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 ObjectMonitor * omInUseList; // SLL to track monitors in circulation
229 int omInUseCount; // length of omInUseList
230
231 public:
232 enum {
233 is_definitely_current_thread = true
234 };
235
236 // Constructor
237 Thread();
238 virtual ~Thread();
239
240 // initializtion
241 void initialize_thread_local_storage();
242
243 // thread entry point
244 virtual void run();
245
246 // Testers
247 virtual bool is_VM_thread() const { return false; }
248 virtual bool is_Java_thread() const { return false; }
249 // Remove this ifdef when C1 is ported to the compiler interface.
250 virtual bool is_Compiler_thread() const { return false; }
251 virtual bool is_hidden_from_external_view() const { return false; }
252 virtual bool is_jvmti_agent_thread() const { return false; }
253 // True iff the thread can perform GC operations at a safepoint.
254 // Generally will be true only of VM thread and parallel GC WorkGang
255 // threads.
256 virtual bool is_GC_task_thread() const { return false; }
257 virtual bool is_Watcher_thread() const { return false; }
258 virtual bool is_ConcurrentGC_thread() const { return false; }
259 virtual bool is_Named_thread() const { return false; }
260
261 virtual char* name() const { return (char*)"Unknown thread"; }
262
263 // Returns the current thread
264 static inline Thread* current();
265
266 // Common thread operations
267 static void set_priority(Thread* thread, ThreadPriority priority);
268 static ThreadPriority get_priority(const Thread* const thread);
269 static void start(Thread* thread);
270 static void interrupt(Thread* thr);
271 static bool is_interrupted(Thread* thr, bool clear_interrupted);
272
273 ObjectMonitor** omInUseList_addr() { return (ObjectMonitor **)&omInUseList; }
274 Monitor* SR_lock() const { return _SR_lock; }
275
276 bool has_async_exception() const { return (_suspend_flags & _has_async_exception) != 0; }
277
278 void set_suspend_flag(SuspendFlags f) {
279 assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
280 uint32_t flags;
281 do {
282 flags = _suspend_flags;
283 }
284 while (Atomic::cmpxchg((jint)(flags | f),
285 (volatile jint*)&_suspend_flags,
286 (jint)flags) != (jint)flags);
287 }
288 void clear_suspend_flag(SuspendFlags f) {
289 assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
290 uint32_t flags;
291 do {
292 flags = _suspend_flags;
293 }
294 while (Atomic::cmpxchg((jint)(flags & ~f),
295 (volatile jint*)&_suspend_flags,
296 (jint)flags) != (jint)flags);
297 }
298
299 void set_has_async_exception() {
300 set_suspend_flag(_has_async_exception);
301 }
302 void clear_has_async_exception() {
303 clear_suspend_flag(_has_async_exception);
304 }
305
306 // Support for Unhandled Oop detection
307 #ifdef CHECK_UNHANDLED_OOPS
308 private:
309 UnhandledOops *_unhandled_oops;
310 public:
311 UnhandledOops* unhandled_oops() { return _unhandled_oops; }
312 // Mark oop safe for gc. It may be stack allocated but won't move.
313 void allow_unhandled_oop(oop *op) {
314 if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
315 }
316 // Clear oops at safepoint so crashes point to unhandled oop violator
317 void clear_unhandled_oops() {
318 if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
319 }
320 bool is_gc_locked_out() { return _gc_locked_out_count > 0; }
321 #endif // CHECK_UNHANDLED_OOPS
322
323 #ifndef PRODUCT
324 bool skip_gcalot() { return _skip_gcalot; }
325 void set_skip_gcalot(bool v) { _skip_gcalot = v; }
326 #endif
327
328 public:
329 // Installs a pending exception to be inserted later
330 static void send_async_exception(oop thread_oop, oop java_throwable);
331
332 // Resource area
333 ResourceArea* resource_area() const { return _resource_area; }
334 void set_resource_area(ResourceArea* area) { _resource_area = area; }
335
336 OSThread* osthread() const { return _osthread; }
337 void set_osthread(OSThread* thread) { _osthread = thread; }
338
339 // JNI handle support
340 JNIHandleBlock* active_handles() const { return _active_handles; }
341 void set_active_handles(JNIHandleBlock* block) { _active_handles = block; }
342 JNIHandleBlock* free_handle_block() const { return _free_handle_block; }
343 void set_free_handle_block(JNIHandleBlock* block) { _free_handle_block = block; }
344
345 // Internal handle support
346 HandleArea* handle_area() const { return _handle_area; }
347 void set_handle_area(HandleArea* area) { _handle_area = area; }
348
349 // Thread-Local Allocation Buffer (TLAB) support
350 ThreadLocalAllocBuffer& tlab() { return _tlab; }
351 void initialize_tlab() {
352 if (UseTLAB) {
353 tlab().initialize();
354 }
355 }
356
357 // VM operation support
358 int vm_operation_ticket() { return ++_vm_operation_started_count; }
359 int vm_operation_completed_count() { return _vm_operation_completed_count; }
360 void increment_vm_operation_completed_count() { _vm_operation_completed_count++; }
361
362 // For tracking the heavyweight monitor the thread is pending on.
363 ObjectMonitor* current_pending_monitor() {
364 return _current_pending_monitor;
365 }
366 void set_current_pending_monitor(ObjectMonitor* monitor) {
367 _current_pending_monitor = monitor;
368 }
369 void set_current_pending_monitor_is_from_java(bool from_java) {
370 _current_pending_monitor_is_from_java = from_java;
371 }
372 bool current_pending_monitor_is_from_java() {
373 return _current_pending_monitor_is_from_java;
374 }
375
376 // For tracking the ObjectMonitor on which this thread called Object.wait()
377 ObjectMonitor* current_waiting_monitor() {
378 return _current_waiting_monitor;
379 }
380 void set_current_waiting_monitor(ObjectMonitor* monitor) {
381 _current_waiting_monitor = monitor;
382 }
383
384 // GC support
385 // Apply "f->do_oop" to all root oops in "this".
386 // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
387 void oops_do(OopClosure* f, CodeBlobClosure* cf);
388
389 // Handles the parallel case for the method below.
390 private:
391 bool claim_oops_do_par_case(int collection_parity);
392 public:
393 // Requires that "collection_parity" is that of the current strong roots
394 // iteration. If "is_par" is false, sets the parity of "this" to
395 // "collection_parity", and returns "true". If "is_par" is true,
396 // uses an atomic instruction to set the current threads parity to
397 // "collection_parity", if it is not already. Returns "true" iff the
398 // calling thread does the update, this indicates that the calling thread
399 // has claimed the thread's stack as a root groop in the current
400 // collection.
401 bool claim_oops_do(bool is_par, int collection_parity) {
402 if (!is_par) {
403 _oops_do_parity = collection_parity;
404 return true;
405 } else {
406 return claim_oops_do_par_case(collection_parity);
407 }
408 }
409
410 // Sweeper support
411 void nmethods_do(CodeBlobClosure* cf);
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 bool on_local_stack(address adr) const {
450 /* QQQ this has knowledge of direction, ought to be a stack method */
451 return (_stack_base >= adr && adr >= (_stack_base - _stack_size));
452 }
453
454 int lgrp_id() const { return _lgrp_id; }
455 void set_lgrp_id(int value) { _lgrp_id = value; }
456
457 // Printing
458 void print_on(outputStream* st) const;
459 void print() const { print_on(tty); }
460 virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
461
462 // Debug-only code
463
464 #ifdef ASSERT
465 private:
466 // Deadlock detection support for Mutex locks. List of locks own by thread.
