src/hotspot/share/oops/weakHandle.cpp

/*
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * 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).
 *
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 * 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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#include "gc/shared/oopStorage.hpp"
#include "oops/access.inline.hpp"
#include "oops/oop.hpp"
#include "oops/weakHandle.inline.hpp"
#include "utilities/debug.hpp"
#include "utilities/ostream.hpp"

WeakHandle::WeakHandle(OopStorage* storage, Handle obj) :
    WeakHandle(storage, obj()) {}

WeakHandle::WeakHandle(OopStorage* storage, oop obj) :
    _obj(storage->allocate()) {
  assert(obj != nullptr, "no need to create weak null oop");

  if (_obj == nullptr) {
    vm_exit_out_of_memory(sizeof(oop*), OOM_MALLOC_ERROR,
                          "Unable to create new weak oop handle in OopStorage %s",
                          storage->name());
  }

  NativeAccess<ON_PHANTOM_OOP_REF>::oop_store(_obj, obj);
}

void WeakHandle::release(OopStorage* storage) {
  // Only release if the pointer to the object has been created.
  if (_obj != nullptr) {
    // Clear the WeakHandle.  For race in creating ClassLoaderData, we can release this
    // WeakHandle before it is cleared by GC.
    NativeAccess<ON_PHANTOM_OOP_REF>::oop_store(_obj, nullptr);
    storage->release(_obj);
    _obj = nullptr;
  }
}

void WeakHandle::print() const { print_on(tty); }

void WeakHandle::print_on(outputStream* st) const {
  st->print("WeakHandle: " PTR_FORMAT, p2i(peek()));
}