rev 50392 : JEP 331

   1 /*
   2  * Copyright (c) 1997, 2018, 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 #ifndef SHARE_VM_RUNTIME_THREAD_HPP
  26 #define SHARE_VM_RUNTIME_THREAD_HPP
  27 
  28 #include "jni.h"
  29 #include "gc/shared/gcThreadLocalData.hpp"
  30 #include "gc/shared/threadLocalAllocBuffer.hpp"
  31 #include "memory/allocation.hpp"
  32 #include "oops/oop.hpp"
  33 #include "prims/jvmtiExport.hpp"
  34 #include "runtime/frame.hpp"
  35 #include "runtime/globals.hpp"
  36 #include "runtime/handshake.hpp"
  37 #include "runtime/javaFrameAnchor.hpp"
  38 #include "runtime/jniHandles.hpp"
  39 #include "runtime/mutexLocker.hpp"
  40 #include "runtime/os.hpp"
  41 #include "runtime/osThread.hpp"
  42 #include "runtime/park.hpp"
  43 #include "runtime/safepoint.hpp"
  44 #include "runtime/stubRoutines.hpp"
  45 #include "runtime/threadHeapSampler.hpp"
  46 #include "runtime/threadLocalStorage.hpp"
  47 #include "runtime/unhandledOops.hpp"
  48 #include "utilities/align.hpp"
  49 #include "utilities/exceptions.hpp"
  50 #include "utilities/macros.hpp"
  51 #ifdef ZERO
  52 # include "stack_zero.hpp"
  53 #endif
  54 #if INCLUDE_JFR
  55 #include "jfr/support/jfrThreadExtension.hpp"
  56 #endif
  57 
  58 
  59 class SafeThreadsListPtr;
  60 class ThreadSafepointState;
  61 class ThreadsList;
  62 class ThreadsSMRSupport;
  63 
  64 class JvmtiThreadState;
  65 class JvmtiGetLoadedClassesClosure;
  66 class ThreadStatistics;
  67 class ConcurrentLocksDump;
  68 class ParkEvent;
  69 class Parker;
  70 
  71 class ciEnv;
  72 class CompileThread;
  73 class CompileLog;
  74 class CompileTask;
  75 class CompileQueue;
  76 class CompilerCounters;
  77 class vframeArray;
  78 
  79 class DeoptResourceMark;
  80 class jvmtiDeferredLocalVariableSet;
  81 
  82 class GCTaskQueue;
  83 class ThreadClosure;
  84 class IdealGraphPrinter;
  85 
  86 class Metadata;
  87 template <class T, MEMFLAGS F> class ChunkedList;
  88 typedef ChunkedList<Metadata*, mtInternal> MetadataOnStackBuffer;
  89 
  90 DEBUG_ONLY(class ResourceMark;)
  91 
  92 class WorkerThread;
  93 
  94 // Class hierarchy
  95 // - Thread
  96 //   - NamedThread
  97 //     - VMThread
  98 //     - ConcurrentGCThread
  99 //     - WorkerThread
 100 //       - GangWorker
 101 //       - GCTaskThread
 102 //   - JavaThread
 103 //     - various subclasses eg CompilerThread, ServiceThread
 104 //   - WatcherThread
 105 
 106 class Thread: public ThreadShadow {
 107   friend class VMStructs;
 108   friend class JVMCIVMStructs;
 109  private:
 110 
 111 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 112   // Current thread is maintained as a thread-local variable
 113   static THREAD_LOCAL_DECL Thread* _thr_current;
 114 #endif
 115 
 116  private:
 117   // Thread local data area available to the GC. The internal
 118   // structure and contents of this data area is GC-specific.
 119   // Only GC and GC barrier code should access this data area.
 120   GCThreadLocalData _gc_data;
 121 
 122  public:
 123   static ByteSize gc_data_offset() {
 124     return byte_offset_of(Thread, _gc_data);
 125   }
 126 
 127   template <typename T> T* gc_data() {
 128     STATIC_ASSERT(sizeof(T) <= sizeof(_gc_data));
 129     return reinterpret_cast<T*>(&_gc_data);
 130   }
 131 
 132   // Exception handling
 133   // (Note: _pending_exception and friends are in ThreadShadow)
 134   //oop       _pending_exception;                // pending exception for current thread
 135   // const char* _exception_file;                   // file information for exception (debugging only)
 136   // int         _exception_line;                   // line information for exception (debugging only)
 137  protected:
 138   // Support for forcing alignment of thread objects for biased locking
 139   void*       _real_malloc_address;
 140 
 141   // JavaThread lifecycle support:
 142   friend class SafeThreadsListPtr;  // for _threads_list_ptr, cmpxchg_threads_hazard_ptr(), {dec_,inc_,}nested_threads_hazard_ptr_cnt(), {g,s}et_threads_hazard_ptr(), inc_nested_handle_cnt(), tag_hazard_ptr() access
 143   friend class ScanHazardPtrGatherProtectedThreadsClosure;  // for cmpxchg_threads_hazard_ptr(), get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
 144   friend class ScanHazardPtrGatherThreadsListClosure;  // for get_threads_hazard_ptr(), untag_hazard_ptr() access
 145   friend class ScanHazardPtrPrintMatchingThreadsClosure;  // for get_threads_hazard_ptr(), is_hazard_ptr_tagged() access
 146   friend class ThreadsSMRSupport;  // for _nested_threads_hazard_ptr_cnt, _threads_hazard_ptr, _threads_list_ptr access
 147 
 148   ThreadsList* volatile _threads_hazard_ptr;
 149   SafeThreadsListPtr*   _threads_list_ptr;
 150   ThreadsList*          cmpxchg_threads_hazard_ptr(ThreadsList* exchange_value, ThreadsList* compare_value);
 151   ThreadsList*          get_threads_hazard_ptr();
 152   void                  set_threads_hazard_ptr(ThreadsList* new_list);
 153   static bool           is_hazard_ptr_tagged(ThreadsList* list) {
 154     return (intptr_t(list) & intptr_t(1)) == intptr_t(1);
 155   }
 156   static ThreadsList*   tag_hazard_ptr(ThreadsList* list) {
 157     return (ThreadsList*)(intptr_t(list) | intptr_t(1));
 158   }
 159   static ThreadsList*   untag_hazard_ptr(ThreadsList* list) {
 160     return (ThreadsList*)(intptr_t(list) & ~intptr_t(1));
 161   }
 162   // This field is enabled via -XX:+EnableThreadSMRStatistics:
 163   uint _nested_threads_hazard_ptr_cnt;
 164   void dec_nested_threads_hazard_ptr_cnt() {
 165     assert(_nested_threads_hazard_ptr_cnt != 0, "mismatched {dec,inc}_nested_threads_hazard_ptr_cnt()");
 166     _nested_threads_hazard_ptr_cnt--;
 167   }
 168   void inc_nested_threads_hazard_ptr_cnt() {
 169     _nested_threads_hazard_ptr_cnt++;
 170   }
 171   uint nested_threads_hazard_ptr_cnt() {
 172     return _nested_threads_hazard_ptr_cnt;
 173   }
 174 
 175  public:
 176   void* operator new(size_t size) throw() { return allocate(size, true); }
 177   void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
 178     return allocate(size, false); }
 179   void  operator delete(void* p);
 180 
 181  protected:
 182   static void* allocate(size_t size, bool throw_excpt, MEMFLAGS flags = mtThread);
 183  private:
 184 
 185   // ***************************************************************
 186   // Suspend and resume support
 187   // ***************************************************************
 188   //
 189   // VM suspend/resume no longer exists - it was once used for various
 190   // things including safepoints but was deprecated and finally removed
 191   // in Java 7. Because VM suspension was considered "internal" Java-level
 192   // suspension was considered "external", and this legacy naming scheme
 193   // remains.
 194   //
 195   // External suspend/resume requests come from JVM_SuspendThread,
 196   // JVM_ResumeThread, JVMTI SuspendThread, and finally JVMTI
 197   // ResumeThread. External
 198   // suspend requests cause _external_suspend to be set and external
 199   // resume requests cause _external_suspend to be cleared.
 200   // External suspend requests do not nest on top of other external
 201   // suspend requests. The higher level APIs reject suspend requests
 202   // for already suspended threads.
 203   //
 204   // The external_suspend
 205   // flag is checked by has_special_runtime_exit_condition() and java thread
 206   // will self-suspend when handle_special_runtime_exit_condition() is
 207   // called. Most uses of the _thread_blocked state in JavaThreads are
 208   // considered the same as being externally suspended; if the blocking
 209   // condition lifts, the JavaThread will self-suspend. Other places
 210   // where VM checks for external_suspend include:
 211   //   + mutex granting (do not enter monitors when thread is suspended)
 212   //   + state transitions from _thread_in_native
 213   //
 214   // In general, java_suspend() does not wait for an external suspend
 215   // request to complete. When it returns, the only guarantee is that
 216   // the _external_suspend field is true.
 217   //
 218   // wait_for_ext_suspend_completion() is used to wait for an external
 219   // suspend request to complete. External suspend requests are usually
 220   // followed by some other interface call that requires the thread to
 221   // be quiescent, e.g., GetCallTrace(). By moving the "wait time" into
 222   // the interface that requires quiescence, we give the JavaThread a
 223   // chance to self-suspend before we need it to be quiescent. This
 224   // improves overall suspend/query performance.
 225   //
 226   // _suspend_flags controls the behavior of java_ suspend/resume.
 227   // It must be set under the protection of SR_lock. Read from the flag is
 228   // OK without SR_lock as long as the value is only used as a hint.
 229   // (e.g., check _external_suspend first without lock and then recheck
 230   // inside SR_lock and finish the suspension)
 231   //
 232   // _suspend_flags is also overloaded for other "special conditions" so
 233   // that a single check indicates whether any special action is needed
 234   // eg. for async exceptions.
 235   // -------------------------------------------------------------------
 236   // Notes:
 237   // 1. The suspend/resume logic no longer uses ThreadState in OSThread
 238   // but we still update its value to keep other part of the system (mainly
 239   // JVMTI) happy. ThreadState is legacy code (see notes in
 240   // osThread.hpp).
 241   //
 242   // 2. It would be more natural if set_external_suspend() is private and
 243   // part of java_suspend(), but that probably would affect the suspend/query
 244   // performance. Need more investigation on this.
 245 
 246   // suspend/resume lock: used for self-suspend
 247   Monitor* _SR_lock;
 248 
 249  protected:
 250   enum SuspendFlags {
 251     // NOTE: avoid using the sign-bit as cc generates different test code
 252     //       when the sign-bit is used, and sometimes incorrectly - see CR 6398077
 253 
 254     _external_suspend       = 0x20000000U, // thread is asked to self suspend
 255     _ext_suspended          = 0x40000000U, // thread has self-suspended
 256     _deopt_suspend          = 0x10000000U, // thread needs to self suspend for deopt
 257 
 258     _has_async_exception    = 0x00000001U, // there is a pending async exception
 259     _critical_native_unlock = 0x00000002U, // Must call back to unlock JNI critical lock
 260 
 261     _trace_flag             = 0x00000004U  // call tracing backend
 262   };
 263 
 264   // various suspension related flags - atomically updated
 265   // overloaded for async exception checking in check_special_condition_for_native_trans.
 266   volatile uint32_t _suspend_flags;
 267 
 268  private:
 269   int _num_nested_signal;
 270 
 271   DEBUG_ONLY(bool _suspendible_thread;)
 272 
 273  public:
 274   void enter_signal_handler() { _num_nested_signal++; }
 275   void leave_signal_handler() { _num_nested_signal--; }
 276   bool is_inside_signal_handler() const { return _num_nested_signal > 0; }
 277 
 278 #ifdef ASSERT
 279   void set_suspendible_thread() {
 280     _suspendible_thread = true;
 281   }
 282 
 283   void clear_suspendible_thread() {
 284     _suspendible_thread = false;
 285   }
 286 
 287   bool is_suspendible_thread() { return _suspendible_thread; }
 288 #endif
 289 
 290  private:
 291   // Active_handles points to a block of handles
 292   JNIHandleBlock* _active_handles;
 293 
 294   // One-element thread local free list
 295   JNIHandleBlock* _free_handle_block;
 296 
 297   // Point to the last handle mark
 298   HandleMark* _last_handle_mark;
 299 
 300   // The parity of the last strong_roots iteration in which this thread was
 301   // claimed as a task.