467 Monitor *_owned_locks;
468 // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
469 // thus the friendship
470 friend class Mutex;
471 friend class Monitor;
472
473 public:
474 void print_owned_locks_on(outputStream* st) const;
475 void print_owned_locks() const { print_owned_locks_on(tty); }
476 Monitor * owned_locks() const { return _owned_locks; }
477 bool owns_locks() const { return owned_locks() != NULL; }
478 bool owns_locks_but_compiled_lock() const;
479
480 // Deadlock detection
481 bool allow_allocation() { return _allow_allocation_count == 0; }
482 #endif
483
484 void check_for_valid_safepoint_state(bool potential_vm_operation) PRODUCT_RETURN;
485
486 private:
487 volatile int _jvmti_env_iteration_count;
488
489 public:
490 void entering_jvmti_env_iteration() { ++_jvmti_env_iteration_count; }
491 void leaving_jvmti_env_iteration() { --_jvmti_env_iteration_count; }
492 bool is_inside_jvmti_env_iteration() { return _jvmti_env_iteration_count > 0; }
493
494 // Code generation
495 static ByteSize exception_file_offset() { return byte_offset_of(Thread, _exception_file ); }
496 static ByteSize exception_line_offset() { return byte_offset_of(Thread, _exception_line ); }
497 static ByteSize active_handles_offset() { return byte_offset_of(Thread, _active_handles ); }
498
499 static ByteSize stack_base_offset() { return byte_offset_of(Thread, _stack_base ); }
500 static ByteSize stack_size_offset() { return byte_offset_of(Thread, _stack_size ); }
501
502 #define TLAB_FIELD_OFFSET(name) \
503 static ByteSize tlab_##name##_offset() { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::name##_offset(); }
504
505 TLAB_FIELD_OFFSET(start)
506 TLAB_FIELD_OFFSET(end)
507 TLAB_FIELD_OFFSET(top)
508 TLAB_FIELD_OFFSET(pf_top)
509 TLAB_FIELD_OFFSET(size) // desired_size
510 TLAB_FIELD_OFFSET(refill_waste_limit)
511 TLAB_FIELD_OFFSET(number_of_refills)
512 TLAB_FIELD_OFFSET(fast_refill_waste)
513 TLAB_FIELD_OFFSET(slow_allocations)
514
515 #undef TLAB_FIELD_OFFSET
516
517 public:
518 volatile intptr_t _Stalled ;
519 volatile int _TypeTag ;
520 ParkEvent * _ParkEvent ; // for synchronized()
521 ParkEvent * _SleepEvent ; // for Thread.sleep
522 ParkEvent * _MutexEvent ; // for native internal Mutex/Monitor
523 ParkEvent * _MuxEvent ; // for low-level muxAcquire-muxRelease
524 int NativeSyncRecursion ; // diagnostic
525
526 volatile int _OnTrap ; // Resume-at IP delta
527 jint _hashStateW ; // Marsaglia Shift-XOR thread-local RNG
528 jint _hashStateX ; // thread-specific hashCode generator state
529 jint _hashStateY ;
530 jint _hashStateZ ;
531 void * _schedctl ;
532
533 intptr_t _ScratchA, _ScratchB ; // Scratch locations for fast-path sync code
534 static ByteSize ScratchA_offset() { return byte_offset_of(Thread, _ScratchA ); }
535 static ByteSize ScratchB_offset() { return byte_offset_of(Thread, _ScratchB ); }
536
537 volatile jint rng [4] ; // RNG for spin loop
538
539 // Low-level leaf-lock primitives used to implement synchronization
540 // and native monitor-mutex infrastructure.
541 // Not for general synchronization use.
542 static void SpinAcquire (volatile int * Lock, const char * Name) ;
543 static void SpinRelease (volatile int * Lock) ;
544 static void muxAcquire (volatile intptr_t * Lock, const char * Name) ;
545 static void muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) ;
546 static void muxRelease (volatile intptr_t * Lock) ;
547
548 };
549
550 // Inline implementation of Thread::current()
551 // Thread::current is "hot" it's called > 128K times in the 1st 500 msecs of
552 // startup.
553 // ThreadLocalStorage::thread is warm -- it's called > 16K times in the same
554 // period. This is inlined in thread_<os_family>.inline.hpp.
555
556 inline Thread* Thread::current() {
557 #ifdef ASSERT
558 // This function is very high traffic. Define PARANOID to enable expensive
559 // asserts.
560 #ifdef PARANOID
561 // Signal handler should call ThreadLocalStorage::get_thread_slow()
562 Thread* t = ThreadLocalStorage::get_thread_slow();
563 assert(t != NULL && !t->is_inside_signal_handler(),
564 "Don't use Thread::current() inside signal handler");
565 #endif
566 #endif
567 Thread* thread = ThreadLocalStorage::thread();
568 assert(thread != NULL, "just checking");
569 return thread;
570 }
571
572 // Name support for threads. non-JavaThread subclasses with multiple
573 // uniquely named instances should derive from this.
574 class NamedThread: public Thread {
575 friend class VMStructs;
576 enum {
577 max_name_len = 64
578 };
579 private:
580 char* _name;
581 // log JavaThread being processed by oops_do
582 JavaThread* _processed_thread;
583
584 public:
585 NamedThread();
586 ~NamedThread();
587 // May only be called once per thread.
588 void set_name(const char* format, ...);
589 virtual bool is_Named_thread() const { return true; }
590 virtual char* name() const { return _name == NULL ? (char*)"Unknown Thread" : _name; }
591 JavaThread *processed_thread() { return _processed_thread; }
592 void set_processed_thread(JavaThread *thread) { _processed_thread = thread; }
593 };
594
595 // Worker threads are named and have an id of an assigned work.
596 class WorkerThread: public NamedThread {
597 private:
598 uint _id;
599 public:
600 WorkerThread() : _id(0) { }
601 void set_id(uint work_id) { _id = work_id; }
602 uint id() const { return _id; }
603 };
604
605 // A single WatcherThread is used for simulating timer interrupts.
606 class WatcherThread: public Thread {
607 friend class VMStructs;
608 public:
609 virtual void run();
610
611 private:
612 static WatcherThread* _watcher_thread;
613
614 volatile static bool _should_terminate; // updated without holding lock
615 public:
616 enum SomeConstants {
617 delay_interval = 10 // interrupt delay in milliseconds
618 };
619
620 // Constructor
621 WatcherThread();
622
623 // Tester
624 bool is_Watcher_thread() const { return true; }
625
626 // Printing
627 char* name() const { return (char*)"VM Periodic Task Thread"; }
628 void print_on(outputStream* st) const;
629 void print() const { print_on(tty); }
630
631 // Returns the single instance of WatcherThread
632 static WatcherThread* watcher_thread() { return _watcher_thread; }
633
634 // Create and start the single instance of WatcherThread, or stop it on shutdown
635 static void start();
636 static void stop();
637 };
638
639
640 class CompilerThread;
641
642 typedef void (*ThreadFunction)(JavaThread*, TRAPS);
643
644 class JavaThread: public Thread {
645 friend class VMStructs;
646 private:
647 JavaThread* _next; // The next thread in the Threads list
648 oop _threadObj; // The Java level thread object
649
650 #ifdef ASSERT
651 private:
652 int _java_call_counter;
653
654 public:
655 int java_call_counter() { return _java_call_counter; }
656 void inc_java_call_counter() { _java_call_counter++; }
657 void dec_java_call_counter() {
658 assert(_java_call_counter > 0, "Invalid nesting of JavaCallWrapper");
659 _java_call_counter--;
660 }
661 private: // restore original namespace restriction
662 #endif // ifdef ASSERT
663
664 #ifndef PRODUCT
665 public:
666 enum {
667 jump_ring_buffer_size = 16
668 };
669 private: // restore original namespace restriction
670 #endif
671
672 JavaFrameAnchor _anchor; // Encapsulation of current java frame and it state
673
674 ThreadFunction _entry_point;
675
676 JNIEnv _jni_environment;
677
678 // Deopt support
679 DeoptResourceMark* _deopt_mark; // Holds special ResourceMark for deoptimization
680
681 intptr_t* _must_deopt_id; // id of frame that needs to be deopted once we
682 // transition out of native
683 nmethod* _deopt_nmethod; // nmethod that is currently being deoptimized
684 vframeArray* _vframe_array_head; // Holds the heap of the active vframeArrays
685 vframeArray* _vframe_array_last; // Holds last vFrameArray we popped
686 // Because deoptimization is lazy we must save jvmti requests to set locals
687 // in compiled frames until we deoptimize and we have an interpreter frame.
688 // This holds the pointer to array (yeah like there might be more than one) of
689 // description of compiled vframes that have locals that need to be updated.
690 GrowableArray<jvmtiDeferredLocalVariableSet*>* _deferred_locals_updates;
691
692 // Handshake value for fixing 6243940. We need a place for the i2c
693 // adapter to store the callee methodOop. This value is NEVER live
694 // across a gc point so it does NOT have to be gc'd
695 // The handshake is open ended since we can't be certain that it will
696 // be NULLed. This is because we rarely ever see the race and end up
697 // in handle_wrong_method which is the backend of the handshake. See
698 // code in i2c adapters and handle_wrong_method.
