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Java example source code file (thread.hpp)

This example Java source code file (thread.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

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assert, bytesize, compilerthread, growablearray, include_all_gcs, javathread, jni, null, objectmonitor, product, product_return, thread, tlab_field_offset, workerthread

The thread.hpp Java example source code

/*
 * Copyright (c) 1997, 2013, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 *
 */

#ifndef SHARE_VM_RUNTIME_THREAD_HPP
#define SHARE_VM_RUNTIME_THREAD_HPP

#include "memory/allocation.hpp"
#include "memory/threadLocalAllocBuffer.hpp"
#include "oops/oop.hpp"
#include "prims/jni.h"
#include "prims/jvmtiExport.hpp"
#include "runtime/frame.hpp"
#include "runtime/javaFrameAnchor.hpp"
#include "runtime/jniHandles.hpp"
#include "runtime/mutexLocker.hpp"
#include "runtime/os.hpp"
#include "runtime/osThread.hpp"
#include "runtime/park.hpp"
#include "runtime/safepoint.hpp"
#include "runtime/stubRoutines.hpp"
#include "runtime/threadLocalStorage.hpp"
#include "runtime/unhandledOops.hpp"
#include "utilities/macros.hpp"

#if INCLUDE_NMT
#include "services/memRecorder.hpp"
#endif // INCLUDE_NMT

#include "trace/traceBackend.hpp"
#include "trace/traceMacros.hpp"
#include "utilities/exceptions.hpp"
#include "utilities/top.hpp"
#if INCLUDE_ALL_GCS
#include "gc_implementation/g1/dirtyCardQueue.hpp"
#include "gc_implementation/g1/satbQueue.hpp"
#endif // INCLUDE_ALL_GCS
#ifdef ZERO
#ifdef TARGET_ARCH_zero
# include "stack_zero.hpp"
#endif
#endif

class ThreadSafepointState;
class ThreadProfiler;

class JvmtiThreadState;
class JvmtiGetLoadedClassesClosure;
class ThreadStatistics;
class ConcurrentLocksDump;
class ParkEvent;
class Parker;

class ciEnv;
class CompileThread;
class CompileLog;
class CompileTask;
class CompileQueue;
class CompilerCounters;
class vframeArray;

class DeoptResourceMark;
class jvmtiDeferredLocalVariableSet;

class GCTaskQueue;
class ThreadClosure;
class IdealGraphPrinter;

DEBUG_ONLY(class ResourceMark;)

class WorkerThread;

// Class hierarchy
// - Thread
//   - NamedThread
//     - VMThread
//     - ConcurrentGCThread
//     - WorkerThread
//       - GangWorker
//       - GCTaskThread
//   - JavaThread
//   - WatcherThread

class Thread: public ThreadShadow {
  friend class VMStructs;
 private:
  // Exception handling
  // (Note: _pending_exception and friends are in ThreadShadow)
  //oop       _pending_exception;                // pending exception for current thread
  // const char* _exception_file;                   // file information for exception (debugging only)
  // int         _exception_line;                   // line information for exception (debugging only)
 protected:
  // Support for forcing alignment of thread objects for biased locking
  void*       _real_malloc_address;
 public:
  void* operator new(size_t size) throw() { return allocate(size, true); }
  void* operator new(size_t size, const std::nothrow_t& nothrow_constant) throw() {
    return allocate(size, false); }
  void  operator delete(void* p);

 protected:
   static void* allocate(size_t size, bool throw_excpt, MEMFLAGS flags = mtThread);
 private:

  // ***************************************************************
  // Suspend and resume support
  // ***************************************************************
  //
  // VM suspend/resume no longer exists - it was once used for various
  // things including safepoints but was deprecated and finally removed
  // in Java 7. Because VM suspension was considered "internal" Java-level
  // suspension was considered "external", and this legacy naming scheme
  // remains.
  //
  // External suspend/resume requests come from JVM_SuspendThread,
  // JVM_ResumeThread, JVMTI SuspendThread, and finally JVMTI
  // ResumeThread. External
  // suspend requests cause _external_suspend to be set and external
  // resume requests cause _external_suspend to be cleared.
  // External suspend requests do not nest on top of other external
  // suspend requests. The higher level APIs reject suspend requests
  // for already suspended threads.
  //
  // The external_suspend
  // flag is checked by has_special_runtime_exit_condition() and java thread
  // will self-suspend when handle_special_runtime_exit_condition() is
  // called. Most uses of the _thread_blocked state in JavaThreads are
  // considered the same as being externally suspended; if the blocking
  // condition lifts, the JavaThread will self-suspend. Other places
  // where VM checks for external_suspend include:
  //   + mutex granting (do not enter monitors when thread is suspended)
  //   + state transitions from _thread_in_native
  //
  // In general, java_suspend() does not wait for an external suspend
  // request to complete. When it returns, the only guarantee is that
  // the _external_suspend field is true.
  //
  // wait_for_ext_suspend_completion() is used to wait for an external
  // suspend request to complete. External suspend requests are usually
  // followed by some other interface call that requires the thread to
  // be quiescent, e.g., GetCallTrace(). By moving the "wait time" into
  // the interface that requires quiescence, we give the JavaThread a
  // chance to self-suspend before we need it to be quiescent. This
  // improves overall suspend/query performance.
  //
  // _suspend_flags controls the behavior of java_ suspend/resume.
  // It must be set under the protection of SR_lock. Read from the flag is
  // OK without SR_lock as long as the value is only used as a hint.
  // (e.g., check _external_suspend first without lock and then recheck
  // inside SR_lock and finish the suspension)
  //
  // _suspend_flags is also overloaded for other "special conditions" so
  // that a single check indicates whether any special action is needed
  // eg. for async exceptions.
  // -------------------------------------------------------------------
  // Notes:
  // 1. The suspend/resume logic no longer uses ThreadState in OSThread
  // but we still update its value to keep other part of the system (mainly
  // JVMTI) happy. ThreadState is legacy code (see notes in
  // osThread.hpp).
  //
  // 2. It would be more natural if set_external_suspend() is private and
  // part of java_suspend(), but that probably would affect the suspend/query
  // performance. Need more investigation on this.
  //

  // suspend/resume lock: used for self-suspend
  Monitor* _SR_lock;

 protected:
  enum SuspendFlags {
    // NOTE: avoid using the sign-bit as cc generates different test code
    //       when the sign-bit is used, and sometimes incorrectly - see CR 6398077

    _external_suspend       = 0x20000000U, // thread is asked to self suspend
    _ext_suspended          = 0x40000000U, // thread has self-suspended
    _deopt_suspend          = 0x10000000U, // thread needs to self suspend for deopt

    _has_async_exception    = 0x00000001U, // there is a pending async exception
    _critical_native_unlock = 0x00000002U  // Must call back to unlock JNI critical lock
  };

  // various suspension related flags - atomically updated
  // overloaded for async exception checking in check_special_condition_for_native_trans.
  volatile uint32_t _suspend_flags;

 private:
  int _num_nested_signal;

 public:
  void enter_signal_handler() { _num_nested_signal++; }
  void leave_signal_handler() { _num_nested_signal--; }
  bool is_inside_signal_handler() const { return _num_nested_signal > 0; }

 private:
  // Debug tracing
  static void trace(const char* msg, const Thread* const thread) PRODUCT_RETURN;

  // Active_handles points to a block of handles
  JNIHandleBlock* _active_handles;

  // One-element thread local free list
  JNIHandleBlock* _free_handle_block;

  // Point to the last handle mark
  HandleMark* _last_handle_mark;

  // The parity of the last strong_roots iteration in which this thread was
  // claimed as a task.
  jint _oops_do_parity;

  public:
   void set_last_handle_mark(HandleMark* mark)   { _last_handle_mark = mark; }
   HandleMark* last_handle_mark() const          { return _last_handle_mark; }
  private:

  // debug support for checking if code does allow safepoints or not
  // GC points in the VM can happen because of allocation, invoking a VM operation, or blocking on
  // mutex, or blocking on an object synchronizer (Java locking).
  // If !allow_safepoint(), then an assertion failure will happen in any of the above cases
  // If !allow_allocation(), then an assertion failure will happen during allocation
  // (Hence, !allow_safepoint() => !allow_allocation()).
  //
  // The two classes No_Safepoint_Verifier and No_Allocation_Verifier are used to set these counters.
  //
  NOT_PRODUCT(int _allow_safepoint_count;)      // If 0, thread allow a safepoint to happen
  debug_only (int _allow_allocation_count;)     // If 0, the thread is allowed to allocate oops.

  // Used by SkipGCALot class.
  NOT_PRODUCT(bool _skip_gcalot;)               // Should we elide gc-a-lot?