 302   int _oops_do_parity;
 303 
 304   // Support for GlobalCounter
 305  private:
 306   volatile uintx _rcu_counter;
 307  public:
 308   volatile uintx* get_rcu_counter() {
 309     return &_rcu_counter;
 310   }
 311 
 312  public:
 313   void set_last_handle_mark(HandleMark* mark)   { _last_handle_mark = mark; }
 314   HandleMark* last_handle_mark() const          { return _last_handle_mark; }
 315  private:
 316 
 317   // debug support for checking if code does allow safepoints or not
 318   // GC points in the VM can happen because of allocation, invoking a VM operation, or blocking on
 319   // mutex, or blocking on an object synchronizer (Java locking).
 320   // If !allow_safepoint(), then an assertion failure will happen in any of the above cases
 321   // If !allow_allocation(), then an assertion failure will happen during allocation
 322   // (Hence, !allow_safepoint() => !allow_allocation()).
 323   //
 324   // The two classes NoSafepointVerifier and No_Allocation_Verifier are used to set these counters.
 325   //
 326   NOT_PRODUCT(int _allow_safepoint_count;)      // If 0, thread allow a safepoint to happen
 327   debug_only(int _allow_allocation_count;)     // If 0, the thread is allowed to allocate oops.
 328 
 329   // Used by SkipGCALot class.
 330   NOT_PRODUCT(bool _skip_gcalot;)               // Should we elide gc-a-lot?
 331 
 332   friend class NoAllocVerifier;
 333   friend class NoSafepointVerifier;
 334   friend class PauseNoSafepointVerifier;
 335   friend class GCLocker;
 336 
 337   volatile void* _polling_page;                 // Thread local polling page
 338 
 339   ThreadLocalAllocBuffer _tlab;                 // Thread-local eden
 340   jlong _allocated_bytes;                       // Cumulative number of bytes allocated on
 341                                                 // the Java heap
 342   ThreadHeapSampler _heap_sampler;              // For use when sampling the memory.
 343 
 344   JFR_ONLY(DEFINE_THREAD_LOCAL_FIELD_JFR;)      // Thread-local data for jfr
 345 
 346   int   _vm_operation_started_count;            // VM_Operation support
 347   int   _vm_operation_completed_count;          // VM_Operation support
 348 
 349   ObjectMonitor* _current_pending_monitor;      // ObjectMonitor this thread
 350                                                 // is waiting to lock
 351   bool _current_pending_monitor_is_from_java;   // locking is from Java code
 352 
 353   // ObjectMonitor on which this thread called Object.wait()
 354   ObjectMonitor* _current_waiting_monitor;
 355 
 356   // Private thread-local objectmonitor list - a simple cache organized as a SLL.
 357  public:
 358   ObjectMonitor* omFreeList;
 359   int omFreeCount;                              // length of omFreeList
 360   int omFreeProvision;                          // reload chunk size
 361   ObjectMonitor* omInUseList;                   // SLL to track monitors in circulation
 362   int omInUseCount;                             // length of omInUseList
 363 
 364 #ifdef ASSERT
 365  private:
 366   bool _visited_for_critical_count;
 367 
 368  public:
 369   void set_visited_for_critical_count(bool z) { _visited_for_critical_count = z; }
 370   bool was_visited_for_critical_count() const   { return _visited_for_critical_count; }
 371 #endif
 372 
 373  public:
 374   enum {
 375     is_definitely_current_thread = true
 376   };
 377 
 378   // Constructor
 379   Thread();
 380   virtual ~Thread();
 381 
 382   // Manage Thread::current()
 383   void initialize_thread_current();
 384   void clear_thread_current(); // TLS cleanup needed before threads terminate
 385 
 386  public:
 387   // thread entry point
 388   virtual void run();
 389 
 390   // Testers
 391   virtual bool is_VM_thread()       const            { return false; }
 392   virtual bool is_Java_thread()     const            { return false; }
 393   virtual bool is_Compiler_thread() const            { return false; }
 394   virtual bool is_Code_cache_sweeper_thread() const  { return false; }
 395   virtual bool is_hidden_from_external_view() const  { return false; }
 396   virtual bool is_jvmti_agent_thread() const         { return false; }
 397   // True iff the thread can perform GC operations at a safepoint.
 398   // Generally will be true only of VM thread and parallel GC WorkGang
 399   // threads.
 400   virtual bool is_GC_task_thread() const             { return false; }
 401   virtual bool is_Watcher_thread() const             { return false; }
 402   virtual bool is_ConcurrentGC_thread() const        { return false; }
 403   virtual bool is_Named_thread() const               { return false; }
 404   virtual bool is_Worker_thread() const              { return false; }
 405 
 406   // Can this thread make Java upcalls
 407   virtual bool can_call_java() const                 { return false; }
 408 
 409   // Casts
 410   virtual WorkerThread* as_Worker_thread() const     { return NULL; }
 411 
 412   virtual char* name() const { return (char*)"Unknown thread"; }
 413 
 414   // Returns the current thread (ASSERTS if NULL)
 415   static inline Thread* current();
 416   // Returns the current thread, or NULL if not attached
 417   static inline Thread* current_or_null();
 418   // Returns the current thread, or NULL if not attached, and is
 419   // safe for use from signal-handlers
 420   static inline Thread* current_or_null_safe();
 421 
 422   // Common thread operations
 423 #ifdef ASSERT
 424   static void check_for_dangling_thread_pointer(Thread *thread);
 425 #endif
 426   static void set_priority(Thread* thread, ThreadPriority priority);
 427   static ThreadPriority get_priority(const Thread* const thread);
 428   static void start(Thread* thread);
 429   static void interrupt(Thread* thr);
 430   static bool is_interrupted(Thread* thr, bool clear_interrupted);
 431 
 432   void set_native_thread_name(const char *name) {
 433     assert(Thread::current() == this, "set_native_thread_name can only be called on the current thread");
 434     os::set_native_thread_name(name);
 435   }
 436 
 437   ObjectMonitor** omInUseList_addr()             { return (ObjectMonitor **)&omInUseList; }
 438   Monitor* SR_lock() const                       { return _SR_lock; }
 439 
 440   bool has_async_exception() const { return (_suspend_flags & _has_async_exception) != 0; }
 441 
 442   inline void set_suspend_flag(SuspendFlags f);
 443   inline void clear_suspend_flag(SuspendFlags f);
 444 
 445   inline void set_has_async_exception();
 446   inline void clear_has_async_exception();
 447 
 448   bool do_critical_native_unlock() const { return (_suspend_flags & _critical_native_unlock) != 0; }
 449 
 450   inline void set_critical_native_unlock();
 451   inline void clear_critical_native_unlock();
 452 
 453   inline void set_trace_flag();
 454   inline void clear_trace_flag();
 455 
 456   // Support for Unhandled Oop detection
 457   // Add the field for both, fastdebug and debug, builds to keep
 458   // Thread's fields layout the same.
 459   // Note: CHECK_UNHANDLED_OOPS is defined only for fastdebug build.
 460 #ifdef CHECK_UNHANDLED_OOPS
 461  private:
 462   UnhandledOops* _unhandled_oops;
 463 #elif defined(ASSERT)
 464  private:
 465   void* _unhandled_oops;
 466 #endif
 467 #ifdef CHECK_UNHANDLED_OOPS
 468  public:
 469   UnhandledOops* unhandled_oops() { return _unhandled_oops; }
 470   // Mark oop safe for gc.  It may be stack allocated but won't move.
 471   void allow_unhandled_oop(oop *op) {
 472     if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
 473   }
 474   // Clear oops at safepoint so crashes point to unhandled oop violator
 475   void clear_unhandled_oops() {
 476     if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
 477   }
 478 #endif // CHECK_UNHANDLED_OOPS
 479 
 480  public:
 481 #ifndef PRODUCT
 482   bool skip_gcalot()           { return _skip_gcalot; }
 483   void set_skip_gcalot(bool v) { _skip_gcalot = v;    }
 484 #endif
 485 
 486   // Installs a pending exception to be inserted later
 487   static void send_async_exception(oop thread_oop, oop java_throwable);
 488 
 489   // Resource area
 490   ResourceArea* resource_area() const            { return _resource_area; }
 491   void set_resource_area(ResourceArea* area)     { _resource_area = area; }
 492 
 493   OSThread* osthread() const                     { return _osthread;   }
 494   void set_osthread(OSThread* thread)            { _osthread = thread; }
 495 
 496   // JNI handle support
 497   JNIHandleBlock* active_handles() const         { return _active_handles; }
 498   void set_active_handles(JNIHandleBlock* block) { _active_handles = block; }
 499   JNIHandleBlock* free_handle_block() const      { return _free_handle_block; }
 500   void set_free_handle_block(JNIHandleBlock* block) { _free_handle_block = block; }
 501 
 502   // Internal handle support
 503   HandleArea* handle_area() const                { return _handle_area; }
 504   void set_handle_area(HandleArea* area)         { _handle_area = area; }
 505 
 506   GrowableArray<Metadata*>* metadata_handles() const          { return _metadata_handles; }
 507   void set_metadata_handles(GrowableArray<Metadata*>* handles){ _metadata_handles = handles; }
 508 
 509   // Thread-Local Allocation Buffer (TLAB) support
 510   ThreadLocalAllocBuffer& tlab()                 { return _tlab; }
 511   void initialize_tlab() {
 512     if (UseTLAB) {
 513       tlab().initialize();
 514     }
 515   }
 516 
 517   jlong allocated_bytes()               { return _allocated_bytes; }
 518   void set_allocated_bytes(jlong value) { _allocated_bytes = value; }
 519   void incr_allocated_bytes(jlong size) { _allocated_bytes += size; }
 520   inline jlong cooked_allocated_bytes();
 521 
 522   ThreadHeapSampler& heap_sampler()     { return _heap_sampler; }
 523 
 524   JFR_ONLY(DEFINE_THREAD_LOCAL_ACCESSOR_JFR;)
 525 
 526   bool is_trace_suspend()               { return (_suspend_flags & _trace_flag) != 0; }
 527 
 528   // VM operation support
 529   int vm_operation_ticket()                      { return ++_vm_operation_started_count; }
 530   int vm_operation_completed_count()             { return _vm_operation_completed_count; }
 531   void increment_vm_operation_completed_count()  { _vm_operation_completed_count++; }
 532 
 533   // For tracking the heavyweight monitor the thread is pending on.
 534   ObjectMonitor* current_pending_monitor() {
 535     return _current_pending_monitor;
 536   }
 537   void set_current_pending_monitor(ObjectMonitor* monitor) {
 538     _current_pending_monitor = monitor;
 539   }
 540   void set_current_pending_monitor_is_from_java(bool from_java) {
 541     _current_pending_monitor_is_from_java = from_java;
 542   }
 543   bool current_pending_monitor_is_from_java() {
 544     return _current_pending_monitor_is_from_java;
 545   }
 546 
 547   // For tracking the ObjectMonitor on which this thread called Object.wait()
 548   ObjectMonitor* current_waiting_monitor() {
 549     return _current_waiting_monitor;
 550   }
 551   void set_current_waiting_monitor(ObjectMonitor* monitor) {
 552     _current_waiting_monitor = monitor;
 553   }
 554 
 555   // GC support
 556   // Apply "f->do_oop" to all root oops in "this".
 557   //   Used by JavaThread::oops_do.
 558   // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
 559   virtual void oops_do(OopClosure* f, CodeBlobClosure* cf);
 560 
 561   // Handles the parallel case for the method below.
 562  private:
 563   bool claim_oops_do_par_case(int collection_parity);
 564  public:
 565   // Requires that "collection_parity" is that of the current roots
 566   // iteration.  If "is_par" is false, sets the parity of "this" to
 567   // "collection_parity", and returns "true".  If "is_par" is true,
 568   // uses an atomic instruction to set the current threads parity to
 569   // "collection_parity", if it is not already.  Returns "true" iff the
 570   // calling thread does the update, this indicates that the calling thread
 571   // has claimed the thread's stack as a root groop in the current
 572   // collection.
