1 /*
2 * Copyright 1997-2009 Sun Microsystems, Inc. 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 Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
20 * CA 95054 USA or visit www.sun.com if you need additional information or
21 * have any 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 // - VMThread
52 // - JavaThread
53 // - WatcherThread
54
55 class Thread: public ThreadShadow {
56 friend class VMStructs;
57 private:
58 // Exception handling
59 // (Note: _pending_exception and friends are in ThreadShadow)
60 //oop _pending_exception; // pending exception for current thread
61 // const char* _exception_file; // file information for exception (debugging only)
62 // int _exception_line; // line information for exception (debugging only)
63
64 // Support for forcing alignment of thread objects for biased locking
65 void* _real_malloc_address;
66 public:
67 void* operator new(size_t size);
68 void operator delete(void* p);
69 private:
70
71 // ***************************************************************
72 // Suspend and resume support
73 // ***************************************************************
74 //
75 // VM suspend/resume no longer exists - it was once used for various
76 // things including safepoints but was deprecated and finally removed
77 // in Java 7. Because VM suspension was considered "internal" Java-level
78 // suspension was considered "external", and this legacy naming scheme
79 // remains.
80 //
81 // External suspend/resume requests come from JVM_SuspendThread,
82 // JVM_ResumeThread, JVMTI SuspendThread, and finally JVMTI
83 // ResumeThread. External
84 // suspend requests cause _external_suspend to be set and external
85 // resume requests cause _external_suspend to be cleared.
86 // External suspend requests do not nest on top of other external
87 // suspend requests. The higher level APIs reject suspend requests
88 // for already suspended threads.
89 //
90 // The external_suspend
91 // flag is checked by has_special_runtime_exit_condition() and java thread
92 // will self-suspend when handle_special_runtime_exit_condition() is
93 // called. Most uses of the _thread_blocked state in JavaThreads are
94 // considered the same as being externally suspended; if the blocking
95 // condition lifts, the JavaThread will self-suspend. Other places
96 // where VM checks for external_suspend include:
97 // + mutex granting (do not enter monitors when thread is suspended)
98 // + state transitions from _thread_in_native
99 //
100 // In general, java_suspend() does not wait for an external suspend
101 // request to complete. When it returns, the only guarantee is that
102 // the _external_suspend field is true.
103 //
104 // wait_for_ext_suspend_completion() is used to wait for an external
105 // suspend request to complete. External suspend requests are usually
106 // followed by some other interface call that requires the thread to
107 // be quiescent, e.g., GetCallTrace(). By moving the "wait time" into
108 // the interface that requires quiescence, we give the JavaThread a
109 // chance to self-suspend before we need it to be quiescent. This
110 // improves overall suspend/query performance.
111 //
112 // _suspend_flags controls the behavior of java_ suspend/resume.
113 // It must be set under the protection of SR_lock. Read from the flag is
114 // OK without SR_lock as long as the value is only used as a hint.
115 // (e.g., check _external_suspend first without lock and then recheck
116 // inside SR_lock and finish the suspension)
117 //
118 // _suspend_flags is also overloaded for other "special conditions" so
119 // that a single check indicates whether any special action is needed
120 // eg. for async exceptions.
121 // -------------------------------------------------------------------
122 // Notes:
123 // 1. The suspend/resume logic no longer uses ThreadState in OSThread
124 // but we still update its value to keep other part of the system (mainly
125 // JVMTI) happy. ThreadState is legacy code (see notes in
126 // osThread.hpp).
127 //
128 // 2. It would be more natural if set_external_suspend() is private and
129 // part of java_suspend(), but that probably would affect the suspend/query
130 // performance. Need more investigation on this.
131 //
132
133 // suspend/resume lock: used for self-suspend
134 Monitor* _SR_lock;
135
136 protected:
137 enum SuspendFlags {
138 // NOTE: avoid using the sign-bit as cc generates different test code
139 // when the sign-bit is used, and sometimes incorrectly - see CR 6398077
140
141 _external_suspend = 0x20000000U, // thread is asked to self suspend
142 _ext_suspended = 0x40000000U, // thread has self-suspended
143 _deopt_suspend = 0x10000000U, // thread needs to self suspend for deopt
144
145 _has_async_exception = 0x00000001U // there is a pending async exception
146 };
147
148 // various suspension related flags - atomically updated
149 // overloaded for async exception checking in check_special_condition_for_native_trans.
150 volatile uint32_t _suspend_flags;
151
152 private:
153 int _num_nested_signal;
154
155 public:
156 void enter_signal_handler() { _num_nested_signal++; }
157 void leave_signal_handler() { _num_nested_signal--; }
158 bool is_inside_signal_handler() const { return _num_nested_signal > 0; }
159
160 private:
161 // Debug tracing
162 static void trace(const char* msg, const Thread* const thread) PRODUCT_RETURN;
163
164 // Active_handles points to a block of handles
165 JNIHandleBlock* _active_handles;
166
167 // One-element thread local free list
168 JNIHandleBlock* _free_handle_block;
169
170 // Point to the last handle mark
171 HandleMark* _last_handle_mark;
172
173 // The parity of the last strong_roots iteration in which this thread was
174 // claimed as a task.
175 jint _oops_do_parity;
176
177 public:
178 void set_last_handle_mark(HandleMark* mark) { _last_handle_mark = mark; }
179 HandleMark* last_handle_mark() const { return _last_handle_mark; }
180 private:
181
182 // debug support for checking if code does allow safepoints or not
183 // GC points in the VM can happen because of allocation, invoking a VM operation, or blocking on
184 // mutex, or blocking on an object synchronizer (Java locking).
185 // If !allow_safepoint(), then an assertion failure will happen in any of the above cases
186 // If !allow_allocation(), then an assertion failure will happen during allocation
187 // (Hence, !allow_safepoint() => !allow_allocation()).
188 //
189 // The two classes No_Safepoint_Verifier and No_Allocation_Verifier are used to set these counters.
190 //
191 NOT_PRODUCT(int _allow_safepoint_count;) // If 0, thread allow a safepoint to happen
192 debug_only (int _allow_allocation_count;) // If 0, the thread is allowed to allocate oops.
193
194 // Used by SkipGCALot class.
195 NOT_PRODUCT(bool _skip_gcalot;) // Should we elide gc-a-lot?
196
197 // Record when GC is locked out via the GC_locker mechanism
198 CHECK_UNHANDLED_OOPS_ONLY(int _gc_locked_out_count;)
199
200 friend class No_Alloc_Verifier;
201 friend class No_Safepoint_Verifier;
202 friend class Pause_No_Safepoint_Verifier;
203 friend class ThreadLocalStorage;
204 friend class GC_locker;
205
206 ThreadLocalAllocBuffer _tlab; // Thread-local eden
207
208 int _vm_operation_started_count; // VM_Operation support
209 int _vm_operation_completed_count; // VM_Operation support
210
211 ObjectMonitor* _current_pending_monitor; // ObjectMonitor this thread
212 // is waiting to lock
213 bool _current_pending_monitor_is_from_java; // locking is from Java code
214
215 // ObjectMonitor on which this thread called Object.wait()
216 ObjectMonitor* _current_waiting_monitor;
217
218 // Private thread-local objectmonitor list - a simple cache organized as a SLL.
219 public:
220 ObjectMonitor * omFreeList ;
221 int omFreeCount ; // length of omFreeList
222 int omFreeProvision ; // reload chunk size
223
224 public:
225 enum {
226 is_definitely_current_thread = true
227 };
228
229 // Constructor
230 Thread();
231 virtual ~Thread();
232
233 // initializtion
234 void initialize_thread_local_storage();
235
236 // thread entry point
237 virtual void run();
238
239 // Testers
240 virtual bool is_VM_thread() const { return false; }
241 virtual bool is_Java_thread() const { return false; }
242 // Remove this ifdef when C1 is ported to the compiler interface.
243 virtual bool is_Compiler_thread() const { return false; }
244 virtual bool is_hidden_from_external_view() const { return false; }
245 virtual bool is_jvmti_agent_thread() const { return false; }
246 // True iff the thread can perform GC operations at a safepoint.
247 // Generally will be true only of VM thread and parallel GC WorkGang
248 // threads.
249 virtual bool is_GC_task_thread() const { return false; }
250 virtual bool is_Watcher_thread() const { return false; }
251 virtual bool is_ConcurrentGC_thread() const { return false; }
252
253 virtual char* name() const { return (char*)"Unknown thread"; }
254
255 // Returns the current thread
256 static inline Thread* current();
257
258 // Common thread operations
259 static void set_priority(Thread* thread, ThreadPriority priority);
260 static ThreadPriority get_priority(const Thread* const thread);
261 static void start(Thread* thread);
262 static void interrupt(Thread* thr);
263 static bool is_interrupted(Thread* thr, bool clear_interrupted);
264
265 Monitor* SR_lock() const { return _SR_lock; }
266
267 bool has_async_exception() const { return (_suspend_flags & _has_async_exception) != 0; }
268
269 void set_suspend_flag(SuspendFlags f) {
270 assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
271 uint32_t flags;
272 do {
273 flags = _suspend_flags;
274 }
275 while (Atomic::cmpxchg((jint)(flags | f),
276 (volatile jint*)&_suspend_flags,
277 (jint)flags) != (jint)flags);
278 }
279 void clear_suspend_flag(SuspendFlags f) {
280 assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
281 uint32_t flags;
282 do {
283 flags = _suspend_flags;
284 }
285 while (Atomic::cmpxchg((jint)(flags & ~f),
286 (volatile jint*)&_suspend_flags,
287 (jint)flags) != (jint)flags);
288 }
289
290 void set_has_async_exception() {
291 set_suspend_flag(_has_async_exception);
292 }
293 void clear_has_async_exception() {
294 clear_suspend_flag(_has_async_exception);
295 }
296
297 // Support for Unhandled Oop detection
298 #ifdef CHECK_UNHANDLED_OOPS
299 private:
300 UnhandledOops *_unhandled_oops;
301 public:
302 UnhandledOops* unhandled_oops() { return _unhandled_oops; }
303 // Mark oop safe for gc. It may be stack allocated but won't move.