  // Record when GC is locked out via the GC_locker mechanism
  CHECK_UNHANDLED_OOPS_ONLY(int _gc_locked_out_count;)

  friend class No_Alloc_Verifier;
  friend class No_Safepoint_Verifier;
  friend class Pause_No_Safepoint_Verifier;
  friend class ThreadLocalStorage;
  friend class GC_locker;

  ThreadLocalAllocBuffer _tlab;                 // Thread-local eden
  jlong _allocated_bytes;                       // Cumulative number of bytes allocated on
                                                // the Java heap

  TRACE_DATA _trace_data;                       // Thread-local data for tracing

  int   _vm_operation_started_count;            // VM_Operation support
  int   _vm_operation_completed_count;          // VM_Operation support

  ObjectMonitor* _current_pending_monitor;      // ObjectMonitor this thread
                                                // is waiting to lock
  bool _current_pending_monitor_is_from_java;   // locking is from Java code

  // ObjectMonitor on which this thread called Object.wait()
  ObjectMonitor* _current_waiting_monitor;

  // Private thread-local objectmonitor list - a simple cache organized as a SLL.
 public:
  ObjectMonitor* omFreeList;
  int omFreeCount;                              // length of omFreeList
  int omFreeProvision;                          // reload chunk size
  ObjectMonitor* omInUseList;                   // SLL to track monitors in circulation
  int omInUseCount;                             // length of omInUseList

#ifdef ASSERT
 private:
  bool _visited_for_critical_count;

 public:
  void set_visited_for_critical_count(bool z) { _visited_for_critical_count = z; }
  bool was_visited_for_critical_count() const   { return _visited_for_critical_count; }
#endif

 public:
  enum {
    is_definitely_current_thread = true
  };

  // Constructor
  Thread();
  virtual ~Thread();

  // initializtion
  void initialize_thread_local_storage();

  // thread entry point
  virtual void run();

  // Testers
  virtual bool is_VM_thread()       const            { return false; }
  virtual bool is_Java_thread()     const            { return false; }
  virtual bool is_Compiler_thread() const            { return false; }
  virtual bool is_hidden_from_external_view() const  { return false; }
  virtual bool is_jvmti_agent_thread() const         { return false; }
  // True iff the thread can perform GC operations at a safepoint.
  // Generally will be true only of VM thread and parallel GC WorkGang
  // threads.
  virtual bool is_GC_task_thread() const             { return false; }
  virtual bool is_Watcher_thread() const             { return false; }
  virtual bool is_ConcurrentGC_thread() const        { return false; }
  virtual bool is_Named_thread() const               { return false; }
  virtual bool is_Worker_thread() const              { return false; }

  // Casts
  virtual WorkerThread* as_Worker_thread() const     { return NULL; }

  virtual char* name() const { return (char*)"Unknown thread"; }

  // Returns the current thread
  static inline Thread* current();

  // Common thread operations
  static void set_priority(Thread* thread, ThreadPriority priority);
  static ThreadPriority get_priority(const Thread* const thread);
  static void start(Thread* thread);
  static void interrupt(Thread* thr);
  static bool is_interrupted(Thread* thr, bool clear_interrupted);

  void set_native_thread_name(const char *name) {
    assert(Thread::current() == this, "set_native_thread_name can only be called on the current thread");
    os::set_native_thread_name(name);
  }

  ObjectMonitor** omInUseList_addr()             { return (ObjectMonitor **)&omInUseList; }
  Monitor* SR_lock() const                       { return _SR_lock; }

  bool has_async_exception() const { return (_suspend_flags & _has_async_exception) != 0; }

  void set_suspend_flag(SuspendFlags f) {
    assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
    uint32_t flags;
    do {
      flags = _suspend_flags;
    }
    while (Atomic::cmpxchg((jint)(flags | f),
                           (volatile jint*)&_suspend_flags,
                           (jint)flags) != (jint)flags);
  }
  void clear_suspend_flag(SuspendFlags f) {
    assert(sizeof(jint) == sizeof(_suspend_flags), "size mismatch");
    uint32_t flags;
    do {
      flags = _suspend_flags;
    }
    while (Atomic::cmpxchg((jint)(flags & ~f),
                           (volatile jint*)&_suspend_flags,
                           (jint)flags) != (jint)flags);
  }

  void set_has_async_exception() {
    set_suspend_flag(_has_async_exception);
  }
  void clear_has_async_exception() {
    clear_suspend_flag(_has_async_exception);
  }

  bool do_critical_native_unlock() const { return (_suspend_flags & _critical_native_unlock) != 0; }

  void set_critical_native_unlock() {
    set_suspend_flag(_critical_native_unlock);
  }
  void clear_critical_native_unlock() {
    clear_suspend_flag(_critical_native_unlock);
  }

  // Support for Unhandled Oop detection
#ifdef CHECK_UNHANDLED_OOPS
 private:
  UnhandledOops* _unhandled_oops;
 public:
  UnhandledOops* unhandled_oops() { return _unhandled_oops; }
  // Mark oop safe for gc.  It may be stack allocated but won't move.
  void allow_unhandled_oop(oop *op) {
    if (CheckUnhandledOops) unhandled_oops()->allow_unhandled_oop(op);
  }
  // Clear oops at safepoint so crashes point to unhandled oop violator
  void clear_unhandled_oops() {
    if (CheckUnhandledOops) unhandled_oops()->clear_unhandled_oops();
  }
  bool is_gc_locked_out() { return _gc_locked_out_count > 0; }
#endif // CHECK_UNHANDLED_OOPS

#ifndef PRODUCT
  bool skip_gcalot()           { return _skip_gcalot; }
  void set_skip_gcalot(bool v) { _skip_gcalot = v;    }
#endif

 public:
  // Installs a pending exception to be inserted later
  static void send_async_exception(oop thread_oop, oop java_throwable);

  // Resource area
  ResourceArea* resource_area() const            { return _resource_area; }
  void set_resource_area(ResourceArea* area)     { _resource_area = area; }

  OSThread* osthread() const                     { return _osthread;   }
  void set_osthread(OSThread* thread)            { _osthread = thread; }

  // JNI handle support
  JNIHandleBlock* active_handles() const         { return _active_handles; }
  void set_active_handles(JNIHandleBlock* block) { _active_handles = block; }
  JNIHandleBlock* free_handle_block() const      { return _free_handle_block; }
  void set_free_handle_block(JNIHandleBlock* block) { _free_handle_block = block; }

  // Internal handle support
  HandleArea* handle_area() const                { return _handle_area; }
  void set_handle_area(HandleArea* area)         { _handle_area = area; }

  GrowableArray<Metadata*>* metadata_handles() const          { return _metadata_handles; }
  void set_metadata_handles(GrowableArray<Metadata*>* handles){ _metadata_handles = handles; }

  // Thread-Local Allocation Buffer (TLAB) support
  ThreadLocalAllocBuffer& tlab()                 { return _tlab; }
  void initialize_tlab() {
    if (UseTLAB) {
      tlab().initialize();
    }
  }

  jlong allocated_bytes()               { return _allocated_bytes; }
  void set_allocated_bytes(jlong value) { _allocated_bytes = value; }
  void incr_allocated_bytes(jlong size) { _allocated_bytes += size; }
  jlong cooked_allocated_bytes() {
    jlong allocated_bytes = OrderAccess::load_acquire(&_allocated_bytes);
    if (UseTLAB) {
      size_t used_bytes = tlab().used_bytes();
      if ((ssize_t)used_bytes > 0) {
        // More-or-less valid tlab.  The load_acquire above should ensure
        // that the result of the add is <= the instantaneous value
        return allocated_bytes + used_bytes;
      }
    }
    return allocated_bytes;
  }

  TRACE_DATA* trace_data()              { return &_trace_data; }

  // VM operation support
  int vm_operation_ticket()                      { return ++_vm_operation_started_count; }
  int vm_operation_completed_count()             { return _vm_operation_completed_count; }
  void increment_vm_operation_completed_count()  { _vm_operation_completed_count++; }

  // For tracking the heavyweight monitor the thread is pending on.
  ObjectMonitor* current_pending_monitor() {
    return _current_pending_monitor;
  }
  void set_current_pending_monitor(ObjectMonitor* monitor) {
    _current_pending_monitor = monitor;
  }
  void set_current_pending_monitor_is_from_java(bool from_java) {
    _current_pending_monitor_is_from_java = from_java;
  }
  bool current_pending_monitor_is_from_java() {
    return _current_pending_monitor_is_from_java;
  }

  // For tracking the ObjectMonitor on which this thread called Object.wait()
  ObjectMonitor* current_waiting_monitor() {
    return _current_waiting_monitor;
  }
  void set_current_waiting_monitor(ObjectMonitor* monitor) {
    _current_waiting_monitor = monitor;
  }

  // GC support
  // Apply "f->do_oop" to all root oops in "this".
  // Apply "cld_f->do_cld" to CLDs that are otherwise not kept alive.
  //   Used by JavaThread::oops_do.
  // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
  virtual void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);

  // Handles the parallel case for the method below.
private:
  bool claim_oops_do_par_case(int collection_parity);
public:
  // Requires that "collection_parity" is that of the current strong roots
  // iteration.  If "is_par" is false, sets the parity of "this" to
  // "collection_parity", and returns "true".  If "is_par" is true,
  // uses an atomic instruction to set the current threads parity to
  // "collection_parity", if it is not already.  Returns "true" iff the
  // calling thread does the update, this indicates that the calling thread
  // has claimed the thread's stack as a root groop in the current
  // collection.
  bool claim_oops_do(bool is_par, int collection_parity) {
    if (!is_par) {
      _oops_do_parity = collection_parity;
      return true;
    } else {
      return claim_oops_do_par_case(collection_parity);
    }
  }

  // Sweeper support
  void nmethods_do(CodeBlobClosure* cf);

  // jvmtiRedefineClasses support
  void metadata_do(void f(Metadata*));

  // Used by fast lock support
  virtual bool is_lock_owned(address adr) const;

  // Check if address is in the stack of the thread (not just for locks).
  // Warning: the method can only be used on the running thread
  bool is_in_stack(address adr) const;
  // Check if address is in the usable part of the stack (excludes protected
  // guard pages)
  bool is_in_usable_stack(address adr) const;

  // Sets this thread as starting thread. Returns failure if thread
  // creation fails due to lack of memory, too many threads etc.
  bool set_as_starting_thread();

 protected:
  // OS data associated with the thread
  OSThread* _osthread;  // Platform-specific thread information

  // Thread local resource area for temporary allocation within the VM
  ResourceArea* _resource_area;

  DEBUG_ONLY(ResourceMark* _current_resource_mark;)

  // Thread local handle area for allocation of handles within the VM
  HandleArea* _handle_area;
  GrowableArray<Metadata*>* _metadata_handles;

