 // - other OS-level initialization (signal masks etc)
92 // - handshake with creating thread (if not started suspended)
93 // - this->call_run() // common shared entry point
94 // - shared common initialization
95 // - this->pre_run() // virtual per-thread-type initialization
96 // - this->run() // virtual per-thread-type "main" logic
97 // - shared common tear-down
98 // - this->post_run() // virtual per-thread-type tear-down
99 // - // 'this' no longer referenceable
100 // - OS-level tear-down (minimal)
101 // - final logging
102 //
103 // For JavaThread:
104 // - this->run() // virtual but not normally overridden
105 // - this->thread_main_inner() // extra call level to ensure correct stack calculations
106 // - this->entry_point() // set differently for each kind of JavaThread
107
108 class Thread: public ThreadShadow {
109 friend class VMError;
110 friend class VMErrorCallbackMark;
111 friend class VMStructs;
112 friend class JVMCIVMStructs;
113 friend class JavaThread;
114 private:
115
116 // Current thread is maintained as a thread-local variable
117 static THREAD_LOCAL Thread* _thr_current;
118
119 // On AArch64, the high order 32 bits are used by a "patching epoch" number
120 // which reflects if this thread has executed the required fences, after
121 // an nmethod gets disarmed. The low order 32 bits denote the disarmed value.
122 uint64_t _nmethod_disarmed_guard_value;
123
124 public:
125 void set_nmethod_disarmed_guard_value(int value) {
126 _nmethod_disarmed_guard_value = (uint64_t)(uint32_t)value;
127 }
128
129 static ByteSize nmethod_disarmed_guard_value_offset() {
130 ByteSize offset = byte_offset_of(Thread, _nmethod_disarmed_guard_value);
131 // At least on x86_64, nmethod entry barrier encodes disarmed value offset
132 // in instruction as disp8 immed
133 assert(in_bytes(offset) < 128, "Offset >= 128");
134 return offset;
135 }
136
137 private:
138 // Poll data is used in generated code for safepoint polls.
139 // It is important for performance to put this at lower offset
140 // in Thread. The accessors are in JavaThread.
141 SafepointMechanism::ThreadData _poll_data;
142
143 // Thread local data area available to the GC. The internal
144 // structure and contents of this data area is GC-specific.
145 // Only GC and GC barrier code should access this data area.
146 GCThreadLocalData _gc_data;
147
148 public:
149 static ByteSize gc_data_offset() {
150 return byte_offset_of(Thread, _gc_data);
151 }
152
153 template <typename T> T* gc_data() {
154 STATIC_ASSERT(sizeof(T) <= sizeof(_gc_data));
155 return reinterpret_cast<T*>(&_gc_data);
156 }
157
158 // Exception handling
159 // (Note: _pending_exception and friends are in ThreadShadow)
160 //oop _pending_exception; // pending exception for current thread
161 // const char* _exception_file; // file information for exception (debugging only)
162 // int _exception_line; // line information for exception (debugging only)
163 protected:
164 // JavaThread lifecycle support:
165 friend class SafeThreadsListPtr; // for _threads_list_ptr, cmpxchg_threads_hazard_ptr(), {dec_,inc_,}nested_threads_hazard_ptr_cnt(), {g,s}et_threads_hazard_ptr(), inc_nested_handle_cnt(), tag_hazard_ptr() access
166 friend class ScanHazardPtrGatherProtectedThreadsClosure; // for cmpxchg_threads_hazard_ptr(), get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
167 friend class ScanHazardPtrGatherThreadsListClosure; // for get_threads_hazard_ptr(), untag_hazard_ptr() access
168 friend class ScanHazardPtrPrintMatchingThreadsClosure; // for get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
169 friend class ThreadsSMRSupport; // for _nested_threads_hazard_ptr_cnt, _threads_hazard_ptr, _threads_list_ptr access
170 friend class ThreadsListHandleTest; // for _nested_threads_hazard_ptr_cnt, _threads_hazard_ptr, _threads_list_ptr access
171 friend class ValidateHazardPtrsClosure; // for get_threads_hazard_ptr(), untag_hazard_ptr() access
