1 /*
2 * Copyright (c) 1997, 2024, 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 "jni.h"
30 #include "gc/shared/gcThreadLocalData.hpp"
31 #include "gc/shared/threadLocalAllocBuffer.hpp"
32 #include "memory/allocation.hpp"
33 #include "runtime/atomic.hpp"
34 #include "runtime/globals.hpp"
35 #include "runtime/os.hpp"
36 #include "runtime/threadHeapSampler.hpp"
37 #include "runtime/threadLocalStorage.hpp"
38 #include "runtime/threadStatisticalInfo.hpp"
39 #include "runtime/unhandledOops.hpp"
40 #include "utilities/globalDefinitions.hpp"
41 #include "utilities/macros.hpp"
42 #if INCLUDE_JFR
43 #include "jfr/support/jfrThreadExtension.hpp"
44 #endif
45
46 class CompilerThread;
47 class HandleArea;
48 class HandleMark;
49 class JvmtiRawMonitor;
50 class NMethodClosure;
51 class Metadata;
52 class OopClosure;
53 class OSThread;
54 class ParkEvent;
55 class ResourceArea;
56 class SafeThreadsListPtr;
57 class ThreadClosure;
58 class ThreadsList;
59 class ThreadsSMRSupport;
60 class VMErrorCallback;
61
62
63 DEBUG_ONLY(class ResourceMark;)
64
65 class WorkerThread;
66
67 class JavaThread;
68
69 // Class hierarchy
70 // - Thread
71 // - JavaThread
72 // - various subclasses eg CompilerThread, ServiceThread
73 // - NonJavaThread
74 // - NamedThread
75 // - VMThread
76 // - ConcurrentGCThread
77 // - WorkerThread
78 // - WatcherThread
79 // - JfrThreadSampler
80 // - LogAsyncWriter
81 //
82 // All Thread subclasses must be either JavaThread or NonJavaThread.
83 // This means !t->is_Java_thread() iff t is a NonJavaThread, or t is
84 // a partially constructed/destroyed Thread.
85
86 // Thread execution sequence and actions:
87 // All threads:
88 // - thread_native_entry // per-OS native entry point
89 // - stack initialization
90 // - other OS-level initialization (signal masks etc)
91 // - handshake with creating thread (if not started suspended)
92 // - this->call_run() // common shared entry point
93 // - shared common initialization
94 // - this->pre_run() // virtual per-thread-type initialization
95 // - this->run() // virtual per-thread-type "main" logic
96 // - shared common tear-down
97 // - this->post_run() // virtual per-thread-type tear-down
98 // - // 'this' no longer referenceable
99 // - OS-level tear-down (minimal)
100 // - final logging
101 //
102 // For JavaThread:
103 // - this->run() // virtual but not normally overridden
104 // - this->thread_main_inner() // extra call level to ensure correct stack calculations
105 // - this->entry_point() // set differently for each kind of JavaThread
106
107 class Thread: public ThreadShadow {
108 friend class VMError;
109 friend class VMErrorCallbackMark;
110 friend class VMStructs;
111 friend class JVMCIVMStructs;
112 private:
113
114 #ifndef USE_LIBRARY_BASED_TLS_ONLY
115 // Current thread is maintained as a thread-local variable
116 static THREAD_LOCAL Thread* _thr_current;
117 #endif
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 // Thread local data area available to the GC. The internal
139 // structure and contents of this data area is GC-specific.
140 // Only GC and GC barrier code should access this data area.
