1 /*
2 * Copyright (c) 1997, 2010, 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 class ThreadSafepointState;
26 class ThreadProfiler;
27
28 class JvmtiThreadState;
29 class JvmtiGetLoadedClassesClosure;
30 class ThreadStatistics;
31 class ConcurrentLocksDump;
32 class ParkEvent ;
33
34 class ciEnv;
35 class CompileThread;
36 class CompileLog;
37 class CompileTask;
38 class CompileQueue;
39 class CompilerCounters;
40 class vframeArray;
41
42 class DeoptResourceMark;
43 class jvmtiDeferredLocalVariableSet;
44
45 class GCTaskQueue;
46 class ThreadClosure;
47 class IdealGraphPrinter;
48
49 // Class hierarchy
50 // - Thread
51 // - NamedThread
52 // - VMThread
53 // - ConcurrentGCThread
54 // - WorkerThread
55 // - GangWorker
56 // - GCTaskThread
57 // - JavaThread
58 // - WatcherThread
59
60 class Thread: public ThreadShadow {
61 friend class VMStructs;
62 private:
63 // Exception handling
64 // (Note: _pending_exception and friends are in ThreadShadow)
65 //oop _pending_exception; // pending exception for current thread
66 // const char* _exception_file; // file information for exception (debugging only)
67 // int _exception_line; // line information for exception (debugging only)
68
69 // Support for forcing alignment of thread objects for biased locking
70 void* _real_malloc_address;
71 public:
72 void* operator new(size_t size);
73 void operator delete(void* p);
74 private:
75
76 // ***************************************************************
77 // Suspend and resume support
78 // ***************************************************************
79 //
80 // VM suspend/resume no longer exists - it was once used for various
81 // things including safepoints but was deprecated and finally removed
82 // in Java 7. Because VM suspension was considered "internal" Java-level
83 // suspension was considered "external", and this legacy naming scheme
84 // remains.
85 //
86 // External suspend/resume requests come from JVM_SuspendThread,
87 // JVM_ResumeThread, JVMTI SuspendThread, and finally JVMTI
88 // ResumeThread. External
89 // suspend requests cause _external_suspend to be set and external
90 // resume requests cause _external_suspend to be cleared.
91 // External suspend requests do not nest on top of other external
92 // suspend requests. The higher level APIs reject suspend requests
93 // for already suspended threads.
94 //
95 // The external_suspend
96 // flag is checked by has_special_runtime_exit_condition() and java thread
97 // will self-suspend when handle_special_runtime_exit_condition() is
98 // called. Most uses of the _thread_blocked state in JavaThreads are
99 // considered the same as being externally suspended; if the blocking
100 // condition lifts, the JavaThread will self-suspend. Other places
101 // where VM checks for external_suspend include:
102 // + mutex granting (do not enter monitors when thread is suspended)
103 // + state transitions from _thread_in_native
104 //
105 // In general, java_suspend() does not wait for an external suspend
106 // request to complete. When it returns, the only guarantee is that
107 // the _external_suspend field is true.
108 //
109 // wait_for_ext_suspend_completion() is used to wait for an external
110 // suspend request to complete. External suspend requests are usually
111 // followed by some other interface call that requires the thread to
112 // be quiescent, e.g., GetCallTrace(). By moving the "wait time" into
113 // the interface that requires quiescence, we give the JavaThread a
114 // chance to self-suspend before we need it to be quiescent. This
115 // improves overall suspend/query performance.
116 //
117 // _suspend_flags controls the behavior of java_ suspend/resume.
118 // It must be set under the protection of SR_lock. Read from the flag is
119 // OK without SR_lock as long as the value is only used as a hint.
120 // (e.g., check _external_suspend first without lock and then recheck
121 // inside SR_lock and finish the suspension)
122 //
123 // _suspend_flags is also overloaded for other "special conditions" so
124 // that a single check indicates whether any special action is needed
125 // eg. for async exceptions.
126 // -------------------------------------------------------------------
127 // Notes:
128 // 1. The suspend/resume logic no longer uses ThreadState in OSThread
129 // but we still update its value to keep other part of the system (mainly
130 // JVMTI) happy. ThreadState is legacy code (see notes in
131 // osThread.hpp).
132 //
133 // 2. It would be more natural if set_external_suspend() is private and
134 // part of java_suspend(), but that probably would affect the suspend/query
135 // performance. Need more investigation on this.
136 //
137
138 // suspend/resume lock: used for self-suspend
139 Monitor* _SR_lock;
140
141 protected:
142 enum SuspendFlags {
143 // NOTE: avoid using the sign-bit as cc generates different test code
144 // when the sign-bit is used, and sometimes incorrectly - see CR 6398077
145
146 _external_suspend = 0x20000000U, // thread is asked to self suspend
147 _ext_suspended = 0x40000000U, // thread has self-suspended
148 _deopt_suspend = 0x10000000U, // thread needs to self suspend for deopt
149
150 _has_async_exception = 0x00000001U // there is a pending async exception
151 };
152
153 // various suspension related flags - atomically updated
154 // overloaded for async exception checking in check_special_condition_for_native_trans.
155 volatile uint32_t _suspend_flags;
156
157 private:
158 int _num_nested_signal;
159
160 public:
161 void enter_signal_handler() { _num_nested_signal++; }
162 void leave_signal_handler() { _num_nested_signal--; }
163 bool is_inside_signal_handler() const { return _num_nested_signal > 0; }
164
165 private:
166 // Debug tracing
167 static void trace(const char* msg, const Thread* const thread) PRODUCT_RETURN;
168
169 // Active_handles points to a block of handles
170 JNIHandleBlock* _active_handles;
171
172 // One-element thread local free list
173 JNIHandleBlock* _free_handle_block;
174
175 // Point to the last handle mark
176 HandleMark* _last_handle_mark;
177
178 // The parity of the last strong_roots iteration in which this thread was
179 // claimed as a task.
180 jint _oops_do_parity;
181
182 public:
183 void set_last_handle_mark(HandleMark* mark) { _last_handle_mark = mark; }
184 HandleMark* last_handle_mark() const { return _last_handle_mark; }
185 private:
186
187 // debug support for checking if code does allow safepoints or not
188 // GC points in the VM can happen because of allocation, invoking a VM operation, or blocking on
189 // mutex, or blocking on an object synchronizer (Java locking).
190 // If !allow_safepoint(), then an assertion failure will happen in any of the above cases
191 // If !allow_allocation(), then an assertion failure will happen during allocation
192 // (Hence, !allow_safepoint() => !allow_allocation()).
193 //
194 // The two classes No_Safepoint_Verifier and No_Allocation_Verifier are used to set these counters.
195 //
196 NOT_PRODUCT(int _allow_safepoint_count;) // If 0, thread allow a safepoint to happen
197 debug_only (int _allow_allocation_count;) // If 0, the thread is allowed to allocate oops.
198
199 // Used by SkipGCALot class.
200 NOT_PRODUCT(bool _skip_gcalot;) // Should we elide gc-a-lot?
201
202 // Record when GC is locked out via the GC_locker mechanism
203 CHECK_UNHANDLED_OOPS_ONLY(int _gc_locked_out_count;)
204
205 friend class No_Alloc_Verifier;
206 friend class No_Safepoint_Verifier;
207 friend class Pause_No_Safepoint_Verifier;
208 friend class ThreadLocalStorage;
209 friend class GC_locker;
210
211 ThreadLocalAllocBuffer _tlab; // Thread-local eden
212
213 int _vm_operation_started_count; // VM_Operation support
214 int _vm_operation_completed_count; // VM_Operation support
215
216 ObjectMonitor* _current_pending_monitor; // ObjectMonitor this thread
217 // is waiting to lock
218 bool _current_pending_monitor_is_from_java; // locking is from Java code
219
220 // ObjectMonitor on which this thread called Object.wait()
221 ObjectMonitor* _current_waiting_monitor;
222
223 // Private thread-local objectmonitor list - a simple cache organized as a SLL.
224 public:
225 ObjectMonitor * omFreeList ;
226 int omFreeCount ; // length of omFreeList
227 int omFreeProvision ; // reload chunk size
228
229 public:
230 enum {
231 is_definitely_current_thread = true
232 };
233
234 // Constructor
235 Thread();
236 virtual ~Thread();
237
238 // initializtion
239 void initialize_thread_local_storage();
240
241 // thread entry point
242 virtual void run();
243
244 // Testers
245 virtual bool is_VM_thread() const { return false; }
246 virtual bool is_Java_thread() const { return false; }
247 // Remove this ifdef when C1 is ported to the compiler interface.
248 virtual bool is_Compiler_thread() const { return false; }
249 virtual bool is_hidden_from_external_view() const { return false; }
250 virtual bool is_jvmti_agent_thread() const { return false; }
251 // True iff the thread can perform GC operations at a safepoint.
252 // Generally will be true only of VM thread and parallel GC WorkGang
253 // threads.