172
173 ThreadsList* volatile _threads_hazard_ptr;
174 SafeThreadsListPtr* _threads_list_ptr;
175 ThreadsList* cmpxchg_threads_hazard_ptr(ThreadsList* exchange_value, ThreadsList* compare_value);
176 ThreadsList* get_threads_hazard_ptr() const;
177 void set_threads_hazard_ptr(ThreadsList* new_list);
178 static bool is_hazard_ptr_tagged(ThreadsList* list) {
179 return (intptr_t(list) & intptr_t(1)) == intptr_t(1);
180 }
181 static ThreadsList* tag_hazard_ptr(ThreadsList* list) {
182 return (ThreadsList*)(intptr_t(list) | intptr_t(1));
183 }
184 static ThreadsList* untag_hazard_ptr(ThreadsList* list) {
185 return (ThreadsList*)(intptr_t(list) & ~intptr_t(1));
186 }
187 // This field is enabled via -XX:+EnableThreadSMRStatistics:
188 uint _nested_threads_hazard_ptr_cnt;
189 void dec_nested_threads_hazard_ptr_cnt() {
190 assert(_nested_threads_hazard_ptr_cnt != 0, "mismatched {dec,inc}_nested_threads_hazard_ptr_cnt()");
191 _nested_threads_hazard_ptr_cnt--;
192 }
193 void inc_nested_threads_hazard_ptr_cnt() {
194 _nested_threads_hazard_ptr_cnt++;
195 }
196 uint nested_threads_hazard_ptr_cnt() {
197 return _nested_threads_hazard_ptr_cnt;
198 }
199
200 public:
201 // Is the target JavaThread protected by the calling Thread or by some other
202 // mechanism?
203 static bool is_JavaThread_protected(const JavaThread* target);
204 // Is the target JavaThread protected by a ThreadsListHandle (TLH) associated
205 // with the calling Thread?
206 static bool is_JavaThread_protected_by_TLH(const JavaThread* target);
207
208 private:
209 DEBUG_ONLY(static Thread* _starting_thread;)
210 DEBUG_ONLY(bool _suspendible_thread;)
211 DEBUG_ONLY(bool _indirectly_suspendible_thread;)
212 DEBUG_ONLY(bool _indirectly_safepoint_thread;)
213
214 public:
215 #ifdef ASSERT
216 static bool is_starting_thread(const Thread* t);
217
218 void set_suspendible_thread() { _suspendible_thread = true; }
219 void clear_suspendible_thread() { _suspendible_thread = false; }
220 bool is_suspendible_thread() { return _suspendible_thread; }
221
222 void set_indirectly_suspendible_thread() { _indirectly_suspendible_thread = true; }
223 void clear_indirectly_suspendible_thread() { _indirectly_suspendible_thread = false; }
224 bool is_indirectly_suspendible_thread() { return _indirectly_suspendible_thread; }
225
226 void set_indirectly_safepoint_thread() { _indirectly_safepoint_thread = true; }
227 void clear_indirectly_safepoint_thread() { _indirectly_safepoint_thread = false; }
228 bool is_indirectly_safepoint_thread() { return _indirectly_safepoint_thread; }
229 #endif
230
231 private:
232 // Point to the last handle mark
233 HandleMark* _last_handle_mark;
234
235 // Claim value for parallel iteration over threads.
236 uintx _threads_do_token;
237
238 // Support for GlobalCounter
239 private:
240 volatile uintx _rcu_counter;
241 public:
242 volatile uintx* get_rcu_counter() {
243 return &_rcu_counter;
244 }
245
246 public:
247 void set_last_handle_mark(HandleMark* mark) { _last_handle_mark = mark; }
248 HandleMark* last_handle_mark() const { return _last_handle_mark; }
249
250 private:
251 // Used by SkipGCALot class.
252 NOT_PRODUCT(bool _skip_gcalot;) // Should we elide gc-a-lot?
253
254 friend class GCLocker;
255
256 private:
257 ThreadLocalAllocBuffer _tlab; // Thread-local eden
258 jlong _allocated_bytes; // Cumulative number of bytes allocated on
259 // the Java heap
260 ThreadHeapSampler _heap_sampler; // For use when sampling the memory.
261
262 ThreadStatisticalInfo _statistical_info; // Statistics about the thread
263
264 JFR_ONLY(DEFINE_THREAD_LOCAL_FIELD_JFR;) // Thread-local data for jfr
265
266 JvmtiRawMonitor* _current_pending_raw_monitor; // JvmtiRawMonitor this thread
267 // is waiting to lock
268 public:
269 // Constructor
270 Thread(MemTag mem_tag = mtThread);
271 virtual ~Thread() = 0; // Thread is abstract.