699
700 methodOop _callee_target;
701
702 // Oop results of VM runtime calls
703 oop _vm_result; // Used to pass back an oop result into Java code, GC-preserved
704 oop _vm_result_2; // Used to pass back an oop result into Java code, GC-preserved
705
706 // See ReduceInitialCardMarks: this holds the precise space interval of
707 // the most recent slow path allocation for which compiled code has
708 // elided card-marks for performance along the fast-path.
709 MemRegion _deferred_card_mark;
710
711 MonitorChunk* _monitor_chunks; // Contains the off stack monitors
712 // allocated during deoptimization
713 // and by JNI_MonitorEnter/Exit
714
715 // Async. requests support
716 enum AsyncRequests {
717 _no_async_condition = 0,
718 _async_exception,
719 _async_unsafe_access_error
720 };
721 AsyncRequests _special_runtime_exit_condition; // Enum indicating pending async. request
722 oop _pending_async_exception;
723
724 // Safepoint support
725 public: // Expose _thread_state for SafeFetchInt()
726 volatile JavaThreadState _thread_state;
727 private:
728 ThreadSafepointState *_safepoint_state; // Holds information about a thread during a safepoint
729 address _saved_exception_pc; // Saved pc of instruction where last implicit exception happened
730
731 // JavaThread termination support
732 enum TerminatedTypes {
733 _not_terminated = 0xDEAD - 2,
734 _thread_exiting, // JavaThread::exit() has been called for this thread
735 _thread_terminated, // JavaThread is removed from thread list
736 _vm_exited // JavaThread is still executing native code, but VM is terminated
737 // only VM_Exit can set _vm_exited
738 };
739
740 // In general a JavaThread's _terminated field transitions as follows:
741 //
742 // _not_terminated => _thread_exiting => _thread_terminated
743 //
744 // _vm_exited is a special value to cover the case of a JavaThread
745 // executing native code after the VM itself is terminated.
746 TerminatedTypes _terminated;
747 // suspend/resume support
748 volatile bool _suspend_equivalent; // Suspend equivalent condition
749 jint _in_deopt_handler; // count of deoptimization
750 // handlers thread is in
751 volatile bool _doing_unsafe_access; // Thread may fault due to unsafe access
752 bool _do_not_unlock_if_synchronized; // Do not unlock the receiver of a synchronized method (since it was
753 // never locked) when throwing an exception. Used by interpreter only.
754
755 // Flag to mark a JNI thread in the process of attaching - See CR 6404306
756 // This flag is never set true other than at construction, and in that case
757 // is shortly thereafter set false
758 volatile bool _is_attaching;
759
760 public:
761 // State of the stack guard pages for this thread.
762 enum StackGuardState {
763 stack_guard_unused, // not needed
764 stack_guard_yellow_disabled,// disabled (temporarily) after stack overflow
765 stack_guard_enabled // enabled
766 };
767
768 private:
769
770 StackGuardState _stack_guard_state;
771
772 // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
773 // used to temp. parsing values into and out of the runtime system during exception handling for compiled
774 // code)
775 volatile oop _exception_oop; // Exception thrown in compiled code
776 volatile address _exception_pc; // PC where exception happened
777 volatile address _exception_handler_pc; // PC for handler of exception
778 volatile int _exception_stack_size; // Size of frame where exception happened
779 volatile int _is_method_handle_return; // true (== 1) if the current exception PC is a MethodHandle call site.
780
781 // support for compilation
782 bool _is_compiling; // is true if a compilation is active inthis thread (one compilation per thread possible)
783
784 // support for JNI critical regions
785 jint _jni_active_critical; // count of entries into JNI critical region
786
787 // For deadlock detection.
788 int _depth_first_number;
789
790 // JVMTI PopFrame support
791 // This is set to popframe_pending to signal that top Java frame should be popped immediately
792 int _popframe_condition;
793
794 #ifndef PRODUCT
795 int _jmp_ring_index;
796 struct {
797 // We use intptr_t instead of address so debugger doesn't try and display strings
798 intptr_t _target;
799 intptr_t _instruction;
800 const char* _file;
801 int _line;
802 } _jmp_ring[ jump_ring_buffer_size ];
803 #endif /* PRODUCT */
804
805 #ifndef SERIALGC
806 // Support for G1 barriers
807
808 ObjPtrQueue _satb_mark_queue; // Thread-local log for SATB barrier.
809 // Set of all such queues.
810 static SATBMarkQueueSet _satb_mark_queue_set;
811
812 DirtyCardQueue _dirty_card_queue; // Thread-local log for dirty cards.
813 // Set of all such queues.
814 static DirtyCardQueueSet _dirty_card_queue_set;
815
816 void flush_barrier_queues();
817 #endif // !SERIALGC
818
819 friend class VMThread;
820 friend class ThreadWaitTransition;
821 friend class VM_Exit;
822
823 void initialize(); // Initialized the instance variables
824
825 public:
826 // Constructor
827 JavaThread(bool is_attaching = false); // for main thread and JNI attached threads
828 JavaThread(ThreadFunction entry_point, size_t stack_size = 0);
829 ~JavaThread();
830
831 #ifdef ASSERT
832 // verify this JavaThread hasn't be published in the Threads::list yet
833 void verify_not_published();
834 #endif
835
836 //JNI functiontable getter/setter for JVMTI jni function table interception API.
837 void set_jni_functions(struct JNINativeInterface_* functionTable) {
838 _jni_environment.functions = functionTable;
839 }
840 struct JNINativeInterface_* get_jni_functions() {
841 return (struct JNINativeInterface_ *)_jni_environment.functions;
842 }
843
844 // This function is called at thread creation to allow
845 // platform specific thread variables to be initialized.
846 void cache_global_variables();
847
848 // Executes Shutdown.shutdown()
849 void invoke_shutdown_hooks();
850
851 // Cleanup on thread exit
852 enum ExitType {
853 normal_exit,
854 jni_detach
855 };
856 void exit(bool destroy_vm, ExitType exit_type = normal_exit);
857
858 void cleanup_failed_attach_current_thread();
859
860 // Testers
861 virtual bool is_Java_thread() const { return true; }
862
863 // compilation
864 void set_is_compiling(bool f) { _is_compiling = f; }
865 bool is_compiling() const { return _is_compiling; }
866
867 // Thread chain operations
868 JavaThread* next() const { return _next; }
869 void set_next(JavaThread* p) { _next = p; }
870
871 // Thread oop. threadObj() can be NULL for initial JavaThread
872 // (or for threads attached via JNI)
873 oop threadObj() const { return _threadObj; }
874 void set_threadObj(oop p) { _threadObj = p; }
875
876 ThreadPriority java_priority() const; // Read from threadObj()
877
878 // Prepare thread and add to priority queue. If a priority is
879 // not specified, use the priority of the thread object. Threads_lock
880 // must be held while this function is called.
881 void prepare(jobject jni_thread, ThreadPriority prio=NoPriority);
882
883 void set_saved_exception_pc(address pc) { _saved_exception_pc = pc; }
884 address saved_exception_pc() { return _saved_exception_pc; }
885
886
887 ThreadFunction entry_point() const { return _entry_point; }
888
889 // Allocates a new Java level thread object for this thread. thread_name may be NULL.
890 void allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS);
891
892 // Last frame anchor routines
893
894 JavaFrameAnchor* frame_anchor(void) { return &_anchor; }
895
896 // last_Java_sp
897 bool has_last_Java_frame() const { return _anchor.has_last_Java_frame(); }
898 intptr_t* last_Java_sp() const { return _anchor.last_Java_sp(); }
899
900 // last_Java_pc
901
902 address last_Java_pc(void) { return _anchor.last_Java_pc(); }
903
904 // Safepoint support
905 JavaThreadState thread_state() const { return _thread_state; }
906 void set_thread_state(JavaThreadState s) { _thread_state=s; }
907 ThreadSafepointState *safepoint_state() const { return _safepoint_state; }
908 void set_safepoint_state(ThreadSafepointState *state) { _safepoint_state = state; }
909 bool is_at_poll_safepoint() { return _safepoint_state->is_at_poll_safepoint(); }
910
911 // thread has called JavaThread::exit() or is terminated
912 bool is_exiting() { return _terminated == _thread_exiting || is_terminated(); }
913 // thread is terminated (no longer on the threads list); we compare
914 // against the two non-terminated values so that a freed JavaThread
915 // will also be considered terminated.