254 virtual bool is_GC_task_thread() const { return false; }
255 virtual bool is_Watcher_thread() const { return false; }
256 virtual bool is_ConcurrentGC_thread() const { return false; }
257 virtual bool is_Named_thread() const { return false; }
258
259 virtual char* name() const { return (char*)"Unknown thread"; }
260
261 // Returns the current thread
262 static inline Thread* current();
263
264 // Common thread operations
265 static void set_priority(Thread* thread, ThreadPriority priority);
266 static ThreadPriority get_priority(const Thread* const thread);
267 static void start(Thread* thread);
268 static void interrupt(Thread* thr);
269 static bool is_interrupted(Thread* thr, bool clear_interrupted);
270
271 Monitor* SR_lock() const { return _SR_lock; }
272
273 bool has_async_exception() const { return (_suspend_flags & _has_async_exception) != 0; }
274
275 void set_suspend_flag(SuspendFlags f) {
276 assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
277 uint32_t flags;
278 do {
279 flags = _suspend_flags;
280 }
281 while (Atomic::cmpxchg((jint)(flags | f),
282 (volatile jint*)&_suspend_flags,
283 (jint)flags) != (jint)flags);
284 }
285 void clear_suspend_flag(SuspendFlags f) {
286 assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
287 uint32_t flags;
288 do {
289 flags = _suspend_flags;
290 }
291 while (Atomic::cmpxchg((jint)(flags & ~f),
292 (volatile jint*)&_suspend_flags,
293 (jint)flags) != (jint)flags);
294 }
295
296 void set_has_async_exception() {
297 set_suspend_flag(_has_async_exception);
298 }
299 void clear_has_async_exception() {
300 clear_suspend_flag(_has_async_exception);
301 }
302
303 // Support for Unhandled Oop detection
304 #ifdef CHECK_UNHANDLED_OOPS
305 private:
306 UnhandledOops *_unhandled_oops;
307 public:
308 UnhandledOops* unhandled_oops() { return _unhandled_oops; }
309 // Mark oop safe for gc. It may be stack allocated but won't move.
310 void allow_unhandled_oop(oop *op) {
311 if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
312 }
313 // Clear oops at safepoint so crashes point to unhandled oop violator
314 void clear_unhandled_oops() {
315 if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
316 }
317 bool is_gc_locked_out() { return _gc_locked_out_count > 0; }
318 #endif // CHECK_UNHANDLED_OOPS
319
320 #ifndef PRODUCT
321 bool skip_gcalot() { return _skip_gcalot; }
322 void set_skip_gcalot(bool v) { _skip_gcalot = v; }
323 #endif
324
325 public:
326 // Installs a pending exception to be inserted later
327 static void send_async_exception(oop thread_oop, oop java_throwable);
328
329 // Resource area
330 ResourceArea* resource_area() const { return _resource_area; }
331 void set_resource_area(ResourceArea* area) { _resource_area = area; }
332
333 OSThread* osthread() const { return _osthread; }
334 void set_osthread(OSThread* thread) { _osthread = thread; }
335
336 // JNI handle support
337 JNIHandleBlock* active_handles() const { return _active_handles; }
338 void set_active_handles(JNIHandleBlock* block) { _active_handles = block; }
339 JNIHandleBlock* free_handle_block() const { return _free_handle_block; }
340 void set_free_handle_block(JNIHandleBlock* block) { _free_handle_block = block; }
341
342 // Internal handle support
343 HandleArea* handle_area() const { return _handle_area; }
344 void set_handle_area(HandleArea* area) { _handle_area = area; }
345
346 // Thread-Local Allocation Buffer (TLAB) support
347 ThreadLocalAllocBuffer& tlab() { return _tlab; }
348 void initialize_tlab() {
349 if (UseTLAB) {
350 tlab().initialize();
351 }
352 }
353
354 // VM operation support
355 int vm_operation_ticket() { return ++_vm_operation_started_count; }
356 int vm_operation_completed_count() { return _vm_operation_completed_count; }
357 void increment_vm_operation_completed_count() { _vm_operation_completed_count++; }
358
359 // For tracking the heavyweight monitor the thread is pending on.
360 ObjectMonitor* current_pending_monitor() {
361 return _current_pending_monitor;
362 }
363 void set_current_pending_monitor(ObjectMonitor* monitor) {
364 _current_pending_monitor = monitor;
365 }
366 void set_current_pending_monitor_is_from_java(bool from_java) {
367 _current_pending_monitor_is_from_java = from_java;
368 }
369 bool current_pending_monitor_is_from_java() {
370 return _current_pending_monitor_is_from_java;
371 }
372
373 // For tracking the ObjectMonitor on which this thread called Object.wait()
374 ObjectMonitor* current_waiting_monitor() {
375 return _current_waiting_monitor;
376 }
377 void set_current_waiting_monitor(ObjectMonitor* monitor) {
378 _current_waiting_monitor = monitor;
379 }
380
381 // GC support
382 // Apply "f->do_oop" to all root oops in "this".
383 // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
384 void oops_do(OopClosure* f, CodeBlobClosure* cf);
385
386 // Handles the parallel case for the method below.
387 private:
388 bool claim_oops_do_par_case(int collection_parity);
389 public:
390 // Requires that "collection_parity" is that of the current strong roots
391 // iteration. If "is_par" is false, sets the parity of "this" to
392 // "collection_parity", and returns "true". If "is_par" is true,
393 // uses an atomic instruction to set the current threads parity to
394 // "collection_parity", if it is not already. Returns "true" iff the
395 // calling thread does the update, this indicates that the calling thread
396 // has claimed the thread's stack as a root groop in the current
397 // collection.
398 bool claim_oops_do(bool is_par, int collection_parity) {
399 if (!is_par) {
400 _oops_do_parity = collection_parity;
401 return true;
402 } else {
403 return claim_oops_do_par_case(collection_parity);
404 }
405 }
406
407 // Sweeper support
408 void nmethods_do(CodeBlobClosure* cf);
409
410 // Tells if adr belong to this thread. This is used
411 // for checking if a lock is owned by the running thread.
412
413 // Used by fast lock support
414 virtual bool is_lock_owned(address adr) const;
415
416 // Check if address is in the stack of the thread (not just for locks).
417 // Warning: the method can only be used on the running thread
418 bool is_in_stack(address adr) const;
419
420 // Sets this thread as starting thread. Returns failure if thread
421 // creation fails due to lack of memory, too many threads etc.
422 bool set_as_starting_thread();
423
424 protected:
425 // OS data associated with the thread
426 OSThread* _osthread; // Platform-specific thread information
427
428 // Thread local resource area for temporary allocation within the VM
429 ResourceArea* _resource_area;
430
431 // Thread local handle area for allocation of handles within the VM
432 HandleArea* _handle_area;
433
434 // Support for stack overflow handling, get_thread, etc.
435 address _stack_base;
436 size_t _stack_size;
437 uintptr_t _self_raw_id; // used by get_thread (mutable)
438 int _lgrp_id;
439
440 public:
441 // Stack overflow support
442 address stack_base() const { assert(_stack_base != NULL,"Sanity check"); return _stack_base; }
443
444 void set_stack_base(address base) { _stack_base = base; }
445 size_t stack_size() const { return _stack_size; }
446 void set_stack_size(size_t size) { _stack_size = size; }
447 void record_stack_base_and_size();
448
449 int lgrp_id() const { return _lgrp_id; }
450 void set_lgrp_id(int value) { _lgrp_id = value; }
451
452 // Printing
453 void print_on(outputStream* st) const;
454 void print() const { print_on(tty); }
455 virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
456
457 // Debug-only code
458
459 #ifdef ASSERT
460 private:
461 // Deadlock detection support for Mutex locks. List of locks own by thread.
462 Monitor *_owned_locks;
463 // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
464 // thus the friendship
465 friend class Mutex;
466 friend class Monitor;
467
468 public:
469 void print_owned_locks_on(outputStream* st) const;
470 void print_owned_locks() const { print_owned_locks_on(tty); }
471 Monitor * owned_locks() const { return _owned_locks; }
472 bool owns_locks() const { return owned_locks() != NULL; }
473 bool owns_locks_but_compiled_lock() const;
474
475 // Deadlock detection
476 bool allow_allocation() { return _allow_allocation_count == 0; }
477 #endif
478
479 void check_for_valid_safepoint_state(bool potential_vm_operation) PRODUCT_RETURN;
480
481 private:
482 volatile int _jvmti_env_iteration_count;
483
484 public:
485 void entering_jvmti_env_iteration() { ++_jvmti_env_iteration_count; }
486 void leaving_jvmti_env_iteration() { --_jvmti_env_iteration_count; }
487 bool is_inside_jvmti_env_iteration() { return _jvmti_env_iteration_count > 0; }
488
489 // Code generation
490 static ByteSize exception_file_offset() { return byte_offset_of(Thread, _exception_file ); }
491 static ByteSize exception_line_offset() { return byte_offset_of(Thread, _exception_line ); }
492 static ByteSize active_handles_offset() { return byte_offset_of(Thread, _active_handles ); }
493
494 static ByteSize stack_base_offset() { return byte_offset_of(Thread, _stack_base ); }
495 static ByteSize stack_size_offset() { return byte_offset_of(Thread, _stack_size ); }
496 static ByteSize omFreeList_offset() { return byte_offset_of(Thread, omFreeList); }
497
498 #define TLAB_FIELD_OFFSET(name) \
499 static ByteSize tlab_##name##_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::name##_offset(); }
500
501 TLAB_FIELD_OFFSET(start)
502 TLAB_FIELD_OFFSET(end)
503 TLAB_FIELD_OFFSET(top)
504 TLAB_FIELD_OFFSET(pf_top)
505 TLAB_FIELD_OFFSET(size) // desired_size
506 TLAB_FIELD_OFFSET(refill_waste_limit)
507 TLAB_FIELD_OFFSET(number_of_refills)
508 TLAB_FIELD_OFFSET(fast_refill_waste)
509 TLAB_FIELD_OFFSET(slow_allocations)
510
511 #undef TLAB_FIELD_OFFSET
512
513 public:
514 volatile intptr_t _Stalled ;
515 volatile int _TypeTag ;
516 ParkEvent * _ParkEvent ; // for synchronized()
517 ParkEvent * _SleepEvent ; // for Thread.sleep
518 ParkEvent * _MutexEvent ; // for native internal Mutex/Monitor
519 ParkEvent * _MuxEvent ; // for low-level muxAcquire-muxRelease
520 int NativeSyncRecursion ; // diagnostic
521
522 volatile int _OnTrap ; // Resume-at IP delta
523 jint _hashStateW ; // Marsaglia Shift-XOR thread-local RNG
524 jint _hashStateX ; // thread-specific hashCode generator state
525 jint _hashStateY ;
526 jint _hashStateZ ;
527 void * _schedctl ;
528
529 intptr_t _ScratchA, _ScratchB ; // Scratch locations for fast-path sync code
530 static ByteSize ScratchA_offset() { return byte_offset_of(Thread, _ScratchA ); }
531 static ByteSize ScratchB_offset() { return byte_offset_of(Thread, _ScratchB ); }
532
533 volatile jint rng [4] ; // RNG for spin loop
534
535 // Low-level leaf-lock primitives used to implement synchronization
536 // and native monitor-mutex infrastructure.