  // Support for stack overflow handling, get_thread, etc.
  address          _stack_base;
  size_t           _stack_size;
  uintptr_t        _self_raw_id;      // used by get_thread (mutable)
  int              _lgrp_id;

 public:
  // Stack overflow support
  address stack_base() const           { assert(_stack_base != NULL,"Sanity check"); return _stack_base; }

  void    set_stack_base(address base) { _stack_base = base; }
  size_t  stack_size() const           { return _stack_size; }
  void    set_stack_size(size_t size)  { _stack_size = size; }
  void    record_stack_base_and_size();

  bool    on_local_stack(address adr) const {
    /* QQQ this has knowledge of direction, ought to be a stack method */
    return (_stack_base >= adr && adr >= (_stack_base - _stack_size));
  }

  uintptr_t self_raw_id()                    { return _self_raw_id; }
  void      set_self_raw_id(uintptr_t value) { _self_raw_id = value; }

  int     lgrp_id() const        { return _lgrp_id; }
  void    set_lgrp_id(int value) { _lgrp_id = value; }

  // Printing
  void print_on(outputStream* st) const;
  void print() const { print_on(tty); }
  virtual void print_on_error(outputStream* st, char* buf, int buflen) const;

  // Debug-only code
#ifdef ASSERT
 private:
  // Deadlock detection support for Mutex locks. List of locks own by thread.
  Monitor* _owned_locks;
  // Mutex::set_owner_implementation is the only place where _owned_locks is modified,
  // thus the friendship
  friend class Mutex;
  friend class Monitor;

 public:
  void print_owned_locks_on(outputStream* st) const;
  void print_owned_locks() const                 { print_owned_locks_on(tty);    }
  Monitor* owned_locks() const                   { return _owned_locks;          }
  bool owns_locks() const                        { return owned_locks() != NULL; }
  bool owns_locks_but_compiled_lock() const;

  // Deadlock detection
  bool allow_allocation()                        { return _allow_allocation_count == 0; }
  ResourceMark* current_resource_mark()          { return _current_resource_mark; }
  void set_current_resource_mark(ResourceMark* rm) { _current_resource_mark = rm; }
#endif

  void check_for_valid_safepoint_state(bool potential_vm_operation) PRODUCT_RETURN;

 private:
  volatile int _jvmti_env_iteration_count;

 public:
  void entering_jvmti_env_iteration()            { ++_jvmti_env_iteration_count; }
  void leaving_jvmti_env_iteration()             { --_jvmti_env_iteration_count; }
  bool is_inside_jvmti_env_iteration()           { return _jvmti_env_iteration_count > 0; }

  // Code generation
  static ByteSize exception_file_offset()        { return byte_offset_of(Thread, _exception_file   ); }
  static ByteSize exception_line_offset()        { return byte_offset_of(Thread, _exception_line   ); }
  static ByteSize active_handles_offset()        { return byte_offset_of(Thread, _active_handles   ); }

  static ByteSize stack_base_offset()            { return byte_offset_of(Thread, _stack_base ); }
  static ByteSize stack_size_offset()            { return byte_offset_of(Thread, _stack_size ); }

#define TLAB_FIELD_OFFSET(name) \
  static ByteSize tlab_##name##_offset()         { return byte_offset_of(Thread, _tlab) + ThreadLocalAllocBuffer::name##_offset(); }

  TLAB_FIELD_OFFSET(start)
  TLAB_FIELD_OFFSET(end)
  TLAB_FIELD_OFFSET(top)
  TLAB_FIELD_OFFSET(pf_top)
  TLAB_FIELD_OFFSET(size)                   // desired_size
  TLAB_FIELD_OFFSET(refill_waste_limit)
  TLAB_FIELD_OFFSET(number_of_refills)
  TLAB_FIELD_OFFSET(fast_refill_waste)
  TLAB_FIELD_OFFSET(slow_allocations)

#undef TLAB_FIELD_OFFSET

  static ByteSize allocated_bytes_offset()       { return byte_offset_of(Thread, _allocated_bytes ); }

 public:
  volatile intptr_t _Stalled ;
  volatile int _TypeTag ;
  ParkEvent * _ParkEvent ;                     // for synchronized()
  ParkEvent * _SleepEvent ;                    // for Thread.sleep
  ParkEvent * _MutexEvent ;                    // for native internal Mutex/Monitor
  ParkEvent * _MuxEvent ;                      // for low-level muxAcquire-muxRelease
  int NativeSyncRecursion ;                    // diagnostic

  volatile int _OnTrap ;                       // Resume-at IP delta
  jint _hashStateW ;                           // Marsaglia Shift-XOR thread-local RNG
  jint _hashStateX ;                           // thread-specific hashCode generator state
  jint _hashStateY ;
  jint _hashStateZ ;
  void * _schedctl ;


  volatile jint rng [4] ;                      // RNG for spin loop

  // Low-level leaf-lock primitives used to implement synchronization
  // and native monitor-mutex infrastructure.
  // Not for general synchronization use.
  static void SpinAcquire (volatile int * Lock, const char * Name) ;
  static void SpinRelease (volatile int * Lock) ;
  static void muxAcquire  (volatile intptr_t * Lock, const char * Name) ;
  static void muxAcquireW (volatile intptr_t * Lock, ParkEvent * ev) ;
  static void muxRelease  (volatile intptr_t * Lock) ;
};

// Inline implementation of Thread::current()
// Thread::current is "hot" it's called > 128K times in the 1st 500 msecs of
// startup.
// ThreadLocalStorage::thread is warm -- it's called > 16K times in the same
// period.   This is inlined in thread_<os_family>.inline.hpp.

inline Thread* Thread::current() {
#ifdef ASSERT
// This function is very high traffic. Define PARANOID to enable expensive
// asserts.
#ifdef PARANOID
  // Signal handler should call ThreadLocalStorage::get_thread_slow()
  Thread* t = ThreadLocalStorage::get_thread_slow();
  assert(t != NULL && !t->is_inside_signal_handler(),
         "Don't use Thread::current() inside signal handler");
#endif
#endif
  Thread* thread = ThreadLocalStorage::thread();
  assert(thread != NULL, "just checking");
  return thread;
}

// Name support for threads.  non-JavaThread subclasses with multiple
// uniquely named instances should derive from this.
class NamedThread: public Thread {
  friend class VMStructs;
  enum {
    max_name_len = 64
  };
 private:
  char* _name;
  // log JavaThread being processed by oops_do
  JavaThread* _processed_thread;

 public:
  NamedThread();
  ~NamedThread();
  // May only be called once per thread.
  void set_name(const char* format, ...);
  virtual bool is_Named_thread() const { return true; }
  virtual char* name() const { return _name == NULL ? (char*)"Unknown Thread" : _name; }
  JavaThread *processed_thread() { return _processed_thread; }
  void set_processed_thread(JavaThread *thread) { _processed_thread = thread; }
};

// Worker threads are named and have an id of an assigned work.
class WorkerThread: public NamedThread {
private:
  uint _id;
public:
  WorkerThread() : _id(0)               { }
  virtual bool is_Worker_thread() const { return true; }

  virtual WorkerThread* as_Worker_thread() const {
    assert(is_Worker_thread(), "Dubious cast to WorkerThread*?");
    return (WorkerThread*) this;
  }

  void set_id(uint work_id)             { _id = work_id; }
  uint id() const                       { return _id; }
};

// A single WatcherThread is used for simulating timer interrupts.
class WatcherThread: public Thread {
  friend class VMStructs;
 public:
  virtual void run();

 private:
  static WatcherThread* _watcher_thread;

  static bool _startable;
  volatile static bool _should_terminate; // updated without holding lock

  os::WatcherThreadCrashProtection* _crash_protection;
 public:
  enum SomeConstants {
    delay_interval = 10                          // interrupt delay in milliseconds
  };

  // Constructor
  WatcherThread();

  // Tester
  bool is_Watcher_thread() const                 { return true; }

  // Printing
  char* name() const { return (char*)"VM Periodic Task Thread"; }
  void print_on(outputStream* st) const;
  void print() const { print_on(tty); }
  void unpark();

  // Returns the single instance of WatcherThread
  static WatcherThread* watcher_thread()         { return _watcher_thread; }

  // Create and start the single instance of WatcherThread, or stop it on shutdown
  static void start();
  static void stop();
  // Only allow start once the VM is sufficiently initialized
  // Otherwise the first task to enroll will trigger the start
  static void make_startable();

  void set_crash_protection(os::WatcherThreadCrashProtection* crash_protection) {
    assert(Thread::current()->is_Watcher_thread(), "Can only be set by WatcherThread");
    _crash_protection = crash_protection;
  }

  bool has_crash_protection() const { return _crash_protection != NULL; }
  os::WatcherThreadCrashProtection* crash_protection() const { return _crash_protection; }

 private:
  int sleep() const;
};


class CompilerThread;

typedef void (*ThreadFunction)(JavaThread*, TRAPS);

class JavaThread: public Thread {
  friend class VMStructs;
 private:
  JavaThread*    _next;                          // The next thread in the Threads list
  oop            _threadObj;                     // The Java level thread object

#ifdef ASSERT
 private:
  int _java_call_counter;

 public:
  int  java_call_counter()                       { return _java_call_counter; }
  void inc_java_call_counter()                   { _java_call_counter++; }
  void dec_java_call_counter() {
    assert(_java_call_counter > 0, "Invalid nesting of JavaCallWrapper");
    _java_call_counter--;
  }
 private:  // restore original namespace restriction
#endif  // ifdef ASSERT

#ifndef PRODUCT
 public:
  enum {
    jump_ring_buffer_size = 16
  };
 private:  // restore original namespace restriction
#endif

  JavaFrameAnchor _anchor;                       // Encapsulation of current java frame and it state

  ThreadFunction _entry_point;

  JNIEnv        _jni_environment;

  // Deopt support
  DeoptResourceMark*  _deopt_mark;               // Holds special ResourceMark for deoptimization

  intptr_t*      _must_deopt_id;                 // id of frame that needs to be deopted once we
                                                 // transition out of native
  nmethod*       _deopt_nmethod;                 // nmethod that is currently being deoptimized
  vframeArray*  _vframe_array_head;              // Holds the heap of the active vframeArrays
  vframeArray*  _vframe_array_last;              // Holds last vFrameArray we popped
  // Because deoptimization is lazy we must save jvmti requests to set locals
  // in compiled frames until we deoptimize and we have an interpreter frame.
  // This holds the pointer to array (yeah like there might be more than one) of
  // description of compiled vframes that have locals that need to be updated.
  GrowableArray<jvmtiDeferredLocalVariableSet*>* _deferred_locals_updates;

  // Handshake value for fixing 6243940. We need a place for the i2c
  // adapter to store the callee Method*. This value is NEVER live
  // across a gc point so it does NOT have to be gc'd
  // The handshake is open ended since we can't be certain that it will
  // be NULLed. This is because we rarely ever see the race and end up
  // in handle_wrong_method which is the backend of the handshake. See
  // code in i2c adapters and handle_wrong_method.

