weakArrayKlass.cpp

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/* Copyright 1994, 1995 LongView Technologies L.L.C. $Revision: 1.7 $ */
/* Copyright (c) 2006, Sun Microsystems, Inc.
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# include "incls/_precompiled.incl"
# include "incls/_weakArrayKlass.cpp.incl"

klassOop weakArrayKlass::create_subclass(mixinOop mixin, Format format) {
  if (format == mem_klass || format == weakArray_klass) {
    return weakArrayKlass::create_class(as_klassOop(), mixin);
  }
  return NULL;
}

klassOop weakArrayKlass::create_class(klassOop super_class, mixinOop mixin) {
  weakArrayKlass o;
  return create_generic_class(super_class, mixin, o.vtbl_value());
}

void set_weakArrayKlass_vtbl(Klass* k) {
  weakArrayKlass o;
  k->set_vtbl_value(o.vtbl_value());
}

void weakArrayKlass::oop_layout_iterate(oop obj, ObjectLayoutClosure* blk) {
  // Retrieve length information in case the iterator mutates the object
  oop* p   = objArrayOop(obj)->objs(0);
  int  len = objArrayOop(obj)->length();
  // header + instance variables
  memOopKlass::oop_layout_iterate(obj, blk);
  // indexables
  blk->do_oop("length", p++);
  blk->begin_indexables();
  for (int index = 1; index <= len; index++) {
    blk->do_indexable_oop(index, p++);
  }
  blk->end_indexables();
}

void weakArrayKlass::oop_oop_iterate(oop obj, OopClosure* blk) {
  // Retrieve length information in case the iterator mutates the object
  oop* p   = weakArrayOop(obj)->objs(0);
  int  len = weakArrayOop(obj)->length();
  // header + instance variables
  memOopKlass::oop_oop_iterate(obj, blk);
  // indexables
  blk->do_oop(p++);
  for (int index = 1; index <= len; index++) {
    blk->do_oop(p++);
  }
}

int weakArrayKlass::oop_scavenge_contents(oop obj) {
  // header + instance variables
  memOopKlass::oop_scavenge_contents(obj);
  // indexables
  weakArrayOop o = weakArrayOop(obj);
  if (!WeakArrayRegister::scavenge_register(o)) {
    oop* base = o->objs(1);
    oop* end  = base + o->length();
    while (base <= end) { scavenge_oop(base++); }
  }
  return object_size(o->length());  
}

int weakArrayKlass::oop_scavenge_tenured_contents(oop obj) {
  // header + instance variables
  memOopKlass::oop_scavenge_tenured_contents(obj);
  // indexables
  weakArrayOop o = weakArrayOop(obj);
  if (!WeakArrayRegister::scavenge_register(o)){
    oop* base = o->objs(1);
    oop* end  = base + o->length();
    while (base <= end) scavenge_tenured_oop(base++);
  }
  return object_size(o->length());  
}

void weakArrayKlass::oop_follow_contents(oop obj) {
  // indexables
  if (!WeakArrayRegister::mark_sweep_register(weakArrayOop(obj), non_indexable_size())){
    oop* base = weakArrayOop(obj)->objs(1);
    oop* end  = base + weakArrayOop(obj)->length();
    while (base <= end) MarkSweep::reverse_and_follow(base++);
  } 

  // header + instance variables
  memOopKlass::oop_follow_contents(obj);
}

// WeakArrayRegister 
// - static variables
bool WeakArrayRegister::during_registration = false;
GrowableArray<weakArrayOop>* WeakArrayRegister::weakArrays = NULL;
GrowableArray<int>* WeakArrayRegister::nis                 = NULL;

// - Scavenge operations
void WeakArrayRegister::begin_scavenge() {
  during_registration = true;
  weakArrays          = new GrowableArray<weakArrayOop>(10); 
}

bool WeakArrayRegister::scavenge_register(weakArrayOop obj) {
  if (during_registration) weakArrays->push(obj);
  return during_registration;
}

void WeakArrayRegister::check_and_scavenge_contents() {
  scavenge_check_for_dying_objects();
  scavenge_contents();
  during_registration = false;
  weakArrays = NULL;
}

void WeakArrayRegister::scavenge_contents() {
  for(int index = 0; index < weakArrays->length(); index++)
    weakArrays->at(index)->scavenge_contents_after_registration(); 
}

inline bool WeakArrayRegister::scavenge_is_near_death(oop obj) {
  // must be memOop and unmarked (no forward pointer)
  return obj->is_new() && !memOop(obj)->is_forwarded();
}

void WeakArrayRegister::scavenge_check_for_dying_objects() {
  NotificationQueue::mark_elements();
  for(int index = 0; index < weakArrays->length(); index++) {
    weakArrayOop w = weakArrays->at(index);
    bool encounted_near_death_objects = false;
    for(int i = 1; i <= w->length(); i++) {
      oop obj = w->obj_at(i);
      if (scavenge_is_near_death(obj)) {
        encounted_near_death_objects = true;
        memOop(obj)->mark_as_dying();
      }
    }
    if (encounted_near_death_objects && !w->is_queued())
      NotificationQueue::put(w);
  }
  NotificationQueue::clear_elements();
}