 573   bool claim_oops_do(bool is_par, int collection_parity) {
 574     if (!is_par) {
 575       _oops_do_parity = collection_parity;
 576       return true;
 577     } else {
 578       return claim_oops_do_par_case(collection_parity);
 579     }
 580   }
 581 
 582   // jvmtiRedefineClasses support
 583   void metadata_handles_do(void f(Metadata*));
 584 
 585   // Used by fast lock support
 586   virtual bool is_lock_owned(address adr) const;
 587 
 588   // Check if address is in the stack of the thread (not just for locks).
 589   // Warning: the method can only be used on the running thread
 590   bool is_in_stack(address adr) const;
 591   // Check if address is in the usable part of the stack (excludes protected
 592   // guard pages)
 593   bool is_in_usable_stack(address adr) const;
 594 
 595   // Sets this thread as starting thread. Returns failure if thread
 596   // creation fails due to lack of memory, too many threads etc.
 597   bool set_as_starting_thread();
 598 
 599 protected:
 600   // OS data associated with the thread
 601   OSThread* _osthread;  // Platform-specific thread information
 602 
 603   // Thread local resource area for temporary allocation within the VM
 604   ResourceArea* _resource_area;
 605 
 606   DEBUG_ONLY(ResourceMark* _current_resource_mark;)
 607 
 608   // Thread local handle area for allocation of handles within the VM
 609   HandleArea* _handle_area;
 610   GrowableArray<Metadata*>* _metadata_handles;
 611 
 612   // Support for stack overflow handling, get_thread, etc.
 613   address          _stack_base;
 614   size_t           _stack_size;
 615   uintptr_t        _self_raw_id;      // used by get_thread (mutable)
 616   int              _lgrp_id;
 617 
 618   volatile void** polling_page_addr() { return &_polling_page; }
 619 
 620  public:
 621   // Stack overflow support
 622   address stack_base() const           { assert(_stack_base != NULL,"Sanity check"); return _stack_base; }
 623   void    set_stack_base(address base) { _stack_base = base; }
 624   size_t  stack_size() const           { return _stack_size; }
 625   void    set_stack_size(size_t size)  { _stack_size = size; }
 626   address stack_end()  const           { return stack_base() - stack_size(); }
 627   void    record_stack_base_and_size();
 628 
 629   bool    on_local_stack(address adr) const {
 630     // QQQ this has knowledge of direction, ought to be a stack method
 631     return (_stack_base >= adr && adr >= stack_end());
 632   }
 633 
 634   uintptr_t self_raw_id()                    { return _self_raw_id; }
 635   void      set_self_raw_id(uintptr_t value) { _self_raw_id = value; }
 636 
 637   int     lgrp_id() const        { return _lgrp_id; }
 638   void    set_lgrp_id(int value) { _lgrp_id = value; }
 639 
 640   // Printing
 641   virtual void print_on(outputStream* st) const;
 642   void print() const { print_on(tty); }
 643   virtual void print_on_error(outputStream* st, char* buf, int buflen) const;
 644   void print_value_on(outputStream* st) const;
 645 
 646   // Debug-only code
 647 #ifdef ASSERT
 648  private:
 649   // Deadlock detection support for Mutex locks. List of locks own by thread.
 650   Monitor* _owned_locks;
 651   // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
 652   // thus the friendship
 653   friend class Mutex;
 654   friend class Monitor;
 655 
 656  public:
 657   void print_owned_locks_on(outputStream* st) const;
 658   void print_owned_locks() const                 { print_owned_locks_on(tty);    }
 659   Monitor* owned_locks() const                   { return _owned_locks;          }
 660   bool owns_locks() const                        { return owned_locks() != NULL; }
 661   bool owns_locks_but_compiled_lock() const;
 662   int oops_do_parity() const                     { return _oops_do_parity; }
 663 
 664   // Deadlock detection
 665   bool allow_allocation()                        { return _allow_allocation_count == 0; }
 666   ResourceMark* current_resource_mark()          { return _current_resource_mark; }
 667   void set_current_resource_mark(ResourceMark* rm) { _current_resource_mark = rm; }
 668 #endif
 669 
 670   void check_for_valid_safepoint_state(bool potential_vm_operation) PRODUCT_RETURN;
 671 
 672  private:
 673   volatile int _jvmti_env_iteration_count;
 674 
 675  public:
 676   void entering_jvmti_env_iteration()            { ++_jvmti_env_iteration_count; }
 677   void leaving_jvmti_env_iteration()             { --_jvmti_env_iteration_count; }
 678   bool is_inside_jvmti_env_iteration()           { return _jvmti_env_iteration_count > 0; }
 679 
 680   // Code generation
 681   static ByteSize exception_file_offset()        { return byte_offset_of(Thread, _exception_file); }
 682   static ByteSize exception_line_offset()        { return byte_offset_of(Thread, _exception_line); }
 683   static ByteSize active_handles_offset()        { return byte_offset_of(Thread, _active_handles); }
 684 
 685   static ByteSize stack_base_offset()            { return byte_offset_of(Thread, _stack_base); }
 686   static ByteSize stack_size_offset()            { return byte_offset_of(Thread, _stack_size); }
 687 
 688   static ByteSize polling_page_offset()          { return byte_offset_of(Thread, _polling_page); }
 689 
 690 #define TLAB_FIELD_OFFSET(name) \
 691   static ByteSize tlab_##name##_offset()         { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::name##_offset(); }
 692 
 693   TLAB_FIELD_OFFSET(start)
 694   TLAB_FIELD_OFFSET(end)
 695   TLAB_FIELD_OFFSET(top)
 696   TLAB_FIELD_OFFSET(pf_top)
 697   TLAB_FIELD_OFFSET(size)                   // desired_size
 698   TLAB_FIELD_OFFSET(refill_waste_limit)
 699   TLAB_FIELD_OFFSET(number_of_refills)
 700   TLAB_FIELD_OFFSET(fast_refill_waste)
 701   TLAB_FIELD_OFFSET(slow_allocations)
 702 
 703 #undef TLAB_FIELD_OFFSET
 704 
 705   static ByteSize allocated_bytes_offset()       { return byte_offset_of(Thread, _allocated_bytes); }
 706 
 707   JFR_ONLY(DEFINE_THREAD_LOCAL_OFFSET_JFR;)
 708 
 709  public:
 710   volatile intptr_t _Stalled;
 711   volatile int _TypeTag;
 712   ParkEvent * _ParkEvent;                     // for synchronized()
 713   ParkEvent * _SleepEvent;                    // for Thread.sleep
 714   ParkEvent * _MutexEvent;                    // for native internal Mutex/Monitor
 715   ParkEvent * _MuxEvent;                      // for low-level muxAcquire-muxRelease
 716   int NativeSyncRecursion;                    // diagnostic
 717 
 718   volatile int _OnTrap;                       // Resume-at IP delta
 719   jint _hashStateW;                           // Marsaglia Shift-XOR thread-local RNG
 720   jint _hashStateX;                           // thread-specific hashCode generator state
 721   jint _hashStateY;
 722   jint _hashStateZ;
 723   void * _schedctl;
 724 
 725 
 726   volatile jint rng[4];                      // RNG for spin loop
 727 
 728   // Low-level leaf-lock primitives used to implement synchronization
 729   // and native monitor-mutex infrastructure.
 730   // Not for general synchronization use.
 731   static void SpinAcquire(volatile int * Lock, const char * Name);
 732   static void SpinRelease(volatile int * Lock);
 733   static void muxAcquire(volatile intptr_t * Lock, const char * Name);
 734   static void muxAcquireW(volatile intptr_t * Lock, ParkEvent * ev);
 735   static void muxRelease(volatile intptr_t * Lock);
 736 };
 737 
 738 // Inline implementation of Thread::current()
 739 inline Thread* Thread::current() {
 740   Thread* current = current_or_null();
 741   assert(current != NULL, "Thread::current() called on detached thread");
 742   return current;
 743 }
 744 
 745 inline Thread* Thread::current_or_null() {
 746 #ifndef USE_LIBRARY_BASED_TLS_ONLY
 747   return _thr_current;
 748 #else
 749   if (ThreadLocalStorage::is_initialized()) {
 750     return ThreadLocalStorage::thread();
 751   }
 752   return NULL;
 753 #endif
 754 }
 755 
 756 inline Thread* Thread::current_or_null_safe() {
 757   if (ThreadLocalStorage::is_initialized()) {
 758     return ThreadLocalStorage::thread();
 759   }
 760   return NULL;
 761 }
 762 
 763 // Name support for threads.  non-JavaThread subclasses with multiple
 764 // uniquely named instances should derive from this.
 765 class NamedThread: public Thread {
 766   friend class VMStructs;
 767   enum {
 768     max_name_len = 64
 769   };
 770  private:
 771   char* _name;
 772   // log JavaThread being processed by oops_do
 773   JavaThread* _processed_thread;
 774   uint _gc_id; // The current GC id when a thread takes part in GC
 775 
 776  public:
 777   NamedThread();
 778   ~NamedThread();
 779   // May only be called once per thread.
 780   void set_name(const char* format, ...)  ATTRIBUTE_PRINTF(2, 3);
 781   void initialize_named_thread();
 782   virtual bool is_Named_thread() const { return true; }
 783   virtual char* name() const { return _name == NULL ? (char*)"Unknown Thread" : _name; }
 784   JavaThread *processed_thread() { return _processed_thread; }
 785   void set_processed_thread(JavaThread *thread) { _processed_thread = thread; }
 786   virtual void print_on(outputStream* st) const;
 787 
 788   void set_gc_id(uint gc_id) { _gc_id = gc_id; }
 789   uint gc_id() { return _gc_id; }
 790 };
 791 
 792 // Worker threads are named and have an id of an assigned work.
 793 class WorkerThread: public NamedThread {
 794  private:
 795   uint _id;
 796  public:
 797   WorkerThread() : _id(0)               { }
 798   virtual bool is_Worker_thread() const { return true; }
 799 
 800   virtual WorkerThread* as_Worker_thread() const {
 801     assert(is_Worker_thread(), "Dubious cast to WorkerThread*?");
 802     return (WorkerThread*) this;
 803   }
 804 
 805   void set_id(uint work_id)             { _id = work_id; }
 806   uint id() const                       { return _id; }
 807 };
 808 
 809 // A single WatcherThread is used for simulating timer interrupts.
 810 class WatcherThread: public Thread {
 811   friend class VMStructs;
 812  public:
 813   virtual void run();
 814 
 815  private:
 816   static WatcherThread* _watcher_thread;
 817 
 818   static bool _startable;
 819   // volatile due to at least one lock-free read
 820   volatile static bool _should_terminate;
 821  public:
 822   enum SomeConstants {
 823     delay_interval = 10                          // interrupt delay in milliseconds
 824   };
 825 
 826   // Constructor
 827   WatcherThread();
 828 
 829   // No destruction allowed
 830   ~WatcherThread() {
 831     guarantee(false, "WatcherThread deletion must fix the race with VM termination");
 832   }
 833 
 834   // Tester
 835   bool is_Watcher_thread() const                 { return true; }
 836 
 837   // Printing
 838   char* name() const { return (char*)"VM Periodic Task Thread"; }
 839   void print_on(outputStream* st) const;
 840   void unpark();
 841 
 842   // Returns the single instance of WatcherThread
 843   static WatcherThread* watcher_thread()         { return _watcher_thread; }
 844 
 845   // Create and start the single instance of WatcherThread, or stop it on shutdown
 846   static void start();
 847   static void stop();
 848   // Only allow start once the VM is sufficiently initialized
 849   // Otherwise the first task to enroll will trigger the start
 850   static void make_startable();
 851  private:
 852   int sleep() const;
 853 };
 854 
 855 
 856 class CompilerThread;
 857 
 858 typedef void (*ThreadFunction)(JavaThread*, TRAPS);
 859 
 860 class JavaThread: public Thread {
 861   friend class VMStructs;
 862   friend class JVMCIVMStructs;
 863   friend class WhiteBox;
 864  private:
 865   JavaThread*    _next;                          // The next thread in the Threads list
 866   bool           _on_thread_list;                // Is set when this JavaThread is added to the Threads list
 867   oop            _threadObj;                     // The Java level thread object
 868 
 869 #ifdef ASSERT
 870  private:
 871   int _java_call_counter;
 872 
 873  public:
 874   int  java_call_counter()                       { return _java_call_counter; }
 875   void inc_java_call_counter()                   { _java_call_counter++; }
 876   void dec_java_call_counter() {
 877     assert(_java_call_counter > 0, "Invalid nesting of JavaCallWrapper");
 878     _java_call_counter--;
 879   }
 880  private:  // restore original namespace restriction
 881 #endif  // ifdef ASSERT
 882 
 883 #ifndef PRODUCT
 884  public:
 885   enum {
 886     jump_ring_buffer_size = 16
 887   };
 888  private:  // restore original namespace restriction
 889 #endif
 890 
 891   JavaFrameAnchor _anchor;                       // Encapsulation of current java frame and it state
 892 
 893   ThreadFunction _entry_point;
 894 
 895   JNIEnv        _jni_environment;
 896 
 897   // Deopt support
 898   DeoptResourceMark*  _deopt_mark;               // Holds special ResourceMark for deoptimization
 899 
 900   intptr_t*      _must_deopt_id;                 // id of frame that needs to be deopted once we
 901                                                  // transition out of native
 902   CompiledMethod*       _deopt_nmethod;         // CompiledMethod that is currently being deoptimized
 903   vframeArray*  _vframe_array_head;              // Holds the heap of the active vframeArrays
 904   vframeArray*  _vframe_array_last;              // Holds last vFrameArray we popped
 905   // Because deoptimization is lazy we must save jvmti requests to set locals
 906   // in compiled frames until we deoptimize and we have an interpreter frame.