916 bool is_terminated() { return _terminated != _not_terminated && _terminated != _thread_exiting; }
917 void set_terminated(TerminatedTypes t) { _terminated = t; }
918 // special for Threads::remove() which is static:
919 void set_terminated_value() { _terminated = _thread_terminated; }
920 void block_if_vm_exited();
921
922 bool doing_unsafe_access() { return _doing_unsafe_access; }
923 void set_doing_unsafe_access(bool val) { _doing_unsafe_access = val; }
924
925 bool do_not_unlock_if_synchronized() { return _do_not_unlock_if_synchronized; }
926 void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }
927
928
929 // Suspend/resume support for JavaThread
930
931 private:
932 void set_ext_suspended() { set_suspend_flag (_ext_suspended); }
933 void clear_ext_suspended() { clear_suspend_flag(_ext_suspended); }
934
935 public:
936 void java_suspend();
937 void java_resume();
938 int java_suspend_self();
939
940 void check_and_wait_while_suspended() {
941 assert(JavaThread::current() == this, "sanity check");
942
943 bool do_self_suspend;
944 do {
945 // were we externally suspended while we were waiting?
946 do_self_suspend = handle_special_suspend_equivalent_condition();
947 if (do_self_suspend) {
948 // don't surprise the thread that suspended us by returning
949 java_suspend_self();
950 set_suspend_equivalent();
951 }
952 } while (do_self_suspend);
953 }
954 static void check_safepoint_and_suspend_for_native_trans(JavaThread *thread);
955 // Check for async exception in addition to safepoint and suspend request.
956 static void check_special_condition_for_native_trans(JavaThread *thread);
957
958 bool is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits);
959 bool is_ext_suspend_completed_with_lock(uint32_t *bits) {
960 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
961 // Warning: is_ext_suspend_completed() may temporarily drop the
962 // SR_lock to allow the thread to reach a stable thread state if
963 // it is currently in a transient thread state.
964 return is_ext_suspend_completed(false /*!called_by_wait */,
965 SuspendRetryDelay, bits);
966 }
967
968 // We cannot allow wait_for_ext_suspend_completion() to run forever or
969 // we could hang. SuspendRetryCount and SuspendRetryDelay are normally
970 // passed as the count and delay parameters. Experiments with specific
971 // calls to wait_for_ext_suspend_completion() can be done by passing
972 // other values in the code. Experiments with all calls can be done
973 // via the appropriate -XX options.
974 bool wait_for_ext_suspend_completion(int count, int delay, uint32_t *bits);
975
976 void set_external_suspend() { set_suspend_flag (_external_suspend); }
977 void clear_external_suspend() { clear_suspend_flag(_external_suspend); }
978
979 void set_deopt_suspend() { set_suspend_flag (_deopt_suspend); }
980 void clear_deopt_suspend() { clear_suspend_flag(_deopt_suspend); }
981 bool is_deopt_suspend() { return (_suspend_flags & _deopt_suspend) != 0; }
982
983 bool is_external_suspend() const {
984 return (_suspend_flags & _external_suspend) != 0;
985 }
986 // Whenever a thread transitions from native to vm/java it must suspend
987 // if external|deopt suspend is present.
988 bool is_suspend_after_native() const {
989 return (_suspend_flags & (_external_suspend | _deopt_suspend) ) != 0;
990 }
991
992 // external suspend request is completed
993 bool is_ext_suspended() const {
994 return (_suspend_flags & _ext_suspended) != 0;
995 }
996
997 bool is_external_suspend_with_lock() const {
998 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
999 return is_external_suspend();
1000 }
1001
1002 // Special method to handle a pending external suspend request
1003 // when a suspend equivalent condition lifts.
1004 bool handle_special_suspend_equivalent_condition() {
1005 assert(is_suspend_equivalent(),
1006 "should only be called in a suspend equivalence condition");
1007 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1008 bool ret = is_external_suspend();
1009 if (!ret) {
1010 // not about to self-suspend so clear suspend equivalence
1011 clear_suspend_equivalent();
1012 }
1013 // implied else:
1014 // We have a pending external suspend request so we leave the
1015 // suspend_equivalent flag set until java_suspend_self() sets
1016 // the ext_suspended flag and clears the suspend_equivalent
1017 // flag. This insures that wait_for_ext_suspend_completion()
1018 // will return consistent values.
1019 return ret;
1020 }
1021
1022 // utility methods to see if we are doing some kind of suspension
1023 bool is_being_ext_suspended() const {
1024 MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1025 return is_ext_suspended() || is_external_suspend();
1026 }
1027
1028 bool is_suspend_equivalent() const { return _suspend_equivalent; }
1029
1030 void set_suspend_equivalent() { _suspend_equivalent = true; };
1031 void clear_suspend_equivalent() { _suspend_equivalent = false; };
1032
1033 // Thread.stop support
1034 void send_thread_stop(oop throwable);
1035 AsyncRequests clear_special_runtime_exit_condition() {
1036 AsyncRequests x = _special_runtime_exit_condition;
1037 _special_runtime_exit_condition = _no_async_condition;
1038 return x;
1039 }
1040
1041 // Are any async conditions present?
1042 bool has_async_condition() { return (_special_runtime_exit_condition != _no_async_condition); }
1043
1044 void check_and_handle_async_exceptions(bool check_unsafe_error = true);
1045
1046 // these next two are also used for self-suspension and async exception support
1047 void handle_special_runtime_exit_condition(bool check_asyncs = true);
1048
1049 // Return true if JavaThread has an asynchronous condition or
1050 // if external suspension is requested.
1051 bool has_special_runtime_exit_condition() {
1052 // We call is_external_suspend() last since external suspend should
1053 // be less common. Because we don't use is_external_suspend_with_lock
1054 // it is possible that we won't see an asynchronous external suspend
1055 // request that has just gotten started, i.e., SR_lock grabbed but
1056 // _external_suspend field change either not made yet or not visible
1057 // yet. However, this is okay because the request is asynchronous and
1058 // we will see the new flag value the next time through. It's also
1059 // possible that the external suspend request is dropped after
1060 // we have checked is_external_suspend(), we will recheck its value
1061 // under SR_lock in java_suspend_self().
1062 return (_special_runtime_exit_condition != _no_async_condition) ||
1063 is_external_suspend() || is_deopt_suspend();
1064 }
1065
1066 void set_pending_unsafe_access_error() { _special_runtime_exit_condition = _async_unsafe_access_error; }
1067
1068 void set_pending_async_exception(oop e) {
1069 _pending_async_exception = e;
1070 _special_runtime_exit_condition = _async_exception;
1071 set_has_async_exception();
1072 }
1073
1074 // Fast-locking support
1075 bool is_lock_owned(address adr) const;
1076
1077 // Accessors for vframe array top
1078 // The linked list of vframe arrays are sorted on sp. This means when we
1079 // unpack the head must contain the vframe array to unpack.