304 void allow_unhandled_oop(oop *op) {
305 if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
306 }
307 // Clear oops at safepoint so crashes point to unhandled oop violator
308 void clear_unhandled_oops() {
309 if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
310 }
311 bool is_gc_locked_out() { return _gc_locked_out_count > 0; }
312 #endif // CHECK_UNHANDLED_OOPS
313
314 #ifndef PRODUCT
315 bool skip_gcalot() { return _skip_gcalot; }
316 void set_skip_gcalot(bool v) { _skip_gcalot = v; }
317 #endif
318
319 public:
320 // Installs a pending exception to be inserted later
321 static void send_async_exception(oop thread_oop, oop java_throwable);
322
323 // Resource area
324 ResourceArea* resource_area() const { return _resource_area; }
325 void set_resource_area(ResourceArea* area) { _resource_area = area; }
326
327 OSThread* osthread() const { return _osthread; }
328 void set_osthread(OSThread* thread) { _osthread = thread; }
329
330 // JNI handle support
331 JNIHandleBlock* active_handles() const { return _active_handles; }
332 void set_active_handles(JNIHandleBlock* block) { _active_handles = block; }
333 JNIHandleBlock* free_handle_block() const { return _free_handle_block; }
334 void set_free_handle_block(JNIHandleBlock* block) { _free_handle_block = block; }
335
336 // Internal handle support
337 HandleArea* handle_area() const { return _handle_area; }
338 void set_handle_area(HandleArea* area) { _handle_area = area; }
339
340 // Thread-Local Allocation Buffer (TLAB) support
341 ThreadLocalAllocBuffer& tlab() { return _tlab; }
342 void initialize_tlab() {
343 if (UseTLAB) {
344 tlab().initialize();
345 }
346 }
347
348 // VM operation support
349 int vm_operation_ticket() { return ++_vm_operation_started_count; }
350 int vm_operation_completed_count() { return _vm_operation_completed_count; }
351 void increment_vm_operation_completed_count() { _vm_operation_completed_count++; }
352
353 // For tracking the heavyweight monitor the thread is pending on.
354 ObjectMonitor* current_pending_monitor() {
355 return _current_pending_monitor;
356 }
357 void set_current_pending_monitor(ObjectMonitor* monitor) {
358 _current_pending_monitor = monitor;
359 }
360 void set_current_pending_monitor_is_from_java(bool from_java) {
361 _current_pending_monitor_is_from_java = from_java;
362 }
363 bool current_pending_monitor_is_from_java() {
364 return _current_pending_monitor_is_from_java;
365 }
366
367 // For tracking the ObjectMonitor on which this thread called Object.wait()
368 ObjectMonitor* current_waiting_monitor() {
369 return _current_waiting_monitor;
370 }
371 void set_current_waiting_monitor(ObjectMonitor* monitor) {
372 _current_waiting_monitor = monitor;
373 }
374
375 // GC support
376 // Apply "f->do_oop" to all root oops in "this".
377 // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
378 void oops_do(OopClosure* f, CodeBlobClosure* cf);
379
380 // Handles the parallel case for the method below.
381 private:
382 bool claim_oops_do_par_case(int collection_parity);
383 public:
384 // Requires that "collection_parity" is that of the current strong roots
385 // iteration. If "is_par" is false, sets the parity of "this" to
386 // "collection_parity", and returns "true". If "is_par" is true,
387 // uses an atomic instruction to set the current threads parity to
388 // "collection_parity", if it is not already. Returns "true" iff the
389 // calling thread does the update, this indicates that the calling thread
390 // has claimed the thread's stack as a root groop in the current
391 // collection.
392 bool claim_oops_do(bool is_par, int collection_parity) {
393 if (!is_par) {
394 _oops_do_parity = collection_parity;
395 return true;
396 } else {
397 return claim_oops_do_par_case(collection_parity);
398 }
399 }
400
401 // Sweeper support
402 void nmethods_do(CodeBlobClosure* cf);
403
404 // Tells if adr belong to this thread. This is used
405 // for checking if a lock is owned by the running thread.
406
407 // Used by fast lock support
408 virtual bool is_lock_owned(address adr) const;
409
410 // Check if address is in the stack of the thread (not just for locks).
411 // Warning: the method can only be used on the running thread
412 bool is_in_stack(address adr) const;
413
414 // Sets this thread as starting thread. Returns failure if thread
415 // creation fails due to lack of memory, too many threads etc.
416 bool set_as_starting_thread();
417
418 protected:
419 // OS data associated with the thread
420 OSThread* _osthread; // Platform-specific thread information
421
422 // Thread local resource area for temporary allocation within the VM
423 ResourceArea* _resource_area;
424
425 // Thread local handle area for allocation of handles within the VM
426 HandleArea* _handle_area;
427
428 // Support for stack overflow handling, get_thread, etc.
429 address _stack_base;
430 size_t _stack_size;
431 uintptr_t _self_raw_id; // used by get_thread (mutable)
432 int _lgrp_id;
433
434 public:
435 // Stack overflow support
436 address stack_base() const { assert(_stack_base != NULL,"Sanity check"); return _stack_base; }
437
438 void set_stack_base(address base) { _stack_base = base; }
439 size_t stack_size() const { return _stack_size; }
440 void set_stack_size(size_t size) { _stack_size = size; }
441 void record_stack_base_and_size();
442
443 int lgrp_id() const { return _lgrp_id; }
444 void set_lgrp_id(int value) { _lgrp_id = value; }
445
446 // Printing
447 void print_on(outputStream* st) const;
448 void print() const { print_on(tty); }
449 virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
450
451 // Debug-only code
452
453 #ifdef ASSERT
454 private:
455 // Deadlock detection support for Mutex locks. List of locks own by thread.
456 Monitor *_owned_locks;
457 // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
458 // thus the friendship
459 friend class Mutex;
460 friend class Monitor;
461
462 public:
463 void print_owned_locks_on(outputStream* st) const;
464 void print_owned_locks() const { print_owned_locks_on(tty); }
465 Monitor * owned_locks() const { return _owned_locks; }
466 bool owns_locks() const { return owned_locks() != NULL; }
467 bool owns_locks_but_compiled_lock() const;
468
469 // Deadlock detection
470 bool allow_allocation() { return _allow_allocation_count == 0; }
471 #endif
472
473 void check_for_valid_safepoint_state(bool potential_vm_operation) PRODUCT_RETURN;
474
475 private:
476 volatile int _jvmti_env_iteration_count;
477
478 public:
479 void entering_jvmti_env_iteration() { ++_jvmti_env_iteration_count; }
480 void leaving_jvmti_env_iteration() { --_jvmti_env_iteration_count; }
481 bool is_inside_jvmti_env_iteration() { return _jvmti_env_iteration_count > 0; }
482
483 // Code generation
484 static ByteSize exception_file_offset() { return byte_offset_of(Thread, _exception_file ); }
485 static ByteSize exception_line_offset() { return byte_offset_of(Thread, _exception_line ); }
486 static ByteSize active_handles_offset() { return byte_offset_of(Thread, _active_handles ); }
487
488 static ByteSize stack_base_offset() { return byte_offset_of(Thread, _stack_base ); }
489 static ByteSize stack_size_offset() { return byte_offset_of(Thread, _stack_size ); }
490 static ByteSize omFreeList_offset() { return byte_offset_of(Thread, omFreeList); }
491
492 #define TLAB_FIELD_OFFSET(name) \
493 static ByteSize tlab_##name##_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::name##_offset(); }
494
495 TLAB_FIELD_OFFSET(start)
496 TLAB_FIELD_OFFSET(end)
497 TLAB_FIELD_OFFSET(top)
498 TLAB_FIELD_OFFSET(pf_top)
499 TLAB_FIELD_OFFSET(size) // desired_size
500 TLAB_FIELD_OFFSET(refill_waste_limit)
501 TLAB_FIELD_OFFSET(number_of_refills)
502 TLAB_FIELD_OFFSET(fast_refill_waste)
503 TLAB_FIELD_OFFSET(slow_allocations)
504
505 #undef TLAB_FIELD_OFFSET
506
507 public:
508 volatile intptr_t _Stalled ;
509 volatile int _TypeTag ;
510 ParkEvent * _ParkEvent ; // for synchronized()
511 ParkEvent * _SleepEvent ; // for Thread.sleep
512 ParkEvent * _MutexEvent ; // for native internal Mutex/Monitor
513 ParkEvent * _MuxEvent ; // for low-level muxAcquire-muxRelease
514 int NativeSyncRecursion ; // diagnostic
515
516 volatile int _OnTrap ; // Resume-at IP delta
517 jint _hashStateW ; // Marsaglia Shift-XOR thread-local RNG
518 jint _hashStateX ; // thread-specific hashCode generator state
519 jint _hashStateY ;
520 jint _hashStateZ ;
521 void * _schedctl ;
522
523 intptr_t _ScratchA, _ScratchB ; // Scratch locations for fast-path sync code
524 static ByteSize ScratchA_offset() { return byte_offset_of(Thread, _ScratchA ); }
525 static ByteSize ScratchB_offset() { return byte_offset_of(Thread, _ScratchB ); }
526
527 volatile jint rng [4] ; // RNG for spin loop
528
529 // Low-level leaf-lock primitives used to implement synchronization
530 // and native monitor-mutex infrastructure.