 907   // This holds the pointer to array (yeah like there might be more than one) of
 908   // description of compiled vframes that have locals that need to be updated.
 909   GrowableArray<jvmtiDeferredLocalVariableSet*>* _deferred_locals_updates;
 910 
 911   // Handshake value for fixing 6243940. We need a place for the i2c
 912   // adapter to store the callee Method*. This value is NEVER live
 913   // across a gc point so it does NOT have to be gc'd
 914   // The handshake is open ended since we can't be certain that it will
 915   // be NULLed. This is because we rarely ever see the race and end up
 916   // in handle_wrong_method which is the backend of the handshake. See
 917   // code in i2c adapters and handle_wrong_method.
 918 
 919   Method*       _callee_target;
 920 
 921   // Used to pass back results to the interpreter or generated code running Java code.
 922   oop           _vm_result;    // oop result is GC-preserved
 923   Metadata*     _vm_result_2;  // non-oop result
 924 
 925   // See ReduceInitialCardMarks: this holds the precise space interval of
 926   // the most recent slow path allocation for which compiled code has
 927   // elided card-marks for performance along the fast-path.
 928   MemRegion     _deferred_card_mark;
 929 
 930   MonitorChunk* _monitor_chunks;                 // Contains the off stack monitors
 931                                                  // allocated during deoptimization
 932                                                  // and by JNI_MonitorEnter/Exit
 933 
 934   // Async. requests support
 935   enum AsyncRequests {
 936     _no_async_condition = 0,
 937     _async_exception,
 938     _async_unsafe_access_error
 939   };
 940   AsyncRequests _special_runtime_exit_condition; // Enum indicating pending async. request
 941   oop           _pending_async_exception;
 942 
 943   // Safepoint support
 944  public:                                         // Expose _thread_state for SafeFetchInt()
 945   volatile JavaThreadState _thread_state;
 946  private:
 947   ThreadSafepointState *_safepoint_state;        // Holds information about a thread during a safepoint
 948   address               _saved_exception_pc;     // Saved pc of instruction where last implicit exception happened
 949 
 950   // JavaThread termination support
 951   enum TerminatedTypes {
 952     _not_terminated = 0xDEAD - 2,
 953     _thread_exiting,                             // JavaThread::exit() has been called for this thread
 954     _thread_terminated,                          // JavaThread is removed from thread list
 955     _vm_exited                                   // JavaThread is still executing native code, but VM is terminated
 956                                                  // only VM_Exit can set _vm_exited
 957   };
 958 
 959   // In general a JavaThread's _terminated field transitions as follows:
 960   //
 961   //   _not_terminated => _thread_exiting => _thread_terminated
 962   //
 963   // _vm_exited is a special value to cover the case of a JavaThread
 964   // executing native code after the VM itself is terminated.
 965   volatile TerminatedTypes _terminated;
 966   // suspend/resume support
 967   volatile bool         _suspend_equivalent;     // Suspend equivalent condition
 968   jint                  _in_deopt_handler;       // count of deoptimization
 969                                                  // handlers thread is in
 970   volatile bool         _doing_unsafe_access;    // Thread may fault due to unsafe access
 971   bool                  _do_not_unlock_if_synchronized;  // Do not unlock the receiver of a synchronized method (since it was
 972                                                          // never locked) when throwing an exception. Used by interpreter only.
 973 
 974   // JNI attach states:
 975   enum JNIAttachStates {
 976     _not_attaching_via_jni = 1,  // thread is not attaching via JNI
 977     _attaching_via_jni,          // thread is attaching via JNI
 978     _attached_via_jni            // thread has attached via JNI
 979   };
 980 
 981   // A regular JavaThread's _jni_attach_state is _not_attaching_via_jni.
 982   // A native thread that is attaching via JNI starts with a value
 983   // of _attaching_via_jni and transitions to _attached_via_jni.
 984   volatile JNIAttachStates _jni_attach_state;
 985 
 986  public:
 987   // State of the stack guard pages for this thread.
 988   enum StackGuardState {
 989     stack_guard_unused,         // not needed
 990     stack_guard_reserved_disabled,
 991     stack_guard_yellow_reserved_disabled,// disabled (temporarily) after stack overflow
 992     stack_guard_enabled         // enabled
 993   };
 994 
 995  private:
 996 
 997 #if INCLUDE_JVMCI
 998   // The _pending_* fields below are used to communicate extra information
 999   // from an uncommon trap in JVMCI compiled code to the uncommon trap handler.
1000 
1001   // Communicates the DeoptReason and DeoptAction of the uncommon trap
1002   int       _pending_deoptimization;
1003 
1004   // Specifies whether the uncommon trap is to bci 0 of a synchronized method
1005   // before the monitor has been acquired.
1006   bool      _pending_monitorenter;
1007 
1008   // Specifies if the DeoptReason for the last uncommon trap was Reason_transfer_to_interpreter
1009   bool      _pending_transfer_to_interpreter;
1010 
1011   // Guard for re-entrant call to JVMCIRuntime::adjust_comp_level
1012   bool      _adjusting_comp_level;
1013 
1014   // An object that JVMCI compiled code can use to further describe and
1015   // uniquely identify the  speculative optimization guarded by the uncommon trap
1016   oop       _pending_failed_speculation;
1017 
1018   // These fields are mutually exclusive in terms of live ranges.
1019   union {
1020     // Communicates the pc at which the most recent implicit exception occurred
1021     // from the signal handler to a deoptimization stub.
1022     address   _implicit_exception_pc;
1023 
1024     // Communicates an alternative call target to an i2c stub from a JavaCall .
1025     address   _alternate_call_target;
1026   } _jvmci;
1027 
1028   // Support for high precision, thread sensitive counters in JVMCI compiled code.
1029   jlong*    _jvmci_counters;
1030 
1031  public:
1032   static jlong* _jvmci_old_thread_counters;
1033   static void collect_counters(typeArrayOop array);
1034  private:
1035 #endif // INCLUDE_JVMCI
1036 
1037   StackGuardState  _stack_guard_state;
1038 
1039   // Precompute the limit of the stack as used in stack overflow checks.
1040   // We load it from here to simplify the stack overflow check in assembly.
1041   address          _stack_overflow_limit;
1042   address          _reserved_stack_activation;
1043 
1044   // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
1045   // used to temp. parsing values into and out of the runtime system during exception handling for compiled
1046   // code)
1047   volatile oop     _exception_oop;               // Exception thrown in compiled code
1048   volatile address _exception_pc;                // PC where exception happened
1049   volatile address _exception_handler_pc;        // PC for handler of exception
1050   volatile int     _is_method_handle_return;     // true (== 1) if the current exception PC is a MethodHandle call site.
1051 
1052  private:
1053   // support for JNI critical regions
1054   jint    _jni_active_critical;                  // count of entries into JNI critical region
1055 
1056   // Checked JNI: function name requires exception check
1057   char* _pending_jni_exception_check_fn;
1058 
1059   // For deadlock detection.
1060   int _depth_first_number;
1061 
1062   // JVMTI PopFrame support
1063   // This is set to popframe_pending to signal that top Java frame should be popped immediately
1064   int _popframe_condition;
1065 
1066   // If reallocation of scalar replaced objects fails, we throw OOM
1067   // and during exception propagation, pop the top
1068   // _frames_to_pop_failed_realloc frames, the ones that reference
1069   // failed reallocations.
1070   int _frames_to_pop_failed_realloc;
1071 
1072 #ifndef PRODUCT
1073   int _jmp_ring_index;
1074   struct {
1075     // We use intptr_t instead of address so debugger doesn't try and display strings
1076     intptr_t _target;
1077     intptr_t _instruction;
1078     const char*  _file;
1079     int _line;
1080   }   _jmp_ring[jump_ring_buffer_size];
1081 #endif // PRODUCT
1082 
1083   friend class VMThread;
1084   friend class ThreadWaitTransition;
1085   friend class VM_Exit;
1086 
1087   void initialize();                             // Initialized the instance variables
1088 
1089  public:
1090   // Constructor
1091   JavaThread(bool is_attaching_via_jni = false); // for main thread and JNI attached threads
1092   JavaThread(ThreadFunction entry_point, size_t stack_size = 0);
1093   ~JavaThread();
1094 
1095 #ifdef ASSERT
1096   // verify this JavaThread hasn't be published in the Threads::list yet
1097   void verify_not_published();
1098 #endif
1099 
1100   //JNI functiontable getter/setter for JVMTI jni function table interception API.
1101   void set_jni_functions(struct JNINativeInterface_* functionTable) {
1102     _jni_environment.functions = functionTable;
1103   }
1104   struct JNINativeInterface_* get_jni_functions() {
1105     return (struct JNINativeInterface_ *)_jni_environment.functions;
1106   }
1107 
1108   // This function is called at thread creation to allow
1109   // platform specific thread variables to be initialized.
1110   void cache_global_variables();
1111 
1112   // Executes Shutdown.shutdown()
1113   void invoke_shutdown_hooks();
1114 
1115   // Cleanup on thread exit
1116   enum ExitType {
1117     normal_exit,
1118     jni_detach
1119   };
1120   void exit(bool destroy_vm, ExitType exit_type = normal_exit);
1121 
1122   void cleanup_failed_attach_current_thread();
1123 
1124   // Testers
1125   virtual bool is_Java_thread() const            { return true;  }
1126   virtual bool can_call_java() const             { return true; }
1127 
1128   // Thread chain operations
1129   JavaThread* next() const                       { return _next; }
1130   void set_next(JavaThread* p)                   { _next = p; }
1131 
1132   // Thread oop. threadObj() can be NULL for initial JavaThread
1133   // (or for threads attached via JNI)
1134   oop threadObj() const                          { return _threadObj; }
1135   void set_threadObj(oop p)                      { _threadObj = p; }
1136 
1137   ThreadPriority java_priority() const;          // Read from threadObj()
1138 
1139   // Prepare thread and add to priority queue.  If a priority is
1140   // not specified, use the priority of the thread object. Threads_lock
1141   // must be held while this function is called.
1142   void prepare(jobject jni_thread, ThreadPriority prio=NoPriority);
1143 
1144   void set_saved_exception_pc(address pc)        { _saved_exception_pc = pc; }
1145   address saved_exception_pc()                   { return _saved_exception_pc; }
1146 
1147 
1148   ThreadFunction entry_point() const             { return _entry_point; }
1149 
1150   // Allocates a new Java level thread object for this thread. thread_name may be NULL.
1151   void allocate_threadObj(Handle thread_group, const char* thread_name, bool daemon, TRAPS);
1152 
1153   // Last frame anchor routines
1154 
1155   JavaFrameAnchor* frame_anchor(void)            { return &_anchor; }
1156 
1157   // last_Java_sp
1158   bool has_last_Java_frame() const               { return _anchor.has_last_Java_frame(); }
1159   intptr_t* last_Java_sp() const                 { return _anchor.last_Java_sp(); }
1160 
1161   // last_Java_pc
1162 
1163   address last_Java_pc(void)                     { return _anchor.last_Java_pc(); }
1164 
1165   // Safepoint support
1166 #if !(defined(PPC64) || defined(AARCH64))
1167   JavaThreadState thread_state() const           { return _thread_state; }
1168   void set_thread_state(JavaThreadState s)       { _thread_state = s;    }
1169 #else
1170   // Use membars when accessing volatile _thread_state. See
1171   // Threads::create_vm() for size checks.