  Method*       _callee_target;

  // Used to pass back results to the interpreter or generated code running Java code.
  oop           _vm_result;    // oop result is GC-preserved
  Metadata*     _vm_result_2;  // non-oop result

  // See ReduceInitialCardMarks: this holds the precise space interval of
  // the most recent slow path allocation for which compiled code has
  // elided card-marks for performance along the fast-path.
  MemRegion     _deferred_card_mark;

  MonitorChunk* _monitor_chunks;                 // Contains the off stack monitors
                                                 // allocated during deoptimization
                                                 // and by JNI_MonitorEnter/Exit

  // Async. requests support
  enum AsyncRequests {
    _no_async_condition = 0,
    _async_exception,
    _async_unsafe_access_error
  };
  AsyncRequests _special_runtime_exit_condition; // Enum indicating pending async. request
  oop           _pending_async_exception;

  // Safepoint support
 public:                                         // Expose _thread_state for SafeFetchInt()
  volatile JavaThreadState _thread_state;
 private:
  ThreadSafepointState *_safepoint_state;        // Holds information about a thread during a safepoint
  address               _saved_exception_pc;     // Saved pc of instruction where last implicit exception happened

  // JavaThread termination support
  enum TerminatedTypes {
    _not_terminated = 0xDEAD - 2,
    _thread_exiting,                             // JavaThread::exit() has been called for this thread
    _thread_terminated,                          // JavaThread is removed from thread list
    _vm_exited                                   // JavaThread is still executing native code, but VM is terminated
                                                 // only VM_Exit can set _vm_exited
  };

  // In general a JavaThread's _terminated field transitions as follows:
  //
  //   _not_terminated => _thread_exiting => _thread_terminated
  //
  // _vm_exited is a special value to cover the case of a JavaThread
  // executing native code after the VM itself is terminated.
  volatile TerminatedTypes _terminated;
  // suspend/resume support
  volatile bool         _suspend_equivalent;     // Suspend equivalent condition
  jint                  _in_deopt_handler;       // count of deoptimization
                                                 // handlers thread is in
  volatile bool         _doing_unsafe_access;    // Thread may fault due to unsafe access
  bool                  _do_not_unlock_if_synchronized; // Do not unlock the receiver of a synchronized method (since it was
                                                 // never locked) when throwing an exception. Used by interpreter only.

  // JNI attach states:
  enum JNIAttachStates {
    _not_attaching_via_jni = 1,  // thread is not attaching via JNI
    _attaching_via_jni,          // thread is attaching via JNI
    _attached_via_jni            // thread has attached via JNI
  };

  // A regular JavaThread's _jni_attach_state is _not_attaching_via_jni.
  // A native thread that is attaching via JNI starts with a value
  // of _attaching_via_jni and transitions to _attached_via_jni.
  volatile JNIAttachStates _jni_attach_state;

 public:
  // State of the stack guard pages for this thread.
  enum StackGuardState {
    stack_guard_unused,         // not needed
    stack_guard_yellow_disabled,// disabled (temporarily) after stack overflow
    stack_guard_enabled         // enabled
  };

 private:

  StackGuardState        _stack_guard_state;

  // Compiler exception handling (NOTE: The _exception_oop is *NOT* the same as _pending_exception. It is
  // used to temp. parsing values into and out of the runtime system during exception handling for compiled
  // code)
  volatile oop     _exception_oop;               // Exception thrown in compiled code
  volatile address _exception_pc;                // PC where exception happened
  volatile address _exception_handler_pc;        // PC for handler of exception
  volatile int     _is_method_handle_return;     // true (== 1) if the current exception PC is a MethodHandle call site.

  // support for JNI critical regions
  jint    _jni_active_critical;                  // count of entries into JNI critical region

  // For deadlock detection.
  int _depth_first_number;

  // JVMTI PopFrame support
  // This is set to popframe_pending to signal that top Java frame should be popped immediately
  int _popframe_condition;

#ifndef PRODUCT
  int _jmp_ring_index;
  struct {
      // We use intptr_t instead of address so debugger doesn't try and display strings
      intptr_t _target;
      intptr_t _instruction;
      const char*  _file;
      int _line;
  }   _jmp_ring[ jump_ring_buffer_size ];
#endif /* PRODUCT */

#if INCLUDE_ALL_GCS
  // Support for G1 barriers

  ObjPtrQueue _satb_mark_queue;          // Thread-local log for SATB barrier.
  // Set of all such queues.
  static SATBMarkQueueSet _satb_mark_queue_set;

  DirtyCardQueue _dirty_card_queue;      // Thread-local log for dirty cards.
  // Set of all such queues.
  static DirtyCardQueueSet _dirty_card_queue_set;

  void flush_barrier_queues();
#endif // INCLUDE_ALL_GCS

  friend class VMThread;
  friend class ThreadWaitTransition;
  friend class VM_Exit;

  void initialize();                             // Initialized the instance variables

 public:
  // Constructor
  JavaThread(bool is_attaching_via_jni = false); // for main thread and JNI attached threads
  JavaThread(ThreadFunction entry_point, size_t stack_size = 0);
  ~JavaThread();

#ifdef ASSERT
  // verify this JavaThread hasn't be published in the Threads::list yet
  void verify_not_published();
#endif

  //JNI functiontable getter/setter for JVMTI jni function table interception API.
  void set_jni_functions(struct JNINativeInterface_* functionTable) {
    _jni_environment.functions = functionTable;
  }
  struct JNINativeInterface_* get_jni_functions() {
    return (struct JNINativeInterface_ *)_jni_environment.functions;
  }

  // This function is called at thread creation to allow
  // platform specific thread variables to be initialized.
  void cache_global_variables();

  // Executes Shutdown.shutdown()
  void invoke_shutdown_hooks();

  // Cleanup on thread exit
  enum ExitType {
    normal_exit,
    jni_detach
  };
  void exit(bool destroy_vm, ExitType exit_type = normal_exit);

  void cleanup_failed_attach_current_thread();

  // Testers
  virtual bool is_Java_thread() const            { return true;  }

  // Thread chain operations
  JavaThread* next() const                       { return _next; }
  void set_next(JavaThread* p)                   { _next = p; }

  // Thread oop. threadObj() can be NULL for initial JavaThread
  // (or for threads attached via JNI)
  oop threadObj() const                          { return _threadObj; }
  void set_threadObj(oop p)                      { _threadObj = p; }

  ThreadPriority java_priority() const;          // Read from threadObj()

  // Prepare thread and add to priority queue.  If a priority is
  // not specified, use the priority of the thread object. Threads_lock
  // must be held while this function is called.
  void prepare(jobject jni_thread, ThreadPriority prio=NoPriority);

  void set_saved_exception_pc(address pc)        { _saved_exception_pc = pc; }
  address saved_exception_pc()                   { return _saved_exception_pc; }


  ThreadFunction entry_point() const             { return _entry_point; }

  // Allocates a new Java level thread object for this thread. thread_name may be NULL.
  void allocate_threadObj(Handle thread_group, char* thread_name, bool daemon, TRAPS);

  // Last frame anchor routines

  JavaFrameAnchor* frame_anchor(void)                { return &_anchor; }

  // last_Java_sp
  bool has_last_Java_frame() const                   { return _anchor.has_last_Java_frame(); }
  intptr_t* last_Java_sp() const                     { return _anchor.last_Java_sp(); }

  // last_Java_pc

  address last_Java_pc(void)                         { return _anchor.last_Java_pc(); }

  // Safepoint support
  JavaThreadState thread_state() const           { return _thread_state; }
  void set_thread_state(JavaThreadState s)       { _thread_state=s;      }
  ThreadSafepointState *safepoint_state() const  { return _safepoint_state;  }
  void set_safepoint_state(ThreadSafepointState *state) { _safepoint_state = state; }
  bool is_at_poll_safepoint()                    { return _safepoint_state->is_at_poll_safepoint(); }