537 // Not for general synchronization use.
538 static void SpinAcquire (volatile int * Lock, const char * Name) ;
539 static void SpinRelease (volatile int * Lock) ;
540 static void muxAcquire (volatile intptr_t * Lock, const char * Name) ;
541 static void muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) ;
542 static void muxRelease (volatile intptr_t * Lock) ;
543
544 };
545
546 // Inline implementation of Thread::current()
547 // Thread::current is "hot" it's called > 128K times in the 1st 500 msecs of
548 // startup.
549 // ThreadLocalStorage::thread is warm -- it's called > 16K times in the same
550 // period. This is inlined in thread_<os_family>.inline.hpp.
551
552 inline Thread* Thread::current() {
553 #ifdef ASSERT
554 // This function is very high traffic. Define PARANOID to enable expensive
555 // asserts.
556 #ifdef PARANOID
557 // Signal handler should call ThreadLocalStorage::get_thread_slow()
558 Thread* t = ThreadLocalStorage::get_thread_slow();
559 assert(t != NULL && !t->is_inside_signal_handler(),
560 "Don't use Thread::current() inside signal handler");
561 #endif
562 #endif
563 Thread* thread = ThreadLocalStorage::thread();
564 assert(thread != NULL, "just checking");
565 return thread;
566 }
567
568 // Name support for threads. non-JavaThread subclasses with multiple
569 // uniquely named instances should derive from this.
570 class NamedThread: public Thread {
571 friend class VMStructs;
572 enum {
573 max_name_len = 64
574 };
575 private:
576 char* _name;
577 // log JavaThread being processed by oops_do
578 JavaThread* _processed_thread;
579
580 public:
581 NamedThread();
582 ~NamedThread();
583 // May only be called once per thread.
584 void set_name(const char* format, ...);
585 virtual bool is_Named_thread() const { return true; }
586 virtual char* name() const { return _name == NULL ? (char*)"Unknown Thread" : _name; }
587 JavaThread *processed_thread() { return _processed_thread; }
588 void set_processed_thread(JavaThread *thread) { _processed_thread = thread; }
589 };
590
591 // Worker threads are named and have an id of an assigned work.
592 class WorkerThread: public NamedThread {
593 private:
594 uint _id;
595 public:
596 WorkerThread() : _id(0) { }
597 void set_id(uint work_id) { _id = work_id; }
598 uint id() const { return _id; }
599 };
600
601 // A single WatcherThread is used for simulating timer interrupts.
602 class WatcherThread: public Thread {
603 friend class VMStructs;
604 public:
605 virtual void run();
606
607 private:
608 static WatcherThread* _watcher_thread;
609
610 static bool _should_terminate;
611 public:
612 enum SomeConstants {
613 delay_interval = 10 // interrupt delay in milliseconds
614 };
615
616 // Constructor
617 WatcherThread();
618
619 // Tester
620 bool is_Watcher_thread() const { return true; }
621
622 // Printing
623 char* name() const { return (char*)"VM Periodic Task Thread"; }
624 void print_on(outputStream* st) const;
625 void print() const { print_on(tty); }
626
627 // Returns the single instance of WatcherThread
628 static WatcherThread* watcher_thread() { return _watcher_thread; }
629
630 // Create and start the single instance of WatcherThread, or stop it on shutdown
631 static void start();
632 static void stop();
633 };
634
635
636 class CompilerThread;
637
638 typedef void (*ThreadFunction)(JavaThread*, TRAPS);
639
640 class JavaThread: public Thread {
641 friend class VMStructs;
642 private:
643 JavaThread* _next; // The next thread in the Threads list
644 oop _threadObj; // The Java level thread object
645
646 #ifdef ASSERT
647 private:
648 int _java_call_counter;
649
650 public:
651 int java_call_counter() { return _java_call_counter; }
652 void inc_java_call_counter() { _java_call_counter++; }
653 void dec_java_call_counter() {
654 assert(_java_call_counter > 0, "Invalid nesting of JavaCallWrapper");
655 _java_call_counter--;
656 }
657 private: // restore original namespace restriction
658 #endif // ifdef ASSERT
659
660 #ifndef PRODUCT
661 public:
662 enum {
663 jump_ring_buffer_size = 16
664 };
665 private: // restore original namespace restriction
666 #endif
667
668 JavaFrameAnchor _anchor; // Encapsulation of current java frame and it state
669
670 ThreadFunction _entry_point;
671
672 JNIEnv _jni_environment;
673
674 // Deopt support
675 DeoptResourceMark* _deopt_mark; // Holds special ResourceMark for deoptimization
676
677 intptr_t* _must_deopt_id; // id of frame that needs to be deopted once we
678 // transition out of native
679
680 vframeArray* _vframe_array_head; // Holds the heap of the active vframeArrays
681 vframeArray* _vframe_array_last; // Holds last vFrameArray we popped
682 // Because deoptimization is lazy we must save jvmti requests to set locals
683 // in compiled frames until we deoptimize and we have an interpreter frame.
684 // This holds the pointer to array (yeah like there might be more than one) of
685 // description of compiled vframes that have locals that need to be updated.
686 GrowableArray<jvmtiDeferredLocalVariableSet*>* _deferred_locals_updates;
687
688 // Handshake value for fixing 6243940. We need a place for the i2c
689 // adapter to store the callee methodOop. This value is NEVER live
690 // across a gc point so it does NOT have to be gc'd
691 // The handshake is open ended since we can't be certain that it will
692 // be NULLed. This is because we rarely ever see the race and end up
693 // in handle_wrong_method which is the backend of the handshake. See
694 // code in i2c adapters and handle_wrong_method.
695
696 methodOop _callee_target;
697
698 // Oop results of VM runtime calls
699 oop _vm_result; // Used to pass back an oop result into Java code, GC-preserved
700 oop _vm_result_2; // Used to pass back an oop result into Java code, GC-preserved
701
702 // See ReduceInitialCardMarks: this holds the precise space interval of
703 // the most recent slow path allocation for which compiled code has
704 // elided card-marks for performance along the fast-path.
705 MemRegion _deferred_card_mark;
706
707 MonitorChunk* _monitor_chunks; // Contains the off stack monitors
708 // allocated during deoptimization
709 // and by JNI_MonitorEnter/Exit
710
711 // Async. requests support
712 enum AsyncRequests {
713 _no_async_condition = 0,
714 _async_exception,
715 _async_unsafe_access_error
716 };
717 AsyncRequests _special_runtime_exit_condition; // Enum indicating pending async. request
718 oop _pending_async_exception;
719
720 // Safepoint support
721 public: // Expose _thread_state for SafeFetchInt()
722 volatile JavaThreadState _thread_state;
723 private:
724 ThreadSafepointState *_safepoint_state; // Holds information about a thread during a safepoint
725 address _saved_exception_pc; // Saved pc of instruction where last implicit exception happened
726
727 // JavaThread termination support
728 enum TerminatedTypes {
729 _not_terminated = 0xDEAD - 2,
730 _thread_exiting, // JavaThread::exit() has been called for this thread
731 _thread_terminated, // JavaThread is removed from thread list
732 _vm_exited // JavaThread is still executing native code, but VM is terminated
733 // only VM_Exit can set _vm_exited
734 };
735
736 // In general a JavaThread's _terminated field transitions as follows:
737 //
738 // _not_terminated => _thread_exiting => _thread_terminated
739 //
740 // _vm_exited is a special value to cover the case of a JavaThread
741 // executing native code after the VM itself is terminated.
742 TerminatedTypes _terminated;
743 // suspend/resume support
744 volatile bool _suspend_equivalent; // Suspend equivalent condition
745 jint _in_deopt_handler; // count of deoptimization
746 // handlers thread is in
747 volatile bool _doing_unsafe_access; // Thread may fault due to unsafe access
748 bool _do_not_unlock_if_synchronized; // Do not unlock the receiver of a synchronized method (since it was
749 // never locked) when throwing an exception. Used by interpreter only.
750
751 // Flag to mark a JNI thread in the process of attaching - See CR 6404306
752 // This flag is never set true other than at construction, and in that case
753 // is shortly thereafter set false
754 volatile bool _is_attaching;
755
756 public:
757 // State of the stack guard pages for this thread.
