vm/prims/jvmtiThreadState.hpp

/*
 * Copyright (c) 2003, 2017, 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.
 *
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#ifndef SHARE_VM_PRIMS_JVMTITHREADSTATE_HPP
#define SHARE_VM_PRIMS_JVMTITHREADSTATE_HPP

#include "jvmtifiles/jvmti.h"
#include "memory/allocation.hpp"
#include "memory/allocation.inline.hpp"
#include "prims/jvmtiEventController.hpp"
#include "runtime/thread.hpp"
#include "utilities/growableArray.hpp"

//
// Forward Declarations
//

class JvmtiEnvBase;
class JvmtiEnvThreadState;
class JvmtiDynamicCodeEventCollector;

enum JvmtiClassLoadKind {
  jvmti_class_load_kind_load = 100,
  jvmti_class_load_kind_retransform,
  jvmti_class_load_kind_redefine
};

///////////////////////////////////////////////////////////////
//
// class JvmtiEnvThreadStateIterator
//
// The only safe means of iterating through the JvmtiEnvThreadStates
// in a JvmtiThreadState.
// Note that this iteratation includes invalid environments pending
// deallocation -- in fact, some uses depend on this behavior.
//
class JvmtiEnvThreadStateIterator : public StackObj {
 private:
  JvmtiThreadState* state;
 public:
  JvmtiEnvThreadStateIterator(JvmtiThreadState* thread_state);
  ~JvmtiEnvThreadStateIterator();
  JvmtiEnvThreadState* first();
  JvmtiEnvThreadState* next(JvmtiEnvThreadState* ets);
};


///////////////////////////////////////////////////////////////
//
// class JvmtiThreadState
//
// The Jvmti state for each thread (across all JvmtiEnv):
// 1. Local table of enabled events.
class JvmtiThreadState : public CHeapObj<mtInternal> {
 private:
  friend class JvmtiEnv;
  JavaThread        *_thread;
  bool              _hide_single_stepping;
  bool              _pending_step_for_popframe;
  bool              _pending_step_for_earlyret;
  int               _hide_level;

 public:
  enum ExceptionState {
    ES_CLEARED,
    ES_DETECTED,
    ES_CAUGHT
  };

 private:
  ExceptionState _exception_state;

  // Used to send class being redefined/retransformed and kind of transform
  // info to the class file load hook event handler.
  Klass*                _class_being_redefined;
  JvmtiClassLoadKind    _class_load_kind;

  // This is only valid when is_interp_only_mode() returns true
  int               _cur_stack_depth;

  JvmtiThreadEventEnable _thread_event_enable;

  // for support of JvmtiEnvThreadState
  JvmtiEnvThreadState*   _head_env_thread_state;

  // doubly-linked linear list of active thread state
  // needed in order to iterate the list without holding Threads_lock
  static JvmtiThreadState *_head;
  JvmtiThreadState *_next;
  JvmtiThreadState *_prev;

  // holds the current dynamic code event collector, NULL if no event collector in use
  JvmtiDynamicCodeEventCollector* _dynamic_code_event_collector;
  // holds the current vm object alloc event collector, NULL if no event collector in use
  JvmtiVMObjectAllocEventCollector* _vm_object_alloc_event_collector;

  // Should only be created by factory methods
  JvmtiThreadState(JavaThread *thread);

  friend class JvmtiEnvThreadStateIterator;
  inline JvmtiEnvThreadState* head_env_thread_state();
  inline void set_head_env_thread_state(JvmtiEnvThreadState* ets);

 public:
  ~JvmtiThreadState();

  // is event_type enabled and usable for this thread in any enviroments?
  bool is_enabled(jvmtiEvent event_type) {
    return _thread_event_enable.is_enabled(event_type);
  }

  JvmtiThreadEventEnable *thread_event_enable() {
    return &_thread_event_enable;
  }