  // thread has called JavaThread::exit() or is terminated
  bool is_exiting()                              { return _terminated == _thread_exiting || is_terminated(); }
  // thread is terminated (no longer on the threads list); we compare
  // against the two non-terminated values so that a freed JavaThread
  // will also be considered terminated.
  bool is_terminated()                           { return _terminated != _not_terminated && _terminated != _thread_exiting; }
  void set_terminated(TerminatedTypes t)         { _terminated = t; }
  // special for Threads::remove() which is static:
  void set_terminated_value()                    { _terminated = _thread_terminated; }
  void block_if_vm_exited();

  bool doing_unsafe_access()                     { return _doing_unsafe_access; }
  void set_doing_unsafe_access(bool val)         { _doing_unsafe_access = val; }

  bool do_not_unlock_if_synchronized()             { return _do_not_unlock_if_synchronized; }
  void set_do_not_unlock_if_synchronized(bool val) { _do_not_unlock_if_synchronized = val; }

#if INCLUDE_NMT
  // native memory tracking
  inline MemRecorder* get_recorder() const          { return (MemRecorder*)_recorder; }
  inline void         set_recorder(MemRecorder* rc) { _recorder = rc; }

 private:
  // per-thread memory recorder
  MemRecorder* volatile _recorder;
#endif // INCLUDE_NMT

  // Suspend/resume support for JavaThread
 private:
  void set_ext_suspended()       { set_suspend_flag (_ext_suspended);  }
  void clear_ext_suspended()     { clear_suspend_flag(_ext_suspended); }

 public:
  void java_suspend();
  void java_resume();
  int  java_suspend_self();

  void check_and_wait_while_suspended() {
    assert(JavaThread::current() == this, "sanity check");

    bool do_self_suspend;
    do {
      // were we externally suspended while we were waiting?
      do_self_suspend = handle_special_suspend_equivalent_condition();
      if (do_self_suspend) {
        // don't surprise the thread that suspended us by returning
        java_suspend_self();
        set_suspend_equivalent();
      }
    } while (do_self_suspend);
  }
  static void check_safepoint_and_suspend_for_native_trans(JavaThread *thread);
  // Check for async exception in addition to safepoint and suspend request.
  static void check_special_condition_for_native_trans(JavaThread *thread);

  // Same as check_special_condition_for_native_trans but finishes the
  // transition into thread_in_Java mode so that it can potentially
  // block.
  static void check_special_condition_for_native_trans_and_transition(JavaThread *thread);

  bool is_ext_suspend_completed(bool called_by_wait, int delay, uint32_t *bits);
  bool is_ext_suspend_completed_with_lock(uint32_t *bits) {
    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
    // Warning: is_ext_suspend_completed() may temporarily drop the
    // SR_lock to allow the thread to reach a stable thread state if
    // it is currently in a transient thread state.
    return is_ext_suspend_completed(false /*!called_by_wait */,
                                    SuspendRetryDelay, bits);
  }

  // We cannot allow wait_for_ext_suspend_completion() to run forever or
  // we could hang. SuspendRetryCount and SuspendRetryDelay are normally
  // passed as the count and delay parameters. Experiments with specific
  // calls to wait_for_ext_suspend_completion() can be done by passing
  // other values in the code. Experiments with all calls can be done
  // via the appropriate -XX options.
  bool wait_for_ext_suspend_completion(int count, int delay, uint32_t *bits);

  void set_external_suspend()     { set_suspend_flag  (_external_suspend); }
  void clear_external_suspend()   { clear_suspend_flag(_external_suspend); }

  void set_deopt_suspend()        { set_suspend_flag  (_deopt_suspend); }
  void clear_deopt_suspend()      { clear_suspend_flag(_deopt_suspend); }
  bool is_deopt_suspend()         { return (_suspend_flags & _deopt_suspend) != 0; }

  bool is_external_suspend() const {
    return (_suspend_flags & _external_suspend) != 0;
  }
  // Whenever a thread transitions from native to vm/java it must suspend
  // if external|deopt suspend is present.
  bool is_suspend_after_native() const {
    return (_suspend_flags & (_external_suspend | _deopt_suspend) ) != 0;
  }

  // external suspend request is completed
  bool is_ext_suspended() const {
    return (_suspend_flags & _ext_suspended) != 0;
  }

  bool is_external_suspend_with_lock() const {
    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
    return is_external_suspend();
  }

  // Special method to handle a pending external suspend request
  // when a suspend equivalent condition lifts.
  bool handle_special_suspend_equivalent_condition() {
    assert(is_suspend_equivalent(),
      "should only be called in a suspend equivalence condition");
    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
    bool ret = is_external_suspend();
    if (!ret) {
      // not about to self-suspend so clear suspend equivalence
      clear_suspend_equivalent();
    }
    // implied else:
    // We have a pending external suspend request so we leave the
    // suspend_equivalent flag set until java_suspend_self() sets
    // the ext_suspended flag and clears the suspend_equivalent
    // flag. This insures that wait_for_ext_suspend_completion()
    // will return consistent values.
    return ret;
  }

  // utility methods to see if we are doing some kind of suspension
  bool is_being_ext_suspended() const            {
    MutexLockerEx ml(SR_lock(), Mutex::_no_safepoint_check_flag);
    return is_ext_suspended() || is_external_suspend();
  }

  bool is_suspend_equivalent() const             { return _suspend_equivalent; }

  void set_suspend_equivalent()                  { _suspend_equivalent = true; };
  void clear_suspend_equivalent()                { _suspend_equivalent = false; };

  // Thread.stop support
  void send_thread_stop(oop throwable);
  AsyncRequests clear_special_runtime_exit_condition() {
    AsyncRequests x = _special_runtime_exit_condition;
    _special_runtime_exit_condition = _no_async_condition;
    return x;
  }

  // Are any async conditions present?
  bool has_async_condition() { return (_special_runtime_exit_condition != _no_async_condition); }

  void check_and_handle_async_exceptions(bool check_unsafe_error = true);

  // these next two are also used for self-suspension and async exception support
  void handle_special_runtime_exit_condition(bool check_asyncs = true);

  // Return true if JavaThread has an asynchronous condition or
  // if external suspension is requested.
  bool has_special_runtime_exit_condition() {
    // We call is_external_suspend() last since external suspend should
    // be less common. Because we don't use is_external_suspend_with_lock
    // it is possible that we won't see an asynchronous external suspend
    // request that has just gotten started, i.e., SR_lock grabbed but
    // _external_suspend field change either not made yet or not visible
    // yet. However, this is okay because the request is asynchronous and
    // we will see the new flag value the next time through. It's also
    // possible that the external suspend request is dropped after
    // we have checked is_external_suspend(), we will recheck its value
    // under SR_lock in java_suspend_self().
    return (_special_runtime_exit_condition != _no_async_condition) ||
            is_external_suspend() || is_deopt_suspend();
  }

  void set_pending_unsafe_access_error()          { _special_runtime_exit_condition = _async_unsafe_access_error; }

  void set_pending_async_exception(oop e) {
    _pending_async_exception = e;
    _special_runtime_exit_condition = _async_exception;
    set_has_async_exception();
  }

  // Fast-locking support
  bool is_lock_owned(address adr) const;

  // Accessors for vframe array top
  // The linked list of vframe arrays are sorted on sp. This means when we
  // unpack the head must contain the vframe array to unpack.
  void set_vframe_array_head(vframeArray* value) { _vframe_array_head = value; }
  vframeArray* vframe_array_head() const         { return _vframe_array_head;  }

  // Side structure for defering update of java frame locals until deopt occurs
  GrowableArray<jvmtiDeferredLocalVariableSet*>* deferred_locals() const { return _deferred_locals_updates; }
  void set_deferred_locals(GrowableArray<jvmtiDeferredLocalVariableSet *>* vf) { _deferred_locals_updates = vf; }

  // These only really exist to make debugging deopt problems simpler

  void set_vframe_array_last(vframeArray* value) { _vframe_array_last = value; }
  vframeArray* vframe_array_last() const         { return _vframe_array_last;  }

  // The special resourceMark used during deoptimization

  void set_deopt_mark(DeoptResourceMark* value)  { _deopt_mark = value; }
  DeoptResourceMark* deopt_mark(void)            { return _deopt_mark; }

  intptr_t* must_deopt_id()                      { return _must_deopt_id; }
  void     set_must_deopt_id(intptr_t* id)       { _must_deopt_id = id; }
  void     clear_must_deopt_id()                 { _must_deopt_id = NULL; }

  void set_deopt_nmethod(nmethod* nm)            { _deopt_nmethod = nm;   }
  nmethod* deopt_nmethod()                       { return _deopt_nmethod; }

  Method*    callee_target() const               { return _callee_target; }
  void set_callee_target  (Method* x)          { _callee_target   = x; }

  // Oop results of vm runtime calls
  oop  vm_result() const                         { return _vm_result; }
  void set_vm_result  (oop x)                    { _vm_result   = x; }

  Metadata*    vm_result_2() const               { return _vm_result_2; }
  void set_vm_result_2  (Metadata* x)          { _vm_result_2   = x; }

  MemRegion deferred_card_mark() const           { return _deferred_card_mark; }
  void set_deferred_card_mark(MemRegion mr)      { _deferred_card_mark = mr;   }

  // Exception handling for compiled methods
  oop      exception_oop() const                 { return _exception_oop; }
  address  exception_pc() const                  { return _exception_pc; }
  address  exception_handler_pc() const          { return _exception_handler_pc; }
  bool     is_method_handle_return() const       { return _is_method_handle_return == 1; }

  void set_exception_oop(oop o)                  { (void)const_cast<oop&>(_exception_oop = o); }
  void set_exception_pc(address a)               { _exception_pc = a; }
  void set_exception_handler_pc(address a)       { _exception_handler_pc = a; }
  void set_is_method_handle_return(bool value)   { _is_method_handle_return = value ? 1 : 0; }

  void clear_exception_oop_and_pc() {
    set_exception_oop(NULL);
    set_exception_pc(NULL);
  }