272
273 // Manage Thread::current()
274 void initialize_thread_current();
275 static void clear_thread_current(); // TLS cleanup needed before threads terminate
276
277 protected:
278 // To be implemented by children.
279 virtual void run() = 0;
280 virtual void pre_run() = 0;
281 virtual void post_run() = 0; // Note: Thread must not be deleted prior to calling this!
282
283 #ifdef ASSERT
284 enum RunState {
285 PRE_CALL_RUN,
286 CALL_RUN,
287 PRE_RUN,
288 RUN,
289 POST_RUN
290 // POST_CALL_RUN - can't define this one as 'this' may be deleted when we want to set it
291 };
292 RunState _run_state; // for lifecycle checks
293 #endif
294
295
296 public:
297 // invokes <ChildThreadClass>::run(), with common preparations and cleanups.
298 void call_run();
299
300 // Testers
301 virtual bool is_VM_thread() const { return false; }
302 virtual bool is_Java_thread() const { return false; }
303 virtual bool is_Compiler_thread() const { return false; }
304 virtual bool is_service_thread() const { return false; }
305 virtual bool is_hidden_from_external_view() const { return false; }
306 virtual bool is_jvmti_agent_thread() const { return false; }
307 virtual bool is_Watcher_thread() const { return false; }
308 virtual bool is_ConcurrentGC_thread() const { return false; }
309 virtual bool is_Named_thread() const { return false; }
310 virtual bool is_Worker_thread() const { return false; }
311 virtual bool is_JfrSampler_thread() const { return false; }
312 virtual bool is_JfrRecorder_thread() const { return false; }
313 virtual bool is_AttachListener_thread() const { return false; }
314 virtual bool is_monitor_deflation_thread() const { return false; }
315
316 // Convenience cast functions
317 CompilerThread* as_Compiler_thread() const {
318 assert(is_Compiler_thread(), "Must be compiler thread");
319 return (CompilerThread*)this;
320 }
321
322 // Can this thread make Java upcalls
323 virtual bool can_call_java() const { return false; }
324
325 // Is this a JavaThread that is on the VM's current ThreadsList?
326 // If so it must participate in the safepoint protocol.
327 virtual bool is_active_Java_thread() const { return false; }
328
329 // All threads are given names. For singleton subclasses we can
330 // just hard-wire the known name of the instance. JavaThreads and
331 // NamedThreads support multiple named instances, and dynamic
332 // changing of the name of an instance.
333 virtual const char* name() const { return "Unknown thread"; }
334
335 // A thread's type name is also made available for debugging
336 // and logging.
337 virtual const char* type_name() const { return "Thread"; }
338
339 // Returns the current thread (ASSERTS if null)
340 static inline Thread* current();
341 // Returns the current thread, or null if not attached
342 static inline Thread* current_or_null();
343 // Returns the current thread, or null if not attached, and is
344 // safe for use from signal-handlers
345 static inline Thread* current_or_null_safe();
346
347 // Common thread operations
348 #ifdef ASSERT
349 static void check_for_dangling_thread_pointer(Thread *thread);
350 #endif
351 static void set_priority(Thread* thread, ThreadPriority priority);
352 static void start(Thread* thread);
353
354 void set_native_thread_name(const char *name) {
355 assert(Thread::current() == this, "set_native_thread_name can only be called on the current thread");
356 os::set_native_thread_name(name);
357 }
358
359 // Support for Unhandled Oop detection
360 // Add the field for both, fastdebug and debug, builds to keep
361 // Thread's fields layout the same.
362 // Note: CHECK_UNHANDLED_OOPS is defined only for fastdebug build.
363 #ifdef CHECK_UNHANDLED_OOPS
364 private:
365 UnhandledOops* _unhandled_oops;
366 #elif defined(ASSERT)
367 private:
368 void* _unhandled_oops;
369 #endif
370 #ifdef CHECK_UNHANDLED_OOPS
371 public:
372 UnhandledOops* unhandled_oops() { return _unhandled_oops; }
373 // Mark oop safe for gc. It may be stack allocated but won't move.