  // Must only be called in situations where the state is for the current thread and
  // the environment can not go away.  To be safe, the returned JvmtiEnvThreadState
  // must be used in such a way as there can be no intervening safepoints.
  inline JvmtiEnvThreadState* env_thread_state(JvmtiEnvBase *env);

  static void periodic_clean_up();

  void add_env(JvmtiEnvBase *env);

  // Used by the interpreter for fullspeed debugging support
  bool is_interp_only_mode()                { return _thread->is_interp_only_mode(); }
  void enter_interp_only_mode();
  void leave_interp_only_mode();

  // access to the linked list of all JVMTI thread states
  static JvmtiThreadState *first() {
    assert(Threads::number_of_threads() == 0 || JvmtiThreadState_lock->is_locked(), "sanity check");
    return _head;
  }

  JvmtiThreadState *next()                  {
    return _next;
  }

  // Current stack depth is only valid when is_interp_only_mode() returns true.
  // These functions should only be called at a safepoint - usually called from same thread.
  // Returns the number of Java activations on the stack.
  int cur_stack_depth();
  void invalidate_cur_stack_depth();
  void incr_cur_stack_depth();
  void decr_cur_stack_depth();

  int count_frames();

  inline JavaThread *get_thread()      { return _thread;              }

  inline bool is_exception_detected()  { return _exception_state == ES_DETECTED;  }
  inline bool is_exception_caught()    { return _exception_state == ES_CAUGHT;  }

  inline void set_exception_detected() { _exception_state = ES_DETECTED; }
  inline void set_exception_caught()   { _exception_state = ES_CAUGHT; }

  inline void clear_exception_state() { _exception_state = ES_CLEARED; }

  // We need to save and restore exception state inside JvmtiEventMark
  inline ExceptionState get_exception_state() { return _exception_state; }
  inline void restore_exception_state(ExceptionState state) { _exception_state = state; }

  inline void clear_hide_single_stepping() {
    if (_hide_level > 0) {
      _hide_level--;
    } else {
      assert(_hide_single_stepping, "hide_single_stepping is out of phase");
      _hide_single_stepping = false;
    }
  }
  inline bool hide_single_stepping() { return _hide_single_stepping; }
  inline void set_hide_single_stepping() {
    if (_hide_single_stepping) {
      _hide_level++;
    } else {
      assert(_hide_level == 0, "hide_level is out of phase");
      _hide_single_stepping = true;
    }
  }

  // Step pending flag is set when PopFrame is called and it is cleared
  // when step for the Pop Frame is completed.
  // This logic is used to distinguish b/w step for pop frame and repeat step.
  void set_pending_step_for_popframe() { _pending_step_for_popframe = true;  }
  void clr_pending_step_for_popframe() { _pending_step_for_popframe = false; }
  bool is_pending_step_for_popframe()  { return _pending_step_for_popframe;  }
  void process_pending_step_for_popframe();

  // Step pending flag is set when ForceEarlyReturn is called and it is cleared
  // when step for the ForceEarlyReturn is completed.
  // This logic is used to distinguish b/w step for early return and repeat step.
  void set_pending_step_for_earlyret() { _pending_step_for_earlyret = true;  }
  void clr_pending_step_for_earlyret() { _pending_step_for_earlyret = false; }
  bool is_pending_step_for_earlyret()  { return _pending_step_for_earlyret;  }
  void process_pending_step_for_earlyret();

  // Setter and getter method is used to send redefined class info
  // when class file load hook event is posted.
  // It is set while loading redefined class and cleared before the
  // class file load hook event is posted.
  inline void set_class_being_redefined(Klass* k, JvmtiClassLoadKind kind) {
    _class_being_redefined = k;
    _class_load_kind = kind;
  }

  inline void clear_class_being_redefined() {
    _class_being_redefined = NULL;
    _class_load_kind = jvmti_class_load_kind_load;
  }

  inline Klass* get_class_being_redefined() {
    return _class_being_redefined;
  }

  inline JvmtiClassLoadKind get_class_load_kind() {
    return _class_load_kind;
  }