758 enum StackGuardState {
759 stack_guard_unused, // not needed
760 stack_guard_yellow_disabled,// disabled (temporarily) after stack overflow
761 stack_guard_enabled // enabled
762 };
763
764 private:
765
766 StackGuardState _stack_guard_state;
767
768 // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
769 // used to temp. parsing values into and out of the runtime system during exception handling for compiled
770 // code)
771 volatile oop _exception_oop; // Exception thrown in compiled code
772 volatile address _exception_pc; // PC where exception happened
773 volatile address _exception_handler_pc; // PC for handler of exception
774 volatile int _exception_stack_size; // Size of frame where exception happened
775 volatile int _is_method_handle_return; // true (== 1) if the current exception PC is a MethodHandle call site.
776
777 // support for compilation
778 bool _is_compiling; // is true if a compilation is active inthis thread (one compilation per thread possible)
779
780 // support for JNI critical regions
781 jint _jni_active_critical; // count of entries into JNI critical region
782
783 // For deadlock detection.
784 int _depth_first_number;
785
786 // JVMTI PopFrame support
787 // This is set to popframe_pending to signal that top Java frame should be popped immediately
788 int _popframe_condition;
789
790 #ifndef PRODUCT
791 int _jmp_ring_index;
792 struct {
793 // We use intptr_t instead of address so debugger doesn't try and display strings
794 intptr_t _target;
795 intptr_t _instruction;
796 const char* _file;
797 int _line;
798 } _jmp_ring[ jump_ring_buffer_size ];
799 #endif /* PRODUCT */
800
801 #ifndef SERIALGC
802 // Support for G1 barriers
803
804 ObjPtrQueue _satb_mark_queue; // Thread-local log for SATB barrier.
805 // Set of all such queues.
806 static SATBMarkQueueSet _satb_mark_queue_set;
807
808 DirtyCardQueue _dirty_card_queue; // Thread-local log for dirty cards.
809 // Set of all such queues.
810 static DirtyCardQueueSet _dirty_card_queue_set;
811
812 void flush_barrier_queues();
813 #endif // !SERIALGC
814
815 friend class VMThread;
816 friend class ThreadWaitTransition;
817 friend class VM_Exit;
818
819 void initialize(); // Initialized the instance variables
820
821 public:
822 // Constructor
823 JavaThread(bool is_attaching = false); // for main thread and JNI attached threads
824 JavaThread(ThreadFunction entry_point, size_t stack_size = 0);
825 ~JavaThread();
826
827 #ifdef ASSERT
828 // verify this JavaThread hasn't be published in the Threads::list yet
829 void verify_not_published();
830 #endif
831
832 //JNI functiontable getter/setter for JVMTI jni function table interception API.
833 void set_jni_functions(struct JNINativeInterface_* functionTable) {
834 _jni_environment.functions = functionTable;
835 }
836 struct JNINativeInterface_* get_jni_functions() {
837 return (struct JNINativeInterface_ *)_jni_environment.functions;
838 }
839
840 // Executes Shutdown.shutdown()
841 void invoke_shutdown_hooks();
842
843 // Cleanup on thread exit
844 enum ExitType {
845 normal_exit,
846 jni_detach
847 };
848 void exit(bool destroy_vm, ExitType exit_type = normal_exit);
849
850 void cleanup_failed_attach_current_thread();
851
852 // Testers
853 virtual bool is_Java_thread() const { return true; }
854
855 // compilation
856 void set_is_compiling(bool f) { _is_compiling = f; }
857 bool is_compiling() const { return _is_compiling; }
858
859 // Thread chain operations
860 JavaThread* next() const { return _next; }
861 void set_next(JavaThread* p) { _next = p; }
862
863 // Thread oop. threadObj() can be NULL for initial JavaThread
864 // (or for threads attached via JNI)
865 oop threadObj() const { return _threadObj; }
866 void set_threadObj(oop p) { _threadObj = p; }
867
868 ThreadPriority java_priority() const; // Read from threadObj()
869
870 // Prepare thread and add to priority queue. If a priority is
871 // not specified, use the priority of the thread object. Threads_lock
872 // must be held while this function is called.
873 void prepare(jobject jni_thread, ThreadPriority prio=NoPriority);
874
875 void set_saved_exception_pc(address pc) { _saved_exception_pc = pc; }
876 address saved_exception_pc() { return _saved_exception_pc; }
877
878
879 ThreadFunction entry_point() const { return _entry_point; }
880
881 // Allocates a new Java level thread object for this thread. thread_name may be NULL.
882 void allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS);
883
884 // Last frame anchor routines
885
886 JavaFrameAnchor* frame_anchor(void) { return &_anchor; }
887
888 // last_Java_sp
889 bool has_last_Java_frame() const { return _anchor.has_last_Java_frame(); }
890 intptr_t* last_Java_sp() const { return _anchor.last_Java_sp(); }
891
892 // last_Java_pc
893
894 address last_Java_pc(void) { return _anchor.last_Java_pc(); }
895
896 // Safepoint support
897 JavaThreadState thread_state() const { return _thread_state; }
898 void set_thread_state(JavaThreadState s) { _thread_state=s; }
899 ThreadSafepointState *safepoint_state() const { return _safepoint_state; }
900 void set_safepoint_state(ThreadSafepointState *state) { _safepoint_state = state; }
901 bool is_at_poll_safepoint() { return _safepoint_state->is_at_poll_safepoint(); }
902
903 // thread has called JavaThread::exit() or is terminated
904 bool is_exiting() { return _terminated == _thread_exiting || is_terminated(); }
905 // thread is terminated (no longer on the threads list); we compare
906 // against the two non-terminated values so that a freed JavaThread
907 // will also be considered terminated.
908 bool is_terminated() { return _terminated != _not_terminated && _terminated != _thread_exiting; }
909 void set_terminated(TerminatedTypes t) { _terminated = t; }
910 // special for Threads::remove() which is static:
911 void set_terminated_value() { _terminated = _thread_terminated; }
912 void block_if_vm_exited();
913
914 bool doing_unsafe_access() { return _doing_unsafe_access; }
915 void set_doing_unsafe_access(bool val) { _doing_unsafe_access = val; }
916
917 bool do_not_unlock_if_synchronized() { return _do_not_unlock_if_synchronized; }
918 void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }
919
920
921 // Suspend/resume support for JavaThread
922
923 private:
924 void set_ext_suspended() { set_suspend_flag (_ext_suspended); }
925 void clear_ext_suspended() { clear_suspend_flag(_ext_suspended); }
926
927 public:
928 void java_suspend();
929 void java_resume();
930 int java_suspend_self();
931
932 void check_and_wait_while_suspended() {
933 assert(JavaThread::current() == this, "sanity check");
934
935 bool do_self_suspend;
936 do {
937 // were we externally suspended while we were waiting?
938 do_self_suspend = handle_special_suspend_equivalent_condition();
939 if (do_self_suspend) {
940 // don't surprise the thread that suspended us by returning
941 java_suspend_self();
942 set_suspend_equivalent();
943 }
944 } while (do_self_suspend);
945 }
946 static void check_safepoint_and_suspend_for_native_trans(JavaThread *thread);
947 // Check for async exception in addition to safepoint and suspend request.
948 static void check_special_condition_for_native_trans(JavaThread *thread);
949
950 bool is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits);
951 bool is_ext_suspend_completed_with_lock(uint32_t *bits) {
952 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
953 // Warning: is_ext_suspend_completed() may temporarily drop the
954 // SR_lock to allow the thread to reach a stable thread state if
955 // it is currently in a transient thread state.
956 return is_ext_suspend_completed(false /*!called_by_wait */,
957 SuspendRetryDelay, bits);
958 }
959
960 // We cannot allow wait_for_ext_suspend_completion() to run forever or
961 // we could hang. SuspendRetryCount and SuspendRetryDelay are normally
962 // passed as the count and delay parameters. Experiments with specific
963 // calls to wait_for_ext_suspend_completion() can be done by passing
964 // other values in the code. Experiments with all calls can be done
965 // via the appropriate -XX options.
966 bool wait_for_ext_suspend_completion(int count, int delay, uint32_t *bits);
967
968 void set_external_suspend() { set_suspend_flag (_external_suspend); }
969 void clear_external_suspend() { clear_suspend_flag(_external_suspend); }
970
971 void set_deopt_suspend() { set_suspend_flag (_deopt_suspend); }
972 void clear_deopt_suspend() { clear_suspend_flag(_deopt_suspend); }
973 bool is_deopt_suspend() { return (_suspend_flags & _deopt_suspend) != 0; }
974
975 bool is_external_suspend() const {
976 return (_suspend_flags & _external_suspend) != 0;
977 }
978 // Whenever a thread transitions from native to vm/java it must suspend
979 // if external|deopt suspend is present.
980 bool is_suspend_after_native() const {
981 return (_suspend_flags & (_external_suspend | _deopt_suspend) ) != 0;
982 }
983
984 // external suspend request is completed
985 bool is_ext_suspended() const {
986 return (_suspend_flags & _ext_suspended) != 0;
987 }
988
989 bool is_external_suspend_with_lock() const {
990 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
991 return is_external_suspend();
992 }
993
994 // Special method to handle a pending external suspend request
995 // when a suspend equivalent condition lifts.