531 // Not for general synchronization use.
532 static void SpinAcquire (volatile int * Lock, const char * Name) ;
533 static void SpinRelease (volatile int * Lock) ;
534 static void muxAcquire (volatile intptr_t * Lock, const char * Name) ;
535 static void muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) ;
536 static void muxRelease (volatile intptr_t * Lock) ;
537
538 };
539
540 // Inline implementation of Thread::current()
541 // Thread::current is "hot" it's called > 128K times in the 1st 500 msecs of
542 // startup.
543 // ThreadLocalStorage::thread is warm -- it's called > 16K times in the same
544 // period. This is inlined in thread_<os_family>.inline.hpp.
545
546 inline Thread* Thread::current() {
547 #ifdef ASSERT
548 // This function is very high traffic. Define PARANOID to enable expensive
549 // asserts.
550 #ifdef PARANOID
551 // Signal handler should call ThreadLocalStorage::get_thread_slow()
552 Thread* t = ThreadLocalStorage::get_thread_slow();
553 assert(t != NULL && !t->is_inside_signal_handler(),
554 "Don't use Thread::current() inside signal handler");
555 #endif
556 #endif
557 Thread* thread = ThreadLocalStorage::thread();
558 assert(thread != NULL, "just checking");
559 return thread;
560 }
561
562 // Name support for threads. non-JavaThread subclasses with multiple
563 // uniquely named instances should derive from this.
564 class NamedThread: public Thread {
565 friend class VMStructs;
566 enum {
567 max_name_len = 64
568 };
569 private:
570 char* _name;
571 public:
572 NamedThread();
573 ~NamedThread();
574 // May only be called once per thread.
575 void set_name(const char* format, ...);
576 virtual char* name() const { return _name == NULL ? (char*)"Unknown Thread" : _name; }
577 };
578
579 // Worker threads are named and have an id of an assigned work.
580 class WorkerThread: public NamedThread {
581 private:
582 uint _id;
583 public:
584 WorkerThread() : _id(0) { }
585 void set_id(uint work_id) { _id = work_id; }
586 uint id() const { return _id; }
587 };
588
589 // A single WatcherThread is used for simulating timer interrupts.
590 class WatcherThread: public Thread {
591 friend class VMStructs;
592 public:
593 virtual void run();
594
595 private:
596 static WatcherThread* _watcher_thread;
597
598 static bool _should_terminate;
599 public:
600 enum SomeConstants {
601 delay_interval = 10 // interrupt delay in milliseconds
602 };
603
604 // Constructor
605 WatcherThread();
606
607 // Tester
608 bool is_Watcher_thread() const { return true; }
609
610 // Printing
611 char* name() const { return (char*)"VM Periodic Task Thread"; }
612 void print_on(outputStream* st) const;
613 void print() const { print_on(tty); }
614
615 // Returns the single instance of WatcherThread
616 static WatcherThread* watcher_thread() { return _watcher_thread; }
617
618 // Create and start the single instance of WatcherThread, or stop it on shutdown
619 static void start();
620 static void stop();
621 };
622
623
624 class CompilerThread;
625
626 typedef void (*ThreadFunction)(JavaThread*, TRAPS);
627
628 class JavaThread: public Thread {
629 friend class VMStructs;
630 private:
631 JavaThread* _next; // The next thread in the Threads list
632 oop _threadObj; // The Java level thread object
633
634 #ifdef ASSERT
635 private:
636 int _java_call_counter;
637
638 public:
639 int java_call_counter() { return _java_call_counter; }
640 void inc_java_call_counter() { _java_call_counter++; }
641 void dec_java_call_counter() {
642 assert(_java_call_counter > 0, "Invalid nesting of JavaCallWrapper");
643 _java_call_counter--;
644 }
645 private: // restore original namespace restriction
646 #endif // ifdef ASSERT
647
648 #ifndef PRODUCT
649 public:
650 enum {
651 jump_ring_buffer_size = 16
652 };
653 private: // restore original namespace restriction
654 #endif
655
656 JavaFrameAnchor _anchor; // Encapsulation of current java frame and it state
657
658 ThreadFunction _entry_point;
659
660 JNIEnv _jni_environment;
661
662 // Deopt support
663 DeoptResourceMark* _deopt_mark; // Holds special ResourceMark for deoptimization
664
665 intptr_t* _must_deopt_id; // id of frame that needs to be deopted once we
666 // transition out of native
667
668 vframeArray* _vframe_array_head; // Holds the heap of the active vframeArrays
669 vframeArray* _vframe_array_last; // Holds last vFrameArray we popped
670 // Because deoptimization is lazy we must save jvmti requests to set locals
671 // in compiled frames until we deoptimize and we have an interpreter frame.
672 // This holds the pointer to array (yeah like there might be more than one) of
673 // description of compiled vframes that have locals that need to be updated.
674 GrowableArray<jvmtiDeferredLocalVariableSet*>* _deferred_locals_updates;
675
676 // Handshake value for fixing 6243940. We need a place for the i2c
677 // adapter to store the callee methodOop. This value is NEVER live
678 // across a gc point so it does NOT have to be gc'd
679 // The handshake is open ended since we can't be certain that it will
680 // be NULLed. This is because we rarely ever see the race and end up
681 // in handle_wrong_method which is the backend of the handshake. See
682 // code in i2c adapters and handle_wrong_method.
683
684 methodOop _callee_target;
685
686 // Oop results of VM runtime calls
687 oop _vm_result; // Used to pass back an oop result into Java code, GC-preserved
688 oop _vm_result_2; // Used to pass back an oop result into Java code, GC-preserved
689
690 // See ReduceInitialCardMarks: this holds the precise space interval of
691 // the most recent slow path allocation for which compiled code has
692 // elided card-marks for performance along the fast-path.
693 MemRegion _deferred_card_mark;
694
695 MonitorChunk* _monitor_chunks; // Contains the off stack monitors
696 // allocated during deoptimization
697 // and by JNI_MonitorEnter/Exit
698
699 // Async. requests support
700 enum AsyncRequests {
701 _no_async_condition = 0,
702 _async_exception,
703 _async_unsafe_access_error
704 };
705 AsyncRequests _special_runtime_exit_condition; // Enum indicating pending async. request
706 oop _pending_async_exception;
707
708 // Safepoint support
709 public: // Expose _thread_state for SafeFetchInt()
710 volatile JavaThreadState _thread_state;
711 private:
712 ThreadSafepointState *_safepoint_state; // Holds information about a thread during a safepoint
713 address _saved_exception_pc; // Saved pc of instruction where last implicit exception happened
714
715 // JavaThread termination support
716 enum TerminatedTypes {
717 _not_terminated = 0xDEAD - 2,
718 _thread_exiting, // JavaThread::exit() has been called for this thread
719 _thread_terminated, // JavaThread is removed from thread list
720 _vm_exited // JavaThread is still executing native code, but VM is terminated
721 // only VM_Exit can set _vm_exited
722 };
723
724 // In general a JavaThread's _terminated field transitions as follows:
725 //
726 // _not_terminated => _thread_exiting => _thread_terminated
727 //
728 // _vm_exited is a special value to cover the case of a JavaThread
729 // executing native code after the VM itself is terminated.
730 TerminatedTypes _terminated;
731 // suspend/resume support
732 volatile bool _suspend_equivalent; // Suspend equivalent condition
733 jint _in_deopt_handler; // count of deoptimization
734 // handlers thread is in
735 volatile bool _doing_unsafe_access; // Thread may fault due to unsafe access
736 bool _do_not_unlock_if_synchronized; // Do not unlock the receiver of a synchronized method (since it was
737 // never locked) when throwing an exception. Used by interpreter only.
738
739 // Flag to mark a JNI thread in the process of attaching - See CR 6404306
740 // This flag is never set true other than at construction, and in that case
741 // is shortly thereafter set false
742 volatile bool _is_attaching;
743
744 public:
745 // State of the stack guard pages for this thread.