  // Stack overflow support
  inline size_t stack_available(address cur_sp);
  address stack_yellow_zone_base()
    { return (address)(stack_base() - (stack_size() - (stack_red_zone_size() + stack_yellow_zone_size()))); }
  size_t  stack_yellow_zone_size()
    { return StackYellowPages * os::vm_page_size(); }
  address stack_red_zone_base()
    { return (address)(stack_base() - (stack_size() - stack_red_zone_size())); }
  size_t stack_red_zone_size()
    { return StackRedPages * os::vm_page_size(); }
  bool in_stack_yellow_zone(address a)
    { return (a <= stack_yellow_zone_base()) && (a >= stack_red_zone_base()); }
  bool in_stack_red_zone(address a)
    { return (a <= stack_red_zone_base()) && (a >= (address)((intptr_t)stack_base() - stack_size())); }

  void create_stack_guard_pages();
  void remove_stack_guard_pages();

  void enable_stack_yellow_zone();
  void disable_stack_yellow_zone();
  void enable_stack_red_zone();
  void disable_stack_red_zone();

  inline bool stack_guard_zone_unused();
  inline bool stack_yellow_zone_disabled();
  inline bool stack_yellow_zone_enabled();

  // Attempt to reguard the stack after a stack overflow may have occurred.
  // Returns true if (a) guard pages are not needed on this thread, (b) the
  // pages are already guarded, or (c) the pages were successfully reguarded.
  // Returns false if there is not enough stack space to reguard the pages, in
  // which case the caller should unwind a frame and try again.  The argument
  // should be the caller's (approximate) sp.
  bool reguard_stack(address cur_sp);
  // Similar to above but see if current stackpoint is out of the guard area
  // and reguard if possible.
  bool reguard_stack(void);

  // Misc. accessors/mutators
  void set_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = true; }
  void clr_do_not_unlock(void)                   { _do_not_unlock_if_synchronized = false; }
  bool do_not_unlock(void)                       { return _do_not_unlock_if_synchronized; }

#ifndef PRODUCT
  void record_jump(address target, address instr, const char* file, int line);
#endif /* PRODUCT */

  // For assembly stub generation
  static ByteSize threadObj_offset()             { return byte_offset_of(JavaThread, _threadObj           ); }
#ifndef PRODUCT
  static ByteSize jmp_ring_index_offset()        { return byte_offset_of(JavaThread, _jmp_ring_index      ); }
  static ByteSize jmp_ring_offset()              { return byte_offset_of(JavaThread, _jmp_ring            ); }
#endif /* PRODUCT */
  static ByteSize jni_environment_offset()       { return byte_offset_of(JavaThread, _jni_environment     ); }
  static ByteSize last_Java_sp_offset()          {
    return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_sp_offset();
  }
  static ByteSize last_Java_pc_offset()          {
    return byte_offset_of(JavaThread, _anchor) + JavaFrameAnchor::last_Java_pc_offset();
  }
  static ByteSize frame_anchor_offset()          {
    return byte_offset_of(JavaThread, _anchor);
  }
  static ByteSize callee_target_offset()         { return byte_offset_of(JavaThread, _callee_target       ); }
  static ByteSize vm_result_offset()             { return byte_offset_of(JavaThread, _vm_result           ); }
  static ByteSize vm_result_2_offset()           { return byte_offset_of(JavaThread, _vm_result_2         ); }
  static ByteSize thread_state_offset()          { return byte_offset_of(JavaThread, _thread_state        ); }
  static ByteSize saved_exception_pc_offset()    { return byte_offset_of(JavaThread, _saved_exception_pc  ); }
  static ByteSize osthread_offset()              { return byte_offset_of(JavaThread, _osthread            ); }
  static ByteSize exception_oop_offset()         { return byte_offset_of(JavaThread, _exception_oop       ); }
  static ByteSize exception_pc_offset()          { return byte_offset_of(JavaThread, _exception_pc        ); }
  static ByteSize exception_handler_pc_offset()  { return byte_offset_of(JavaThread, _exception_handler_pc); }
  static ByteSize is_method_handle_return_offset() { return byte_offset_of(JavaThread, _is_method_handle_return); }
  static ByteSize stack_guard_state_offset()     { return byte_offset_of(JavaThread, _stack_guard_state   ); }
  static ByteSize suspend_flags_offset()         { return byte_offset_of(JavaThread, _suspend_flags       ); }

  static ByteSize do_not_unlock_if_synchronized_offset() { return byte_offset_of(JavaThread, _do_not_unlock_if_synchronized); }
  static ByteSize should_post_on_exceptions_flag_offset() {
    return byte_offset_of(JavaThread, _should_post_on_exceptions_flag);
  }

#if INCLUDE_ALL_GCS
  static ByteSize satb_mark_queue_offset()       { return byte_offset_of(JavaThread, _satb_mark_queue); }
  static ByteSize dirty_card_queue_offset()      { return byte_offset_of(JavaThread, _dirty_card_queue); }
#endif // INCLUDE_ALL_GCS

  // Returns the jni environment for this thread
  JNIEnv* jni_environment()                      { return &_jni_environment; }

  static JavaThread* thread_from_jni_environment(JNIEnv* env) {
    JavaThread *thread_from_jni_env = (JavaThread*)((intptr_t)env - in_bytes(jni_environment_offset()));
    // Only return NULL if thread is off the thread list; starting to
    // exit should not return NULL.
    if (thread_from_jni_env->is_terminated()) {
       thread_from_jni_env->block_if_vm_exited();
       return NULL;
    } else {
       return thread_from_jni_env;
    }
  }

  // JNI critical regions. These can nest.
  bool in_critical()    { return _jni_active_critical > 0; }
  bool in_last_critical()  { return _jni_active_critical == 1; }
  void enter_critical() { assert(Thread::current() == this ||
                                 Thread::current()->is_VM_thread() && SafepointSynchronize::is_synchronizing(),
                                 "this must be current thread or synchronizing");
                          _jni_active_critical++; }
  void exit_critical()  { assert(Thread::current() == this,
                                 "this must be current thread");
                          _jni_active_critical--;
                          assert(_jni_active_critical >= 0,
                                 "JNI critical nesting problem?"); }

  // For deadlock detection
  int depth_first_number() { return _depth_first_number; }
  void set_depth_first_number(int dfn) { _depth_first_number = dfn; }

 private:
  void set_monitor_chunks(MonitorChunk* monitor_chunks) { _monitor_chunks = monitor_chunks; }

 public:
  MonitorChunk* monitor_chunks() const           { return _monitor_chunks; }
  void add_monitor_chunk(MonitorChunk* chunk);
  void remove_monitor_chunk(MonitorChunk* chunk);
  bool in_deopt_handler() const                  { return _in_deopt_handler > 0; }
  void inc_in_deopt_handler()                    { _in_deopt_handler++; }
  void dec_in_deopt_handler()                    {
    assert(_in_deopt_handler > 0, "mismatched deopt nesting");
    if (_in_deopt_handler > 0) { // robustness
      _in_deopt_handler--;
    }
  }

 private:
  void set_entry_point(ThreadFunction entry_point) { _entry_point = entry_point; }

 public:

  // Frame iteration; calls the function f for all frames on the stack
  void frames_do(void f(frame*, const RegisterMap*));

  // Memory operations
  void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);

  // Sweeper operations
  void nmethods_do(CodeBlobClosure* cf);

  // RedefineClasses Support
  void metadata_do(void f(Metadata*));

  // Memory management operations
  void gc_epilogue();
  void gc_prologue();

  // Misc. operations
  char* name() const { return (char*)get_thread_name(); }
  void print_on(outputStream* st) const;
  void print() const { print_on(tty); }
  void print_value();
  void print_thread_state_on(outputStream* ) const      PRODUCT_RETURN;
  void print_thread_state() const                       PRODUCT_RETURN;
  void print_on_error(outputStream* st, char* buf, int buflen) const;
  void verify();
  const char* get_thread_name() const;
private:
  // factor out low-level mechanics for use in both normal and error cases
  const char* get_thread_name_string(char* buf = NULL, int buflen = 0) const;
public:
  const char* get_threadgroup_name() const;
  const char* get_parent_name() const;

  // Accessing frames
  frame last_frame() {
    _anchor.make_walkable(this);
    return pd_last_frame();
  }
  javaVFrame* last_java_vframe(RegisterMap* reg_map);

  // Returns method at 'depth' java or native frames down the stack
  // Used for security checks
  Klass* security_get_caller_class(int depth);

  // Print stack trace in external format
  void print_stack_on(outputStream* st);
  void print_stack() { print_stack_on(tty); }

  // Print stack traces in various internal formats
  void trace_stack()                             PRODUCT_RETURN;
  void trace_stack_from(vframe* start_vf)        PRODUCT_RETURN;
  void trace_frames()                            PRODUCT_RETURN;
  void trace_oops()                              PRODUCT_RETURN;

  // Print an annotated view of the stack frames
  void print_frame_layout(int depth = 0, bool validate_only = false) NOT_DEBUG_RETURN;
  void validate_frame_layout() {
    print_frame_layout(0, true);
  }

  // Returns the number of stack frames on the stack
  int depth() const;

  // Function for testing deoptimization
  void deoptimize();
  void make_zombies();

  void deoptimized_wrt_marked_nmethods();

  // Profiling operation (see fprofile.cpp)
 public:
   bool profile_last_Java_frame(frame* fr);

 private:
   ThreadProfiler* _thread_profiler;
 private:
   friend class FlatProfiler;                    // uses both [gs]et_thread_profiler.
   friend class FlatProfilerTask;                // uses get_thread_profiler.
   friend class ThreadProfilerMark;              // uses get_thread_profiler.
   ThreadProfiler* get_thread_profiler()         { return _thread_profiler; }
   ThreadProfiler* set_thread_profiler(ThreadProfiler* tp) {
     ThreadProfiler* result = _thread_profiler;
     _thread_profiler = tp;
     return result;
   }