  // RedefineClasses support
  // The bug 6214132 caused the verification to fail.
  //
  // Below is the detailed description of the fix approach taken:
  // 1. What's done in RedefineClasses() before verification:
  //  a) A reference to the class being redefined (_the_class) and a
  //     reference to new version of the class (_scratch_class) are
  //     saved here for use during the bytecode verification phase of
  //     RedefineClasses. See RedefineVerifyMark for how these fields
  //     are managed.
  //   b) The _java_mirror field from _the_class is copied to the
  //     _java_mirror field in _scratch_class. This means that a jclass
  //     returned for _the_class or _scratch_class will refer to the
  //     same Java mirror. The verifier will see the "one true mirror"
  //     for the class being verified.
  // 2. What is done at verification:
  //   When the verifier makes calls into the VM to ask questions about
  //   the class being verified, it will pass the jclass to JVM_* functions.
  //   The jclass is always pointing to the mirror of _the_class.
  //   ~28 JVM_* functions called by the verifier for the information
  //   about CP entries and klass structure should check the jvmtiThreadState
  //   info about equivalent klass versions and use it to replace a Klass*
  //   of _the_class with a Klass* of _scratch_class. The function
  //   class_to_verify_considering_redefinition() must be called for it.
  //
  //   Note again, that this redirection happens only for the verifier thread.
  //   Other threads have very small overhead by checking the existence
  //   of the jvmtiThreadSate and the information about klasses equivalence.
  //   No JNI functions need to be changed, they don't reference the klass guts.
  //   The JavaThread pointer is already available in all JVM_* functions
  //   used by the verifier, so there is no extra performance issue with it.

 private:
  Klass* _the_class_for_redefinition_verification;
  Klass* _scratch_class_for_redefinition_verification;

 public:
  inline void set_class_versions_map(Klass* the_class,
                                     Klass* scratch_class) {
    _the_class_for_redefinition_verification = the_class;
    _scratch_class_for_redefinition_verification = scratch_class;
  }

  inline void clear_class_versions_map() { set_class_versions_map(NULL, NULL); }

  static inline
  Klass* class_to_verify_considering_redefinition(Klass* klass,
                                                    JavaThread *thread) {
    JvmtiThreadState *state = thread->jvmti_thread_state();
    if (state != NULL && state->_the_class_for_redefinition_verification != NULL) {
      if (state->_the_class_for_redefinition_verification == klass) {
        klass = state->_scratch_class_for_redefinition_verification;
      }
    }
    return klass;
  }

  // Todo: get rid of this!
 private:
  bool _debuggable;
 public:
  // Should the thread be enumerated by jvmtiInternal::GetAllThreads?
  bool is_debuggable()                 { return _debuggable; }
  // If a thread cannot be suspended (has no valid last_java_frame) then it gets marked !debuggable
  void set_debuggable(bool debuggable) { _debuggable = debuggable; }

 public:

  bool may_be_walked();

  // Thread local event collector setter and getter methods.
  JvmtiDynamicCodeEventCollector* get_dynamic_code_event_collector() {
    return _dynamic_code_event_collector;
  }
  JvmtiVMObjectAllocEventCollector* get_vm_object_alloc_event_collector() {
    return _vm_object_alloc_event_collector;
  }
  void set_dynamic_code_event_collector(JvmtiDynamicCodeEventCollector* collector) {
    _dynamic_code_event_collector = collector;
  }
  void set_vm_object_alloc_event_collector(JvmtiVMObjectAllocEventCollector* collector) {
    _vm_object_alloc_event_collector = collector;
  }


  //
  // Frame routines
  //

 public:

  //  true when the thread was suspended with a pointer to the last Java frame.
  bool has_last_frame()                     { return _thread->has_last_Java_frame(); }

  void update_for_pop_top_frame();

  // already holding JvmtiThreadState_lock - retrieve or create JvmtiThreadState
  // Can return NULL if JavaThread is exiting.
  inline static JvmtiThreadState *state_for_while_locked(JavaThread *thread) {
    assert(JvmtiThreadState_lock->is_locked(), "sanity check");