746 enum StackGuardState {
747 stack_guard_unused, // not needed
748 stack_guard_yellow_disabled,// disabled (temporarily) after stack overflow
749 stack_guard_enabled // enabled
750 };
751
752 private:
753
754 StackGuardState _stack_guard_state;
755
756 // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
757 // used to temp. parsing values into and out of the runtime system during exception handling for compiled
758 // code)
759 volatile oop _exception_oop; // Exception thrown in compiled code
760 volatile address _exception_pc; // PC where exception happened
761 volatile address _exception_handler_pc; // PC for handler of exception
762 volatile int _exception_stack_size; // Size of frame where exception happened
763 volatile int _is_method_handle_exception; // True if the current exception PC is at a MethodHandle call.
764
765 // support for compilation
766 bool _is_compiling; // is true if a compilation is active inthis thread (one compilation per thread possible)
767
768 // support for JNI critical regions
769 jint _jni_active_critical; // count of entries into JNI critical region
770
771 // For deadlock detection.
772 int _depth_first_number;
773
774 // JVMTI PopFrame support
775 // This is set to popframe_pending to signal that top Java frame should be popped immediately
776 int _popframe_condition;
777
778 #ifndef PRODUCT
779 int _jmp_ring_index;
780 struct {
781 // We use intptr_t instead of address so debugger doesn't try and display strings
782 intptr_t _target;
783 intptr_t _instruction;
784 const char* _file;
785 int _line;
786 } _jmp_ring[ jump_ring_buffer_size ];
787 #endif /* PRODUCT */
788
789 #ifndef SERIALGC
790 // Support for G1 barriers
791
792 ObjPtrQueue _satb_mark_queue; // Thread-local log for SATB barrier.
793 // Set of all such queues.
794 static SATBMarkQueueSet _satb_mark_queue_set;
795
796 DirtyCardQueue _dirty_card_queue; // Thread-local log for dirty cards.
797 // Set of all such queues.
798 static DirtyCardQueueSet _dirty_card_queue_set;
799
800 void flush_barrier_queues();
801 #endif // !SERIALGC
802
803 friend class VMThread;
804 friend class ThreadWaitTransition;
805 friend class VM_Exit;
806
807 void initialize(); // Initialized the instance variables
808
809 public:
810 // Constructor
811 JavaThread(bool is_attaching = false); // for main thread and JNI attached threads
812 JavaThread(ThreadFunction entry_point, size_t stack_size = 0);
813 ~JavaThread();
814
815 #ifdef ASSERT
816 // verify this JavaThread hasn't be published in the Threads::list yet
817 void verify_not_published();
818 #endif
819
820 //JNI functiontable getter/setter for JVMTI jni function table interception API.
821 void set_jni_functions(struct JNINativeInterface_* functionTable) {
822 _jni_environment.functions = functionTable;
823 }
824 struct JNINativeInterface_* get_jni_functions() {
825 return (struct JNINativeInterface_ *)_jni_environment.functions;
826 }
827
828 // Executes Shutdown.shutdown()
829 void invoke_shutdown_hooks();
830
831 // Cleanup on thread exit
832 enum ExitType {
833 normal_exit,
834 jni_detach
835 };
836 void exit(bool destroy_vm, ExitType exit_type = normal_exit);
837
838 void cleanup_failed_attach_current_thread();
839
840 // Testers
841 virtual bool is_Java_thread() const { return true; }
842
843 // compilation
844 void set_is_compiling(bool f) { _is_compiling = f; }
845 bool is_compiling() const { return _is_compiling; }
846
847 // Thread chain operations
848 JavaThread* next() const { return _next; }
849 void set_next(JavaThread* p) { _next = p; }
850
851 // Thread oop. threadObj() can be NULL for initial JavaThread
852 // (or for threads attached via JNI)
853 oop threadObj() const { return _threadObj; }
854 void set_threadObj(oop p) { _threadObj = p; }
855
856 ThreadPriority java_priority() const; // Read from threadObj()
857
858 // Prepare thread and add to priority queue. If a priority is
859 // not specified, use the priority of the thread object. Threads_lock
860 // must be held while this function is called.
861 void prepare(jobject jni_thread, ThreadPriority prio=NoPriority);
862
863 void set_saved_exception_pc(address pc) { _saved_exception_pc = pc; }
864 address saved_exception_pc() { return _saved_exception_pc; }
865
866
867 ThreadFunction entry_point() const { return _entry_point; }
868
869 // Allocates a new Java level thread object for this thread. thread_name may be NULL.
870 void allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS);
871
872 // Last frame anchor routines
873
874 JavaFrameAnchor* frame_anchor(void) { return &_anchor; }
875
876 // last_Java_sp
877 bool has_last_Java_frame() const { return _anchor.has_last_Java_frame(); }
878 intptr_t* last_Java_sp() const { return _anchor.last_Java_sp(); }
879
880 // last_Java_pc
881
882 address last_Java_pc(void) { return _anchor.last_Java_pc(); }
883
884 // Safepoint support
885 JavaThreadState thread_state() const { return _thread_state; }
886 void set_thread_state(JavaThreadState s) { _thread_state=s; }
887 ThreadSafepointState *safepoint_state() const { return _safepoint_state; }
888 void set_safepoint_state(ThreadSafepointState *state) { _safepoint_state = state; }
889 bool is_at_poll_safepoint() { return _safepoint_state->is_at_poll_safepoint(); }
890
891 // thread has called JavaThread::exit() or is terminated
892 bool is_exiting() { return _terminated == _thread_exiting || is_terminated(); }
893 // thread is terminated (no longer on the threads list); we compare
894 // against the two non-terminated values so that a freed JavaThread
895 // will also be considered terminated.
896 bool is_terminated() { return _terminated != _not_terminated && _terminated != _thread_exiting; }
897 void set_terminated(TerminatedTypes t) { _terminated = t; }
898 // special for Threads::remove() which is static:
899 void set_terminated_value() { _terminated = _thread_terminated; }
900 void block_if_vm_exited();
901
902 bool doing_unsafe_access() { return _doing_unsafe_access; }
903 void set_doing_unsafe_access(bool val) { _doing_unsafe_access = val; }
904
905 bool do_not_unlock_if_synchronized() { return _do_not_unlock_if_synchronized; }
906 void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }
907
908
909 // Suspend/resume support for JavaThread
910
911 private:
912 void set_ext_suspended() { set_suspend_flag (_ext_suspended); }
913 void clear_ext_suspended() { clear_suspend_flag(_ext_suspended); }
914
915 public:
916 void java_suspend();
917 void java_resume();
918 int java_suspend_self();
919
920 void check_and_wait_while_suspended() {
921 assert(JavaThread::current() == this, "sanity check");
922
923 bool do_self_suspend;
924 do {
925 // were we externally suspended while we were waiting?
926 do_self_suspend = handle_special_suspend_equivalent_condition();
927 if (do_self_suspend) {
928 // don't surprise the thread that suspended us by returning
929 java_suspend_self();
930 set_suspend_equivalent();
931 }
932 } while (do_self_suspend);
933 }
934 static void check_safepoint_and_suspend_for_native_trans(JavaThread *thread);
935 // Check for async exception in addition to safepoint and suspend request.
936 static void check_special_condition_for_native_trans(JavaThread *thread);
937
938 bool is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits);
939 bool is_ext_suspend_completed_with_lock(uint32_t *bits) {
940 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
941 // Warning: is_ext_suspend_completed() may temporarily drop the
942 // SR_lock to allow the thread to reach a stable thread state if
943 // it is currently in a transient thread state.
944 return is_ext_suspend_completed(false /*!called_by_wait */,
945 SuspendRetryDelay, bits);
946 }
947
948 // We cannot allow wait_for_ext_suspend_completion() to run forever or
949 // we could hang. SuspendRetryCount and SuspendRetryDelay are normally
950 // passed as the count and delay parameters. Experiments with specific
951 // calls to wait_for_ext_suspend_completion() can be done by passing
952 // other values in the code. Experiments with all calls can be done
953 // via the appropriate -XX options.
954 bool wait_for_ext_suspend_completion(int count, int delay, uint32_t *bits);
955
956 void set_external_suspend() { set_suspend_flag (_external_suspend); }
957 void clear_external_suspend() { clear_suspend_flag(_external_suspend); }
958
959 void set_deopt_suspend() { set_suspend_flag (_deopt_suspend); }
960 void clear_deopt_suspend() { clear_suspend_flag(_deopt_suspend); }
961 bool is_deopt_suspend() { return (_suspend_flags & _deopt_suspend) != 0; }
962
963 bool is_external_suspend() const {
964 return (_suspend_flags & _external_suspend) != 0;
965 }
966 // Whenever a thread transitions from native to vm/java it must suspend
967 // if external|deopt suspend is present.
968 bool is_suspend_after_native() const {
969 return (_suspend_flags & (_external_suspend | _deopt_suspend) ) != 0;
970 }
971
972 // external suspend request is completed
973 bool is_ext_suspended() const {
974 return (_suspend_flags & _ext_suspended) != 0;
975 }
976
977 bool is_external_suspend_with_lock() const {
978 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
979 return is_external_suspend();
980 }
981
982 // Special method to handle a pending external suspend request
983 // when a suspend equivalent condition lifts.