 // NMT (Native memory tracking) support.
 // This flag helps NMT to determine if this JavaThread will be blocked
 // at safepoint. If not, ThreadCritical is needed for writing memory records.
 // JavaThread is only safepoint visible when it is in Threads' thread list,
 // it is not visible until it is added to the list and becomes invisible
 // once it is removed from the list.
 public:
  bool is_safepoint_visible() const { return _safepoint_visible; }
  void set_safepoint_visible(bool visible) { _safepoint_visible = visible; }
 private:
  bool _safepoint_visible;

  // Static operations
 public:
  // Returns the running thread as a JavaThread
  static inline JavaThread* current();

  // Returns the active Java thread.  Do not use this if you know you are calling
  // from a JavaThread, as it's slower than JavaThread::current.  If called from
  // the VMThread, it also returns the JavaThread that instigated the VMThread's
  // operation.  You may not want that either.
  static JavaThread* active();

  inline CompilerThread* as_CompilerThread();

 public:
  virtual void run();
  void thread_main_inner();

 private:
  // PRIVILEGED STACK
  PrivilegedElement*  _privileged_stack_top;
  GrowableArray<oop>* _array_for_gc;
 public:

  // Returns the privileged_stack information.
  PrivilegedElement* privileged_stack_top() const       { return _privileged_stack_top; }
  void set_privileged_stack_top(PrivilegedElement *e)   { _privileged_stack_top = e; }
  void register_array_for_gc(GrowableArray<oop>* array) { _array_for_gc = array; }

 public:
  // Thread local information maintained by JVMTI.
  void set_jvmti_thread_state(JvmtiThreadState *value)                           { _jvmti_thread_state = value; }
  // A JvmtiThreadState is lazily allocated. This jvmti_thread_state()
  // getter is used to get this JavaThread's JvmtiThreadState if it has
  // one which means NULL can be returned. JvmtiThreadState::state_for()
  // is used to get the specified JavaThread's JvmtiThreadState if it has
  // one or it allocates a new JvmtiThreadState for the JavaThread and
  // returns it. JvmtiThreadState::state_for() will return NULL only if
  // the specified JavaThread is exiting.
  JvmtiThreadState *jvmti_thread_state() const                                   { return _jvmti_thread_state; }
  static ByteSize jvmti_thread_state_offset()                                    { return byte_offset_of(JavaThread, _jvmti_thread_state); }
  void set_jvmti_get_loaded_classes_closure(JvmtiGetLoadedClassesClosure* value) { _jvmti_get_loaded_classes_closure = value; }
  JvmtiGetLoadedClassesClosure* get_jvmti_get_loaded_classes_closure() const     { return _jvmti_get_loaded_classes_closure; }

  // JVMTI PopFrame support
  // Setting and clearing popframe_condition
  // All of these enumerated values are bits. popframe_pending
  // indicates that a PopFrame() has been requested and not yet been
  // completed. popframe_processing indicates that that PopFrame() is in
  // the process of being completed. popframe_force_deopt_reexecution_bit
  // indicates that special handling is required when returning to a
  // deoptimized caller.
  enum PopCondition {
    popframe_inactive                      = 0x00,
    popframe_pending_bit                   = 0x01,
    popframe_processing_bit                = 0x02,
    popframe_force_deopt_reexecution_bit   = 0x04
  };
  PopCondition popframe_condition()                   { return (PopCondition) _popframe_condition; }
  void set_popframe_condition(PopCondition c)         { _popframe_condition = c; }
  void set_popframe_condition_bit(PopCondition c)     { _popframe_condition |= c; }
  void clear_popframe_condition()                     { _popframe_condition = popframe_inactive; }
  static ByteSize popframe_condition_offset()         { return byte_offset_of(JavaThread, _popframe_condition); }
  bool has_pending_popframe()                         { return (popframe_condition() & popframe_pending_bit) != 0; }
  bool popframe_forcing_deopt_reexecution()           { return (popframe_condition() & popframe_force_deopt_reexecution_bit) != 0; }
  void clear_popframe_forcing_deopt_reexecution()     { _popframe_condition &= ~popframe_force_deopt_reexecution_bit; }
#ifdef CC_INTERP
  bool pop_frame_pending(void)                        { return ((_popframe_condition & popframe_pending_bit) != 0); }
  void clr_pop_frame_pending(void)                    { _popframe_condition = popframe_inactive; }
  bool pop_frame_in_process(void)                     { return ((_popframe_condition & popframe_processing_bit) != 0); }
  void set_pop_frame_in_process(void)                 { _popframe_condition |= popframe_processing_bit; }
  void clr_pop_frame_in_process(void)                 { _popframe_condition &= ~popframe_processing_bit; }
#endif

 private:
  // Saved incoming arguments to popped frame.
  // Used only when popped interpreted frame returns to deoptimized frame.
  void*    _popframe_preserved_args;
  int      _popframe_preserved_args_size;

 public:
  void  popframe_preserve_args(ByteSize size_in_bytes, void* start);
  void* popframe_preserved_args();
  ByteSize popframe_preserved_args_size();
  WordSize popframe_preserved_args_size_in_words();
  void  popframe_free_preserved_args();


 private:
  JvmtiThreadState *_jvmti_thread_state;
  JvmtiGetLoadedClassesClosure* _jvmti_get_loaded_classes_closure;

  // Used by the interpreter in fullspeed mode for frame pop, method
  // entry, method exit and single stepping support. This field is
  // only set to non-zero by the VM_EnterInterpOnlyMode VM operation.
  // It can be set to zero asynchronously (i.e., without a VM operation
  // or a lock) so we have to be very careful.
  int               _interp_only_mode;

 public:
  // used by the interpreter for fullspeed debugging support (see above)
  static ByteSize interp_only_mode_offset() { return byte_offset_of(JavaThread, _interp_only_mode); }
  bool is_interp_only_mode()                { return (_interp_only_mode != 0); }
  int get_interp_only_mode()                { return _interp_only_mode; }
  void increment_interp_only_mode()         { ++_interp_only_mode; }
  void decrement_interp_only_mode()         { --_interp_only_mode; }

  // support for cached flag that indicates whether exceptions need to be posted for this thread
  // if this is false, we can avoid deoptimizing when events are thrown
  // this gets set to reflect whether jvmtiExport::post_exception_throw would actually do anything
 private:
  int    _should_post_on_exceptions_flag;

 public:
  int   should_post_on_exceptions_flag()  { return _should_post_on_exceptions_flag; }
  void  set_should_post_on_exceptions_flag(int val)  { _should_post_on_exceptions_flag = val; }

 private:
  ThreadStatistics *_thread_stat;

 public:
  ThreadStatistics* get_thread_stat() const    { return _thread_stat; }

  // Return a blocker object for which this thread is blocked parking.
  oop current_park_blocker();

 private:
  static size_t _stack_size_at_create;

 public:
  static inline size_t stack_size_at_create(void) {
    return _stack_size_at_create;
  }
  static inline void set_stack_size_at_create(size_t value) {
    _stack_size_at_create = value;
  }

#if INCLUDE_ALL_GCS
  // SATB marking queue support
  ObjPtrQueue& satb_mark_queue() { return _satb_mark_queue; }
  static SATBMarkQueueSet& satb_mark_queue_set() {
    return _satb_mark_queue_set;
  }

  // Dirty card queue support
  DirtyCardQueue& dirty_card_queue() { return _dirty_card_queue; }
  static DirtyCardQueueSet& dirty_card_queue_set() {
    return _dirty_card_queue_set;
  }
#endif // INCLUDE_ALL_GCS

  // This method initializes the SATB and dirty card queues before a
  // JavaThread is added to the Java thread list. Right now, we don't
  // have to do anything to the dirty card queue (it should have been
  // activated when the thread was created), but we have to activate
  // the SATB queue if the thread is created while a marking cycle is
  // in progress. The activation / de-activation of the SATB queues at
  // the beginning / end of a marking cycle is done during safepoints
  // so we have to make sure this method is called outside one to be
  // able to safely read the active field of the SATB queue set. Right
  // now, it is called just before the thread is added to the Java
  // thread list in the Threads::add() method. That method is holding
  // the Threads_lock which ensures we are outside a safepoint. We
  // cannot do the obvious and set the active field of the SATB queue
  // when the thread is created given that, in some cases, safepoints
  // might happen between the JavaThread constructor being called and the
  // thread being added to the Java thread list (an example of this is
  // when the structure for the DestroyJavaVM thread is created).
#if INCLUDE_ALL_GCS
  void initialize_queues();
#else  // INCLUDE_ALL_GCS
  void initialize_queues() { }
#endif // INCLUDE_ALL_GCS

  // Machine dependent stuff
#ifdef TARGET_OS_ARCH_linux_x86
# include "thread_linux_x86.hpp"
#endif
#ifdef TARGET_OS_ARCH_linux_sparc
# include "thread_linux_sparc.hpp"
#endif
#ifdef TARGET_OS_ARCH_linux_zero
# include "thread_linux_zero.hpp"
#endif
#ifdef TARGET_OS_ARCH_solaris_x86
# include "thread_solaris_x86.hpp"
#endif
#ifdef TARGET_OS_ARCH_solaris_sparc
# include "thread_solaris_sparc.hpp"
#endif
#ifdef TARGET_OS_ARCH_windows_x86
# include "thread_windows_x86.hpp"
#endif
#ifdef TARGET_OS_ARCH_linux_arm
# include "thread_linux_arm.hpp"
#endif
#ifdef TARGET_OS_ARCH_linux_ppc
# include "thread_linux_ppc.hpp"
#endif
#ifdef TARGET_OS_ARCH_bsd_x86
# include "thread_bsd_x86.hpp"
#endif
#ifdef TARGET_OS_ARCH_bsd_zero
# include "thread_bsd_zero.hpp"
#endif


 public:
  void set_blocked_on_compilation(bool value) {
    _blocked_on_compilation = value;
  }

  bool blocked_on_compilation() {
    return _blocked_on_compilation;
  }
 protected:
  bool         _blocked_on_compilation;