// - Mark sweep operations

void WeakArrayRegister::begin_mark_sweep() {
  during_registration = true;
  weakArrays          = new GrowableArray<weakArrayOop>(100);
  nis                 = new GrowableArray<int>(100); 
}

bool WeakArrayRegister::mark_sweep_register(weakArrayOop obj, int non_indexable_size) {
  if (during_registration) {
    weakArrays->push(obj);
    nis->push(non_indexable_size);
  }
  return during_registration;
}

void WeakArrayRegister::check_and_follow_contents() {
  mark_sweep_check_for_dying_objects();
  follow_contents();
  during_registration = false;
  weakArrays = NULL;
  nis        = NULL;
}

void WeakArrayRegister::follow_contents() {
  for(int index = 0; index < weakArrays->length(); index++) {
    weakArrayOop w = weakArrays->at(index);
    int non_indexable_size = nis->at(index);
    bool encounted_near_death_objects = false;
    int length = smiOop(w->raw_at(non_indexable_size))->value();
    for(int i = 1; i <= length; i++) {
      MarkSweep::reverse_and_follow(w->oops(non_indexable_size+i));
    }
  }
}

inline bool WeakArrayRegister::mark_sweep_is_near_death(oop obj) {
  return obj->is_mem() && !memOop(obj)->is_gc_marked();
}

void WeakArrayRegister::mark_sweep_check_for_dying_objects() {
  for(int index = 0; index < weakArrays->length(); index++) {
    weakArrayOop w = weakArrays->at(index);
    int non_indexable_size = nis->at(index);
    bool encounted_near_death_objects = false;
    int length = smiOop(w->raw_at(non_indexable_size))->value();
    for(int i = 1; i <= length; i++) {
      oop obj = w->raw_at(non_indexable_size+i);
      if (mark_sweep_is_near_death(obj)) {
        encounted_near_death_objects = true;
        memOop(obj)->mark_as_dying();
      }
    }
    if (encounted_near_death_objects)
      NotificationQueue::put_if_absent(w);
  }
}

// NotificationQueue

oop* NotificationQueue::array = NULL;
int  NotificationQueue::size  = 100;
int  NotificationQueue::first = 0;
int  NotificationQueue::last  = 0;

bool NotificationQueue::is_empty() {
  return first == last;
}

int NotificationQueue::succ(int index) {
  return (index+1) % size;
}

oop NotificationQueue::get() {
  assert(!is_empty(), "must contain elements");
  oop result = array[first];
  first = succ(first);
  return result;
}

void NotificationQueue::put(oop obj) {
  if (array == NULL) array = NEW_C_HEAP_ARRAY(oop, size);
  if (succ(last) == first) {
    int new_size = size * 2;
    int new_last = 0;
    // allocate new_array
    oop* new_array = NEW_C_HEAP_ARRAY(oop, new_size);
    // copy from array to new_array
    for (int index = first; index != last; index = succ(index))
      new_array[new_last++] = array[index];
    free(array);
    // replace array
    array = new_array;
    size  = new_size;
    first = 0;
    last  = new_last;
  } 
  array[last] = obj;
  last = succ(last);
}

void NotificationQueue::put_if_absent(oop obj) {
  for (int index = first; index != last; index = succ(index)) {
    if (array[index] == obj) return;
  }
  put(obj);
}

void NotificationQueue::oops_do(void f(oop*)) {
  for (int index = first; index != last; index = succ(index))
    f(&array[index]);
}

void NotificationQueue::mark_elements() {
  for (int index = first; index != last; index = succ(index)) {
    oop obj = array[index];
    if (obj->is_mem()) memOop(obj)->set_queued();
  }
}

void NotificationQueue::clear_elements() {
  for (int index = first; index != last; index = succ(index)) {
    oop obj = array[index];
    if (obj->is_mem()) memOop(obj)->clear_queued();
  }
}

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