1172   inline JavaThreadState thread_state() const;
1173   inline void set_thread_state(JavaThreadState s);
1174 #endif
1175   ThreadSafepointState *safepoint_state() const  { return _safepoint_state; }
1176   void set_safepoint_state(ThreadSafepointState *state) { _safepoint_state = state; }
1177   bool is_at_poll_safepoint()                    { return _safepoint_state->is_at_poll_safepoint(); }
1178 
1179   // JavaThread termination and lifecycle support:
1180   void smr_delete();
1181   bool on_thread_list() const { return _on_thread_list; }
1182   void set_on_thread_list() { _on_thread_list = true; }
1183 
1184   // thread has called JavaThread::exit() or is terminated
1185   bool is_exiting() const;
1186   // thread is terminated (no longer on the threads list); we compare
1187   // against the two non-terminated values so that a freed JavaThread
1188   // will also be considered terminated.
1189   bool check_is_terminated(TerminatedTypes l_terminated) const {
1190     return l_terminated != _not_terminated && l_terminated != _thread_exiting;
1191   }
1192   bool is_terminated() const;
1193   void set_terminated(TerminatedTypes t);
1194   // special for Threads::remove() which is static:
1195   void set_terminated_value();
1196   void block_if_vm_exited();
1197 
1198   bool doing_unsafe_access()                     { return _doing_unsafe_access; }
1199   void set_doing_unsafe_access(bool val)         { _doing_unsafe_access = val; }
1200 
1201   bool do_not_unlock_if_synchronized()             { return _do_not_unlock_if_synchronized; }
1202   void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }
1203 
1204   inline void set_polling_page(void* poll_value);
1205   inline volatile void* get_polling_page();
1206 
1207  private:
1208   // Support for thread handshake operations
1209   HandshakeState _handshake;
1210  public:
1211   void set_handshake_operation(HandshakeOperation* op) {
1212     _handshake.set_operation(this, op);
1213   }
1214 
1215   bool has_handshake() const {
1216     return _handshake.has_operation();
1217   }
1218 
1219   void cancel_handshake() {
1220     _handshake.cancel(this);
1221   }
1222 
1223   void handshake_process_by_self() {
1224     _handshake.process_by_self(this);
1225   }
1226 
1227   void handshake_process_by_vmthread() {
1228     _handshake.process_by_vmthread(this);
1229   }
1230 
1231   // Suspend/resume support for JavaThread
1232  private:
1233   inline void set_ext_suspended();
1234   inline void clear_ext_suspended();
1235 
1236  public:
1237   void java_suspend();
1238   void java_resume();
1239   int  java_suspend_self();
1240 
1241   void check_and_wait_while_suspended() {
1242     assert(JavaThread::current() == this, "sanity check");
1243 
1244     bool do_self_suspend;
1245     do {
1246       // were we externally suspended while we were waiting?
1247       do_self_suspend = handle_special_suspend_equivalent_condition();
1248       if (do_self_suspend) {
1249         // don't surprise the thread that suspended us by returning
1250         java_suspend_self();
1251         set_suspend_equivalent();
1252       }
1253     } while (do_self_suspend);
1254   }
1255   static void check_safepoint_and_suspend_for_native_trans(JavaThread *thread);
1256   // Check for async exception in addition to safepoint and suspend request.
1257   static void check_special_condition_for_native_trans(JavaThread *thread);
1258 
1259   // Same as check_special_condition_for_native_trans but finishes the
1260   // transition into thread_in_Java mode so that it can potentially
1261   // block.
1262   static void check_special_condition_for_native_trans_and_transition(JavaThread *thread);
1263 
1264   bool is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits);
1265   bool is_ext_suspend_completed_with_lock(uint32_t *bits) {
1266     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1267     // Warning: is_ext_suspend_completed() may temporarily drop the
1268     // SR_lock to allow the thread to reach a stable thread state if
1269     // it is currently in a transient thread state.
1270     return is_ext_suspend_completed(false /* !called_by_wait */,
1271                                     SuspendRetryDelay, bits);
1272   }
1273 
1274   // We cannot allow wait_for_ext_suspend_completion() to run forever or
1275   // we could hang. SuspendRetryCount and SuspendRetryDelay are normally
1276   // passed as the count and delay parameters. Experiments with specific
1277   // calls to wait_for_ext_suspend_completion() can be done by passing
1278   // other values in the code. Experiments with all calls can be done
1279   // via the appropriate -XX options.
1280   bool wait_for_ext_suspend_completion(int count, int delay, uint32_t *bits);
1281 
1282   // test for suspend - most (all?) of these should go away
1283   bool is_thread_fully_suspended(bool wait_for_suspend, uint32_t *bits);
1284 
1285   inline void set_external_suspend();
1286   inline void clear_external_suspend();
1287 
1288   inline void set_deopt_suspend();
1289   inline void clear_deopt_suspend();
1290   bool is_deopt_suspend()         { return (_suspend_flags & _deopt_suspend) != 0; }
1291 
1292   bool is_external_suspend() const {
1293     return (_suspend_flags & _external_suspend) != 0;
1294   }
1295   // Whenever a thread transitions from native to vm/java it must suspend
1296   // if external|deopt suspend is present.
1297   bool is_suspend_after_native() const {
1298     return (_suspend_flags & (_external_suspend | _deopt_suspend)) != 0;
1299   }
1300 
1301   // external suspend request is completed
1302   bool is_ext_suspended() const {
1303     return (_suspend_flags & _ext_suspended) != 0;
1304   }
1305 
1306   bool is_external_suspend_with_lock() const {
1307     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1308     return is_external_suspend();
1309   }
1310 
1311   // Special method to handle a pending external suspend request
1312   // when a suspend equivalent condition lifts.
1313   bool handle_special_suspend_equivalent_condition() {
1314     assert(is_suspend_equivalent(),
1315            "should only be called in a suspend equivalence condition");
1316     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1317     bool ret = is_external_suspend();
1318     if (!ret) {
1319       // not about to self-suspend so clear suspend equivalence
1320       clear_suspend_equivalent();
1321     }
1322     // implied else:
1323     // We have a pending external suspend request so we leave the
1324     // suspend_equivalent flag set until java_suspend_self() sets
1325     // the ext_suspended flag and clears the suspend_equivalent
1326     // flag. This insures that wait_for_ext_suspend_completion()
1327     // will return consistent values.
1328     return ret;
1329   }
1330 
1331   // utility methods to see if we are doing some kind of suspension
1332   bool is_being_ext_suspended() const            {
1333     MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
1334     return is_ext_suspended() || is_external_suspend();
1335   }
1336 
1337   bool is_suspend_equivalent() const             { return _suspend_equivalent; }
1338 
1339   void set_suspend_equivalent()                  { _suspend_equivalent = true; }
1340   void clear_suspend_equivalent()                { _suspend_equivalent = false; }
1341 
1342   // Thread.stop support
1343   void send_thread_stop(oop throwable);
1344   AsyncRequests clear_special_runtime_exit_condition() {
1345     AsyncRequests x = _special_runtime_exit_condition;
1346     _special_runtime_exit_condition = _no_async_condition;
1347     return x;
1348   }
1349 
1350   // Are any async conditions present?
1351   bool has_async_condition() { return (_special_runtime_exit_condition != _no_async_condition); }
1352 
1353   void check_and_handle_async_exceptions(bool check_unsafe_error = true);
1354 
1355   // these next two are also used for self-suspension and async exception support
1356   void handle_special_runtime_exit_condition(bool check_asyncs = true);
1357 
1358   // Return true if JavaThread has an asynchronous condition or
1359   // if external suspension is requested.
1360   bool has_special_runtime_exit_condition() {
1361     // Because we don't use is_external_suspend_with_lock
1362     // it is possible that we won't see an asynchronous external suspend
1363     // request that has just gotten started, i.e., SR_lock grabbed but
1364     // _external_suspend field change either not made yet or not visible
1365     // yet. However, this is okay because the request is asynchronous and
1366     // we will see the new flag value the next time through. It's also
1367     // possible that the external suspend request is dropped after
1368     // we have checked is_external_suspend(), we will recheck its value
1369     // under SR_lock in java_suspend_self().
1370     return (_special_runtime_exit_condition != _no_async_condition) ||
1371             is_external_suspend() || is_trace_suspend();
1372   }
1373 
1374   void set_pending_unsafe_access_error()          { _special_runtime_exit_condition = _async_unsafe_access_error; }
1375 
1376   inline void set_pending_async_exception(oop e);
1377 
1378   // Fast-locking support
1379   bool is_lock_owned(address adr) const;
1380 
1381   // Accessors for vframe array top
1382   // The linked list of vframe arrays are sorted on sp. This means when we
1383   // unpack the head must contain the vframe array to unpack.
1384   void set_vframe_array_head(vframeArray* value) { _vframe_array_head = value; }
1385   vframeArray* vframe_array_head() const         { return _vframe_array_head;  }
1386 
1387   // Side structure for deferring update of java frame locals until deopt occurs
1388   GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred_locals() const { return _deferred_locals_updates; }
1389   void set_deferred_locals(GrowableArray<jvmtiDeferredLocalVariableSet *>* vf) { _deferred_locals_updates = vf; }
1390 
1391   // These only really exist to make debugging deopt problems simpler
1392 
1393   void set_vframe_array_last(vframeArray* value) { _vframe_array_last = value; }
1394   vframeArray* vframe_array_last() const         { return _vframe_array_last;  }
1395 
1396   // The special resourceMark used during deoptimization
1397 
1398   void set_deopt_mark(DeoptResourceMark* value)  { _deopt_mark = value; }
1399   DeoptResourceMark* deopt_mark(void)            { return _deopt_mark; }
1400 
1401   intptr_t* must_deopt_id()                      { return _must_deopt_id; }
1402   void     set_must_deopt_id(intptr_t* id)       { _must_deopt_id = id; }
1403   void     clear_must_deopt_id()                 { _must_deopt_id = NULL; }
1404 
1405   void set_deopt_compiled_method(CompiledMethod* nm)  { _deopt_nmethod = nm; }
1406   CompiledMethod* deopt_compiled_method()        { return _deopt_nmethod; }
1407 
1408   Method*    callee_target() const               { return _callee_target; }
1409   void set_callee_target  (Method* x)          { _callee_target   = x; }
1410 
1411   // Oop results of vm runtime calls
1412   oop  vm_result() const                         { return _vm_result; }
1413   void set_vm_result  (oop x)                    { _vm_result   = x; }
1414 
1415   Metadata*    vm_result_2() const               { return _vm_result_2; }
1416   void set_vm_result_2  (Metadata* x)          { _vm_result_2   = x; }
1417 
1418   MemRegion deferred_card_mark() const           { return _deferred_card_mark; }
1419   void set_deferred_card_mark(MemRegion mr)      { _deferred_card_mark = mr;   }
1420 
1421 #if INCLUDE_JVMCI
1422   int  pending_deoptimization() const             { return _pending_deoptimization; }
1423   oop  pending_failed_speculation() const         { return _pending_failed_speculation; }
1424   bool adjusting_comp_level() const               { return _adjusting_comp_level; }
1425   void set_adjusting_comp_level(bool b)           { _adjusting_comp_level = b; }
1426   bool has_pending_monitorenter() const           { return _pending_monitorenter; }
1427   void set_pending_monitorenter(bool b)           { _pending_monitorenter = b; }
1428   void set_pending_deoptimization(int reason)     { _pending_deoptimization = reason; }
1429   void set_pending_failed_speculation(oop failed_speculation) { _pending_failed_speculation = failed_speculation; }
1430   void set_pending_transfer_to_interpreter(bool b) { _pending_transfer_to_interpreter = b; }
1431   void set_jvmci_alternate_call_target(address a) { assert(_jvmci._alternate_call_target == NULL, "must be"); _jvmci._alternate_call_target = a; }
1432   void set_jvmci_implicit_exception_pc(address a) { assert(_jvmci._implicit_exception_pc == NULL, "must be"); _jvmci._implicit_exception_pc = a; }
1433 #endif // INCLUDE_JVMCI
1434 
1435   // Exception handling for compiled methods
1436   oop      exception_oop() const                 { return _exception_oop; }
1437   address  exception_pc() const                  { return _exception_pc; }
1438   address  exception_handler_pc() const          { return _exception_handler_pc; }
1439   bool     is_method_handle_return() const       { return _is_method_handle_return == 1; }
1440 
1441   void set_exception_oop(oop o)                  { (void)const_cast<oop&>(_exception_oop = o); }
1442   void set_exception_pc(address a)               { _exception_pc = a; }
1443   void set_exception_handler_pc(address a)       { _exception_handler_pc = a; }
1444   void set_is_method_handle_return(bool value)   { _is_method_handle_return = value ? 1 : 0; }
1445 
1446   void clear_exception_oop_and_pc() {
1447     set_exception_oop(NULL);
1448     set_exception_pc(NULL);
1449   }
1450 
1451   // Stack overflow support
1452   //
1453   //  (small addresses)
1454   //
1455   //  --  <-- stack_end()                   ---
1456   //  |                                      |
1457   //  |  red pages                           |
1458   //  |                                      |
1459   //  --  <-- stack_red_zone_base()          |
1460   //  |                                      |
1461   //  |                                     guard
1462   //  |  yellow pages                       zone
1463   //  |                                      |
1464   //  |                                      |
1465   //  --  <-- stack_yellow_zone_base()       |
1466   //  |                                      |
1467   //  |                                      |
1468   //  |  reserved pages                      |
1469   //  |                                      |
1470   //  --  <-- stack_reserved_zone_base()    ---      ---
1471   //                                                 /|\  shadow     <--  stack_overflow_limit() (somewhere in here)
1472   //                                                  |   zone
1473   //                                                 \|/  size
1474   //  some untouched memory                          ---
1475   //
1476   //
1477   //  --
1478   //  |
1479   //  |  shadow zone
1480   //  |
1481   //  --
1482   //  x    frame n
1483   //  --
1484   //  x    frame n-1
1485   //  x
1486   //  --
1487   //  ...