374 void allow_unhandled_oop(oop *op) {
375 if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
376 }
377 // Clear oops at safepoint so crashes point to unhandled oop violator
378 void clear_unhandled_oops() {
379 if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
380 }
381 #endif // CHECK_UNHANDLED_OOPS
382
383 public:
384 #ifndef PRODUCT
385 bool skip_gcalot() { return _skip_gcalot; }
386 void set_skip_gcalot(bool v) { _skip_gcalot = v; }
387 #endif
388
389 // Resource area
390 ResourceArea* resource_area() const { return _resource_area; }
391 void set_resource_area(ResourceArea* area) { _resource_area = area; }
392
393 OSThread* osthread() const { return _osthread; }
394 void set_osthread(OSThread* thread) { _osthread = thread; }
395
396 // Internal handle support
397 HandleArea* handle_area() const { return _handle_area; }
398 void set_handle_area(HandleArea* area) { _handle_area = area; }
399
400 GrowableArray<Metadata*>* metadata_handles() const { return _metadata_handles; }
401 void set_metadata_handles(GrowableArray<Metadata*>* handles){ _metadata_handles = handles; }
402
403 // Thread-Local Allocation Buffer (TLAB) support
404 ThreadLocalAllocBuffer& tlab() { return _tlab; }
405 void initialize_tlab();
406 void retire_tlab(ThreadLocalAllocStats* stats = nullptr);
407 void fill_tlab(HeapWord* start, size_t pre_reserved, size_t new_size);
408
409 jlong allocated_bytes() { return _allocated_bytes; }
410 void set_allocated_bytes(jlong value) { _allocated_bytes = value; }
411 void incr_allocated_bytes(jlong size) { _allocated_bytes += size; }
412 inline jlong cooked_allocated_bytes();
413
414 ThreadHeapSampler& heap_sampler() { return _heap_sampler; }
415
416 ThreadStatisticalInfo& statistical_info() { return _statistical_info; }
417
418 JFR_ONLY(DEFINE_THREAD_LOCAL_ACCESSOR_JFR;)
419
420 // For tracking the Jvmti raw monitor the thread is pending on.
421 JvmtiRawMonitor* current_pending_raw_monitor() {
422 return _current_pending_raw_monitor;
423 }
424 void set_current_pending_raw_monitor(JvmtiRawMonitor* monitor) {
425 _current_pending_raw_monitor = monitor;
426 }
427
428 // GC support
429 // Apply "f->do_oop" to all root oops in "this".
430 // Used by JavaThread::oops_do.
431 // Apply "cf->do_nmethod" (if !nullptr) to all nmethods active in frames
432 virtual void oops_do_no_frames(OopClosure* f, NMethodClosure* cf);
433 virtual void oops_do_frames(OopClosure* f, NMethodClosure* cf) {}
434 void oops_do(OopClosure* f, NMethodClosure* cf);
435
436 // Handles the parallel case for claim_threads_do.
437 private:
438 bool claim_par_threads_do(uintx claim_token);
439 public:
440 // Requires that "claim_token" is that of the current iteration.
441 // If "is_par" is false, sets the token of "this" to
442 // "claim_token", and returns "true". If "is_par" is true,
443 // uses an atomic instruction to set the current thread's token to
444 // "claim_token", if it is not already. Returns "true" iff the
445 // calling thread does the update, this indicates that the calling thread
446 // has claimed the thread in the current iteration.
447 bool claim_threads_do(bool is_par, uintx claim_token) {
448 if (!is_par) {
449 _threads_do_token = claim_token;
450 return true;
451 } else {
452 return claim_par_threads_do(claim_token);
453 }
454 }
455
456 uintx threads_do_token() const { return _threads_do_token; }
457
458 // jvmtiRedefineClasses support
459 void metadata_handles_do(void f(Metadata*));
460
461 private:
462 // Check if address is within the given range of this thread's
463 // stack: stack_base() > adr >/>= limit
464 // The check is inclusive of limit if passed true, else exclusive.