996 bool handle_special_suspend_equivalent_condition() {
997 assert(is_suspend_equivalent(),
998 "should only be called in a suspend equivalence condition");
999 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1000 bool ret = is_external_suspend();
1001 if (!ret) {
1002 // not about to self-suspend so clear suspend equivalence
1003 clear_suspend_equivalent();
1004 }
1005 // implied else:
1006 // We have a pending external suspend request so we leave the
1007 // suspend_equivalent flag set until java_suspend_self() sets
1008 // the ext_suspended flag and clears the suspend_equivalent
1009 // flag. This insures that wait_for_ext_suspend_completion()
1010 // will return consistent values.
1011 return ret;
1012 }
1013
1014 // utility methods to see if we are doing some kind of suspension
1015 bool is_being_ext_suspended() const {
1016 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1017 return is_ext_suspended() || is_external_suspend();
1018 }
1019
1020 bool is_suspend_equivalent() const { return _suspend_equivalent; }
1021
1022 void set_suspend_equivalent() { _suspend_equivalent = true; };
1023 void clear_suspend_equivalent() { _suspend_equivalent = false; };
1024
1025 // Thread.stop support
1026 void send_thread_stop(oop throwable);
1027 AsyncRequests clear_special_runtime_exit_condition() {
1028 AsyncRequests x = _special_runtime_exit_condition;
1029 _special_runtime_exit_condition = _no_async_condition;
1030 return x;
1031 }
1032
1033 // Are any async conditions present?
1034 bool has_async_condition() { return (_special_runtime_exit_condition != _no_async_condition); }
1035
1036 void check_and_handle_async_exceptions(bool check_unsafe_error = true);
1037
1038 // these next two are also used for self-suspension and async exception support
1039 void handle_special_runtime_exit_condition(bool check_asyncs = true);
1040
1041 // Return true if JavaThread has an asynchronous condition or
1042 // if external suspension is requested.
1043 bool has_special_runtime_exit_condition() {
1044 // We call is_external_suspend() last since external suspend should
1045 // be less common. Because we don't use is_external_suspend_with_lock
1046 // it is possible that we won't see an asynchronous external suspend
1047 // request that has just gotten started, i.e., SR_lock grabbed but
1048 // _external_suspend field change either not made yet or not visible
1049 // yet. However, this is okay because the request is asynchronous and
1050 // we will see the new flag value the next time through. It's also
1051 // possible that the external suspend request is dropped after
1052 // we have checked is_external_suspend(), we will recheck its value
1053 // under SR_lock in java_suspend_self().
1054 return (_special_runtime_exit_condition != _no_async_condition) ||
1055 is_external_suspend() || is_deopt_suspend();
1056 }
1057
1058 void set_pending_unsafe_access_error() { _special_runtime_exit_condition = _async_unsafe_access_error; }
1059
1060 void set_pending_async_exception(oop e) {
1061 _pending_async_exception = e;
1062 _special_runtime_exit_condition = _async_exception;
1063 set_has_async_exception();
1064 }
1065
1066 // Fast-locking support
1067 bool is_lock_owned(address adr) const;
1068
1069 // Accessors for vframe array top
1070 // The linked list of vframe arrays are sorted on sp. This means when we
1071 // unpack the head must contain the vframe array to unpack.
1072 void set_vframe_array_head(vframeArray* value) { _vframe_array_head = value; }
1073 vframeArray* vframe_array_head() const { return _vframe_array_head; }
1074
1075 // Side structure for defering update of java frame locals until deopt occurs
1076 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred_locals() const { return _deferred_locals_updates; }
1077 void set_deferred_locals(GrowableArray<jvmtiDeferredLocalVariableSet *>* vf) { _deferred_locals_updates = vf; }
1078
1079 // These only really exist to make debugging deopt problems simpler
1080
1081 void set_vframe_array_last(vframeArray* value) { _vframe_array_last = value; }
1082 vframeArray* vframe_array_last() const { return _vframe_array_last; }
1083
1084 // The special resourceMark used during deoptimization
1085
1086 void set_deopt_mark(DeoptResourceMark* value) { _deopt_mark = value; }
1087 DeoptResourceMark* deopt_mark(void) { return _deopt_mark; }
1088
1089 intptr_t* must_deopt_id() { return _must_deopt_id; }
1090 void set_must_deopt_id(intptr_t* id) { _must_deopt_id = id; }
1091 void clear_must_deopt_id() { _must_deopt_id = NULL; }
1092
1093 methodOop callee_target() const { return _callee_target; }
1094 void set_callee_target (methodOop x) { _callee_target = x; }
1095
1096 // Oop results of vm runtime calls
1097 oop vm_result() const { return _vm_result; }
1098 void set_vm_result (oop x) { _vm_result = x; }
1099
1100 oop vm_result_2() const { return _vm_result_2; }
1101 void set_vm_result_2 (oop x) { _vm_result_2 = x; }
1102
1103 MemRegion deferred_card_mark() const { return _deferred_card_mark; }
1104 void set_deferred_card_mark(MemRegion mr) { _deferred_card_mark = mr; }
1105
1106 // Exception handling for compiled methods
1107 oop exception_oop() const { return _exception_oop; }
1108 int exception_stack_size() const { return _exception_stack_size; }
1109 address exception_pc() const { return _exception_pc; }
1110 address exception_handler_pc() const { return _exception_handler_pc; }
1111 bool is_method_handle_return() const { return _is_method_handle_return == 1; }
1112
1113 void set_exception_oop(oop o) { _exception_oop = o; }
1114 void set_exception_pc(address a) { _exception_pc = a; }
1115 void set_exception_handler_pc(address a) { _exception_handler_pc = a; }
1116 void set_exception_stack_size(int size) { _exception_stack_size = size; }
1117 void set_is_method_handle_return(bool value) { _is_method_handle_return = value ? 1 : 0; }
1118
1119 // Stack overflow support
1120 inline size_t stack_available(address cur_sp);
1121 address stack_yellow_zone_base()
1122 { return (address)(stack_base() - (stack_size() - (stack_red_zone_size() + stack_yellow_zone_size()))); }
1123 size_t stack_yellow_zone_size()
1124 { return StackYellowPages * os::vm_page_size(); }
1125 address stack_red_zone_base()
1126 { return (address)(stack_base() - (stack_size() - stack_red_zone_size())); }
1127 size_t stack_red_zone_size()
1128 { return StackRedPages * os::vm_page_size(); }
1129 bool in_stack_yellow_zone(address a)
1130 { return (a <= stack_yellow_zone_base()) && (a >= stack_red_zone_base()); }
1131 bool in_stack_red_zone(address a)
1132 { return (a <= stack_red_zone_base()) && (a >= (address)((intptr_t)stack_base() - stack_size())); }
1133
1134 void create_stack_guard_pages();
1135 void remove_stack_guard_pages();
1136
1137 void enable_stack_yellow_zone();
1138 void disable_stack_yellow_zone();
1139 void enable_stack_red_zone();
1140 void disable_stack_red_zone();
1141
1142 inline bool stack_yellow_zone_disabled();
1143 inline bool stack_yellow_zone_enabled();
1144
1145 // Attempt to reguard the stack after a stack overflow may have occurred.
1146 // Returns true if (a) guard pages are not needed on this thread, (b) the
1147 // pages are already guarded, or (c) the pages were successfully reguarded.
1148 // Returns false if there is not enough stack space to reguard the pages, in
1149 // which case the caller should unwind a frame and try again. The argument
1150 // should be the caller's (approximate) sp.
1151 bool reguard_stack(address cur_sp);
1152 // Similar to above but see if current stackpoint is out of the guard area
1153 // and reguard if possible.
1154 bool reguard_stack(void);
1155
1156 // Misc. accessors/mutators
1157 void set_do_not_unlock(void) { _do_not_unlock_if_synchronized = true; }
1158 void clr_do_not_unlock(void) { _do_not_unlock_if_synchronized = false; }
1159 bool do_not_unlock(void) { return _do_not_unlock_if_synchronized; }
1160
1161 #ifndef PRODUCT
1162 void record_jump(address target, address instr, const char* file, int line);
1163 #endif /* PRODUCT */
1164
1165 // For assembly stub generation
1166 static ByteSize threadObj_offset() { return byte_offset_of(JavaThread, _threadObj ); }
1167 #ifndef PRODUCT
1168 static ByteSize jmp_ring_index_offset() { return byte_offset_of(JavaThread, _jmp_ring_index ); }
1169 static ByteSize jmp_ring_offset() { return byte_offset_of(JavaThread, _jmp_ring ); }
1170 #endif /* PRODUCT */
1171 static ByteSize jni_environment_offset() { return byte_offset_of(JavaThread, _jni_environment ); }
1172 static ByteSize last_Java_sp_offset() {
1173 return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_sp_offset();
1174 }
1175 static ByteSize last_Java_pc_offset() {
1176 return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_pc_offset();
1177 }
1178 static ByteSize frame_anchor_offset() {
1179 return byte_offset_of(JavaThread, _anchor);
1180 }
1181 static ByteSize callee_target_offset() { return byte_offset_of(JavaThread, _callee_target ); }
1182 static ByteSize vm_result_offset() { return byte_offset_of(JavaThread, _vm_result ); }
1183 static ByteSize vm_result_2_offset() { return byte_offset_of(JavaThread, _vm_result_2 ); }
1184 static ByteSize thread_state_offset() { return byte_offset_of(JavaThread, _thread_state ); }
1185 static ByteSize saved_exception_pc_offset() { return byte_offset_of(JavaThread, _saved_exception_pc ); }
1186 static ByteSize osthread_offset() { return byte_offset_of(JavaThread, _osthread ); }
1187 static ByteSize exception_oop_offset() { return byte_offset_of(JavaThread, _exception_oop ); }
1188 static ByteSize exception_pc_offset() { return byte_offset_of(JavaThread, _exception_pc ); }
1189 static ByteSize exception_handler_pc_offset() { return byte_offset_of(JavaThread, _exception_handler_pc); }
1190 static ByteSize exception_stack_size_offset() { return byte_offset_of(JavaThread, _exception_stack_size); }
1191 static ByteSize is_method_handle_return_offset() { return byte_offset_of(JavaThread, _is_method_handle_return); }
1192 static ByteSize stack_guard_state_offset() { return byte_offset_of(JavaThread, _stack_guard_state ); }
1193 static ByteSize suspend_flags_offset() { return byte_offset_of(JavaThread, _suspend_flags ); }
1194
1195 static ByteSize do_not_unlock_if_synchronized_offset() { return byte_offset_of(JavaThread, _do_not_unlock_if_synchronized); }
1196 static ByteSize should_post_on_exceptions_flag_offset() {
1197 return byte_offset_of(JavaThread, _should_post_on_exceptions_flag);
1198 }
1199
1200 #ifndef SERIALGC
1201 static ByteSize satb_mark_queue_offset() { return byte_offset_of(JavaThread, _satb_mark_queue); }
1202 static ByteSize dirty_card_queue_offset() { return byte_offset_of(JavaThread, _dirty_card_queue); }
1203 #endif // !SERIALGC
1204
1205 // Returns the jni environment for this thread
1206 JNIEnv* jni_environment() { return &_jni_environment; }
1207
1208 static JavaThread* thread_from_jni_environment(JNIEnv* env) {
1209 JavaThread *thread_from_jni_env = (JavaThread*)((intptr_t)env - in_bytes(jni_environment_offset()));
1210 // Only return NULL if thread is off the thread list; starting to
1211 // exit should not return NULL.