1488   //
1489   //  --
1490   //  x    frame 0
1491   //  --  <-- stack_base()
1492   //
1493   //  (large addresses)
1494   //
1495 
1496  private:
1497   // These values are derived from flags StackRedPages, StackYellowPages,
1498   // StackReservedPages and StackShadowPages. The zone size is determined
1499   // ergonomically if page_size > 4K.
1500   static size_t _stack_red_zone_size;
1501   static size_t _stack_yellow_zone_size;
1502   static size_t _stack_reserved_zone_size;
1503   static size_t _stack_shadow_zone_size;
1504  public:
1505   inline size_t stack_available(address cur_sp);
1506 
1507   static size_t stack_red_zone_size() {
1508     assert(_stack_red_zone_size > 0, "Don't call this before the field is initialized.");
1509     return _stack_red_zone_size;
1510   }
1511   static void set_stack_red_zone_size(size_t s) {
1512     assert(is_aligned(s, os::vm_page_size()),
1513            "We can not protect if the red zone size is not page aligned.");
1514     assert(_stack_red_zone_size == 0, "This should be called only once.");
1515     _stack_red_zone_size = s;
1516   }
1517   address stack_red_zone_base() {
1518     return (address)(stack_end() + stack_red_zone_size());
1519   }
1520   bool in_stack_red_zone(address a) {
1521     return a <= stack_red_zone_base() && a >= stack_end();
1522   }
1523 
1524   static size_t stack_yellow_zone_size() {
1525     assert(_stack_yellow_zone_size > 0, "Don't call this before the field is initialized.");
1526     return _stack_yellow_zone_size;
1527   }
1528   static void set_stack_yellow_zone_size(size_t s) {
1529     assert(is_aligned(s, os::vm_page_size()),
1530            "We can not protect if the yellow zone size is not page aligned.");
1531     assert(_stack_yellow_zone_size == 0, "This should be called only once.");
1532     _stack_yellow_zone_size = s;
1533   }
1534 
1535   static size_t stack_reserved_zone_size() {
1536     // _stack_reserved_zone_size may be 0. This indicates the feature is off.
1537     return _stack_reserved_zone_size;
1538   }
1539   static void set_stack_reserved_zone_size(size_t s) {
1540     assert(is_aligned(s, os::vm_page_size()),
1541            "We can not protect if the reserved zone size is not page aligned.");
1542     assert(_stack_reserved_zone_size == 0, "This should be called only once.");
1543     _stack_reserved_zone_size = s;
1544   }
1545   address stack_reserved_zone_base() {
1546     return (address)(stack_end() +
1547                      (stack_red_zone_size() + stack_yellow_zone_size() + stack_reserved_zone_size()));
1548   }
1549   bool in_stack_reserved_zone(address a) {
1550     return (a <= stack_reserved_zone_base()) &&
1551            (a >= (address)((intptr_t)stack_reserved_zone_base() - stack_reserved_zone_size()));
1552   }
1553 
1554   static size_t stack_yellow_reserved_zone_size() {
1555     return _stack_yellow_zone_size + _stack_reserved_zone_size;
1556   }
1557   bool in_stack_yellow_reserved_zone(address a) {
1558     return (a <= stack_reserved_zone_base()) && (a >= stack_red_zone_base());
1559   }
1560 
1561   // Size of red + yellow + reserved zones.
1562   static size_t stack_guard_zone_size() {
1563     return stack_red_zone_size() + stack_yellow_reserved_zone_size();
1564   }
1565 
1566   static size_t stack_shadow_zone_size() {
1567     assert(_stack_shadow_zone_size > 0, "Don't call this before the field is initialized.");
1568     return _stack_shadow_zone_size;
1569   }
1570   static void set_stack_shadow_zone_size(size_t s) {
1571     // The shadow area is not allocated or protected, so
1572     // it needs not be page aligned.
1573     // But the stack bang currently assumes that it is a
1574     // multiple of page size. This guarantees that the bang
1575     // loop touches all pages in the shadow zone.
1576     // This can be guaranteed differently, as well.  E.g., if
1577     // the page size is a multiple of 4K, banging in 4K steps
1578     // suffices to touch all pages. (Some pages are banged
1579     // several times, though.)
1580     assert(is_aligned(s, os::vm_page_size()),
1581            "Stack bang assumes multiple of page size.");
1582     assert(_stack_shadow_zone_size == 0, "This should be called only once.");
1583     _stack_shadow_zone_size = s;
1584   }
1585 
1586   void create_stack_guard_pages();
1587   void remove_stack_guard_pages();
1588 
1589   void enable_stack_reserved_zone();
1590   void disable_stack_reserved_zone();
1591   void enable_stack_yellow_reserved_zone();
1592   void disable_stack_yellow_reserved_zone();
1593   void enable_stack_red_zone();
1594   void disable_stack_red_zone();
1595 
1596   inline bool stack_guard_zone_unused();
1597   inline bool stack_yellow_reserved_zone_disabled();
1598   inline bool stack_reserved_zone_disabled();
1599   inline bool stack_guards_enabled();
1600 
1601   address reserved_stack_activation() const { return _reserved_stack_activation; }
1602   void set_reserved_stack_activation(address addr) {
1603     assert(_reserved_stack_activation == stack_base()
1604             || _reserved_stack_activation == NULL
1605             || addr == stack_base(), "Must not be set twice");
1606     _reserved_stack_activation = addr;
1607   }
1608 
1609   // Attempt to reguard the stack after a stack overflow may have occurred.
1610   // Returns true if (a) guard pages are not needed on this thread, (b) the
1611   // pages are already guarded, or (c) the pages were successfully reguarded.
1612   // Returns false if there is not enough stack space to reguard the pages, in
1613   // which case the caller should unwind a frame and try again.  The argument
1614   // should be the caller's (approximate) sp.
1615   bool reguard_stack(address cur_sp);
1616   // Similar to above but see if current stackpoint is out of the guard area
1617   // and reguard if possible.
1618   bool reguard_stack(void);
1619 
1620   address stack_overflow_limit() { return _stack_overflow_limit; }
1621   void set_stack_overflow_limit() {
1622     _stack_overflow_limit =
1623       stack_end() + MAX2(JavaThread::stack_guard_zone_size(), JavaThread::stack_shadow_zone_size());
1624   }
1625 
1626   // Misc. accessors/mutators
1627   void set_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = true; }
1628   void clr_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = false; }
1629   bool do_not_unlock(void)                       { return _do_not_unlock_if_synchronized; }
1630 
1631 #ifndef PRODUCT
1632   void record_jump(address target, address instr, const char* file, int line);
1633 #endif // PRODUCT
1634 
1635   // For assembly stub generation
1636   static ByteSize threadObj_offset()             { return byte_offset_of(JavaThread, _threadObj); }
1637 #ifndef PRODUCT
1638   static ByteSize jmp_ring_index_offset()        { return byte_offset_of(JavaThread, _jmp_ring_index); }
1639   static ByteSize jmp_ring_offset()              { return byte_offset_of(JavaThread, _jmp_ring); }
1640 #endif // PRODUCT
1641   static ByteSize jni_environment_offset()       { return byte_offset_of(JavaThread, _jni_environment); }
1642   static ByteSize pending_jni_exception_check_fn_offset() {
1643     return byte_offset_of(JavaThread, _pending_jni_exception_check_fn);
1644   }
1645   static ByteSize last_Java_sp_offset() {
1646     return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_sp_offset();
1647   }
1648   static ByteSize last_Java_pc_offset() {
1649     return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_pc_offset();
1650   }
1651   static ByteSize frame_anchor_offset() {
1652     return byte_offset_of(JavaThread, _anchor);
1653   }
1654   static ByteSize callee_target_offset()         { return byte_offset_of(JavaThread, _callee_target); }
1655   static ByteSize vm_result_offset()             { return byte_offset_of(JavaThread, _vm_result); }
1656   static ByteSize vm_result_2_offset()           { return byte_offset_of(JavaThread, _vm_result_2); }
1657   static ByteSize thread_state_offset()          { return byte_offset_of(JavaThread, _thread_state); }
1658   static ByteSize saved_exception_pc_offset()    { return byte_offset_of(JavaThread, _saved_exception_pc); }
1659   static ByteSize osthread_offset()              { return byte_offset_of(JavaThread, _osthread); }
1660 #if INCLUDE_JVMCI
1661   static ByteSize pending_deoptimization_offset() { return byte_offset_of(JavaThread, _pending_deoptimization); }
1662   static ByteSize pending_monitorenter_offset()  { return byte_offset_of(JavaThread, _pending_monitorenter); }
1663   static ByteSize pending_failed_speculation_offset() { return byte_offset_of(JavaThread, _pending_failed_speculation); }
1664   static ByteSize jvmci_alternate_call_target_offset() { return byte_offset_of(JavaThread, _jvmci._alternate_call_target); }
1665   static ByteSize jvmci_implicit_exception_pc_offset() { return byte_offset_of(JavaThread, _jvmci._implicit_exception_pc); }
1666   static ByteSize jvmci_counters_offset()        { return byte_offset_of(JavaThread, _jvmci_counters); }
1667 #endif // INCLUDE_JVMCI
1668   static ByteSize exception_oop_offset()         { return byte_offset_of(JavaThread, _exception_oop); }
1669   static ByteSize exception_pc_offset()          { return byte_offset_of(JavaThread, _exception_pc); }
1670   static ByteSize exception_handler_pc_offset()  { return byte_offset_of(JavaThread, _exception_handler_pc); }
1671   static ByteSize stack_overflow_limit_offset()  { return byte_offset_of(JavaThread, _stack_overflow_limit); }
1672   static ByteSize is_method_handle_return_offset() { return byte_offset_of(JavaThread, _is_method_handle_return); }
1673   static ByteSize stack_guard_state_offset()     { return byte_offset_of(JavaThread, _stack_guard_state); }
1674   static ByteSize reserved_stack_activation_offset() { return byte_offset_of(JavaThread, _reserved_stack_activation); }
1675   static ByteSize suspend_flags_offset()         { return byte_offset_of(JavaThread, _suspend_flags); }
1676 
1677   static ByteSize do_not_unlock_if_synchronized_offset() { return byte_offset_of(JavaThread, _do_not_unlock_if_synchronized); }
1678   static ByteSize should_post_on_exceptions_flag_offset() {
1679     return byte_offset_of(JavaThread, _should_post_on_exceptions_flag);
1680   }
1681 
1682   // Returns the jni environment for this thread
1683   JNIEnv* jni_environment()                      { return &_jni_environment; }
1684 
1685   static JavaThread* thread_from_jni_environment(JNIEnv* env) {
1686     JavaThread *thread_from_jni_env = (JavaThread*)((intptr_t)env - in_bytes(jni_environment_offset()));
1687     // Only return NULL if thread is off the thread list; starting to
1688     // exit should not return NULL.