984 bool handle_special_suspend_equivalent_condition() {
985 assert(is_suspend_equivalent(),
986 "should only be called in a suspend equivalence condition");
987 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
988 bool ret = is_external_suspend();
989 if (!ret) {
990 // not about to self-suspend so clear suspend equivalence
991 clear_suspend_equivalent();
992 }
993 // implied else:
994 // We have a pending external suspend request so we leave the
995 // suspend_equivalent flag set until java_suspend_self() sets
996 // the ext_suspended flag and clears the suspend_equivalent
997 // flag. This insures that wait_for_ext_suspend_completion()
998 // will return consistent values.
999 return ret;
1000 }
1001
1002 // utility methods to see if we are doing some kind of suspension
1003 bool is_being_ext_suspended() const {
1004 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1005 return is_ext_suspended() || is_external_suspend();
1006 }
1007
1008 bool is_suspend_equivalent() const { return _suspend_equivalent; }
1009
1010 void set_suspend_equivalent() { _suspend_equivalent = true; };
1011 void clear_suspend_equivalent() { _suspend_equivalent = false; };
1012
1013 // Thread.stop support
1014 void send_thread_stop(oop throwable);
1015 AsyncRequests clear_special_runtime_exit_condition() {
1016 AsyncRequests x = _special_runtime_exit_condition;
1017 _special_runtime_exit_condition = _no_async_condition;
1018 return x;
1019 }
1020
1021 // Are any async conditions present?
1022 bool has_async_condition() { return (_special_runtime_exit_condition != _no_async_condition); }
1023
1024 void check_and_handle_async_exceptions(bool check_unsafe_error = true);
1025
1026 // these next two are also used for self-suspension and async exception support
1027 void handle_special_runtime_exit_condition(bool check_asyncs = true);
1028
1029 // Return true if JavaThread has an asynchronous condition or
1030 // if external suspension is requested.
1031 bool has_special_runtime_exit_condition() {
1032 // We call is_external_suspend() last since external suspend should
1033 // be less common. Because we don't use is_external_suspend_with_lock
1034 // it is possible that we won't see an asynchronous external suspend
1035 // request that has just gotten started, i.e., SR_lock grabbed but
1036 // _external_suspend field change either not made yet or not visible
1037 // yet. However, this is okay because the request is asynchronous and
1038 // we will see the new flag value the next time through. It's also
1039 // possible that the external suspend request is dropped after
1040 // we have checked is_external_suspend(), we will recheck its value
1041 // under SR_lock in java_suspend_self().
1042 return (_special_runtime_exit_condition != _no_async_condition) ||
1043 is_external_suspend() || is_deopt_suspend();
1044 }
1045
1046 void set_pending_unsafe_access_error() { _special_runtime_exit_condition = _async_unsafe_access_error; }
1047
1048 void set_pending_async_exception(oop e) {
1049 _pending_async_exception = e;
1050 _special_runtime_exit_condition = _async_exception;
1051 set_has_async_exception();
1052 }
1053
1054 // Fast-locking support
1055 bool is_lock_owned(address adr) const;
1056
1057 // Accessors for vframe array top
1058 // The linked list of vframe arrays are sorted on sp. This means when we
1059 // unpack the head must contain the vframe array to unpack.
1060 void set_vframe_array_head(vframeArray* value) { _vframe_array_head = value; }
1061 vframeArray* vframe_array_head() const { return _vframe_array_head; }
1062
1063 // Side structure for defering update of java frame locals until deopt occurs
1064 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred_locals() const { return _deferred_locals_updates; }
1065 void set_deferred_locals(GrowableArray<jvmtiDeferredLocalVariableSet *>* vf) { _deferred_locals_updates = vf; }
1066
1067 // These only really exist to make debugging deopt problems simpler
1068
1069 void set_vframe_array_last(vframeArray* value) { _vframe_array_last = value; }
1070 vframeArray* vframe_array_last() const { return _vframe_array_last; }
1071
1072 // The special resourceMark used during deoptimization
1073
1074 void set_deopt_mark(DeoptResourceMark* value) { _deopt_mark = value; }
1075 DeoptResourceMark* deopt_mark(void) { return _deopt_mark; }
1076
1077 intptr_t* must_deopt_id() { return _must_deopt_id; }
1078 void set_must_deopt_id(intptr_t* id) { _must_deopt_id = id; }
1079 void clear_must_deopt_id() { _must_deopt_id = NULL; }
1080
1081 methodOop callee_target() const { return _callee_target; }
1082 void set_callee_target (methodOop x) { _callee_target = x; }
1083
1084 // Oop results of vm runtime calls
1085 oop vm_result() const { return _vm_result; }
1086 void set_vm_result (oop x) { _vm_result = x; }
1087
1088 oop vm_result_2() const { return _vm_result_2; }
1089 void set_vm_result_2 (oop x) { _vm_result_2 = x; }
1090
1091 MemRegion deferred_card_mark() const { return _deferred_card_mark; }
1092 void set_deferred_card_mark(MemRegion mr) { _deferred_card_mark = mr; }
1093
1094 // Exception handling for compiled methods
1095 oop exception_oop() const { return _exception_oop; }
1096 int exception_stack_size() const { return _exception_stack_size; }
1097 address exception_pc() const { return _exception_pc; }
1098 address exception_handler_pc() const { return _exception_handler_pc; }
1099 int is_method_handle_exception() const { return _is_method_handle_exception; }
1100
1101 void set_exception_oop(oop o) { _exception_oop = o; }
1102 void set_exception_pc(address a) { _exception_pc = a; }
1103 void set_exception_handler_pc(address a) { _exception_handler_pc = a; }
1104 void set_exception_stack_size(int size) { _exception_stack_size = size; }
1105 void set_is_method_handle_exception(int value) { _is_method_handle_exception = value; }
1106
1107 // Stack overflow support
1108 inline size_t stack_available(address cur_sp);
1109 address stack_yellow_zone_base()
1110 { return (address)(stack_base() - (stack_size() - (stack_red_zone_size() + stack_yellow_zone_size()))); }
1111 size_t stack_yellow_zone_size()
1112 { return StackYellowPages * os::vm_page_size(); }
1113 address stack_red_zone_base()
1114 { return (address)(stack_base() - (stack_size() - stack_red_zone_size())); }
1115 size_t stack_red_zone_size()
1116 { return StackRedPages * os::vm_page_size(); }
1117 bool in_stack_yellow_zone(address a)
1118 { return (a <= stack_yellow_zone_base()) && (a >= stack_red_zone_base()); }
1119 bool in_stack_red_zone(address a)
1120 { return (a <= stack_red_zone_base()) && (a >= (address)((intptr_t)stack_base() - stack_size())); }
1121
1122 void create_stack_guard_pages();
1123 void remove_stack_guard_pages();
1124
1125 void enable_stack_yellow_zone();
1126 void disable_stack_yellow_zone();
1127 void enable_stack_red_zone();
1128 void disable_stack_red_zone();
1129
1130 inline bool stack_yellow_zone_disabled();
1131 inline bool stack_yellow_zone_enabled();
1132
1133 // Attempt to reguard the stack after a stack overflow may have occurred.
1134 // Returns true if (a) guard pages are not needed on this thread, (b) the
1135 // pages are already guarded, or (c) the pages were successfully reguarded.
1136 // Returns false if there is not enough stack space to reguard the pages, in
1137 // which case the caller should unwind a frame and try again. The argument
1138 // should be the caller's (approximate) sp.
1139 bool reguard_stack(address cur_sp);
1140 // Similar to above but see if current stackpoint is out of the guard area
1141 // and reguard if possible.
1142 bool reguard_stack(void);
1143
1144 // Misc. accessors/mutators
1145 void set_do_not_unlock(void) { _do_not_unlock_if_synchronized = true; }
1146 void clr_do_not_unlock(void) { _do_not_unlock_if_synchronized = false; }
1147 bool do_not_unlock(void) { return _do_not_unlock_if_synchronized; }
1148
1149 #ifndef PRODUCT
1150 void record_jump(address target, address instr, const char* file, int line);
1151 #endif /* PRODUCT */
1152
1153 // For assembly stub generation
1154 static ByteSize threadObj_offset() { return byte_offset_of(JavaThread, _threadObj ); }
1155 #ifndef PRODUCT
1156 static ByteSize jmp_ring_index_offset() { return byte_offset_of(JavaThread, _jmp_ring_index ); }
1157 static ByteSize jmp_ring_offset() { return byte_offset_of(JavaThread, _jmp_ring ); }
1158 #endif /* PRODUCT */
1159 static ByteSize jni_environment_offset() { return byte_offset_of(JavaThread, _jni_environment ); }
1160 static ByteSize last_Java_sp_offset() {
1161 return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_sp_offset();
1162 }
1163 static ByteSize last_Java_pc_offset() {
1164 return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_pc_offset();
1165 }
1166 static ByteSize frame_anchor_offset() {
1167 return byte_offset_of(JavaThread, _anchor);
1168 }
1169 static ByteSize callee_target_offset() { return byte_offset_of(JavaThread, _callee_target ); }
1170 static ByteSize vm_result_offset() { return byte_offset_of(JavaThread, _vm_result ); }
1171 static ByteSize vm_result_2_offset() { return byte_offset_of(JavaThread, _vm_result_2 ); }
1172 static ByteSize thread_state_offset() { return byte_offset_of(JavaThread, _thread_state ); }
1173 static ByteSize saved_exception_pc_offset() { return byte_offset_of(JavaThread, _saved_exception_pc ); }
1174 static ByteSize osthread_offset() { return byte_offset_of(JavaThread, _osthread ); }
1175 static ByteSize exception_oop_offset() { return byte_offset_of(JavaThread, _exception_oop ); }
1176 static ByteSize exception_pc_offset() { return byte_offset_of(JavaThread, _exception_pc ); }
1177 static ByteSize exception_handler_pc_offset() { return byte_offset_of(JavaThread, _exception_handler_pc); }
1178 static ByteSize exception_stack_size_offset() { return byte_offset_of(JavaThread, _exception_stack_size); }
1179 static ByteSize is_method_handle_exception_offset() { return byte_offset_of(JavaThread, _is_method_handle_exception); }
1180 static ByteSize stack_guard_state_offset() { return byte_offset_of(JavaThread, _stack_guard_state ); }
1181 static ByteSize suspend_flags_offset() { return byte_offset_of(JavaThread, _suspend_flags ); }
1182
1183 static ByteSize do_not_unlock_if_synchronized_offset() { return byte_offset_of(JavaThread, _do_not_unlock_if_synchronized); }
1184
1185 #ifndef SERIALGC
1186 static ByteSize satb_mark_queue_offset() { return byte_offset_of(JavaThread, _satb_mark_queue); }
1187 static ByteSize dirty_card_queue_offset() { return byte_offset_of(JavaThread, _dirty_card_queue); }
1188 #endif // !SERIALGC
1189
1190 // Returns the jni environment for this thread
1191 JNIEnv* jni_environment() { return &_jni_environment; }
1192
1193 static JavaThread* thread_from_jni_environment(JNIEnv* env) {
1194 JavaThread *thread_from_jni_env = (JavaThread*)((intptr_t)env - in_bytes(jni_environment_offset()));
1195 // Only return NULL if thread is off the thread list; starting to
1196 // exit should not return NULL.
