src/hotspot/share/classfile/classLoaderData.cpp

CLD claiming v2

CLD claiming

*** 144,154 ****
    _modified_oops(true), _accumulated_modified_oops(false),
    // An unsafe anonymous class loader data doesn't have anything to keep
    // it from being unloaded during parsing of the unsafe anonymous class.
    // The null-class-loader should always be kept alive.
    _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0),
!   _claimed(0),
    _handles(),
    _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
    _jmethod_ids(NULL),
    _deallocate_list(NULL),
    _next(NULL),
--- 144,154 ----
    _modified_oops(true), _accumulated_modified_oops(false),
    // An unsafe anonymous class loader data doesn't have anything to keep
    // it from being unloaded during parsing of the unsafe anonymous class.
    // The null-class-loader should always be kept alive.
    _keep_alive((is_unsafe_anonymous || h_class_loader.is_null()) ? 1 : 0),
!   _claim(0),
    _handles(),
    _klasses(NULL), _packages(NULL), _modules(NULL), _unnamed_module(NULL), _dictionary(NULL),
    _jmethod_ids(NULL),
    _deallocate_list(NULL),
    _next(NULL),
***************
*** 272,287 ****
    }
    return false;
  }
  #endif // PRODUCT
  
! bool ClassLoaderData::claim() {
!   if (_claimed == 1) {
!     return false;
    }
- 
-   return (int) Atomic::cmpxchg(1, &_claimed, 0) == 0;
  }
  
  // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
  // while the class is being parsed, and if the class appears on the module fixup list.
  // Due to the uniqueness that no other class shares the unsafe anonymous class' name or
--- 272,292 ----
    }
    return false;
  }
  #endif // PRODUCT
  
! bool ClassLoaderData::try_claim(int claim) {
!   for (;;) {
!     int old_claim = Atomic::load(&_claim);
!     if ((old_claim & claim) == claim) {
!       return false;
!     }
!     int new_claim = old_claim | claim;
!     if (Atomic::cmpxchg(new_claim, &_claim, old_claim) == old_claim) {
!       return true;
!     }
    }
  }
  
  // Unsafe anonymous classes have their own ClassLoaderData that is marked to keep alive
  // while the class is being parsed, and if the class appears on the module fixup list.
  // Due to the uniqueness that no other class shares the unsafe anonymous class' name or
***************
*** 299,310 ****
      assert(_keep_alive > 0, "Invalid keep alive decrement count");
      _keep_alive--;
    }
  }
  
! void ClassLoaderData::oops_do(OopClosure* f, bool must_claim, bool clear_mod_oops) {
!   if (must_claim && !claim()) {
      return;
    }
  
    // Only clear modified_oops after the ClassLoaderData is claimed.
    if (clear_mod_oops) {
--- 304,315 ----
      assert(_keep_alive > 0, "Invalid keep alive decrement count");
      _keep_alive--;
    }
  }
  
! void ClassLoaderData::oops_do(OopClosure* f, int claim_value, bool clear_mod_oops) {
!   if (claim_value != ClassLoaderData::_claim_none && !try_claim(claim_value)) {
      return;
    }
  
    // Only clear modified_oops after the ClassLoaderData is claimed.
    if (clear_mod_oops) {
***************
*** 444,454 ****
  }
  
  
  void ClassLoaderDataGraph::clear_claimed_marks() {
    for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
!     cld->clear_claimed();
    }
  }
  
  void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
    {
--- 449,459 ----
  }
  
  
  void ClassLoaderDataGraph::clear_claimed_marks() {
    for (ClassLoaderData* cld = _head; cld != NULL; cld = cld->next()) {
!     cld->clear_claim();
    }
  }
  
  void ClassLoaderData::add_class(Klass* k, bool publicize /* true */) {
    {