465 bool is_in_stack_range(address adr, address limit, bool inclusive) const {
466 assert(stack_base() > limit && limit >= stack_end(), "limit is outside of stack");
467 return stack_base() > adr && (inclusive ? adr >= limit : adr > limit);
468 }
469
470 public:
471 // Check if address is within the given range of this thread's
472 // stack: stack_base() > adr >= limit
473 bool is_in_stack_range_incl(address adr, address limit) const {
474 return is_in_stack_range(adr, limit, true);
475 }
476
477 // Check if address is within the given range of this thread's
478 // stack: stack_base() > adr > limit
479 bool is_in_stack_range_excl(address adr, address limit) const {
480 return is_in_stack_range(adr, limit, false);
481 }
482
483 // Check if address is in the stack mapped to this thread. Used mainly in
484 // error reporting (so has to include guard zone) and frame printing.
485 // Expects _stack_base to be initialized - checked with assert.
486 bool is_in_full_stack_checked(address adr) const {
487 return is_in_stack_range_incl(adr, stack_end());
488 }
489
490 // Like is_in_full_stack_checked but without the assertions as this
491 // may be called in a thread before _stack_base is initialized.
492 bool is_in_full_stack(address adr) const {
493 address stack_end = _stack_base - _stack_size;
494 return _stack_base > adr && adr >= stack_end;
495 }
496
497 // Check if address is in the live stack of this thread (not just for locks).
498 // Warning: can only be called by the current thread on itself.
499 bool is_in_live_stack(address adr) const {
500 assert(Thread::current() == this, "is_in_live_stack can only be called from current thread");
501 return is_in_stack_range_incl(adr, os::current_stack_pointer());
502 }
503
504 // Sets the argument thread as starting thread. Returns failure if thread
505 // creation fails due to lack of memory, too many threads etc.
506 static bool set_as_starting_thread(JavaThread* jt);
507
508 protected:
509 // OS data associated with the thread
510 OSThread* _osthread; // Platform-specific thread information
511
512 // Thread local resource area for temporary allocation within the VM
513 ResourceArea* _resource_area;
514
515 DEBUG_ONLY(ResourceMark* _current_resource_mark;)
516
517 // Thread local handle area for allocation of handles within the VM
518 HandleArea* _handle_area;
519 GrowableArray<Metadata*>* _metadata_handles;
520
521 // Support for stack overflow handling, get_thread, etc.
522 address _stack_base;
523 size_t _stack_size;
524 int _lgrp_id;
525
526 public:
527 // Stack overflow support
528 address stack_base() const DEBUG_ONLY(;) NOT_DEBUG({ return _stack_base; })
529 // Needed for code that can query a new thread before the stack has been set.
530 address stack_base_or_null() const { return _stack_base; }
531 void set_stack_base(address base) { _stack_base = base; }
532 size_t stack_size() const { return _stack_size; }
533 void set_stack_size(size_t size) { _stack_size = size; }
534 address stack_end() const { return stack_base() - stack_size(); }
535 void record_stack_base_and_size();
536 void register_thread_stack_with_NMT();
537 void unregister_thread_stack_with_NMT();
538
539 int lgrp_id() const { return _lgrp_id; }
540 void set_lgrp_id(int value) { _lgrp_id = value; }
541
542 // Printing
543 void print_on(outputStream* st, bool print_extended_info) const;
544 virtual void print_on(outputStream* st) const { print_on(st, false); }
545 void print() const;
546 virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
547 // Basic, non-virtual, printing support that is simple and always safe.
548 void print_value_on(outputStream* st) const;
549
550 // Debug-only code
551 #ifdef ASSERT
552 private:
553 // Deadlock detection support for Mutex locks. List of locks own by thread.