1197 if (thread_from_jni_env->is_terminated()) {
1198 thread_from_jni_env->block_if_vm_exited();
1199 return NULL;
1200 } else {
1201 return thread_from_jni_env;
1202 }
1203 }
1204
1205 // JNI critical regions. These can nest.
1206 bool in_critical() { return _jni_active_critical > 0; }
1207 void enter_critical() { assert(Thread::current() == this,
1208 "this must be current thread");
1209 _jni_active_critical++; }
1210 void exit_critical() { assert(Thread::current() == this,
1211 "this must be current thread");
1212 _jni_active_critical--;
1213 assert(_jni_active_critical >= 0,
1214 "JNI critical nesting problem?"); }
1215
1216 // For deadlock detection
1217 int depth_first_number() { return _depth_first_number; }
1218 void set_depth_first_number(int dfn) { _depth_first_number = dfn; }
1219
1220 private:
1221 void set_monitor_chunks(MonitorChunk* monitor_chunks) { _monitor_chunks = monitor_chunks; }
1222
1223 public:
1224 MonitorChunk* monitor_chunks() const { return _monitor_chunks; }
1225 void add_monitor_chunk(MonitorChunk* chunk);
1226 void remove_monitor_chunk(MonitorChunk* chunk);
1227 bool in_deopt_handler() const { return _in_deopt_handler > 0; }
1228 void inc_in_deopt_handler() { _in_deopt_handler++; }
1229 void dec_in_deopt_handler() {
1230 assert(_in_deopt_handler > 0, "mismatched deopt nesting");
1231 if (_in_deopt_handler > 0) { // robustness
1232 _in_deopt_handler--;
1233 }
1234 }
1235
1236 private:
1237 void set_entry_point(ThreadFunction entry_point) { _entry_point = entry_point; }
1238
1239 public:
1240
1241 // Frame iteration; calls the function f for all frames on the stack
1242 void frames_do(void f(frame*, const RegisterMap*));
1243
1244 // Memory operations
1245 void oops_do(OopClosure* f, CodeBlobClosure* cf);
1246
1247 // Sweeper operations
1248 void nmethods_do(CodeBlobClosure* cf);
1249
1250 // Memory management operations
1251 void gc_epilogue();
1252 void gc_prologue();
1253
1254 // Misc. operations
1255 char* name() const { return (char*)get_thread_name(); }
1256 void print_on(outputStream* st) const;
1257 void print() const { print_on(tty); }
1258 void print_value();
1259 void print_thread_state_on(outputStream* ) const PRODUCT_RETURN;
1260 void print_thread_state() const PRODUCT_RETURN;
1261 void print_on_error(outputStream* st, char* buf, int buflen) const;
1262 void verify();
1263 const char* get_thread_name() const;
1264 private:
1265 // factor out low-level mechanics for use in both normal and error cases
1266 const char* get_thread_name_string(char* buf = NULL, int buflen = 0) const;
1267 public:
1268 const char* get_threadgroup_name() const;
1269 const char* get_parent_name() const;
1270
1271 // Accessing frames
1272 frame last_frame() {
1273 _anchor.make_walkable(this);
1274 return pd_last_frame();
1275 }
1276 javaVFrame* last_java_vframe(RegisterMap* reg_map);
1277
1278 // Returns method at 'depth' java or native frames down the stack
1279 // Used for security checks
1280 klassOop security_get_caller_class(int depth);
1281
1282 // Print stack trace in external format
1283 void print_stack_on(outputStream* st);
1284 void print_stack() { print_stack_on(tty); }
1285
1286 // Print stack traces in various internal formats
1287 void trace_stack() PRODUCT_RETURN;
1288 void trace_stack_from(vframe* start_vf) PRODUCT_RETURN;
1289 void trace_frames() PRODUCT_RETURN;
1290
1291 // Returns the number of stack frames on the stack
1292 int depth() const;
1293
1294 // Function for testing deoptimization
1295 void deoptimize();
1296 void make_zombies();
1297
1298 void deoptimized_wrt_marked_nmethods();
1299
1300 // Profiling operation (see fprofile.cpp)
1301 public:
1302 bool profile_last_Java_frame(frame* fr);
1303
1304 private:
1305 ThreadProfiler* _thread_profiler;
1306 private:
1307 friend class FlatProfiler; // uses both [gs]et_thread_profiler.
1308 friend class FlatProfilerTask; // uses get_thread_profiler.
1309 friend class ThreadProfilerMark; // uses get_thread_profiler.
1310 ThreadProfiler* get_thread_profiler() { return _thread_profiler; }
1311 ThreadProfiler* set_thread_profiler(ThreadProfiler* tp) {
1312 ThreadProfiler* result = _thread_profiler;
1313 _thread_profiler = tp;
1314 return result;
1315 }
1316
1317 // Static operations
1318 public:
1319 // Returns the running thread as a JavaThread
1320 static inline JavaThread* current();
1321
1322 // Returns the active Java thread. Do not use this if you know you are calling
1323 // from a JavaThread, as it's slower than JavaThread::current. If called from
1324 // the VMThread, it also returns the JavaThread that instigated the VMThread's
1325 // operation. You may not want that either.
1326 static JavaThread* active();
1327
1328 inline CompilerThread* as_CompilerThread();
1329
1330 public:
1331 virtual void run();
1332 void thread_main_inner();
1333
1334 private:
1335 // PRIVILEGED STACK
1336 PrivilegedElement* _privileged_stack_top;
1337 GrowableArray<oop>* _array_for_gc;
1338 public:
1339
1340 // Returns the privileged_stack information.
1341 PrivilegedElement* privileged_stack_top() const { return _privileged_stack_top; }
1342 void set_privileged_stack_top(PrivilegedElement *e) { _privileged_stack_top = e; }
1343 void register_array_for_gc(GrowableArray<oop>* array) { _array_for_gc = array; }
1344
1345 public:
1346 // Thread local information maintained by JVMTI.
1347 void set_jvmti_thread_state(JvmtiThreadState *value) { _jvmti_thread_state = value; }
1348 // A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
1349 // getter is used to get this JavaThread's JvmtiThreadState if it has
1350 // one which means NULL can be returned. JvmtiThreadState::state_for()
1351 // is used to get the specified JavaThread's JvmtiThreadState if it has
1352 // one or it allocates a new JvmtiThreadState for the JavaThread and
1353 // returns it. JvmtiThreadState::state_for() will return NULL only if
1354 // the specified JavaThread is exiting.
1355 JvmtiThreadState *jvmti_thread_state() const { return _jvmti_thread_state; }
1356 static ByteSize jvmti_thread_state_offset() { return byte_offset_of(JavaThread, _jvmti_thread_state); }
1357 void set_jvmti_get_loaded_classes_closure(JvmtiGetLoadedClassesClosure* value) { _jvmti_get_loaded_classes_closure = value; }
1358 JvmtiGetLoadedClassesClosure* get_jvmti_get_loaded_classes_closure() const { return _jvmti_get_loaded_classes_closure; }
1359
1360 // JVMTI PopFrame support
1361 // Setting and clearing popframe_condition
1362 // All of these enumerated values are bits. popframe_pending
1363 // indicates that a PopFrame() has been requested and not yet been
1364 // completed. popframe_processing indicates that that PopFrame() is in
1365 // the process of being completed. popframe_force_deopt_reexecution_bit
1366 // indicates that special handling is required when returning to a
1367 // deoptimized caller.