1212 if (thread_from_jni_env->is_terminated()) {
1213 thread_from_jni_env->block_if_vm_exited();
1214 return NULL;
1215 } else {
1216 return thread_from_jni_env;
1217 }
1218 }
1219
1220 // JNI critical regions. These can nest.
1221 bool in_critical() { return _jni_active_critical > 0; }
1222 void enter_critical() { assert(Thread::current() == this,
1223 "this must be current thread");
1224 _jni_active_critical++; }
1225 void exit_critical() { assert(Thread::current() == this,
1226 "this must be current thread");
1227 _jni_active_critical--;
1228 assert(_jni_active_critical >= 0,
1229 "JNI critical nesting problem?"); }
1230
1231 // For deadlock detection
1232 int depth_first_number() { return _depth_first_number; }
1233 void set_depth_first_number(int dfn) { _depth_first_number = dfn; }
1234
1235 private:
1236 void set_monitor_chunks(MonitorChunk* monitor_chunks) { _monitor_chunks = monitor_chunks; }
1237
1238 public:
1239 MonitorChunk* monitor_chunks() const { return _monitor_chunks; }
1240 void add_monitor_chunk(MonitorChunk* chunk);
1241 void remove_monitor_chunk(MonitorChunk* chunk);
1242 bool in_deopt_handler() const { return _in_deopt_handler > 0; }
1243 void inc_in_deopt_handler() { _in_deopt_handler++; }
1244 void dec_in_deopt_handler() {
1245 assert(_in_deopt_handler > 0, "mismatched deopt nesting");
1246 if (_in_deopt_handler > 0) { // robustness
1247 _in_deopt_handler--;
1248 }
1249 }
1250
1251 private:
1252 void set_entry_point(ThreadFunction entry_point) { _entry_point = entry_point; }
1253
1254 public:
1255
1256 // Frame iteration; calls the function f for all frames on the stack
1257 void frames_do(void f(frame*, const RegisterMap*));
1258
1259 // Memory operations
1260 void oops_do(OopClosure* f, CodeBlobClosure* cf);
1261
1262 // Sweeper operations
1263 void nmethods_do(CodeBlobClosure* cf);
1264
1265 // Memory management operations
1266 void gc_epilogue();
1267 void gc_prologue();
1268
1269 // Misc. operations
1270 char* name() const { return (char*)get_thread_name(); }
1271 void print_on(outputStream* st) const;
1272 void print() const { print_on(tty); }
1273 void print_value();
1274 void print_thread_state_on(outputStream* ) const PRODUCT_RETURN;
1275 void print_thread_state() const PRODUCT_RETURN;
1276 void print_on_error(outputStream* st, char* buf, int buflen) const;
1277 void verify();
1278 const char* get_thread_name() const;
1279 private:
1280 // factor out low-level mechanics for use in both normal and error cases
1281 const char* get_thread_name_string(char* buf = NULL, int buflen = 0) const;
1282 public:
1283 const char* get_threadgroup_name() const;
1284 const char* get_parent_name() const;
1285
1286 // Accessing frames
1287 frame last_frame() {
1288 _anchor.make_walkable(this);
1289 return pd_last_frame();
1290 }
1291 javaVFrame* last_java_vframe(RegisterMap* reg_map);
1292
1293 // Returns method at 'depth' java or native frames down the stack
1294 // Used for security checks
1295 klassOop security_get_caller_class(int depth);
1296
1297 // Print stack trace in external format
1298 void print_stack_on(outputStream* st);
1299 void print_stack() { print_stack_on(tty); }
1300
1301 // Print stack traces in various internal formats
1302 void trace_stack() PRODUCT_RETURN;
1303 void trace_stack_from(vframe* start_vf) PRODUCT_RETURN;
1304 void trace_frames() PRODUCT_RETURN;
1305
1306 // Returns the number of stack frames on the stack
1307 int depth() const;
1308
1309 // Function for testing deoptimization
1310 void deoptimize();
1311 void make_zombies();
1312
1313 void deoptimized_wrt_marked_nmethods();
1314
1315 // Profiling operation (see fprofile.cpp)
1316 public:
1317 bool profile_last_Java_frame(frame* fr);
1318
1319 private:
1320 ThreadProfiler* _thread_profiler;
1321 private:
1322 friend class FlatProfiler; // uses both [gs]et_thread_profiler.
1323 friend class FlatProfilerTask; // uses get_thread_profiler.
1324 friend class ThreadProfilerMark; // uses get_thread_profiler.
1325 ThreadProfiler* get_thread_profiler() { return _thread_profiler; }
1326 ThreadProfiler* set_thread_profiler(ThreadProfiler* tp) {
1327 ThreadProfiler* result = _thread_profiler;
1328 _thread_profiler = tp;
1329 return result;
1330 }
1331
1332 // Static operations
1333 public:
1334 // Returns the running thread as a JavaThread
1335 static inline JavaThread* current();
1336
1337 // Returns the active Java thread. Do not use this if you know you are calling
1338 // from a JavaThread, as it's slower than JavaThread::current. If called from
1339 // the VMThread, it also returns the JavaThread that instigated the VMThread's
1340 // operation. You may not want that either.
1341 static JavaThread* active();
1342
1343 inline CompilerThread* as_CompilerThread();
1344
1345 public:
1346 virtual void run();
1347 void thread_main_inner();
1348
1349 private:
1350 // PRIVILEGED STACK
1351 PrivilegedElement* _privileged_stack_top;
1352 GrowableArray<oop>* _array_for_gc;
1353 public:
1354
1355 // Returns the privileged_stack information.
1356 PrivilegedElement* privileged_stack_top() const { return _privileged_stack_top; }
1357 void set_privileged_stack_top(PrivilegedElement *e) { _privileged_stack_top = e; }
1358 void register_array_for_gc(GrowableArray<oop>* array) { _array_for_gc = array; }
1359
1360 public:
1361 // Thread local information maintained by JVMTI.
1362 void set_jvmti_thread_state(JvmtiThreadState *value) { _jvmti_thread_state = value; }
1363 // A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
1364 // getter is used to get this JavaThread's JvmtiThreadState if it has
1365 // one which means NULL can be returned. JvmtiThreadState::state_for()
1366 // is used to get the specified JavaThread's JvmtiThreadState if it has
1367 // one or it allocates a new JvmtiThreadState for the JavaThread and
1368 // returns it. JvmtiThreadState::state_for() will return NULL only if
1369 // the specified JavaThread is exiting.
1370 JvmtiThreadState *jvmti_thread_state() const { return _jvmti_thread_state; }
1371 static ByteSize jvmti_thread_state_offset() { return byte_offset_of(JavaThread, _jvmti_thread_state); }
1372 void set_jvmti_get_loaded_classes_closure(JvmtiGetLoadedClassesClosure* value) { _jvmti_get_loaded_classes_closure = value; }
1373 JvmtiGetLoadedClassesClosure* get_jvmti_get_loaded_classes_closure() const { return _jvmti_get_loaded_classes_closure; }
1374
1375 // JVMTI PopFrame support
1376 // Setting and clearing popframe_condition
1377 // All of these enumerated values are bits. popframe_pending
1378 // indicates that a PopFrame() has been requested and not yet been
1379 // completed. popframe_processing indicates that that PopFrame() is in
1380 // the process of being completed. popframe_force_deopt_reexecution_bit
1381 // indicates that special handling is required when returning to a
1382 // deoptimized caller.