1689     if (thread_from_jni_env->is_terminated()) {
1690       thread_from_jni_env->block_if_vm_exited();
1691       return NULL;
1692     } else {
1693       return thread_from_jni_env;
1694     }
1695   }
1696 
1697   // JNI critical regions. These can nest.
1698   bool in_critical()    { return _jni_active_critical > 0; }
1699   bool in_last_critical()  { return _jni_active_critical == 1; }
1700   void enter_critical() {
1701     assert(Thread::current() == this ||
1702            (Thread::current()->is_VM_thread() &&
1703            SafepointSynchronize::is_synchronizing()),
1704            "this must be current thread or synchronizing");
1705     _jni_active_critical++;
1706   }
1707   void exit_critical() {
1708     assert(Thread::current() == this, "this must be current thread");
1709     _jni_active_critical--;
1710     assert(_jni_active_critical >= 0, "JNI critical nesting problem?");
1711   }
1712 
1713   // Checked JNI: is the programmer required to check for exceptions, if so specify
1714   // which function name. Returning to a Java frame should implicitly clear the
1715   // pending check, this is done for Native->Java transitions (i.e. user JNI code).
1716   // VM->Java transistions are not cleared, it is expected that JNI code enclosed
1717   // within ThreadToNativeFromVM makes proper exception checks (i.e. VM internal).
1718   bool is_pending_jni_exception_check() const { return _pending_jni_exception_check_fn != NULL; }
1719   void clear_pending_jni_exception_check() { _pending_jni_exception_check_fn = NULL; }
1720   const char* get_pending_jni_exception_check() const { return _pending_jni_exception_check_fn; }
1721   void set_pending_jni_exception_check(const char* fn_name) { _pending_jni_exception_check_fn = (char*) fn_name; }
1722 
1723   // For deadlock detection
1724   int depth_first_number() { return _depth_first_number; }
1725   void set_depth_first_number(int dfn) { _depth_first_number = dfn; }
1726 
1727  private:
1728   void set_monitor_chunks(MonitorChunk* monitor_chunks) { _monitor_chunks = monitor_chunks; }
1729 
1730  public:
1731   MonitorChunk* monitor_chunks() const           { return _monitor_chunks; }
1732   void add_monitor_chunk(MonitorChunk* chunk);
1733   void remove_monitor_chunk(MonitorChunk* chunk);
1734   bool in_deopt_handler() const                  { return _in_deopt_handler > 0; }
1735   void inc_in_deopt_handler()                    { _in_deopt_handler++; }
1736   void dec_in_deopt_handler() {
1737     assert(_in_deopt_handler > 0, "mismatched deopt nesting");
1738     if (_in_deopt_handler > 0) { // robustness
1739       _in_deopt_handler--;
1740     }
1741   }
1742 
1743  private:
1744   void set_entry_point(ThreadFunction entry_point) { _entry_point = entry_point; }
1745 
1746  public:
1747 
1748   // Frame iteration; calls the function f for all frames on the stack
1749   void frames_do(void f(frame*, const RegisterMap*));
1750 
1751   // Memory operations
1752   void oops_do(OopClosure* f, CodeBlobClosure* cf);
1753 
1754   // Sweeper operations
1755   virtual void nmethods_do(CodeBlobClosure* cf);
1756 
1757   // RedefineClasses Support
1758   void metadata_do(void f(Metadata*));
1759 
1760   // Misc. operations
1761   char* name() const { return (char*)get_thread_name(); }
1762   void print_on(outputStream* st) const;
1763   void print_value();
1764   void print_thread_state_on(outputStream*) const      PRODUCT_RETURN;
1765   void print_thread_state() const                      PRODUCT_RETURN;
1766   void print_on_error(outputStream* st, char* buf, int buflen) const;
1767   void print_name_on_error(outputStream* st, char* buf, int buflen) const;
1768   void verify();
1769   const char* get_thread_name() const;
1770  private:
1771   // factor out low-level mechanics for use in both normal and error cases
1772   const char* get_thread_name_string(char* buf = NULL, int buflen = 0) const;
1773  public:
1774   const char* get_threadgroup_name() const;
1775   const char* get_parent_name() const;
1776 
1777   // Accessing frames
1778   frame last_frame() {
1779     _anchor.make_walkable(this);
1780     return pd_last_frame();
1781   }
1782   javaVFrame* last_java_vframe(RegisterMap* reg_map);
1783 
1784   // Returns method at 'depth' java or native frames down the stack
1785   // Used for security checks
1786   Klass* security_get_caller_class(int depth);
1787 
1788   // Print stack trace in external format
1789   void print_stack_on(outputStream* st);
1790   void print_stack() { print_stack_on(tty); }
1791 
1792   // Print stack traces in various internal formats
1793   void trace_stack()                             PRODUCT_RETURN;
1794   void trace_stack_from(vframe* start_vf)        PRODUCT_RETURN;
1795   void trace_frames()                            PRODUCT_RETURN;
1796   void trace_oops()                              PRODUCT_RETURN;
1797 
1798   // Print an annotated view of the stack frames
1799   void print_frame_layout(int depth = 0, bool validate_only = false) NOT_DEBUG_RETURN;
1800   void validate_frame_layout() {
1801     print_frame_layout(0, true);
1802   }
1803 
1804   // Returns the number of stack frames on the stack
1805   int depth() const;
1806 
1807   // Function for testing deoptimization
1808   void deoptimize();
1809   void make_zombies();
1810 
1811   void deoptimized_wrt_marked_nmethods();
1812 
1813  public:
1814   // Returns the running thread as a JavaThread
1815   static inline JavaThread* current();
1816 
1817   // Returns the active Java thread.  Do not use this if you know you are calling
1818   // from a JavaThread, as it's slower than JavaThread::current.  If called from
1819   // the VMThread, it also returns the JavaThread that instigated the VMThread's
1820   // operation.  You may not want that either.
1821   static JavaThread* active();
1822 
1823   inline CompilerThread* as_CompilerThread();
1824 
1825  public:
1826   virtual void run();
1827   void thread_main_inner();
1828 
1829  private:
1830   // PRIVILEGED STACK
1831   PrivilegedElement*  _privileged_stack_top;
1832   GrowableArray<oop>* _array_for_gc;
1833  public:
1834 
1835   // Returns the privileged_stack information.
1836   PrivilegedElement* privileged_stack_top() const       { return _privileged_stack_top; }
1837   void set_privileged_stack_top(PrivilegedElement *e)   { _privileged_stack_top = e; }
1838   void register_array_for_gc(GrowableArray<oop>* array) { _array_for_gc = array; }
1839 
1840  public:
1841   // Thread local information maintained by JVMTI.
1842   void set_jvmti_thread_state(JvmtiThreadState *value)                           { _jvmti_thread_state = value; }
1843   // A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
1844   // getter is used to get this JavaThread's JvmtiThreadState if it has
1845   // one which means NULL can be returned. JvmtiThreadState::state_for()
1846   // is used to get the specified JavaThread's JvmtiThreadState if it has
1847   // one or it allocates a new JvmtiThreadState for the JavaThread and
1848   // returns it. JvmtiThreadState::state_for() will return NULL only if
1849   // the specified JavaThread is exiting.
1850   JvmtiThreadState *jvmti_thread_state() const                                   { return _jvmti_thread_state; }
1851   static ByteSize jvmti_thread_state_offset()                                    { return byte_offset_of(JavaThread, _jvmti_thread_state); }
1852   void set_jvmti_get_loaded_classes_closure(JvmtiGetLoadedClassesClosure* value) { _jvmti_get_loaded_classes_closure = value; }
1853   JvmtiGetLoadedClassesClosure* get_jvmti_get_loaded_classes_closure() const     { return _jvmti_get_loaded_classes_closure; }
1854 
1855   // JVMTI PopFrame support
1856   // Setting and clearing popframe_condition
1857   // All of these enumerated values are bits. popframe_pending
1858   // indicates that a PopFrame() has been requested and not yet been
1859   // completed. popframe_processing indicates that that PopFrame() is in
1860   // the process of being completed. popframe_force_deopt_reexecution_bit
1861   // indicates that special handling is required when returning to a
1862   // deoptimized caller.
1863   enum PopCondition {
1864     popframe_inactive                      = 0x00,
1865     popframe_pending_bit                   = 0x01,
1866     popframe_processing_bit                = 0x02,
1867     popframe_force_deopt_reexecution_bit   = 0x04
1868   };
1869   PopCondition popframe_condition()                   { return (PopCondition) _popframe_condition; }
1870   void set_popframe_condition(PopCondition c)         { _popframe_condition = c; }
1871   void set_popframe_condition_bit(PopCondition c)     { _popframe_condition |= c; }
1872   void clear_popframe_condition()                     { _popframe_condition = popframe_inactive; }
1873   static ByteSize popframe_condition_offset()         { return byte_offset_of(JavaThread, _popframe_condition); }
1874   bool has_pending_popframe()                         { return (popframe_condition() & popframe_pending_bit) != 0; }
1875   bool popframe_forcing_deopt_reexecution()           { return (popframe_condition() & popframe_force_deopt_reexecution_bit) != 0; }
1876   void clear_popframe_forcing_deopt_reexecution()     { _popframe_condition &= ~popframe_force_deopt_reexecution_bit; }
1877 #ifdef CC_INTERP
1878   bool pop_frame_pending(void)                        { return ((_popframe_condition & popframe_pending_bit) != 0); }
1879   void clr_pop_frame_pending(void)                    { _popframe_condition = popframe_inactive; }
1880   bool pop_frame_in_process(void)                     { return ((_popframe_condition & popframe_processing_bit) != 0); }
1881   void set_pop_frame_in_process(void)                 { _popframe_condition |= popframe_processing_bit; }
1882   void clr_pop_frame_in_process(void)                 { _popframe_condition &= ~popframe_processing_bit; }
1883 #endif
1884 
1885   int frames_to_pop_failed_realloc() const            { return _frames_to_pop_failed_realloc; }
1886   void set_frames_to_pop_failed_realloc(int nb)       { _frames_to_pop_failed_realloc = nb; }
1887   void dec_frames_to_pop_failed_realloc()             { _frames_to_pop_failed_realloc--; }
1888 
1889  private:
1890   // Saved incoming arguments to popped frame.
1891   // Used only when popped interpreted frame returns to deoptimized frame.
1892   void*    _popframe_preserved_args;
1893   int      _popframe_preserved_args_size;
1894 
1895  public:
1896   void  popframe_preserve_args(ByteSize size_in_bytes, void* start);
1897   void* popframe_preserved_args();
1898   ByteSize popframe_preserved_args_size();
1899   WordSize popframe_preserved_args_size_in_words();
1900   void  popframe_free_preserved_args();
1901 
1902 
1903  private:
1904   JvmtiThreadState *_jvmti_thread_state;
1905   JvmtiGetLoadedClassesClosure* _jvmti_get_loaded_classes_closure;
1906 
1907   // Used by the interpreter in fullspeed mode for frame pop, method
1908   // entry, method exit and single stepping support. This field is
1909   // only set to non-zero by the VM_EnterInterpOnlyMode VM operation.
1910   // It can be set to zero asynchronously (i.e., without a VM operation
1911   // or a lock) so we have to be very careful.