    JvmtiThreadState *state = thread->jvmti_thread_state();
    if (state == NULL) {
      if (thread->is_exiting()) {
        // don't add a JvmtiThreadState to a thread that is exiting
        return NULL;
      }

      state = new JvmtiThreadState(thread);
    }
    return state;
  }

  // retrieve or create JvmtiThreadState
  // Can return NULL if JavaThread is exiting.
  inline static JvmtiThreadState *state_for(JavaThread *thread) {
    JvmtiThreadState *state = thread->jvmti_thread_state();
    if (state == NULL) {
      MutexLocker mu(JvmtiThreadState_lock);
      // check again with the lock held
      state = state_for_while_locked(thread);
    } else {
      CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
    }
    return state;
  }

  // JVMTI ForceEarlyReturn support

  // This is set to earlyret_pending to signal that top Java frame
  // should be returned immediately
 public:
  int           _earlyret_state;
  TosState      _earlyret_tos;
  jvalue        _earlyret_value;
  oop           _earlyret_oop;         // Used to return an oop result into Java code from
                                       // ForceEarlyReturnObject, GC-preserved

  // Setting and clearing earlyret_state
  // earlyret_pending indicates that a ForceEarlyReturn() has been
  // requested and not yet been completed.
 public:
  enum EarlyretState {
    earlyret_inactive = 0,
    earlyret_pending  = 1
  };

  void set_earlyret_pending(void) { _earlyret_state = earlyret_pending;  }
  void clr_earlyret_pending(void) { _earlyret_state = earlyret_inactive; }
  bool is_earlyret_pending(void)  { return (_earlyret_state == earlyret_pending);  }

  TosState earlyret_tos()                            { return _earlyret_tos; }
  oop  earlyret_oop() const                          { return _earlyret_oop; }
  void set_earlyret_oop (oop x)                      { _earlyret_oop = x;    }
  jvalue earlyret_value()                            { return _earlyret_value; }
  void set_earlyret_value(jvalue val, TosState tos)  { _earlyret_tos = tos;  _earlyret_value = val;  }
  void clr_earlyret_value()                          { _earlyret_tos = ilgl; _earlyret_value.j = 0L; }

  static ByteSize earlyret_state_offset() { return byte_offset_of(JvmtiThreadState, _earlyret_state); }
  static ByteSize earlyret_tos_offset()   { return byte_offset_of(JvmtiThreadState, _earlyret_tos); }
  static ByteSize earlyret_oop_offset()   { return byte_offset_of(JvmtiThreadState, _earlyret_oop); }
  static ByteSize earlyret_value_offset() { return byte_offset_of(JvmtiThreadState, _earlyret_value); }

  void oops_do(OopClosure* f) NOT_JVMTI_RETURN; // GC support

public:
  void set_should_post_on_exceptions(bool val) { _thread->set_should_post_on_exceptions_flag(val ? JNI_TRUE : JNI_FALSE); }
};

class RedefineVerifyMark : public StackObj {
 private:
  JvmtiThreadState* _state;
  Klass*            _scratch_class;
  Handle            _scratch_mirror;

 public:
  RedefineVerifyMark(Klass* the_class, Klass* scratch_class,
                     JvmtiThreadState *state) : _state(state), _scratch_class(scratch_class)
  {
    _state->set_class_versions_map(the_class, scratch_class);
    _scratch_mirror = Handle(Thread::current(), _scratch_class->java_mirror());
    _scratch_class->set_java_mirror(the_class->java_mirror());
  }

  ~RedefineVerifyMark() {
    // Restore the scratch class's mirror, so when scratch_class is removed
    // the correct mirror pointing to it can be cleared.
    _scratch_class->set_java_mirror(_scratch_mirror());
    _state->clear_class_versions_map();
  }
};

#endif // SHARE_VM_PRIMS_JVMTITHREADSTATE_HPP