1383 enum PopCondition {
1384 popframe_inactive = 0x00,
1385 popframe_pending_bit = 0x01,
1386 popframe_processing_bit = 0x02,
1387 popframe_force_deopt_reexecution_bit = 0x04
1388 };
1389 PopCondition popframe_condition() { return (PopCondition) _popframe_condition; }
1390 void set_popframe_condition(PopCondition c) { _popframe_condition = c; }
1391 void set_popframe_condition_bit(PopCondition c) { _popframe_condition |= c; }
1392 void clear_popframe_condition() { _popframe_condition = popframe_inactive; }
1393 static ByteSize popframe_condition_offset() { return byte_offset_of(JavaThread, _popframe_condition); }
1394 bool has_pending_popframe() { return (popframe_condition() & popframe_pending_bit) != 0; }
1395 bool popframe_forcing_deopt_reexecution() { return (popframe_condition() & popframe_force_deopt_reexecution_bit) != 0; }
1396 void clear_popframe_forcing_deopt_reexecution() { _popframe_condition &= ~popframe_force_deopt_reexecution_bit; }
1397 #ifdef CC_INTERP
1398 bool pop_frame_pending(void) { return ((_popframe_condition & popframe_pending_bit) != 0); }
1399 void clr_pop_frame_pending(void) { _popframe_condition = popframe_inactive; }
1400 bool pop_frame_in_process(void) { return ((_popframe_condition & popframe_processing_bit) != 0); }
1401 void set_pop_frame_in_process(void) { _popframe_condition |= popframe_processing_bit; }
1402 void clr_pop_frame_in_process(void) { _popframe_condition &= ~popframe_processing_bit; }
1403 #endif
1404
1405 private:
1406 // Saved incoming arguments to popped frame.
1407 // Used only when popped interpreted frame returns to deoptimized frame.
1408 void* _popframe_preserved_args;
1409 int _popframe_preserved_args_size;
1410
1411 public:
1412 void popframe_preserve_args(ByteSize size_in_bytes, void* start);
1413 void* popframe_preserved_args();
1414 ByteSize popframe_preserved_args_size();
1415 WordSize popframe_preserved_args_size_in_words();
1416 void popframe_free_preserved_args();
1417
1418
1419 private:
1420 JvmtiThreadState *_jvmti_thread_state;
1421 JvmtiGetLoadedClassesClosure* _jvmti_get_loaded_classes_closure;
1422
1423 // Used by the interpreter in fullspeed mode for frame pop, method
1424 // entry, method exit and single stepping support. This field is
1425 // only set to non-zero by the VM_EnterInterpOnlyMode VM operation.
1426 // It can be set to zero asynchronously (i.e., without a VM operation
1427 // or a lock) so we have to be very careful.
1428 int _interp_only_mode;
1429
1430 public:
1431 // used by the interpreter for fullspeed debugging support (see above)
1432 static ByteSize interp_only_mode_offset() { return byte_offset_of(JavaThread, _interp_only_mode); }
1433 bool is_interp_only_mode() { return (_interp_only_mode != 0); }
1434 int get_interp_only_mode() { return _interp_only_mode; }
1435 void increment_interp_only_mode() { ++_interp_only_mode; }
1436 void decrement_interp_only_mode() { --_interp_only_mode; }
1437
1438 // support for cached flag that indicates whether exceptions need to be posted for this thread
1439 // if this is false, we can avoid deoptimizing when events are thrown
1440 // this gets set to reflect whether jvmtiExport::post_exception_throw would actually do anything
1441 private:
1442 int _should_post_on_exceptions_flag;
1443
1444 public:
1445 int should_post_on_exceptions_flag() { return _should_post_on_exceptions_flag; }
1446 void set_should_post_on_exceptions_flag(int val) { _should_post_on_exceptions_flag = val; }
1447
1448 private:
1449 ThreadStatistics *_thread_stat;
1450
1451 public:
1452 ThreadStatistics* get_thread_stat() const { return _thread_stat; }
1453
1454 // Return a blocker object for which this thread is blocked parking.
1455 oop current_park_blocker();
1456
1457 private:
1458 static size_t _stack_size_at_create;
1459
1460 public:
1461 static inline size_t stack_size_at_create(void) {
1462 return _stack_size_at_create;
1463 }
1464 static inline void set_stack_size_at_create(size_t value) {
1465 _stack_size_at_create = value;
1466 }
1467
1468 #ifndef SERIALGC
1469 // SATB marking queue support
1470 ObjPtrQueue& satb_mark_queue() { return _satb_mark_queue; }
1471 static SATBMarkQueueSet& satb_mark_queue_set() {
1472 return _satb_mark_queue_set;
1473 }
1474
1475 // Dirty card queue support
1476 DirtyCardQueue& dirty_card_queue() { return _dirty_card_queue; }
1477 static DirtyCardQueueSet& dirty_card_queue_set() {
1478 return _dirty_card_queue_set;
1479 }
1480 #endif // !SERIALGC
1481
1482 // Machine dependent stuff
1483 #include "incls/_thread_pd.hpp.incl"
1484
1485 public:
1486 void set_blocked_on_compilation(bool value) {
1487 _blocked_on_compilation = value;
1488 }
1489
1490 bool blocked_on_compilation() {
1491 return _blocked_on_compilation;
1492 }
1493 protected:
1494 bool _blocked_on_compilation;
1495
1496
1497 // JSR166 per-thread parker
1498 private:
1499 Parker* _parker;
1500 public:
1501 Parker* parker() { return _parker; }
1502
1503 // Biased locking support
1504 private:
1505 GrowableArray<MonitorInfo*>* _cached_monitor_info;
1506 public:
1507 GrowableArray<MonitorInfo*>* cached_monitor_info() { return _cached_monitor_info; }
1508 void set_cached_monitor_info(GrowableArray<MonitorInfo*>* info) { _cached_monitor_info = info; }
1509
1510 // clearing/querying jni attach status
1511 bool is_attaching() const { return _is_attaching; }
1512 void set_attached() { _is_attaching = false; OrderAccess::fence(); }
1513 private:
1514 // This field is used to determine if a thread has claimed
1515 // a par_id: it is -1 if the thread has not claimed a par_id;
1516 // otherwise its value is the par_id that has been claimed.
1517 int _claimed_par_id;
1518 public:
1519 int get_claimed_par_id() { return _claimed_par_id; }
1520 void set_claimed_par_id(int id) { _claimed_par_id = id;}
1521 };
1522
1523 // Inline implementation of JavaThread::current
1524 inline JavaThread* JavaThread::current() {
1525 Thread* thread = ThreadLocalStorage::thread();
1526 assert(thread != NULL && thread->is_Java_thread(), "just checking");
1527 return (JavaThread*)thread;
1528 }
1529
1530 inline CompilerThread* JavaThread::as_CompilerThread() {
1531 assert(is_Compiler_thread(), "just checking");
1532 return (CompilerThread*)this;
1533 }
1534
1535 inline bool JavaThread::stack_yellow_zone_disabled() {
1536 return _stack_guard_state == stack_guard_yellow_disabled;
1537 }
1538
1539 inline bool JavaThread::stack_yellow_zone_enabled() {
1540 #ifdef ASSERT
1541 if (os::uses_stack_guard_pages()) {
1542 assert(_stack_guard_state != stack_guard_unused, "guard pages must be in use");
1543 }
1544 #endif
1545 return _stack_guard_state == stack_guard_enabled;
1546 }
1547
1548 inline size_t JavaThread::stack_available(address cur_sp) {
1549 // This code assumes java stacks grow down
1550 address low_addr; // Limit on the address for deepest stack depth
1551 if ( _stack_guard_state == stack_guard_unused) {
1552 low_addr = stack_base() - stack_size();
1553 } else {
1554 low_addr = stack_yellow_zone_base();
1555 }
1556 return cur_sp > low_addr ? cur_sp - low_addr : 0;
1557 }
1558
1559 // A JavaThread for low memory detection support
1560 class LowMemoryDetectorThread : public JavaThread {
1561 friend class VMStructs;
1562 public:
1563 LowMemoryDetectorThread(ThreadFunction entry_point) : JavaThread(entry_point) {};
1564
1565 // Hide this thread from external view.
1566 bool is_hidden_from_external_view() const { return true; }
1567 };
1568
1569 // A thread used for Compilation.
1570 class CompilerThread : public JavaThread {
1571 friend class VMStructs;
1572 private:
1573 CompilerCounters* _counters;
1574
1575 ciEnv* _env;
1576 CompileLog* _log;
1577 CompileTask* _task;
1578 CompileQueue* _queue;
1579 BufferBlob* _buffer_blob;
1580
1581 public:
1582
1583 static CompilerThread* current();
1584
1585 CompilerThread(CompileQueue* queue, CompilerCounters* counters);
1586
1587 bool is_Compiler_thread() const { return true; }
1588 // Hide this compiler thread from external view.
1589 bool is_hidden_from_external_view() const { return true; }
1590
1591 CompileQueue* queue() { return _queue; }
1592 CompilerCounters* counters() { return _counters; }
1593
1594 // Get/set the thread's compilation environment.
1595 ciEnv* env() { return _env; }
1596 void set_env(ciEnv* env) { _env = env; }
1597
1598 BufferBlob* get_buffer_blob() { return _buffer_blob; }
1599 void set_buffer_blob(BufferBlob* b) { _buffer_blob = b; };
1600
1601 // Get/set the thread's logging information
1602 CompileLog* log() { return _log; }
1603 void init_log(CompileLog* log) {
1604 // Set once, for good.