1912   int               _interp_only_mode;
1913 
1914  public:
1915   // used by the interpreter for fullspeed debugging support (see above)
1916   static ByteSize interp_only_mode_offset() { return byte_offset_of(JavaThread, _interp_only_mode); }
1917   bool is_interp_only_mode()                { return (_interp_only_mode != 0); }
1918   int get_interp_only_mode()                { return _interp_only_mode; }
1919   void increment_interp_only_mode()         { ++_interp_only_mode; }
1920   void decrement_interp_only_mode()         { --_interp_only_mode; }
1921 
1922   // support for cached flag that indicates whether exceptions need to be posted for this thread
1923   // if this is false, we can avoid deoptimizing when events are thrown
1924   // this gets set to reflect whether jvmtiExport::post_exception_throw would actually do anything
1925  private:
1926   int    _should_post_on_exceptions_flag;
1927 
1928  public:
1929   int   should_post_on_exceptions_flag()  { return _should_post_on_exceptions_flag; }
1930   void  set_should_post_on_exceptions_flag(int val)  { _should_post_on_exceptions_flag = val; }
1931 
1932  private:
1933   ThreadStatistics *_thread_stat;
1934 
1935  public:
1936   ThreadStatistics* get_thread_stat() const    { return _thread_stat; }
1937 
1938   // Return a blocker object for which this thread is blocked parking.
1939   oop current_park_blocker();
1940 
1941  private:
1942   static size_t _stack_size_at_create;
1943 
1944  public:
1945   static inline size_t stack_size_at_create(void) {
1946     return _stack_size_at_create;
1947   }
1948   static inline void set_stack_size_at_create(size_t value) {
1949     _stack_size_at_create = value;
1950   }
1951 
1952   // Machine dependent stuff
1953 #include OS_CPU_HEADER(thread)
1954 
1955  public:
1956   void set_blocked_on_compilation(bool value) {
1957     _blocked_on_compilation = value;
1958   }
1959 
1960   bool blocked_on_compilation() {
1961     return _blocked_on_compilation;
1962   }
1963  protected:
1964   bool         _blocked_on_compilation;
1965 
1966 
1967   // JSR166 per-thread parker
1968  private:
1969   Parker*    _parker;
1970  public:
1971   Parker*     parker() { return _parker; }
1972 
1973   // Biased locking support
1974  private:
1975   GrowableArray<MonitorInfo*>* _cached_monitor_info;
1976  public:
1977   GrowableArray<MonitorInfo*>* cached_monitor_info() { return _cached_monitor_info; }
1978   void set_cached_monitor_info(GrowableArray<MonitorInfo*>* info) { _cached_monitor_info = info; }
1979 
1980   // clearing/querying jni attach status
1981   bool is_attaching_via_jni() const { return _jni_attach_state == _attaching_via_jni; }
1982   bool has_attached_via_jni() const { return is_attaching_via_jni() || _jni_attach_state == _attached_via_jni; }
1983   inline void set_done_attaching_via_jni();
1984 };
1985 
1986 // Inline implementation of JavaThread::current
1987 inline JavaThread* JavaThread::current() {
1988   Thread* thread = Thread::current();
1989   assert(thread->is_Java_thread(), "just checking");
1990   return (JavaThread*)thread;
1991 }
1992 
1993 inline CompilerThread* JavaThread::as_CompilerThread() {
1994   assert(is_Compiler_thread(), "just checking");
1995   return (CompilerThread*)this;
1996 }
1997 
1998 // Dedicated thread to sweep the code cache
1999 class CodeCacheSweeperThread : public JavaThread {
2000   CompiledMethod*       _scanned_compiled_method; // nmethod being scanned by the sweeper
2001  public:
2002   CodeCacheSweeperThread();
2003   // Track the nmethod currently being scanned by the sweeper
2004   void set_scanned_compiled_method(CompiledMethod* cm) {
2005     assert(_scanned_compiled_method == NULL || cm == NULL, "should reset to NULL before writing a new value");
2006     _scanned_compiled_method = cm;
2007   }
2008 
2009   // Hide sweeper thread from external view.
2010   bool is_hidden_from_external_view() const { return true; }
2011 
2012   bool is_Code_cache_sweeper_thread() const { return true; }
2013 
2014   // Prevent GC from unloading _scanned_compiled_method
2015   void oops_do(OopClosure* f, CodeBlobClosure* cf);
2016   void nmethods_do(CodeBlobClosure* cf);
2017 };
2018 
2019 // A thread used for Compilation.
2020 class CompilerThread : public JavaThread {
2021   friend class VMStructs;
2022  private:
2023   CompilerCounters* _counters;
2024 
2025   ciEnv*                _env;
2026   CompileLog*           _log;
2027   CompileTask* volatile _task;  // print_threads_compiling can read this concurrently.
2028   CompileQueue*         _queue;
2029   BufferBlob*           _buffer_blob;
2030 
2031   AbstractCompiler*     _compiler;
2032   TimeStamp             _idle_time;
2033 
2034  public:
2035 
2036   static CompilerThread* current();
2037 
2038   CompilerThread(CompileQueue* queue, CompilerCounters* counters);
2039   ~CompilerThread();
2040 
2041   bool is_Compiler_thread() const                { return true; }
2042 
2043   virtual bool can_call_java() const;
2044 
2045   // Hide native compiler threads from external view.
2046   bool is_hidden_from_external_view() const      { return !can_call_java(); }
2047 
2048   void set_compiler(AbstractCompiler* c)         { _compiler = c; }
2049   AbstractCompiler* compiler() const             { return _compiler; }
2050 
2051   CompileQueue* queue()        const             { return _queue; }
2052   CompilerCounters* counters() const             { return _counters; }
2053 
2054   // Get/set the thread's compilation environment.
2055   ciEnv*        env()                            { return _env; }
2056   void          set_env(ciEnv* env)              { _env = env; }
2057 
2058   BufferBlob*   get_buffer_blob() const          { return _buffer_blob; }
2059   void          set_buffer_blob(BufferBlob* b)   { _buffer_blob = b; }
2060 
2061   // Get/set the thread's logging information
2062   CompileLog*   log()                            { return _log; }
2063   void          init_log(CompileLog* log) {
2064     // Set once, for good.
2065     assert(_log == NULL, "set only once");
2066     _log = log;
2067   }
2068 
2069   void start_idle_timer()                        { _idle_time.update(); }
2070   jlong idle_time_millis() {
2071     return TimeHelper::counter_to_millis(_idle_time.ticks_since_update());
2072   }
2073 
2074 #ifndef PRODUCT
2075  private:
2076   IdealGraphPrinter *_ideal_graph_printer;
2077  public:
2078   IdealGraphPrinter *ideal_graph_printer()           { return _ideal_graph_printer; }
2079   void set_ideal_graph_printer(IdealGraphPrinter *n) { _ideal_graph_printer = n; }
2080 #endif
2081 
2082   // Get/set the thread's current task
2083   CompileTask* task()                      { return _task; }
2084   void         set_task(CompileTask* task) { _task = task; }
2085 };
2086 
2087 inline CompilerThread* CompilerThread::current() {
2088   return JavaThread::current()->as_CompilerThread();
2089 }
2090 
2091 // The active thread queue. It also keeps track of the current used
2092 // thread priorities.
2093 class Threads: AllStatic {
2094   friend class VMStructs;
2095  private:
2096   static JavaThread* _thread_list;
2097   static int         _number_of_threads;
2098   static int         _number_of_non_daemon_threads;
2099   static int         _return_code;
2100   static int         _thread_claim_parity;
2101 #ifdef ASSERT
2102   static bool        _vm_complete;
2103 #endif
2104 
2105   static void initialize_java_lang_classes(JavaThread* main_thread, TRAPS);
2106   static void initialize_jsr292_core_classes(TRAPS);
2107 
2108  public:
2109   // Thread management
2110   // force_daemon is a concession to JNI, where we may need to add a
2111   // thread to the thread list before allocating its thread object
2112   static void add(JavaThread* p, bool force_daemon = false);
2113   static void remove(JavaThread* p);
2114   static void non_java_threads_do(ThreadClosure* tc);
2115   static void java_threads_do(ThreadClosure* tc);
2116   static void java_threads_and_vm_thread_do(ThreadClosure* tc);
2117   static void threads_do(ThreadClosure* tc);
2118   static void possibly_parallel_threads_do(bool is_par, ThreadClosure* tc);
2119 
2120   // Initializes the vm and creates the vm thread
2121   static jint create_vm(JavaVMInitArgs* args, bool* canTryAgain);
2122   static void convert_vm_init_libraries_to_agents();
2123   static void create_vm_init_libraries();
2124   static void create_vm_init_agents();
2125   static void shutdown_vm_agents();
2126   static bool destroy_vm();
2127   // Supported VM versions via JNI
2128   // Includes JNI_VERSION_1_1
2129   static jboolean is_supported_jni_version_including_1_1(jint version);
2130   // Does not include JNI_VERSION_1_1
2131   static jboolean is_supported_jni_version(jint version);
2132 
2133   // The "thread claim parity" provides a way for threads to be claimed
2134   // by parallel worker tasks.
2135   //
2136   // Each thread contains a a "parity" field. A task will claim the
2137   // thread only if its parity field is the same as the global parity,
2138   // which is updated by calling change_thread_claim_parity().
2139   //
2140   // For this to work change_thread_claim_parity() needs to be called
2141   // exactly once in sequential code before starting parallel tasks
2142   // that should claim threads.
2143   //
2144   // New threads get their parity set to 0 and change_thread_claim_parity()
2145   // never set the global parity to 0.
2146   static int thread_claim_parity() { return _thread_claim_parity; }
2147   static void change_thread_claim_parity();
2148   static void assert_all_threads_claimed() NOT_DEBUG_RETURN;
2149 
2150   // Apply "f->do_oop" to all root oops in all threads.
2151   // This version may only be called by sequential code.
2152   static void oops_do(OopClosure* f, CodeBlobClosure* cf);
2153   // This version may be called by sequential or parallel code.
2154   static void possibly_parallel_oops_do(bool is_par, OopClosure* f, CodeBlobClosure* cf);
2155 
2156   // Apply "f->do_oop" to roots in all threads that
2157   // are part of compiled frames
2158   static void compiled_frame_oops_do(OopClosure* f, CodeBlobClosure* cf);
2159 
2160   static void convert_hcode_pointers();
2161   static void restore_hcode_pointers();
2162 
2163   // Sweeper
2164   static void nmethods_do(CodeBlobClosure* cf);
2165 
2166   // RedefineClasses support
2167   static void metadata_do(void f(Metadata*));
2168   static void metadata_handles_do(void f(Metadata*));
2169 
2170 #ifdef ASSERT
2171   static bool is_vm_complete() { return _vm_complete; }
2172 #endif
2173 
2174   // Verification
2175   static void verify();
2176   static void print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks);
2177   static void print(bool print_stacks, bool internal_format) {
2178     // this function is only used by debug.cpp
2179     print_on(tty, print_stacks, internal_format, false /* no concurrent lock printed */);
2180   }
2181   static void print_on_error(outputStream* st, Thread* current, char* buf, int buflen);
2182   static void print_on_error(Thread* this_thread, outputStream* st, Thread* current, char* buf,
2183                              int buflen, bool* found_current);
2184   static void print_threads_compiling(outputStream* st, char* buf, int buflen);
2185 
2186   // Get Java threads that are waiting to enter a monitor.
2187   static GrowableArray<JavaThread*>* get_pending_threads(ThreadsList * t_list,
2188                                                          int count, address monitor);
2189 
2190   // Get owning Java thread from the monitor's owner field.
2191   static JavaThread *owning_thread_from_monitor_owner(ThreadsList * t_list,
2192                                                       address owner);
2193 
2194   // Number of threads on the active threads list
2195   static int number_of_threads()                 { return _number_of_threads; }
2196   // Number of non-daemon threads on the active threads list
2197   static int number_of_non_daemon_threads()      { return _number_of_non_daemon_threads; }
2198 
2199   // Deoptimizes all frames tied to marked nmethods
2200   static void deoptimized_wrt_marked_nmethods();
2201 };
2202 
2203 
2204 // Thread iterator
2205 class ThreadClosure: public StackObj {
2206  public:
2207   virtual void do_thread(Thread* thread) = 0;
2208 };
2209 
2210 class SignalHandlerMark: public StackObj {
2211  private:
2212   Thread* _thread;
2213  public:
2214   SignalHandlerMark(Thread* t) {
2215     _thread = t;
2216     if (_thread) _thread->enter_signal_handler();
2217   }
2218   ~SignalHandlerMark() {
2219     if (_thread) _thread->leave_signal_handler();
2220     _thread = NULL;
2221   }
2222 };
2223 
2224 
2225 #endif // SHARE_VM_RUNTIME_THREAD_HPP
--- EOF ---