141 GCThreadLocalData _gc_data;
142
143 public:
144 static ByteSize gc_data_offset() {
145 return byte_offset_of(Thread, _gc_data);
146 }
147
148 template <typename T> T* gc_data() {
149 STATIC_ASSERT(sizeof(T) <= sizeof(_gc_data));
150 return reinterpret_cast<T*>(&_gc_data);
151 }
152
153 // Exception handling
154 // (Note: _pending_exception and friends are in ThreadShadow)
155 //oop _pending_exception; // pending exception for current thread
156 // const char* _exception_file; // file information for exception (debugging only)
157 // int _exception_line; // line information for exception (debugging only)
158 protected:
159
160 DEBUG_ONLY(static Thread* _starting_thread;)
161
162 // JavaThread lifecycle support:
163 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
164 friend class ScanHazardPtrGatherProtectedThreadsClosure; // for cmpxchg_threads_hazard_ptr(), get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
165 friend class ScanHazardPtrGatherThreadsListClosure; // for get_threads_hazard_ptr(), untag_hazard_ptr() access
166 friend class ScanHazardPtrPrintMatchingThreadsClosure; // for get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
167 friend class ThreadsSMRSupport; // for _nested_threads_hazard_ptr_cnt, _threads_hazard_ptr, _threads_list_ptr access
168 friend class ThreadsListHandleTest; // for _nested_threads_hazard_ptr_cnt, _threads_hazard_ptr, _threads_list_ptr access
169 friend class ValidateHazardPtrsClosure; // for get_threads_hazard_ptr(), untag_hazard_ptr() access
170
171 ThreadsList* volatile _threads_hazard_ptr;
172 SafeThreadsListPtr* _threads_list_ptr;
173 ThreadsList* cmpxchg_threads_hazard_ptr(ThreadsList* exchange_value, ThreadsList* compare_value);
174 ThreadsList* get_threads_hazard_ptr() const;
175 void set_threads_hazard_ptr(ThreadsList* new_list);
176 static bool is_hazard_ptr_tagged(ThreadsList* list) {
177 return (intptr_t(list) & intptr_t(1)) == intptr_t(1);
178 }
179 static ThreadsList* tag_hazard_ptr(ThreadsList* list) {
180 return (ThreadsList*)(intptr_t(list) | intptr_t(1));
181 }
182 static ThreadsList* untag_hazard_ptr(ThreadsList* list) {
183 return (ThreadsList*)(intptr_t(list) & ~intptr_t(1));
184 }
185 // This field is enabled via -XX:+EnableThreadSMRStatistics:
186 uint _nested_threads_hazard_ptr_cnt;
187 void dec_nested_threads_hazard_ptr_cnt() {
188 assert(_nested_threads_hazard_ptr_cnt != 0, "mismatched {dec,inc}_nested_threads_hazard_ptr_cnt()");
189 _nested_threads_hazard_ptr_cnt--;
190 }
191 void inc_nested_threads_hazard_ptr_cnt() {
192 _nested_threads_hazard_ptr_cnt++;
193 }
194 uint nested_threads_hazard_ptr_cnt() {
195 return _nested_threads_hazard_ptr_cnt;
196 }
197
198 public:
199 // Is the target JavaThread protected by the calling Thread or by some other
200 // mechanism?
201 static bool is_JavaThread_protected(const JavaThread* target);
202 // Is the target JavaThread protected by a ThreadsListHandle (TLH) associated
203 // with the calling Thread?
204 static bool is_JavaThread_protected_by_TLH(const JavaThread* target);
205
206 private:
207 DEBUG_ONLY(bool _suspendible_thread;)
208 DEBUG_ONLY(bool _indirectly_suspendible_thread;)
209 DEBUG_ONLY(bool _indirectly_safepoint_thread;)
210
211 public:
212 #ifdef ASSERT
213 void set_suspendible_thread() { _suspendible_thread = true; }
214 void clear_suspendible_thread() { _suspendible_thread = false; }
215 bool is_suspendible_thread() { return _suspendible_thread; }
216
217 void set_indirectly_suspendible_thread() { _indirectly_suspendible_thread = true; }
218 void clear_indirectly_suspendible_thread() { _indirectly_suspendible_thread = false; }
219 bool is_indirectly_suspendible_thread() { return _indirectly_suspendible_thread; }
220
221 void set_indirectly_safepoint_thread() { _indirectly_safepoint_thread = true; }
222 void clear_indirectly_safepoint_thread() { _indirectly_safepoint_thread = false; }
223 bool is_indirectly_safepoint_thread() { return _indirectly_safepoint_thread; }
224 #endif
225
226 private:
227 // Point to the last handle mark
228 HandleMark* _last_handle_mark;
229
230 // Claim value for parallel iteration over threads.
231 uintx _threads_do_token;
232
233 // Support for GlobalCounter
234 private:
235 volatile uintx _rcu_counter;
236 public:
237 volatile uintx* get_rcu_counter() {
238 return &_rcu_counter;
239 }
240
241 public:
242 void set_last_handle_mark(HandleMark* mark) { _last_handle_mark = mark; }
243 HandleMark* last_handle_mark() const { return _last_handle_mark; }
244
245 private:
246 // Used by SkipGCALot class.