  // JSR166 per-thread parker
private:
  Parker*    _parker;
public:
  Parker*     parker() { return _parker; }

  // Biased locking support
private:
  GrowableArray<MonitorInfo*>* _cached_monitor_info;
public:
  GrowableArray<MonitorInfo*>* cached_monitor_info() { return _cached_monitor_info; }
  void set_cached_monitor_info(GrowableArray<MonitorInfo*>* info) { _cached_monitor_info = info; }

  // clearing/querying jni attach status
  bool is_attaching_via_jni() const { return _jni_attach_state == _attaching_via_jni; }
  bool has_attached_via_jni() const { return is_attaching_via_jni() || _jni_attach_state == _attached_via_jni; }
  void set_done_attaching_via_jni() { _jni_attach_state = _attached_via_jni; OrderAccess::fence(); }
private:
  // This field is used to determine if a thread has claimed
  // a par_id: it is -1 if the thread has not claimed a par_id;
  // otherwise its value is the par_id that has been claimed.
  int _claimed_par_id;
public:
  int get_claimed_par_id() { return _claimed_par_id; }
  void set_claimed_par_id(int id) { _claimed_par_id = id;}
};

// Inline implementation of JavaThread::current
inline JavaThread* JavaThread::current() {
  Thread* thread = ThreadLocalStorage::thread();
  assert(thread != NULL && thread->is_Java_thread(), "just checking");
  return (JavaThread*)thread;
}

inline CompilerThread* JavaThread::as_CompilerThread() {
  assert(is_Compiler_thread(), "just checking");
  return (CompilerThread*)this;
}

inline bool JavaThread::stack_guard_zone_unused() {
  return _stack_guard_state == stack_guard_unused;
}

inline bool JavaThread::stack_yellow_zone_disabled() {
  return _stack_guard_state == stack_guard_yellow_disabled;
}

inline bool JavaThread::stack_yellow_zone_enabled() {
#ifdef ASSERT
  if (os::uses_stack_guard_pages()) {
    assert(_stack_guard_state != stack_guard_unused, "guard pages must be in use");
  }
#endif
    return _stack_guard_state == stack_guard_enabled;
}

inline size_t JavaThread::stack_available(address cur_sp) {
  // This code assumes java stacks grow down
  address low_addr; // Limit on the address for deepest stack depth
  if ( _stack_guard_state == stack_guard_unused) {
    low_addr =  stack_base() - stack_size();
  } else {
    low_addr = stack_yellow_zone_base();
  }
  return cur_sp > low_addr ? cur_sp - low_addr : 0;
}

// A thread used for Compilation.
class CompilerThread : public JavaThread {
  friend class VMStructs;
 private:
  CompilerCounters* _counters;

  ciEnv*            _env;
  CompileLog*       _log;
  CompileTask*      _task;
  CompileQueue*     _queue;
  BufferBlob*       _buffer_blob;

  nmethod*          _scanned_nmethod;  // nmethod being scanned by the sweeper
  AbstractCompiler* _compiler;

 public:

  static CompilerThread* current();

  CompilerThread(CompileQueue* queue, CompilerCounters* counters);

  bool is_Compiler_thread() const                { return true; }
  // Hide this compiler thread from external view.
  bool is_hidden_from_external_view() const      { return true; }

  void set_compiler(AbstractCompiler* c)         { _compiler = c; }
  AbstractCompiler* compiler() const             { return _compiler; }

  CompileQueue* queue()        const             { return _queue; }
  CompilerCounters* counters() const             { return _counters; }

  // Get/set the thread's compilation environment.
  ciEnv*        env()                            { return _env; }
  void          set_env(ciEnv* env)              { _env = env; }

  BufferBlob*   get_buffer_blob() const          { return _buffer_blob; }
  void          set_buffer_blob(BufferBlob* b)   { _buffer_blob = b; };

  // Get/set the thread's logging information
  CompileLog*   log()                            { return _log; }
  void          init_log(CompileLog* log) {
    // Set once, for good.
    assert(_log == NULL, "set only once");
    _log = log;
  }

  // GC support
  // Apply "f->do_oop" to all root oops in "this".
  // Apply "cf->do_code_blob" (if !NULL) to all code blobs active in frames
  void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);

#ifndef PRODUCT
private:
  IdealGraphPrinter *_ideal_graph_printer;
public:
  IdealGraphPrinter *ideal_graph_printer()                       { return _ideal_graph_printer; }
  void set_ideal_graph_printer(IdealGraphPrinter *n)             { _ideal_graph_printer = n; }
#endif

  // Get/set the thread's current task
  CompileTask*  task()                           { return _task; }
  void          set_task(CompileTask* task)      { _task = task; }

  // Track the nmethod currently being scanned by the sweeper
  void          set_scanned_nmethod(nmethod* nm) {
    assert(_scanned_nmethod == NULL || nm == NULL, "should reset to NULL before writing a new value");
    _scanned_nmethod = nm;
  }
};

inline CompilerThread* CompilerThread::current() {
  return JavaThread::current()->as_CompilerThread();
}


// The active thread queue. It also keeps track of the current used
// thread priorities.
class Threads: AllStatic {
  friend class VMStructs;
 private:
  static JavaThread* _thread_list;
  static int         _number_of_threads;
  static int         _number_of_non_daemon_threads;
  static int         _return_code;
#ifdef ASSERT
  static bool        _vm_complete;
#endif

 public:
  // Thread management
  // force_daemon is a concession to JNI, where we may need to add a
  // thread to the thread list before allocating its thread object
  static void add(JavaThread* p, bool force_daemon = false);
  static void remove(JavaThread* p);
  static bool includes(JavaThread* p);
  static JavaThread* first()                     { return _thread_list; }
  static void threads_do(ThreadClosure* tc);

  // Initializes the vm and creates the vm thread
  static jint create_vm(JavaVMInitArgs* args, bool* canTryAgain);
  static void convert_vm_init_libraries_to_agents();
  static void create_vm_init_libraries();
  static void create_vm_init_agents();
  static void shutdown_vm_agents();
  static bool destroy_vm();
  // Supported VM versions via JNI
  // Includes JNI_VERSION_1_1
  static jboolean is_supported_jni_version_including_1_1(jint version);
  // Does not include JNI_VERSION_1_1
  static jboolean is_supported_jni_version(jint version);

  // Garbage collection
  static void follow_other_roots(void f(oop*));

  // Apply "f->do_oop" to all root oops in all threads.
  // This version may only be called by sequential code.
  static void oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
  // This version may be called by sequential or parallel code.
  static void possibly_parallel_oops_do(OopClosure* f, CLDToOopClosure* cld_f, CodeBlobClosure* cf);
  // This creates a list of GCTasks, one per thread.
  static void create_thread_roots_tasks(GCTaskQueue* q);
  // This creates a list of GCTasks, one per thread, for marking objects.
  static void create_thread_roots_marking_tasks(GCTaskQueue* q);

  // Apply "f->do_oop" to roots in all threads that
  // are part of compiled frames
  static void compiled_frame_oops_do(OopClosure* f, CodeBlobClosure* cf);

  static void convert_hcode_pointers();
  static void restore_hcode_pointers();

  // Sweeper
  static void nmethods_do(CodeBlobClosure* cf);

  // RedefineClasses support
  static void metadata_do(void f(Metadata*));

  static void gc_epilogue();
  static void gc_prologue();
#ifdef ASSERT
  static bool is_vm_complete() { return _vm_complete; }
#endif

  // Verification
  static void verify();
  static void print_on(outputStream* st, bool print_stacks, bool internal_format, bool print_concurrent_locks);
  static void print(bool print_stacks, bool internal_format) {
    // this function is only used by debug.cpp
    print_on(tty, print_stacks, internal_format, false /* no concurrent lock printed */);
  }
  static void print_on_error(outputStream* st, Thread* current, char* buf, int buflen);

  // Get Java threads that are waiting to enter a monitor. If doLock
  // is true, then Threads_lock is grabbed as needed. Otherwise, the
  // VM needs to be at a safepoint.
  static GrowableArray<JavaThread*>* get_pending_threads(int count,
    address monitor, bool doLock);

  // Get owning Java thread from the monitor's owner field. If doLock
  // is true, then Threads_lock is grabbed as needed. Otherwise, the
  // VM needs to be at a safepoint.
  static JavaThread *owning_thread_from_monitor_owner(address owner,
    bool doLock);

  // Number of threads on the active threads list
  static int number_of_threads()                 { return _number_of_threads; }
  // Number of non-daemon threads on the active threads list
  static int number_of_non_daemon_threads()      { return _number_of_non_daemon_threads; }

  // Deoptimizes all frames tied to marked nmethods
  static void deoptimized_wrt_marked_nmethods();

};


// Thread iterator
class ThreadClosure: public StackObj {
 public:
  virtual void do_thread(Thread* thread) = 0;
};

class SignalHandlerMark: public StackObj {
private:
  Thread* _thread;
public:
  SignalHandlerMark(Thread* t) {
    _thread = t;
    if (_thread) _thread->enter_signal_handler();
  }
  ~SignalHandlerMark() {
    if (_thread) _thread->leave_signal_handler();
    _thread = NULL;
  }
};


#endif // SHARE_VM_RUNTIME_THREAD_HPP

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