1368 enum PopCondition {
1369 popframe_inactive = 0x00,
1370 popframe_pending_bit = 0x01,
1371 popframe_processing_bit = 0x02,
1372 popframe_force_deopt_reexecution_bit = 0x04
1373 };
1374 PopCondition popframe_condition() { return (PopCondition) _popframe_condition; }
1375 void set_popframe_condition(PopCondition c) { _popframe_condition = c; }
1376 void set_popframe_condition_bit(PopCondition c) { _popframe_condition |= c; }
1377 void clear_popframe_condition() { _popframe_condition = popframe_inactive; }
1378 static ByteSize popframe_condition_offset() { return byte_offset_of(JavaThread, _popframe_condition); }
1379 bool has_pending_popframe() { return (popframe_condition() & popframe_pending_bit) != 0; }
1380 bool popframe_forcing_deopt_reexecution() { return (popframe_condition() & popframe_force_deopt_reexecution_bit) != 0; }
1381 void clear_popframe_forcing_deopt_reexecution() { _popframe_condition &= ~popframe_force_deopt_reexecution_bit; }
1382 #ifdef CC_INTERP
1383 bool pop_frame_pending(void) { return ((_popframe_condition & popframe_pending_bit) != 0); }
1384 void clr_pop_frame_pending(void) { _popframe_condition = popframe_inactive; }
1385 bool pop_frame_in_process(void) { return ((_popframe_condition & popframe_processing_bit) != 0); }
1386 void set_pop_frame_in_process(void) { _popframe_condition |= popframe_processing_bit; }
1387 void clr_pop_frame_in_process(void) { _popframe_condition &= ~popframe_processing_bit; }
1388 #endif
1389
1390 private:
1391 // Saved incoming arguments to popped frame.
1392 // Used only when popped interpreted frame returns to deoptimized frame.
1393 void* _popframe_preserved_args;
1394 int _popframe_preserved_args_size;
1395
1396 public:
1397 void popframe_preserve_args(ByteSize size_in_bytes, void* start);
1398 void* popframe_preserved_args();
1399 ByteSize popframe_preserved_args_size();
1400 WordSize popframe_preserved_args_size_in_words();
1401 void popframe_free_preserved_args();
1402
1403
1404 private:
1405 JvmtiThreadState *_jvmti_thread_state;
1406 JvmtiGetLoadedClassesClosure* _jvmti_get_loaded_classes_closure;
1407
1408 // Used by the interpreter in fullspeed mode for frame pop, method
1409 // entry, method exit and single stepping support. This field is
1410 // only set to non-zero by the VM_EnterInterpOnlyMode VM operation.
1411 // It can be set to zero asynchronously (i.e., without a VM operation
1412 // or a lock) so we have to be very careful.
1413 int _interp_only_mode;
1414
1415 public:
1416 // used by the interpreter for fullspeed debugging support (see above)
1417 static ByteSize interp_only_mode_offset() { return byte_offset_of(JavaThread, _interp_only_mode); }
1418 bool is_interp_only_mode() { return (_interp_only_mode != 0); }
1419 int get_interp_only_mode() { return _interp_only_mode; }
1420 void increment_interp_only_mode() { ++_interp_only_mode; }
1421 void decrement_interp_only_mode() { --_interp_only_mode; }
1422
1423 private:
1424 ThreadStatistics *_thread_stat;
1425
1426 public:
1427 ThreadStatistics* get_thread_stat() const { return _thread_stat; }
1428
1429 // Return a blocker object for which this thread is blocked parking.
1430 oop current_park_blocker();
1431
1432 private:
1433 static size_t _stack_size_at_create;
1434
1435 public:
1436 static inline size_t stack_size_at_create(void) {
1437 return _stack_size_at_create;
1438 }
1439 static inline void set_stack_size_at_create(size_t value) {
1440 _stack_size_at_create = value;
1441 }
1442
1443 #ifndef SERIALGC
1444 // SATB marking queue support
1445 ObjPtrQueue& satb_mark_queue() { return _satb_mark_queue; }
1446 static SATBMarkQueueSet& satb_mark_queue_set() {
1447 return _satb_mark_queue_set;
1448 }
1449
1450 // Dirty card queue support
1451 DirtyCardQueue& dirty_card_queue() { return _dirty_card_queue; }
1452 static DirtyCardQueueSet& dirty_card_queue_set() {
1453 return _dirty_card_queue_set;
1454 }
1455 #endif // !SERIALGC
1456
1457 // Machine dependent stuff
1458 #include "incls/_thread_pd.hpp.incl"
1459
1460 public:
1461 void set_blocked_on_compilation(bool value) {
1462 _blocked_on_compilation = value;
1463 }
1464
1465 bool blocked_on_compilation() {
1466 return _blocked_on_compilation;
1467 }
1468 protected:
1469 bool _blocked_on_compilation;
1470
1471
1472 // JSR166 per-thread parker
1473 private:
1474 Parker* _parker;
1475 public:
1476 Parker* parker() { return _parker; }
1477
1478 // Biased locking support
1479 private:
1480 GrowableArray<MonitorInfo*>* _cached_monitor_info;
1481 public:
1482 GrowableArray<MonitorInfo*>* cached_monitor_info() { return _cached_monitor_info; }
1483 void set_cached_monitor_info(GrowableArray<MonitorInfo*>* info) { _cached_monitor_info = info; }
1484
1485 // clearing/querying jni attach status
1486 bool is_attaching() const { return _is_attaching; }
1487 void set_attached() { _is_attaching = false; OrderAccess::fence(); }
1488 private:
1489 // This field is used to determine if a thread has claimed
1490 // a par_id: it is -1 if the thread has not claimed a par_id;
1491 // otherwise its value is the par_id that has been claimed.
1492 int _claimed_par_id;
1493 public:
1494 int get_claimed_par_id() { return _claimed_par_id; }
1495 void set_claimed_par_id(int id) { _claimed_par_id = id;}
1496 };
1497
1498 // Inline implementation of JavaThread::current
1499 inline JavaThread* JavaThread::current() {
1500 Thread* thread = ThreadLocalStorage::thread();
1501 assert(thread != NULL && thread->is_Java_thread(), "just checking");
1502 return (JavaThread*)thread;
1503 }
1504
1505 inline CompilerThread* JavaThread::as_CompilerThread() {
1506 assert(is_Compiler_thread(), "just checking");
1507 return (CompilerThread*)this;
1508 }
1509
1510 inline bool JavaThread::stack_yellow_zone_disabled() {
1511 return _stack_guard_state == stack_guard_yellow_disabled;
1512 }
1513
1514 inline bool JavaThread::stack_yellow_zone_enabled() {
1515 #ifdef ASSERT
1516 if (os::uses_stack_guard_pages()) {
1517 assert(_stack_guard_state != stack_guard_unused, "guard pages must be in use");
1518 }
1519 #endif
1520 return _stack_guard_state == stack_guard_enabled;
1521 }
1522
1523 inline size_t JavaThread::stack_available(address cur_sp) {
1524 // This code assumes java stacks grow down
1525 address low_addr; // Limit on the address for deepest stack depth
1526 if ( _stack_guard_state == stack_guard_unused) {
1527 low_addr = stack_base() - stack_size();
1528 } else {
1529 low_addr = stack_yellow_zone_base();
1530 }
1531 return cur_sp > low_addr ? cur_sp - low_addr : 0;
1532 }
1533
1534 // A JavaThread for low memory detection support
1535 class LowMemoryDetectorThread : public JavaThread {
1536 friend class VMStructs;
1537 public:
1538 LowMemoryDetectorThread(ThreadFunction entry_point) : JavaThread(entry_point) {};
1539
1540 // Hide this thread from external view.
1541 bool is_hidden_from_external_view() const { return true; }
1542 };
1543
1544 // A thread used for Compilation.
1545 class CompilerThread : public JavaThread {
1546 friend class VMStructs;
1547 private:
1548 CompilerCounters* _counters;
1549
1550 ciEnv* _env;
1551 CompileLog* _log;
1552 CompileTask* _task;
1553 CompileQueue* _queue;
1554
1555 public:
1556
1557 static CompilerThread* current();
1558
1559 CompilerThread(CompileQueue* queue, CompilerCounters* counters);
1560
1561 bool is_Compiler_thread() const { return true; }
1562 // Hide this compiler thread from external view.
1563 bool is_hidden_from_external_view() const { return true; }
1564
1565 CompileQueue* queue() { return _queue; }
1566 CompilerCounters* counters() { return _counters; }
1567
1568 // Get/set the thread's compilation environment.
1569 ciEnv* env() { return _env; }
1570 void set_env(ciEnv* env) { _env = env; }
1571
1572 // Get/set the thread's logging information
1573 CompileLog* log() { return _log; }
1574 void init_log(CompileLog* log) {
1575 // Set once, for good.