1080 void set_vframe_array_head(vframeArray* value) { _vframe_array_head = value; }
1081 vframeArray* vframe_array_head() const { return _vframe_array_head; }
1082
1083 // Side structure for defering update of java frame locals until deopt occurs
1084 GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred_locals() const { return _deferred_locals_updates; }
1085 void set_deferred_locals(GrowableArray<jvmtiDeferredLocalVariableSet *>* vf) { _deferred_locals_updates = vf; }
1086
1087 // These only really exist to make debugging deopt problems simpler
1088
1089 void set_vframe_array_last(vframeArray* value) { _vframe_array_last = value; }
1090 vframeArray* vframe_array_last() const { return _vframe_array_last; }
1091
1092 // The special resourceMark used during deoptimization
1093
1094 void set_deopt_mark(DeoptResourceMark* value) { _deopt_mark = value; }
1095 DeoptResourceMark* deopt_mark(void) { return _deopt_mark; }
1096
1097 intptr_t* must_deopt_id() { return _must_deopt_id; }
1098 void set_must_deopt_id(intptr_t* id) { _must_deopt_id = id; }
1099 void clear_must_deopt_id() { _must_deopt_id = NULL; }
1100
1101 void set_deopt_nmethod(nmethod* nm) { _deopt_nmethod = nm; }
1102 nmethod* deopt_nmethod() { return _deopt_nmethod; }
1103
1104 methodOop callee_target() const { return _callee_target; }
1105 void set_callee_target (methodOop x) { _callee_target = x; }
1106
1107 // Oop results of vm runtime calls
1108 oop vm_result() const { return _vm_result; }
1109 void set_vm_result (oop x) { _vm_result = x; }
1110
1111 oop vm_result_2() const { return _vm_result_2; }
1112 void set_vm_result_2 (oop x) { _vm_result_2 = x; }
1113
1114 MemRegion deferred_card_mark() const { return _deferred_card_mark; }
1115 void set_deferred_card_mark(MemRegion mr) { _deferred_card_mark = mr; }
1116
1117 // Exception handling for compiled methods
1118 oop exception_oop() const { return _exception_oop; }
1119 int exception_stack_size() const { return _exception_stack_size; }
1120 address exception_pc() const { return _exception_pc; }
1121 address exception_handler_pc() const { return _exception_handler_pc; }
1122 bool is_method_handle_return() const { return _is_method_handle_return == 1; }
1123
1124 void set_exception_oop(oop o) { _exception_oop = o; }
1125 void set_exception_pc(address a) { _exception_pc = a; }
1126 void set_exception_handler_pc(address a) { _exception_handler_pc = a; }
1127 void set_exception_stack_size(int size) { _exception_stack_size = size; }
1128 void set_is_method_handle_return(bool value) { _is_method_handle_return = value ? 1 : 0; }
1129
1130 // Stack overflow support
1131 inline size_t stack_available(address cur_sp);
1132 address stack_yellow_zone_base()
1133 { return (address)(stack_base() - (stack_size() - (stack_red_zone_size() + stack_yellow_zone_size()))); }
1134 size_t stack_yellow_zone_size()
1135 { return StackYellowPages * os::vm_page_size(); }
1136 address stack_red_zone_base()
1137 { return (address)(stack_base() - (stack_size() - stack_red_zone_size())); }
1138 size_t stack_red_zone_size()
1139 { return StackRedPages * os::vm_page_size(); }
1140 bool in_stack_yellow_zone(address a)
1141 { return (a <= stack_yellow_zone_base()) && (a >= stack_red_zone_base()); }
1142 bool in_stack_red_zone(address a)
1143 { return (a <= stack_red_zone_base()) && (a >= (address)((intptr_t)stack_base() - stack_size())); }
1144
1145 void create_stack_guard_pages();
1146 void remove_stack_guard_pages();
1147
1148 void enable_stack_yellow_zone();
1149 void disable_stack_yellow_zone();
1150 void enable_stack_red_zone();
1151 void disable_stack_red_zone();
1152
1153 inline bool stack_yellow_zone_disabled();
1154 inline bool stack_yellow_zone_enabled();
1155
1156 // Attempt to reguard the stack after a stack overflow may have occurred.
1157 // Returns true if (a) guard pages are not needed on this thread, (b) the
1158 // pages are already guarded, or (c) the pages were successfully reguarded.
1159 // Returns false if there is not enough stack space to reguard the pages, in
1160 // which case the caller should unwind a frame and try again. The argument
1161 // should be the caller's (approximate) sp.
1162 bool reguard_stack(address cur_sp);
1163 // Similar to above but see if current stackpoint is out of the guard area
1164 // and reguard if possible.
1165 bool reguard_stack(void);
1166
1167 // Misc. accessors/mutators
1168 void set_do_not_unlock(void) { _do_not_unlock_if_synchronized = true; }
1169 void clr_do_not_unlock(void) { _do_not_unlock_if_synchronized = false; }
1170 bool do_not_unlock(void) { return _do_not_unlock_if_synchronized; }
1171
1172 #ifndef PRODUCT
1173 void record_jump(address target, address instr, const char* file, int line);
1174 #endif /* PRODUCT */
1175
1176 // For assembly stub generation
1177 static ByteSize threadObj_offset() { return byte_offset_of(JavaThread, _threadObj ); }
1178 #ifndef PRODUCT
1179 static ByteSize jmp_ring_index_offset() { return byte_offset_of(JavaThread, _jmp_ring_index ); }
1180 static ByteSize jmp_ring_offset() { return byte_offset_of(JavaThread, _jmp_ring ); }
1181 #endif /* PRODUCT */
1182 static ByteSize jni_environment_offset() { return byte_offset_of(JavaThread, _jni_environment ); }
1183 static ByteSize last_Java_sp_offset() {
1184 return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_sp_offset();
1185 }
1186 static ByteSize last_Java_pc_offset() {
1187 return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_pc_offset();
1188 }
1189 static ByteSize frame_anchor_offset() {
1190 return byte_offset_of(JavaThread, _anchor);
1191 }
1192 static ByteSize callee_target_offset() { return byte_offset_of(JavaThread, _callee_target ); }
1193 static ByteSize vm_result_offset() { return byte_offset_of(JavaThread, _vm_result ); }
1194 static ByteSize vm_result_2_offset() { return byte_offset_of(JavaThread, _vm_result_2 ); }
1195 static ByteSize thread_state_offset() { return byte_offset_of(JavaThread, _thread_state ); }
1196 static ByteSize saved_exception_pc_offset() { return byte_offset_of(JavaThread, _saved_exception_pc ); }
1197 static ByteSize osthread_offset() { return byte_offset_of(JavaThread, _osthread ); }
1198 static ByteSize exception_oop_offset() { return byte_offset_of(JavaThread, _exception_oop ); }
1199 static ByteSize exception_pc_offset() { return byte_offset_of(JavaThread, _exception_pc ); }
1200 static ByteSize exception_handler_pc_offset() { return byte_offset_of(JavaThread, _exception_handler_pc); }
1201 static ByteSize exception_stack_size_offset() { return byte_offset_of(JavaThread, _exception_stack_size); }
1202 static ByteSize is_method_handle_return_offset() { return byte_offset_of(JavaThread, _is_method_handle_return); }
1203 static ByteSize stack_guard_state_offset() { return byte_offset_of(JavaThread, _stack_guard_state ); }
1204 static ByteSize suspend_flags_offset() { return byte_offset_of(JavaThread, _suspend_flags ); }
1205
1206 static ByteSize do_not_unlock_if_synchronized_offset() { return byte_offset_of(JavaThread, _do_not_unlock_if_synchronized); }
1207 static ByteSize should_post_on_exceptions_flag_offset() {
1208 return byte_offset_of(JavaThread, _should_post_on_exceptions_flag);
1209 }
1210
1211 #ifndef SERIALGC
1212 static ByteSize satb_mark_queue_offset() { return byte_offset_of(JavaThread, _satb_mark_queue); }
1213 static ByteSize dirty_card_queue_offset() { return byte_offset_of(JavaThread, _dirty_card_queue); }
1214 #endif // !SERIALGC
1215
1216 // Returns the jni environment for this thread
1217 JNIEnv* jni_environment() { return &_jni_environment; }
1218
1219 static JavaThread* thread_from_jni_environment(JNIEnv* env) {
1220 JavaThread *thread_from_jni_env = (JavaThread*)((intptr_t)env - in_bytes(jni_environment_offset()));
1221 // Only return NULL if thread is off the thread list; starting to
1222 // exit should not return NULL.
1223 if (thread_from_jni_env->is_terminated()) {
1224 thread_from_jni_env->block_if_vm_exited();
1225 return NULL;
1226 } else {
1227 return thread_from_jni_env;
1228 }
1229 }
1230
1231 // JNI critical regions. These can nest.