247 NOT_PRODUCT(bool _skip_gcalot;) // Should we elide gc-a-lot?
248
249 friend class GCLocker;
250
251 private:
252 ThreadLocalAllocBuffer _tlab; // Thread-local eden
253 jlong _allocated_bytes; // Cumulative number of bytes allocated on
254 // the Java heap
255 ThreadHeapSampler _heap_sampler; // For use when sampling the memory.
256
257 ThreadStatisticalInfo _statistical_info; // Statistics about the thread
258
259 JFR_ONLY(DEFINE_THREAD_LOCAL_FIELD_JFR;) // Thread-local data for jfr
260
261 JvmtiRawMonitor* _current_pending_raw_monitor; // JvmtiRawMonitor this thread
262 // is waiting to lock
263 public:
264 // Constructor
265 Thread(MemTag mem_tag = mtThread);
266 virtual ~Thread() = 0; // Thread is abstract.
267
268 // Manage Thread::current()
269 void initialize_thread_current();
270 static void clear_thread_current(); // TLS cleanup needed before threads terminate
271
272 protected:
273 // To be implemented by children.
274 virtual void run() = 0;
275 virtual void pre_run() = 0;
276 virtual void post_run() = 0; // Note: Thread must not be deleted prior to calling this!
277
278 #ifdef ASSERT
279 enum RunState {
280 PRE_CALL_RUN,
281 CALL_RUN,
282 PRE_RUN,
283 RUN,
284 POST_RUN
285 // POST_CALL_RUN - can't define this one as 'this' may be deleted when we want to set it
286 };
287 RunState _run_state; // for lifecycle checks
288 #endif
289
290
291 public:
292 // invokes <ChildThreadClass>::run(), with common preparations and cleanups.
293 void call_run();
294
295 // Testers
296 virtual bool is_VM_thread() const { return false; }
297 virtual bool is_Java_thread() const { return false; }
298 virtual bool is_Compiler_thread() const { return false; }
299 virtual bool is_service_thread() const { return false; }
300 virtual bool is_hidden_from_external_view() const { return false; }
301 virtual bool is_jvmti_agent_thread() const { return false; }
302 virtual bool is_Watcher_thread() const { return false; }
303 virtual bool is_ConcurrentGC_thread() const { return false; }
304 virtual bool is_Named_thread() const { return false; }
305 virtual bool is_Worker_thread() const { return false; }
306 virtual bool is_JfrSampler_thread() const { return false; }
307 virtual bool is_AttachListener_thread() const { return false; }
308 virtual bool is_monitor_deflation_thread() const { return false; }
309
310 // Convenience cast functions
311 CompilerThread* as_Compiler_thread() const {
312 assert(is_Compiler_thread(), "Must be compiler thread");
313 return (CompilerThread*)this;
314 }
315
316 // Can this thread make Java upcalls
317 virtual bool can_call_java() const { return false; }
318
319 // Is this a JavaThread that is on the VM's current ThreadsList?
320 // If so it must participate in the safepoint protocol.
321 virtual bool is_active_Java_thread() const { return false; }
322
323 // All threads are given names. For singleton subclasses we can
324 // just hard-wire the known name of the instance. JavaThreads and
325 // NamedThreads support multiple named instances, and dynamic
326 // changing of the name of an instance.
327 virtual const char* name() const { return "Unknown thread"; }
328
329 // A thread's type name is also made available for debugging
330 // and logging.
331 virtual const char* type_name() const { return "Thread"; }
332
333 // Returns the current thread (ASSERTS if null)
334 static inline Thread* current();
335 // Returns the current thread, or null if not attached
336 static inline Thread* current_or_null();
337 // Returns the current thread, or null if not attached, and is
338 // safe for use from signal-handlers
339 static inline Thread* current_or_null_safe();
340
341 // Common thread operations
342 #ifdef ASSERT
343 static void check_for_dangling_thread_pointer(Thread *thread);
344 #endif
345 static void set_priority(Thread* thread, ThreadPriority priority);
346 static void start(Thread* thread);
347
348 void set_native_thread_name(const char *name) {
349 assert(Thread::current() == this, "set_native_thread_name can only be called on the current thread");
350 os::set_native_thread_name(name);
351 }
352
353 // Support for Unhandled Oop detection
354 // Add the field for both, fastdebug and debug, builds to keep
355 // Thread's fields layout the same.