554 Mutex* _owned_locks;
555 // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
556 // thus the friendship
557 friend class Mutex;
558 friend class Monitor;
559
560 public:
561 void print_owned_locks_on(outputStream* st) const;
562 void print_owned_locks() const { print_owned_locks_on(tty); }
563 Mutex* owned_locks() const { return _owned_locks; }
564 bool owns_locks() const { return owned_locks() != nullptr; }
565
566 // Deadlock detection
567 ResourceMark* current_resource_mark() { return _current_resource_mark; }
568 void set_current_resource_mark(ResourceMark* rm) { _current_resource_mark = rm; }
569 #endif // ASSERT
570
571 private:
572 volatile int _jvmti_env_iteration_count;
573
574 public:
575 void entering_jvmti_env_iteration() { ++_jvmti_env_iteration_count; }
576 void leaving_jvmti_env_iteration() { --_jvmti_env_iteration_count; }
577 bool is_inside_jvmti_env_iteration() { return _jvmti_env_iteration_count > 0; }
578
579 // Code generation
580 static ByteSize exception_file_offset() { return byte_offset_of(Thread, _exception_file); }
581 static ByteSize exception_line_offset() { return byte_offset_of(Thread, _exception_line); }
582
583 static ByteSize stack_base_offset() { return byte_offset_of(Thread, _stack_base); }
584 static ByteSize stack_size_offset() { return byte_offset_of(Thread, _stack_size); }
585
586 static ByteSize tlab_start_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::start_offset(); }
587 static ByteSize tlab_end_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::end_offset(); }
588 static ByteSize tlab_top_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::top_offset(); }
589 static ByteSize tlab_pf_top_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::pf_top_offset(); }
590
591 JFR_ONLY(DEFINE_THREAD_LOCAL_OFFSET_JFR;)
592
593 public:
594 ParkEvent * volatile _ParkEvent; // for Object monitors, JVMTI raw monitors,
595 // and ObjectSynchronizer::read_stable_mark
596
597 // Termination indicator used by the signal handler.
598 // _ParkEvent is just a convenient field we can null out after setting the JavaThread termination state
599 // (which can't itself be read from the signal handler if a signal hits during the Thread destructor).
600 bool has_terminated() { return Atomic::load(&_ParkEvent) == nullptr; };
601
602 jint _hashStateW; // Marsaglia Shift-XOR thread-local RNG
603 jint _hashStateX; // thread-specific hashCode generator state
604 jint _hashStateY;
605 jint _hashStateZ;
606
607 // Low-level leaf-lock primitives used to implement synchronization.
608 // Not for general synchronization use.
609 static void SpinAcquire(volatile int * Lock);
610 static void SpinRelease(volatile int * Lock);
611
612 #if defined(__APPLE__) && defined(AARCH64)
613 private:
614 DEBUG_ONLY(bool _wx_init);
615 WXMode _wx_state;
616 public:
617 void init_wx();
618 WXMode enable_wx(WXMode new_state);
619
620 void assert_wx_state(WXMode expected) {
621 assert(_wx_state == expected, "wrong state");
622 }
623 #endif // __APPLE__ && AARCH64
624
625 private:
626 bool _in_asgct = false;
627 public:
628 bool in_asgct() const { return _in_asgct; }
629 void set_in_asgct(bool value) { _in_asgct = value; }
630 static bool current_in_asgct() {
631 Thread *cur = Thread::current_or_null_safe();
632 return cur != nullptr && cur->in_asgct();
633 }
634
635 private:
636 VMErrorCallback* _vm_error_callbacks;
637 };
638
639 class ThreadInAsgct {
640 private:
641 Thread* _thread;
642 bool _saved_in_asgct;
643 public:
644 ThreadInAsgct(Thread* thread) : _thread(thread) {
645 assert(thread != nullptr, "invariant");
646 // Allow AsyncGetCallTrace to be reentrant - save the previous state.
647 _saved_in_asgct = thread->in_asgct();
648 thread->set_in_asgct(true);
649 }
650 ~ThreadInAsgct() {
651 assert(_thread->in_asgct(), "invariant");
652 _thread->set_in_asgct(_saved_in_asgct);
653 }
654 };
655
656 // Inline implementation of Thread::current()
657 inline Thread* Thread::current() {
658 Thread* current = current_or_null();
659 assert(current != nullptr, "Thread::current() called on detached thread");
660 return current;
661 }
662
663 inline Thread* Thread::current_or_null() {
664 return _thr_current;
665 }
666
667 inline Thread* Thread::current_or_null_safe() {
668 if (ThreadLocalStorage::is_initialized()) {
669 return ThreadLocalStorage::thread();
670 }
671 return nullptr;
672 }
673
674 #endif // SHARE_RUNTIME_THREAD_HPP