1232 bool in_critical() { return _jni_active_critical > 0; }
1233 void enter_critical() { assert(Thread::current() == this,
1234 "this must be current thread");
1235 _jni_active_critical++; }
1236 void exit_critical() { assert(Thread::current() == this,
1237 "this must be current thread");
1238 _jni_active_critical--;
1239 assert(_jni_active_critical >= 0,
1240 "JNI critical nesting problem?"); }
1241
1242 // For deadlock detection
1243 int depth_first_number() { return _depth_first_number; }
1244 void set_depth_first_number(int dfn) { _depth_first_number = dfn; }
1245
1246 private:
1247 void set_monitor_chunks(MonitorChunk* monitor_chunks) { _monitor_chunks = monitor_chunks; }
1248
1249 public:
1250 MonitorChunk* monitor_chunks() const { return _monitor_chunks; }
1251 void add_monitor_chunk(MonitorChunk* chunk);
1252 void remove_monitor_chunk(MonitorChunk* chunk);
1253 bool in_deopt_handler() const { return _in_deopt_handler > 0; }
1254 void inc_in_deopt_handler() { _in_deopt_handler++; }
1255 void dec_in_deopt_handler() {
1256 assert(_in_deopt_handler > 0, "mismatched deopt nesting");
1257 if (_in_deopt_handler > 0) { // robustness
1258 _in_deopt_handler--;
1259 }
1260 }
1261
1262 private:
1263 void set_entry_point(ThreadFunction entry_point) { _entry_point = entry_point; }
1264
1265 public:
1266
1267 // Frame iteration; calls the function f for all frames on the stack
1268 void frames_do(void f(frame*, const RegisterMap*));
1269
1270 // Memory operations
1271 void oops_do(OopClosure* f, CodeBlobClosure* cf);
1272
1273 // Sweeper operations
1274 void nmethods_do(CodeBlobClosure* cf);
1275
1276 // Memory management operations
1277 void gc_epilogue();
1278 void gc_prologue();
1279
1280 // Misc. operations
1281 char* name() const { return (char*)get_thread_name(); }
1282 void print_on(outputStream* st) const;
1283 void print() const { print_on(tty); }
1284 void print_value();
1285 void print_thread_state_on(outputStream* ) const PRODUCT_RETURN;
1286 void print_thread_state() const PRODUCT_RETURN;
1287 void print_on_error(outputStream* st, char* buf, int buflen) const;
1288 void verify();
1289 const char* get_thread_name() const;
1290 private:
1291 // factor out low-level mechanics for use in both normal and error cases
1292 const char* get_thread_name_string(char* buf = NULL, int buflen = 0) const;
1293 public:
1294 const char* get_threadgroup_name() const;
1295 const char* get_parent_name() const;
1296
1297 // Accessing frames
1298 frame last_frame() {
1299 _anchor.make_walkable(this);
1300 return pd_last_frame();
1301 }
1302 javaVFrame* last_java_vframe(RegisterMap* reg_map);
1303
1304 // Returns method at 'depth' java or native frames down the stack
1305 // Used for security checks
1306 klassOop security_get_caller_class(int depth);
1307
1308 // Print stack trace in external format
1309 void print_stack_on(outputStream* st);
1310 void print_stack() { print_stack_on(tty); }
1311
1312 // Print stack traces in various internal formats
1313 void trace_stack() PRODUCT_RETURN;
1314 void trace_stack_from(vframe* start_vf) PRODUCT_RETURN;
1315 void trace_frames() PRODUCT_RETURN;
1316
1317 // Returns the number of stack frames on the stack
1318 int depth() const;
1319
1320 // Function for testing deoptimization
1321 void deoptimize();
1322 void make_zombies();
1323
1324 void deoptimized_wrt_marked_nmethods();
1325
1326 // Profiling operation (see fprofile.cpp)
1327 public:
1328 bool profile_last_Java_frame(frame* fr);
1329
1330 private:
1331 ThreadProfiler* _thread_profiler;
1332 private:
1333 friend class FlatProfiler; // uses both [gs]et_thread_profiler.
1334 friend class FlatProfilerTask; // uses get_thread_profiler.
1335 friend class ThreadProfilerMark; // uses get_thread_profiler.
1336 ThreadProfiler* get_thread_profiler() { return _thread_profiler; }
1337 ThreadProfiler* set_thread_profiler(ThreadProfiler* tp) {
1338 ThreadProfiler* result = _thread_profiler;
1339 _thread_profiler = tp;
1340 return result;
1341 }
1342
1343 // Static operations
1344 public:
1345 // Returns the running thread as a JavaThread
1346 static inline JavaThread* current();
1347
1348 // Returns the active Java thread. Do not use this if you know you are calling
1349 // from a JavaThread, as it's slower than JavaThread::current. If called from
1350 // the VMThread, it also returns the JavaThread that instigated the VMThread's
1351 // operation. You may not want that either.
1352 static JavaThread* active();
1353
1354 inline CompilerThread* as_CompilerThread();
1355
1356 public:
1357 virtual void run();
1358 void thread_main_inner();
1359
1360 private:
1361 // PRIVILEGED STACK
1362 PrivilegedElement* _privileged_stack_top;
1363 GrowableArray<oop>* _array_for_gc;
1364 public:
1365
1366 // Returns the privileged_stack information.
1367 PrivilegedElement* privileged_stack_top() const { return _privileged_stack_top; }
1368 void set_privileged_stack_top(PrivilegedElement *e) { _privileged_stack_top = e; }
1369 void register_array_for_gc(GrowableArray<oop>* array) { _array_for_gc = array; }
1370
1371 public:
1372 // Thread local information maintained by JVMTI.
1373 void set_jvmti_thread_state(JvmtiThreadState *value) { _jvmti_thread_state = value; }
1374 // A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
1375 // getter is used to get this JavaThread's JvmtiThreadState if it has
1376 // one which means NULL can be returned. JvmtiThreadState::state_for()
1377 // is used to get the specified JavaThread's JvmtiThreadState if it has
1378 // one or it allocates a new JvmtiThreadState for the JavaThread and
1379 // returns it. JvmtiThreadState::state_for() will return NULL only if
1380 // the specified JavaThread is exiting.
1381 JvmtiThreadState *jvmti_thread_state() const { return _jvmti_thread_state; }
1382 static ByteSize jvmti_thread_state_offset() { return byte_offset_of(JavaThread, _jvmti_thread_state); }
1383 void set_jvmti_get_loaded_classes_closure(JvmtiGetLoadedClassesClosure* value) { _jvmti_get_loaded_classes_closure = value; }
1384 JvmtiGetLoadedClassesClosure* get_jvmti_get_loaded_classes_closure() const { return _jvmti_get_loaded_classes_closure; }
1385
1386 // JVMTI PopFrame support
1387 // Setting and clearing popframe_condition
1388 // All of these enumerated values are bits. popframe_pending
1389 // indicates that a PopFrame() has been requested and not yet been
1390 // completed. popframe_processing indicates that that PopFrame() is in
1391 // the process of being completed. popframe_force_deopt_reexecution_bit
1392 // indicates that special handling is required when returning to a
1393 // deoptimized caller.
1394 enum PopCondition {
1395 popframe_inactive = 0x00,
1396 popframe_pending_bit = 0x01,
1397 popframe_processing_bit = 0x02,
1398 popframe_force_deopt_reexecution_bit = 0x04
1399 };
1400 PopCondition popframe_condition() { return (PopCondition) _popframe_condition; }
1401 void set_popframe_condition(PopCondition c) { _popframe_condition = c; }
1402 void set_popframe_condition_bit(PopCondition c) { _popframe_condition |= c; }
1403 void clear_popframe_condition() { _popframe_condition = popframe_inactive; }
1404 static ByteSize popframe_condition_offset() { return byte_offset_of(JavaThread, _popframe_condition); }
1405 bool has_pending_popframe() { return (popframe_condition() & popframe_pending_bit) != 0; }
1406 bool popframe_forcing_deopt_reexecution() { return (popframe_condition() & popframe_force_deopt_reexecution_bit) != 0; }
1407 void clear_popframe_forcing_deopt_reexecution() { _popframe_condition &= ~popframe_force_deopt_reexecution_bit; }
1408 #ifdef CC_INTERP
1409 bool pop_frame_pending(void) { return ((_popframe_condition & popframe_pending_bit) != 0); }
1410 void clr_pop_frame_pending(void) { _popframe_condition = popframe_inactive; }
1411 bool pop_frame_in_process(void) { return ((_popframe_condition & popframe_processing_bit) != 0); }
1412 void set_pop_frame_in_process(void) { _popframe_condition |= popframe_processing_bit; }
1413 void clr_pop_frame_in_process(void) { _popframe_condition &= ~popframe_processing_bit; }
1414 #endif
1415
1416 private:
1417 // Saved incoming arguments to popped frame.
1418 // Used only when popped interpreted frame returns to deoptimized frame.
1419 void* _popframe_preserved_args;
1420 int _popframe_preserved_args_size;
1421
1422 public:
1423 void popframe_preserve_args(ByteSize size_in_bytes, void* start);
1424 void* popframe_preserved_args();
1425 ByteSize popframe_preserved_args_size();
1426 WordSize popframe_preserved_args_size_in_words();
1427 void popframe_free_preserved_args();
1428
1429
1430 private:
1431 JvmtiThreadState *_jvmti_thread_state;
1432 JvmtiGetLoadedClassesClosure* _jvmti_get_loaded_classes_closure;
1433
1434 // Used by the interpreter in fullspeed mode for frame pop, method
1435 // entry, method exit and single stepping support. This field is
1436 // only set to non-zero by the VM_EnterInterpOnlyMode VM operation.