356 // Note: CHECK_UNHANDLED_OOPS is defined only for fastdebug build.
357 #ifdef CHECK_UNHANDLED_OOPS
358 private:
359 UnhandledOops* _unhandled_oops;
360 #elif defined(ASSERT)
361 private:
362 void* _unhandled_oops;
363 #endif
364 #ifdef CHECK_UNHANDLED_OOPS
365 public:
366 UnhandledOops* unhandled_oops() { return _unhandled_oops; }
367 // Mark oop safe for gc. It may be stack allocated but won't move.
368 void allow_unhandled_oop(oop *op) {
369 if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
370 }
371 // Clear oops at safepoint so crashes point to unhandled oop violator
372 void clear_unhandled_oops() {
373 if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
374 }
375 #endif // CHECK_UNHANDLED_OOPS
376
377 public:
378 #ifndef PRODUCT
379 bool skip_gcalot() { return _skip_gcalot; }
380 void set_skip_gcalot(bool v) { _skip_gcalot = v; }
381 #endif
382
383 // Resource area
384 ResourceArea* resource_area() const { return _resource_area; }
385 void set_resource_area(ResourceArea* area) { _resource_area = area; }
386
387 OSThread* osthread() const { return _osthread; }
388 void set_osthread(OSThread* thread) { _osthread = thread; }
389
390 // Internal handle support
391 HandleArea* handle_area() const { return _handle_area; }
392 void set_handle_area(HandleArea* area) { _handle_area = area; }
393
394 GrowableArray<Metadata*>* metadata_handles() const { return _metadata_handles; }
395 void set_metadata_handles(GrowableArray<Metadata*>* handles){ _metadata_handles = handles; }
396
397 // Thread-Local Allocation Buffer (TLAB) support
398 ThreadLocalAllocBuffer& tlab() { return _tlab; }
399 void initialize_tlab();
400
401 jlong allocated_bytes() { return _allocated_bytes; }
402 void set_allocated_bytes(jlong value) { _allocated_bytes = value; }
403 void incr_allocated_bytes(jlong size) { _allocated_bytes += size; }
404 inline jlong cooked_allocated_bytes();
405
406 ThreadHeapSampler& heap_sampler() { return _heap_sampler; }
407
408 ThreadStatisticalInfo& statistical_info() { return _statistical_info; }
409
410 JFR_ONLY(DEFINE_THREAD_LOCAL_ACCESSOR_JFR;)
411
412 // For tracking the Jvmti raw monitor the thread is pending on.
413 JvmtiRawMonitor* current_pending_raw_monitor() {
414 return _current_pending_raw_monitor;
415 }
416 void set_current_pending_raw_monitor(JvmtiRawMonitor* monitor) {
417 _current_pending_raw_monitor = monitor;
418 }
419
420 // GC support
421 // Apply "f->do_oop" to all root oops in "this".
422 // Used by JavaThread::oops_do.
423 // Apply "cf->do_nmethod" (if !nullptr) to all nmethods active in frames
424 virtual void oops_do_no_frames(OopClosure* f, NMethodClosure* cf);
425 virtual void oops_do_frames(OopClosure* f, NMethodClosure* cf) {}
426 void oops_do(OopClosure* f, NMethodClosure* cf);
427
428 // Handles the parallel case for claim_threads_do.
429 private:
430 bool claim_par_threads_do(uintx claim_token);
431 public:
432 // Requires that "claim_token" is that of the current iteration.
433 // If "is_par" is false, sets the token of "this" to
434 // "claim_token", and returns "true". If "is_par" is true,
435 // uses an atomic instruction to set the current thread's token to
436 // "claim_token", if it is not already. Returns "true" iff the
437 // calling thread does the update, this indicates that the calling thread
438 // has claimed the thread in the current iteration.
439 bool claim_threads_do(bool is_par, uintx claim_token) {
440 if (!is_par) {
441 _threads_do_token = claim_token;
442 return true;
443 } else {
444 return claim_par_threads_do(claim_token);
445 }
446 }
447
448 uintx threads_do_token() const { return _threads_do_token; }
449
450 // jvmtiRedefineClasses support
451 void metadata_handles_do(void f(Metadata*));
452
453 private:
454 // Check if address is within the given range of this thread's
455 // stack: stack_base() > adr >/>= limit
456 // The check is inclusive of limit if passed true, else exclusive.