1576 assert(_log == NULL, "set only once");
1577 _log = log;
1578 }
1579
1580 #ifndef PRODUCT
1581 private:
1582 IdealGraphPrinter *_ideal_graph_printer;
1583 public:
1584 IdealGraphPrinter *ideal_graph_printer() { return _ideal_graph_printer; }
1585 void set_ideal_graph_printer(IdealGraphPrinter *n) { _ideal_graph_printer = n; }
1586 #endif
1587
1588 // Get/set the thread's current task
1589 CompileTask* task() { return _task; }
1590 void set_task(CompileTask* task) { _task = task; }
1591 };
1592
1593 inline CompilerThread* CompilerThread::current() {
1594 return JavaThread::current()->as_CompilerThread();
1595 }
1596
1597
1598 // The active thread queue. It also keeps track of the current used
1599 // thread priorities.
1600 class Threads: AllStatic {
1601 friend class VMStructs;
1602 private:
1603 static JavaThread* _thread_list;
1604 static int _number_of_threads;
1605 static int _number_of_non_daemon_threads;
1606 static int _return_code;
1607
1608 public:
1609 // Thread management
1610 // force_daemon is a concession to JNI, where we may need to add a
1611 // thread to the thread list before allocating its thread object
1612 static void add(JavaThread* p, bool force_daemon = false);
1613 static void remove(JavaThread* p);
1614 static bool includes(JavaThread* p);
1615 static JavaThread* first() { return _thread_list; }
1616 static void threads_do(ThreadClosure* tc);
1617
1618 // Initializes the vm and creates the vm thread
1619 static jint create_vm(JavaVMInitArgs* args, bool* canTryAgain);
1620 static void convert_vm_init_libraries_to_agents();
1621 static void create_vm_init_libraries();
1622 static void create_vm_init_agents();
1623 static void shutdown_vm_agents();
1624 static bool destroy_vm();
1625 // Supported VM versions via JNI
1626 // Includes JNI_VERSION_1_1
1627 static jboolean is_supported_jni_version_including_1_1(jint version);
1628 // Does not include JNI_VERSION_1_1
1629 static jboolean is_supported_jni_version(jint version);
1630
1631 // Garbage collection
1632 static void follow_other_roots(void f(oop*));
1633
1634 // Apply "f->do_oop" to all root oops in all threads.
1635 // This version may only be called by sequential code.
1636 static void oops_do(OopClosure* f, CodeBlobClosure* cf);
1637 // This version may be called by sequential or parallel code.
1638 static void possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf);
1639 // This creates a list of GCTasks, one per thread.
1640 static void create_thread_roots_tasks(GCTaskQueue* q);
1641 // This creates a list of GCTasks, one per thread, for marking objects.
1642 static void create_thread_roots_marking_tasks(GCTaskQueue* q);
1643
1644 // Apply "f->do_oop" to roots in all threads that
1645 // are part of compiled frames
1646 static void compiled_frame_oops_do(OopClosure* f, CodeBlobClosure* cf);
1647
1648 static void convert_hcode_pointers();
1649 static void restore_hcode_pointers();
1650
1651 // Sweeper
1652 static void nmethods_do(CodeBlobClosure* cf);
1653
1654 static void gc_epilogue();
1655 static void gc_prologue();
1656
1657 // Verification
1658 static void verify();
1659 static void print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks);
1660 static void print(bool print_stacks, bool internal_format) {
1661 // this function is only used by debug.cpp
1662 print_on(tty, print_stacks, internal_format, false /* no concurrent lock printed */);
1663 }
1664 static void print_on_error(outputStream* st, Thread* current, char* buf, int buflen);
1665
1666 // Get Java threads that are waiting to enter a monitor. If doLock
1667 // is true, then Threads_lock is grabbed as needed. Otherwise, the
1668 // VM needs to be at a safepoint.
1669 static GrowableArray<JavaThread*>* get_pending_threads(int count,
1670 address monitor, bool doLock);
1671
1672 // Get owning Java thread from the monitor's owner field. If doLock
1673 // is true, then Threads_lock is grabbed as needed. Otherwise, the
1674 // VM needs to be at a safepoint.
1675 static JavaThread *owning_thread_from_monitor_owner(address owner,
1676 bool doLock);
1677
1678 // Number of threads on the active threads list
1679 static int number_of_threads() { return _number_of_threads; }
1680 // Number of non-daemon threads on the active threads list
1681 static int number_of_non_daemon_threads() { return _number_of_non_daemon_threads; }
1682
1683 // Deoptimizes all frames tied to marked nmethods
1684 static void deoptimized_wrt_marked_nmethods();
1685
1686 };
1687
1688
1689 // Thread iterator
1690 class ThreadClosure: public StackObj {
1691 public:
1692 virtual void do_thread(Thread* thread) = 0;
1693 };
1694
1695 class SignalHandlerMark: public StackObj {
1696 private:
1697 Thread* _thread;
1698 public:
1699 SignalHandlerMark(Thread* t) {
1700 _thread = t;
1701 if (_thread) _thread->enter_signal_handler();
1702 }
1703 ~SignalHandlerMark() {
1704 if (_thread) _thread->leave_signal_handler();
1705 _thread = NULL;
1706 }
1707 };
1708
1709 // ParkEvents are type-stable and immortal.
1710 //
1711 // Lifecycle: Once a ParkEvent is associated with a thread that ParkEvent remains
1712 // associated with the thread for the thread's entire lifetime - the relationship is
1713 // stable. A thread will be associated at most one ParkEvent. When the thread
1714 // expires, the ParkEvent moves to the EventFreeList. New threads attempt to allocate from
1715 // the EventFreeList before creating a new Event. Type-stability frees us from
1716 // worrying about stale Event or Thread references in the objectMonitor subsystem.
1717 // (A reference to ParkEvent is always valid, even though the event may no longer be associated
1718 // with the desired or expected thread. A key aspect of this design is that the callers of
1719 // park, unpark, etc must tolerate stale references and spurious wakeups).
1720 //
1721 // Only the "associated" thread can block (park) on the ParkEvent, although
1722 // any other thread can unpark a reachable parkevent. Park() is allowed to
1723 // return spuriously. In fact park-unpark a really just an optimization to
1724 // avoid unbounded spinning and surrender the CPU to be a polite system citizen.
1725 // A degenerate albeit "impolite" park-unpark implementation could simply return.
1726 // See http://blogs.sun.com/dave for more details.
1727 //
1728 // Eventually I'd like to eliminate Events and ObjectWaiters, both of which serve as
1729 // thread proxies, and simply make the THREAD structure type-stable and persistent.
1730 // Currently, we unpark events associated with threads, but ideally we'd just
1731 // unpark threads.
1732 //
1733 // The base-class, PlatformEvent, is platform-specific while the ParkEvent is
1734 // platform-independent. PlatformEvent provides park(), unpark(), etc., and
1735 // is abstract -- that is, a PlatformEvent should never be instantiated except
1736 // as part of a ParkEvent.
1737 // Equivalently we could have defined a platform-independent base-class that
1738 // exported Allocate(), Release(), etc. The platform-specific class would extend
1739 // that base-class, adding park(), unpark(), etc.
1740 //
1741 // A word of caution: The JVM uses 2 very similar constructs:
1742 // 1. ParkEvent are used for Java-level "monitor" synchronization.
1743 // 2. Parkers are used by JSR166-JUC park-unpark.
1744 //
1745 // We'll want to eventually merge these redundant facilities and use ParkEvent.
1746
1747
1748 class ParkEvent : public os::PlatformEvent {
1749 private:
1750 ParkEvent * FreeNext ;
1751
1752 // Current association
1753 Thread * AssociatedWith ;
1754 intptr_t RawThreadIdentity ; // LWPID etc
1755 volatile int Incarnation ;
1756
1757 // diagnostic : keep track of last thread to wake this thread.
1758 // this is useful for construction of dependency graphs.
1759 void * LastWaker ;
1760
1761 public:
1762 // MCS-CLH list linkage and Native Mutex/Monitor
1763 ParkEvent * volatile ListNext ;
1764 ParkEvent * volatile ListPrev ;
1765 volatile intptr_t OnList ;
1766 volatile int TState ;
1767 volatile int Notified ; // for native monitor construct
1768 volatile int IsWaiting ; // Enqueued on WaitSet
1769
1770
1771 private:
1772 static ParkEvent * volatile FreeList ;
1773 static volatile int ListLock ;
1774
1775 // It's prudent to mark the dtor as "private"
1776 // ensuring that it's not visible outside the package.
1777 // Unfortunately gcc warns about such usage, so
1778 // we revert to the less desirable "protected" visibility.
1779 // The other compilers accept private dtors.
1780
1781 protected: // Ensure dtor is never invoked
1782 ~ParkEvent() { guarantee (0, "invariant") ; }
1783
1784 ParkEvent() : PlatformEvent() {
1785 AssociatedWith = NULL ;
1786 FreeNext = NULL ;
1787 ListNext = NULL ;
1788 ListPrev = NULL ;
1789 OnList = 0 ;
1790 TState = 0 ;
1791 Notified = 0 ;
1792 IsWaiting = 0 ;
1793 }
1794
1795 // We use placement-new to force ParkEvent instances to be
1796 // aligned on 256-byte address boundaries. This ensures that the least
1797 // significant byte of a ParkEvent address is always 0.
1798
1799 void * operator new (size_t sz) ;
1800 void operator delete (void * a) ;
1801
1802 public:
1803 static ParkEvent * Allocate (Thread * t) ;
1804 static void Release (ParkEvent * e) ;
1805 } ;