1437 // It can be set to zero asynchronously (i.e., without a VM operation
1438 // or a lock) so we have to be very careful.
1439 int _interp_only_mode;
1440
1441 public:
1442 // used by the interpreter for fullspeed debugging support (see above)
1443 static ByteSize interp_only_mode_offset() { return byte_offset_of(JavaThread, _interp_only_mode); }
1444 bool is_interp_only_mode() { return (_interp_only_mode != 0); }
1445 int get_interp_only_mode() { return _interp_only_mode; }
1446 void increment_interp_only_mode() { ++_interp_only_mode; }
1447 void decrement_interp_only_mode() { --_interp_only_mode; }
1448
1449 // support for cached flag that indicates whether exceptions need to be posted for this thread
1450 // if this is false, we can avoid deoptimizing when events are thrown
1451 // this gets set to reflect whether jvmtiExport::post_exception_throw would actually do anything
1452 private:
1453 int _should_post_on_exceptions_flag;
1454
1455 public:
1456 int should_post_on_exceptions_flag() { return _should_post_on_exceptions_flag; }
1457 void set_should_post_on_exceptions_flag(int val) { _should_post_on_exceptions_flag = val; }
1458
1459 private:
1460 ThreadStatistics *_thread_stat;
1461
1462 public:
1463 ThreadStatistics* get_thread_stat() const { return _thread_stat; }
1464
1465 // Return a blocker object for which this thread is blocked parking.
1466 oop current_park_blocker();
1467
1468 private:
1469 static size_t _stack_size_at_create;
1470
1471 public:
1472 static inline size_t stack_size_at_create(void) {
1473 return _stack_size_at_create;
1474 }
1475 static inline void set_stack_size_at_create(size_t value) {
1476 _stack_size_at_create = value;
1477 }
1478
1479 #ifndef SERIALGC
1480 // SATB marking queue support
1481 ObjPtrQueue& satb_mark_queue() { return _satb_mark_queue; }
1482 static SATBMarkQueueSet& satb_mark_queue_set() {
1483 return _satb_mark_queue_set;
1484 }
1485
1486 // Dirty card queue support
1487 DirtyCardQueue& dirty_card_queue() { return _dirty_card_queue; }
1488 static DirtyCardQueueSet& dirty_card_queue_set() {
1489 return _dirty_card_queue_set;
1490 }
1491 #endif // !SERIALGC
1492
1493 // Machine dependent stuff
1494 #include "incls/_thread_pd.hpp.incl"
1495
1496 public:
1497 void set_blocked_on_compilation(bool value) {
1498 _blocked_on_compilation = value;
1499 }
1500
1501 bool blocked_on_compilation() {
1502 return _blocked_on_compilation;
1503 }
1504 protected:
1505 bool _blocked_on_compilation;
1506
1507
1508 // JSR166 per-thread parker
1509 private:
1510 Parker* _parker;
1511 public:
1512 Parker* parker() { return _parker; }
1513
1514 // Biased locking support
1515 private:
1516 GrowableArray<MonitorInfo*>* _cached_monitor_info;
1517 public:
1518 GrowableArray<MonitorInfo*>* cached_monitor_info() { return _cached_monitor_info; }
1519 void set_cached_monitor_info(GrowableArray<MonitorInfo*>* info) { _cached_monitor_info = info; }
1520
1521 // clearing/querying jni attach status
1522 bool is_attaching() const { return _is_attaching; }
1523 void set_attached() { _is_attaching = false; OrderAccess::fence(); }
1524 private:
1525 // This field is used to determine if a thread has claimed
1526 // a par_id: it is -1 if the thread has not claimed a par_id;
1527 // otherwise its value is the par_id that has been claimed.
1528 int _claimed_par_id;
1529 public:
1530 int get_claimed_par_id() { return _claimed_par_id; }
1531 void set_claimed_par_id(int id) { _claimed_par_id = id;}
1532 };
1533
1534 // Inline implementation of JavaThread::current
1535 inline JavaThread* JavaThread::current() {
1536 Thread* thread = ThreadLocalStorage::thread();
1537 assert(thread != NULL && thread->is_Java_thread(), "just checking");
1538 return (JavaThread*)thread;
1539 }
1540
1541 inline CompilerThread* JavaThread::as_CompilerThread() {
1542 assert(is_Compiler_thread(), "just checking");
1543 return (CompilerThread*)this;
1544 }
1545
1546 inline bool JavaThread::stack_yellow_zone_disabled() {
1547 return _stack_guard_state == stack_guard_yellow_disabled;
1548 }
1549
1550 inline bool JavaThread::stack_yellow_zone_enabled() {
1551 #ifdef ASSERT
1552 if (os::uses_stack_guard_pages()) {
1553 assert(_stack_guard_state != stack_guard_unused, "guard pages must be in use");
1554 }
1555 #endif
1556 return _stack_guard_state == stack_guard_enabled;
1557 }
1558
1559 inline size_t JavaThread::stack_available(address cur_sp) {
1560 // This code assumes java stacks grow down
1561 address low_addr; // Limit on the address for deepest stack depth
1562 if ( _stack_guard_state == stack_guard_unused) {
1563 low_addr = stack_base() - stack_size();
1564 } else {
1565 low_addr = stack_yellow_zone_base();
1566 }
1567 return cur_sp > low_addr ? cur_sp - low_addr : 0;
1568 }
1569
1570 // A JavaThread for low memory detection support
1571 class LowMemoryDetectorThread : public JavaThread {
1572 friend class VMStructs;
1573 public:
1574 LowMemoryDetectorThread(ThreadFunction entry_point) : JavaThread(entry_point) {};
1575
1576 // Hide this thread from external view.
1577 bool is_hidden_from_external_view() const { return true; }
1578 };
1579
1580 // A thread used for Compilation.
1581 class CompilerThread : public JavaThread {
1582 friend class VMStructs;
1583 private:
1584 CompilerCounters* _counters;
1585
1586 ciEnv* _env;
1587 CompileLog* _log;
1588 CompileTask* _task;
1589 CompileQueue* _queue;
1590 BufferBlob* _buffer_blob;
1591
1592 public:
1593
1594 static CompilerThread* current();
1595
1596 CompilerThread(CompileQueue* queue, CompilerCounters* counters);
1597
1598 bool is_Compiler_thread() const { return true; }
1599 // Hide this compiler thread from external view.
1600 bool is_hidden_from_external_view() const { return true; }
1601
1602 CompileQueue* queue() { return _queue; }
1603 CompilerCounters* counters() { return _counters; }
1604
1605 // Get/set the thread's compilation environment.
1606 ciEnv* env() { return _env; }
1607 void set_env(ciEnv* env) { _env = env; }
1608
1609 BufferBlob* get_buffer_blob() { return _buffer_blob; }
1610 void set_buffer_blob(BufferBlob* b) { _buffer_blob = b; };
1611
1612 // Get/set the thread's logging information
1613 CompileLog* log() { return _log; }
1614 void init_log(CompileLog* log) {
1615 // Set once, for good.
1616 assert(_log == NULL, "set only once");
1617 _log = log;
1618 }
1619
1620 #ifndef PRODUCT
1621 private:
1622 IdealGraphPrinter *_ideal_graph_printer;
1623 public:
1624 IdealGraphPrinter *ideal_graph_printer() { return _ideal_graph_printer; }
1625 void set_ideal_graph_printer(IdealGraphPrinter *n) { _ideal_graph_printer = n; }
1626 #endif
1627
1628 // Get/set the thread's current task
1629 CompileTask* task() { return _task; }
1630 void set_task(CompileTask* task) { _task = task; }
1631 };
1632
1633 inline CompilerThread* CompilerThread::current() {
1634 return JavaThread::current()->as_CompilerThread();
1635 }
1636
1637
1638 // The active thread queue. It also keeps track of the current used
1639 // thread priorities.