1605 assert(_log == NULL, "set only once");
1606 _log = log;
1607 }
1608
1609 #ifndef PRODUCT
1610 private:
1611 IdealGraphPrinter *_ideal_graph_printer;
1612 public:
1613 IdealGraphPrinter *ideal_graph_printer() { return _ideal_graph_printer; }
1614 void set_ideal_graph_printer(IdealGraphPrinter *n) { _ideal_graph_printer = n; }
1615 #endif
1616
1617 // Get/set the thread's current task
1618 CompileTask* task() { return _task; }
1619 void set_task(CompileTask* task) { _task = task; }
1620 };
1621
1622 inline CompilerThread* CompilerThread::current() {
1623 return JavaThread::current()->as_CompilerThread();
1624 }
1625
1626
1627 // The active thread queue. It also keeps track of the current used
1628 // thread priorities.
1629 class Threads: AllStatic {
1630 friend class VMStructs;
1631 private:
1632 static JavaThread* _thread_list;
1633 static int _number_of_threads;
1634 static int _number_of_non_daemon_threads;
1635 static int _return_code;
1636
1637 public:
1638 // Thread management
1639 // force_daemon is a concession to JNI, where we may need to add a
1640 // thread to the thread list before allocating its thread object
1641 static void add(JavaThread* p, bool force_daemon = false);
1642 static void remove(JavaThread* p);
1643 static bool includes(JavaThread* p);
1644 static JavaThread* first() { return _thread_list; }
1645 static void threads_do(ThreadClosure* tc);
1646
1647 // Initializes the vm and creates the vm thread
1648 static jint create_vm(JavaVMInitArgs* args, bool* canTryAgain);
1649 static void convert_vm_init_libraries_to_agents();
1650 static void create_vm_init_libraries();
1651 static void create_vm_init_agents();
1652 static void shutdown_vm_agents();
1653 static bool destroy_vm();
1654 // Supported VM versions via JNI
1655 // Includes JNI_VERSION_1_1
1656 static jboolean is_supported_jni_version_including_1_1(jint version);
1657 // Does not include JNI_VERSION_1_1
1658 static jboolean is_supported_jni_version(jint version);
1659
1660 // Garbage collection
1661 static void follow_other_roots(void f(oop*));
1662
1663 // Apply "f->do_oop" to all root oops in all threads.
1664 // This version may only be called by sequential code.
1665 static void oops_do(OopClosure* f, CodeBlobClosure* cf);
1666 // This version may be called by sequential or parallel code.
1667 static void possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf);
1668 // This creates a list of GCTasks, one per thread.
1669 static void create_thread_roots_tasks(GCTaskQueue* q);
1670 // This creates a list of GCTasks, one per thread, for marking objects.
1671 static void create_thread_roots_marking_tasks(GCTaskQueue* q);
1672
1673 // Apply "f->do_oop" to roots in all threads that
1674 // are part of compiled frames
1675 static void compiled_frame_oops_do(OopClosure* f, CodeBlobClosure* cf);
1676
1677 static void convert_hcode_pointers();
1678 static void restore_hcode_pointers();
1679
1680 // Sweeper
1681 static void nmethods_do(CodeBlobClosure* cf);
1682
1683 static void gc_epilogue();
1684 static void gc_prologue();
1685
1686 // Verification
1687 static void verify();
1688 static void print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks);
1689 static void print(bool print_stacks, bool internal_format) {
1690 // this function is only used by debug.cpp
1691 print_on(tty, print_stacks, internal_format, false /* no concurrent lock printed */);
1692 }
1693 static void print_on_error(outputStream* st, Thread* current, char* buf, int buflen);
1694
1695 // Get Java threads that are waiting to enter a monitor. If doLock
1696 // is true, then Threads_lock is grabbed as needed. Otherwise, the
1697 // VM needs to be at a safepoint.
1698 static GrowableArray<JavaThread*>* get_pending_threads(int count,
1699 address monitor, bool doLock);
1700
1701 // Get owning Java thread from the monitor's owner field. If doLock
1702 // is true, then Threads_lock is grabbed as needed. Otherwise, the
1703 // VM needs to be at a safepoint.
1704 static JavaThread *owning_thread_from_monitor_owner(address owner,
1705 bool doLock);
1706
1707 // Number of threads on the active threads list
1708 static int number_of_threads() { return _number_of_threads; }
1709 // Number of non-daemon threads on the active threads list
1710 static int number_of_non_daemon_threads() { return _number_of_non_daemon_threads; }
1711
1712 // Deoptimizes all frames tied to marked nmethods
1713 static void deoptimized_wrt_marked_nmethods();
1714
1715 };
1716
1717
1718 // Thread iterator
1719 class ThreadClosure: public StackObj {
1720 public:
1721 virtual void do_thread(Thread* thread) = 0;
1722 };
1723
1724 class SignalHandlerMark: public StackObj {
1725 private:
1726 Thread* _thread;
1727 public:
1728 SignalHandlerMark(Thread* t) {
1729 _thread = t;
1730 if (_thread) _thread->enter_signal_handler();
1731 }
1732 ~SignalHandlerMark() {
1733 if (_thread) _thread->leave_signal_handler();
1734 _thread = NULL;
1735 }
1736 };
1737
1738 // ParkEvents are type-stable and immortal.
1739 //
1740 // Lifecycle: Once a ParkEvent is associated with a thread that ParkEvent remains
1741 // associated with the thread for the thread's entire lifetime - the relationship is
1742 // stable. A thread will be associated at most one ParkEvent. When the thread
1743 // expires, the ParkEvent moves to the EventFreeList. New threads attempt to allocate from
1744 // the EventFreeList before creating a new Event. Type-stability frees us from
1745 // worrying about stale Event or Thread references in the objectMonitor subsystem.
1746 // (A reference to ParkEvent is always valid, even though the event may no longer be associated
1747 // with the desired or expected thread. A key aspect of this design is that the callers of
1748 // park, unpark, etc must tolerate stale references and spurious wakeups).
1749 //
1750 // Only the "associated" thread can block (park) on the ParkEvent, although
1751 // any other thread can unpark a reachable parkevent. Park() is allowed to
1752 // return spuriously. In fact park-unpark a really just an optimization to
1753 // avoid unbounded spinning and surrender the CPU to be a polite system citizen.
1754 // A degenerate albeit "impolite" park-unpark implementation could simply return.
1755 // See http://blogs.sun.com/dave for more details.
1756 //
1757 // Eventually I'd like to eliminate Events and ObjectWaiters, both of which serve as
1758 // thread proxies, and simply make the THREAD structure type-stable and persistent.
1759 // Currently, we unpark events associated with threads, but ideally we'd just
1760 // unpark threads.
1761 //
1762 // The base-class, PlatformEvent, is platform-specific while the ParkEvent is
1763 // platform-independent. PlatformEvent provides park(), unpark(), etc., and
1764 // is abstract -- that is, a PlatformEvent should never be instantiated except
1765 // as part of a ParkEvent.
1766 // Equivalently we could have defined a platform-independent base-class that
1767 // exported Allocate(), Release(), etc. The platform-specific class would extend
1768 // that base-class, adding park(), unpark(), etc.
1769 //
1770 // A word of caution: The JVM uses 2 very similar constructs:
1771 // 1. ParkEvent are used for Java-level "monitor" synchronization.
1772 // 2. Parkers are used by JSR166-JUC park-unpark.
1773 //
1774 // We'll want to eventually merge these redundant facilities and use ParkEvent.
1775
1776
1777 class ParkEvent : public os::PlatformEvent {
1778 private:
1779 ParkEvent * FreeNext ;
1780
1781 // Current association
1782 Thread * AssociatedWith ;
1783 intptr_t RawThreadIdentity ; // LWPID etc
1784 volatile int Incarnation ;
1785
1786 // diagnostic : keep track of last thread to wake this thread.
1787 // this is useful for construction of dependency graphs.
1788 void * LastWaker ;
1789
1790 public:
1791 // MCS-CLH list linkage and Native Mutex/Monitor
1792 ParkEvent * volatile ListNext ;
1793 ParkEvent * volatile ListPrev ;
1794 volatile intptr_t OnList ;
1795 volatile int TState ;
1796 volatile int Notified ; // for native monitor construct
1797 volatile int IsWaiting ; // Enqueued on WaitSet
1798
1799
1800 private:
1801 static ParkEvent * volatile FreeList ;
1802 static volatile int ListLock ;
1803
1804 // It's prudent to mark the dtor as "private"
1805 // ensuring that it's not visible outside the package.
1806 // Unfortunately gcc warns about such usage, so
1807 // we revert to the less desirable "protected" visibility.
1808 // The other compilers accept private dtors.
1809
1810 protected: // Ensure dtor is never invoked
1811 ~ParkEvent() { guarantee (0, "invariant") ; }
1812
1813 ParkEvent() : PlatformEvent() {
1814 AssociatedWith = NULL ;
1815 FreeNext = NULL ;
1816 ListNext = NULL ;
1817 ListPrev = NULL ;
1818 OnList = 0 ;
1819 TState = 0 ;
1820 Notified = 0 ;
1821 IsWaiting = 0 ;
1822 }
1823
1824 // We use placement-new to force ParkEvent instances to be
1825 // aligned on 256-byte address boundaries. This ensures that the least
1826 // significant byte of a ParkEvent address is always 0.
1827
1828 void * operator new (size_t sz) ;
1829 void operator delete (void * a) ;
1830
1831 public:
1832 static ParkEvent * Allocate (Thread * t) ;
1833 static void Release (ParkEvent * e) ;
1834 } ;