457 bool is_in_stack_range(address adr, address limit, bool inclusive) const {
458 assert(stack_base() > limit && limit >= stack_end(), "limit is outside of stack");
459 return stack_base() > adr && (inclusive ? adr >= limit : adr > limit);
460 }
461
462 public:
463 // Check if address is within the given range of this thread's
464 // stack: stack_base() > adr >= limit
465 bool is_in_stack_range_incl(address adr, address limit) const {
466 return is_in_stack_range(adr, limit, true);
467 }
468
469 // Check if address is within the given range of this thread's
470 // stack: stack_base() > adr > limit
471 bool is_in_stack_range_excl(address adr, address limit) const {
472 return is_in_stack_range(adr, limit, false);
473 }
474
475 // Check if address is in the stack mapped to this thread. Used mainly in
476 // error reporting (so has to include guard zone) and frame printing.
477 // Expects _stack_base to be initialized - checked with assert.
478 bool is_in_full_stack_checked(address adr) const {
479 return is_in_stack_range_incl(adr, stack_end());
480 }
481
482 // Like is_in_full_stack_checked but without the assertions as this
483 // may be called in a thread before _stack_base is initialized.
484 bool is_in_full_stack(address adr) const {
485 address stack_end = _stack_base - _stack_size;
486 return _stack_base > adr && adr >= stack_end;
487 }
488
489 // Check if address is in the live stack of this thread (not just for locks).
490 // Warning: can only be called by the current thread on itself.
491 bool is_in_live_stack(address adr) const {
492 assert(Thread::current() == this, "is_in_live_stack can only be called from current thread");
493 return is_in_stack_range_incl(adr, os::current_stack_pointer());
494 }
495
496 // Sets this thread as starting thread. Returns failure if thread
497 // creation fails due to lack of memory, too many threads etc.
498 bool set_as_starting_thread();
499
500 protected:
501 // OS data associated with the thread
502 OSThread* _osthread; // Platform-specific thread information
503
504 // Thread local resource area for temporary allocation within the VM
505 ResourceArea* _resource_area;
506
507 DEBUG_ONLY(ResourceMark* _current_resource_mark;)
508
509 // Thread local handle area for allocation of handles within the VM
510 HandleArea* _handle_area;
511 GrowableArray<Metadata*>* _metadata_handles;
512
513 // Support for stack overflow handling, get_thread, etc.
514 address _stack_base;
515 size_t _stack_size;
516 int _lgrp_id;
517
518 public:
519 // Stack overflow support
520 address stack_base() const DEBUG_ONLY(;) NOT_DEBUG({ return _stack_base; })
521 void set_stack_base(address base) { _stack_base = base; }
522 size_t stack_size() const { return _stack_size; }
523 void set_stack_size(size_t size) { _stack_size = size; }
524 address stack_end() const { return stack_base() - stack_size(); }
525 void record_stack_base_and_size();
526 void register_thread_stack_with_NMT();
527 void unregister_thread_stack_with_NMT();
528
529 int lgrp_id() const { return _lgrp_id; }
530 void set_lgrp_id(int value) { _lgrp_id = value; }
531
532 // Printing
533 void print_on(outputStream* st, bool print_extended_info) const;
534 virtual void print_on(outputStream* st) const { print_on(st, false); }
535 void print() const;
536 virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
537 // Basic, non-virtual, printing support that is simple and always safe.
538 void print_value_on(outputStream* st) const;
539
540 // Debug-only code
541 #ifdef ASSERT
542 private:
543 // Deadlock detection support for Mutex locks. List of locks own by thread.