1640 class Threads: AllStatic {
1641 friend class VMStructs;
1642 private:
1643 static JavaThread* _thread_list;
1644 static int _number_of_threads;
1645 static int _number_of_non_daemon_threads;
1646 static int _return_code;
1647
1648 public:
1649 // Thread management
1650 // force_daemon is a concession to JNI, where we may need to add a
1651 // thread to the thread list before allocating its thread object
1652 static void add(JavaThread* p, bool force_daemon = false);
1653 static void remove(JavaThread* p);
1654 static bool includes(JavaThread* p);
1655 static JavaThread* first() { return _thread_list; }
1656 static void threads_do(ThreadClosure* tc);
1657
1658 // Initializes the vm and creates the vm thread
1659 static jint create_vm(JavaVMInitArgs* args, bool* canTryAgain);
1660 static void convert_vm_init_libraries_to_agents();
1661 static void create_vm_init_libraries();
1662 static void create_vm_init_agents();
1663 static void shutdown_vm_agents();
1664 static bool destroy_vm();
1665 // Supported VM versions via JNI
1666 // Includes JNI_VERSION_1_1
1667 static jboolean is_supported_jni_version_including_1_1(jint version);
1668 // Does not include JNI_VERSION_1_1
1669 static jboolean is_supported_jni_version(jint version);
1670
1671 // Garbage collection
1672 static void follow_other_roots(void f(oop*));
1673
1674 // Apply "f->do_oop" to all root oops in all threads.
1675 // This version may only be called by sequential code.
1676 static void oops_do(OopClosure* f, CodeBlobClosure* cf);
1677 // This version may be called by sequential or parallel code.
1678 static void possibly_parallel_oops_do(OopClosure* f, CodeBlobClosure* cf);
1679 // This creates a list of GCTasks, one per thread.
1680 static void create_thread_roots_tasks(GCTaskQueue* q);
1681 // This creates a list of GCTasks, one per thread, for marking objects.
1682 static void create_thread_roots_marking_tasks(GCTaskQueue* q);
1683
1684 // Apply "f->do_oop" to roots in all threads that
1685 // are part of compiled frames
1686 static void compiled_frame_oops_do(OopClosure* f, CodeBlobClosure* cf);
1687
1688 static void convert_hcode_pointers();
1689 static void restore_hcode_pointers();
1690
1691 // Sweeper
1692 static void nmethods_do(CodeBlobClosure* cf);
1693
1694 static void gc_epilogue();
1695 static void gc_prologue();
1696
1697 // Verification
1698 static void verify();
1699 static void print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks);
1700 static void print(bool print_stacks, bool internal_format) {
1701 // this function is only used by debug.cpp
1702 print_on(tty, print_stacks, internal_format, false /* no concurrent lock printed */);
1703 }
1704 static void print_on_error(outputStream* st, Thread* current, char* buf, int buflen);
1705
1706 // Get Java threads that are waiting to enter a monitor. If doLock
1707 // is true, then Threads_lock is grabbed as needed. Otherwise, the
1708 // VM needs to be at a safepoint.
1709 static GrowableArray<JavaThread*>* get_pending_threads(int count,
1710 address monitor, bool doLock);
1711
1712 // Get owning Java thread from the monitor's owner field. If doLock
1713 // is true, then Threads_lock is grabbed as needed. Otherwise, the
1714 // VM needs to be at a safepoint.
1715 static JavaThread *owning_thread_from_monitor_owner(address owner,
1716 bool doLock);
1717
1718 // Number of threads on the active threads list
1719 static int number_of_threads() { return _number_of_threads; }
1720 // Number of non-daemon threads on the active threads list
1721 static int number_of_non_daemon_threads() { return _number_of_non_daemon_threads; }
1722
1723 // Deoptimizes all frames tied to marked nmethods
1724 static void deoptimized_wrt_marked_nmethods();
1725
1726 };
1727
1728
1729 // Thread iterator
1730 class ThreadClosure: public StackObj {
1731 public:
1732 virtual void do_thread(Thread* thread) = 0;
1733 };
1734
1735 class SignalHandlerMark: public StackObj {
1736 private:
1737 Thread* _thread;
1738 public:
1739 SignalHandlerMark(Thread* t) {
1740 _thread = t;
1741 if (_thread) _thread->enter_signal_handler();
1742 }
1743 ~SignalHandlerMark() {
1744 if (_thread) _thread->leave_signal_handler();
1745 _thread = NULL;
1746 }
1747 };
1748
1749 // ParkEvents are type-stable and immortal.
1750 //
1751 // Lifecycle: Once a ParkEvent is associated with a thread that ParkEvent remains
1752 // associated with the thread for the thread's entire lifetime - the relationship is
1753 // stable. A thread will be associated at most one ParkEvent. When the thread
1754 // expires, the ParkEvent moves to the EventFreeList. New threads attempt to allocate from
1755 // the EventFreeList before creating a new Event. Type-stability frees us from
1756 // worrying about stale Event or Thread references in the objectMonitor subsystem.
1757 // (A reference to ParkEvent is always valid, even though the event may no longer be associated
1758 // with the desired or expected thread. A key aspect of this design is that the callers of
1759 // park, unpark, etc must tolerate stale references and spurious wakeups).
1760 //
1761 // Only the "associated" thread can block (park) on the ParkEvent, although
1762 // any other thread can unpark a reachable parkevent. Park() is allowed to
1763 // return spuriously. In fact park-unpark a really just an optimization to
1764 // avoid unbounded spinning and surrender the CPU to be a polite system citizen.
1765 // A degenerate albeit "impolite" park-unpark implementation could simply return.
1766 // See http://blogs.sun.com/dave for more details.
1767 //
1768 // Eventually I'd like to eliminate Events and ObjectWaiters, both of which serve as
1769 // thread proxies, and simply make the THREAD structure type-stable and persistent.
1770 // Currently, we unpark events associated with threads, but ideally we'd just
1771 // unpark threads.
1772 //
1773 // The base-class, PlatformEvent, is platform-specific while the ParkEvent is
1774 // platform-independent. PlatformEvent provides park(), unpark(), etc., and
1775 // is abstract -- that is, a PlatformEvent should never be instantiated except
1776 // as part of a ParkEvent.
1777 // Equivalently we could have defined a platform-independent base-class that
1778 // exported Allocate(), Release(), etc. The platform-specific class would extend
1779 // that base-class, adding park(), unpark(), etc.
1780 //
1781 // A word of caution: The JVM uses 2 very similar constructs:
1782 // 1. ParkEvent are used for Java-level "monitor" synchronization.
1783 // 2. Parkers are used by JSR166-JUC park-unpark.
1784 //
1785 // We'll want to eventually merge these redundant facilities and use ParkEvent.
1786
1787
1788 class ParkEvent : public os::PlatformEvent {
1789 private:
1790 ParkEvent * FreeNext ;
1791
1792 // Current association
1793 Thread * AssociatedWith ;
1794 intptr_t RawThreadIdentity ; // LWPID etc
1795 volatile int Incarnation ;
1796
1797 // diagnostic : keep track of last thread to wake this thread.
1798 // this is useful for construction of dependency graphs.
1799 void * LastWaker ;
1800
1801 public:
1802 // MCS-CLH list linkage and Native Mutex/Monitor
1803 ParkEvent * volatile ListNext ;
1804 ParkEvent * volatile ListPrev ;
1805 volatile intptr_t OnList ;
1806 volatile int TState ;
1807 volatile int Notified ; // for native monitor construct
1808 volatile int IsWaiting ; // Enqueued on WaitSet
1809
1810
1811 private:
1812 static ParkEvent * volatile FreeList ;
1813 static volatile int ListLock ;
1814
1815 // It's prudent to mark the dtor as "private"
1816 // ensuring that it's not visible outside the package.
1817 // Unfortunately gcc warns about such usage, so
1818 // we revert to the less desirable "protected" visibility.
1819 // The other compilers accept private dtors.
1820
1821 protected: // Ensure dtor is never invoked
1822 ~ParkEvent() { guarantee (0, "invariant") ; }
1823
1824 ParkEvent() : PlatformEvent() {
1825 AssociatedWith = NULL ;
1826 FreeNext = NULL ;
1827 ListNext = NULL ;
1828 ListPrev = NULL ;
1829 OnList = 0 ;
1830 TState = 0 ;
1831 Notified = 0 ;
1832 IsWaiting = 0 ;
1833 }
1834
1835 // We use placement-new to force ParkEvent instances to be
1836 // aligned on 256-byte address boundaries. This ensures that the least
1837 // significant byte of a ParkEvent address is always 0.
1838
1839 void * operator new (size_t sz) ;
1840 void operator delete (void * a) ;
1841
1842 public:
1843 static ParkEvent * Allocate (Thread * t) ;
1844 static void Release (ParkEvent * e) ;
1845 } ;