544 Mutex* _owned_locks;
545 // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
546 // thus the friendship
547 friend class Mutex;
548 friend class Monitor;
549
550 public:
551 void print_owned_locks_on(outputStream* st) const;
552 void print_owned_locks() const { print_owned_locks_on(tty); }
553 Mutex* owned_locks() const { return _owned_locks; }
554 bool owns_locks() const { return owned_locks() != nullptr; }
555
556 // Deadlock detection
557 ResourceMark* current_resource_mark() { return _current_resource_mark; }
558 void set_current_resource_mark(ResourceMark* rm) { _current_resource_mark = rm; }
559 #endif // ASSERT
560
561 private:
562 volatile int _jvmti_env_iteration_count;
563
564 public:
565 void entering_jvmti_env_iteration() { ++_jvmti_env_iteration_count; }
566 void leaving_jvmti_env_iteration() { --_jvmti_env_iteration_count; }
567 bool is_inside_jvmti_env_iteration() { return _jvmti_env_iteration_count > 0; }
568
569 // Code generation
570 static ByteSize exception_file_offset() { return byte_offset_of(Thread, _exception_file); }
571 static ByteSize exception_line_offset() { return byte_offset_of(Thread, _exception_line); }
572
573 static ByteSize stack_base_offset() { return byte_offset_of(Thread, _stack_base); }
574 static ByteSize stack_size_offset() { return byte_offset_of(Thread, _stack_size); }
575
576 static ByteSize tlab_start_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::start_offset(); }
577 static ByteSize tlab_end_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::end_offset(); }
578 static ByteSize tlab_top_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::top_offset(); }
579 static ByteSize tlab_pf_top_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::pf_top_offset(); }
580
581 JFR_ONLY(DEFINE_THREAD_LOCAL_OFFSET_JFR;)
582
583 public:
584 ParkEvent * volatile _ParkEvent; // for Object monitors, JVMTI raw monitors,
585 // and ObjectSynchronizer::read_stable_mark
586
587 // Termination indicator used by the signal handler.
588 // _ParkEvent is just a convenient field we can null out after setting the JavaThread termination state
589 // (which can't itself be read from the signal handler if a signal hits during the Thread destructor).
590 bool has_terminated() { return Atomic::load(&_ParkEvent) == nullptr; };
591
592 jint _hashStateW; // Marsaglia Shift-XOR thread-local RNG
593 jint _hashStateX; // thread-specific hashCode generator state
594 jint _hashStateY;
595 jint _hashStateZ;
596
597 // Low-level leaf-lock primitives used to implement synchronization.
598 // Not for general synchronization use.
599 static void SpinAcquire(volatile int * Lock, const char * Name);
600 static void SpinRelease(volatile int * Lock);
601
602 #if defined(__APPLE__) && defined(AARCH64)
603 private:
604 DEBUG_ONLY(bool _wx_init);
605 WXMode _wx_state;
606 public:
607 void init_wx();
608 WXMode enable_wx(WXMode new_state);
609
610 void assert_wx_state(WXMode expected) {
611 assert(_wx_state == expected, "wrong state");
612 }
613 #endif // __APPLE__ && AARCH64
614
615 private:
616 bool _in_asgct = false;
617 public:
618 bool in_asgct() const { return _in_asgct; }
619 void set_in_asgct(bool value) { _in_asgct = value; }
620 static bool current_in_asgct() {
621 Thread *cur = Thread::current_or_null_safe();
622 return cur != nullptr && cur->in_asgct();
623 }
624
625 private:
626 VMErrorCallback* _vm_error_callbacks;
627 };
628
629 class ThreadInAsgct {
630 private:
631 Thread* _thread;
632 bool _saved_in_asgct;
633 public:
634 ThreadInAsgct(Thread* thread) : _thread(thread) {
635 assert(thread != nullptr, "invariant");
636 // Allow AsyncGetCallTrace to be reentrant - save the previous state.
637 _saved_in_asgct = thread->in_asgct();
638 thread->set_in_asgct(true);
639 }
640 ~ThreadInAsgct() {
641 assert(_thread->in_asgct(), "invariant");
642 _thread->set_in_asgct(_saved_in_asgct);
643 }
644 };
645
646 // Inline implementation of Thread::current()
647 inline Thread* Thread::current() {
648 Thread* current = current_or_null();
649 assert(current != nullptr, "Thread::current() called on detached thread");
650 return current;
651 }
652
653 inline Thread* Thread::current_or_null() {
654 #ifndef USE_LIBRARY_BASED_TLS_ONLY
655 return _thr_current;
656 #else
657 if (ThreadLocalStorage::is_initialized()) {
658 return ThreadLocalStorage::thread();
659 }
660 return nullptr;
661 #endif
662 }
663
664 inline Thread* Thread::current_or_null_safe() {
665 if (ThreadLocalStorage::is_initialized()) {
666 return ThreadLocalStorage::thread();
667 }
668 return nullptr;
669 }
670
671 #endif // SHARE_RUNTIME_THREAD_HPP