hotspot/src/share/vm/runtime/jniHandles.cpp
author coleenp
Sun, 13 Apr 2008 17:43:42 -0400
changeset 360 21d113ecbf6a
parent 1 489c9b5090e2
child 670 ddf3e9583f2f
permissions -rw-r--r--
6420645: Create a vm that uses compressed oops for up to 32gb heapsizes Summary: Compressed oops in instances, arrays, and headers. Code contributors are coleenp, phh, never, swamyv Reviewed-by: jmasa, kamg, acorn, tbell, kvn, rasbold
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/*
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 * Copyright 1998-2007 Sun Microsystems, Inc.  All Rights Reserved.
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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 *
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 * This code is free software; you can redistribute it and/or modify it
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 * under the terms of the GNU General Public License version 2 only, as
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 * published by the Free Software Foundation.
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 *
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 * This code is distributed in the hope that it will be useful, but WITHOUT
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 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
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 * version 2 for more details (a copy is included in the LICENSE file that
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 * accompanied this code).
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 *
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 * You should have received a copy of the GNU General Public License version
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 * 2 along with this work; if not, write to the Free Software Foundation,
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 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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 *
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 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
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 * CA 95054 USA or visit www.sun.com if you need additional information or
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 * have any questions.
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 *
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 */
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# include "incls/_precompiled.incl"
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# include "incls/_jniHandles.cpp.incl"
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JNIHandleBlock* JNIHandles::_global_handles       = NULL;
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JNIHandleBlock* JNIHandles::_weak_global_handles  = NULL;
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oop             JNIHandles::_deleted_handle       = NULL;
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jobject JNIHandles::make_local(oop obj) {
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  if (obj == NULL) {
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    return NULL;                // ignore null handles
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  } else {
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    Thread* thread = Thread::current();
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    assert(Universe::heap()->is_in_reserved(obj), "sanity check");
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    return thread->active_handles()->allocate_handle(obj);
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  }
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}
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// optimized versions
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jobject JNIHandles::make_local(Thread* thread, oop obj) {
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  if (obj == NULL) {
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    return NULL;                // ignore null handles
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  } else {
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    assert(Universe::heap()->is_in_reserved(obj), "sanity check");
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    return thread->active_handles()->allocate_handle(obj);
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  }
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}
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jobject JNIHandles::make_local(JNIEnv* env, oop obj) {
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  if (obj == NULL) {
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    return NULL;                // ignore null handles
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  } else {
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    JavaThread* thread = JavaThread::thread_from_jni_environment(env);
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    assert(Universe::heap()->is_in_reserved(obj), "sanity check");
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    return thread->active_handles()->allocate_handle(obj);
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  }
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}
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jobject JNIHandles::make_global(Handle obj) {
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  jobject res = NULL;
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  if (!obj.is_null()) {
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    // ignore null handles
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    MutexLocker ml(JNIGlobalHandle_lock);
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    assert(Universe::heap()->is_in_reserved(obj()), "sanity check");
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    res = _global_handles->allocate_handle(obj());
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  } else {
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    CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
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  }
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  return res;
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}
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jobject JNIHandles::make_weak_global(Handle obj) {
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  jobject res = NULL;
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  if (!obj.is_null()) {
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    // ignore null handles
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    MutexLocker ml(JNIGlobalHandle_lock);
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    assert(Universe::heap()->is_in_reserved(obj()), "sanity check");
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    res = _weak_global_handles->allocate_handle(obj());
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  } else {
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    CHECK_UNHANDLED_OOPS_ONLY(Thread::current()->clear_unhandled_oops());
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  }
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  return res;
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}
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jmethodID JNIHandles::make_jmethod_id(methodHandle mh) {
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  return (jmethodID) make_weak_global(mh);
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}
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void JNIHandles::change_method_associated_with_jmethod_id(jmethodID jmid, methodHandle mh) {
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  MutexLocker ml(JNIGlobalHandle_lock); // Is this necessary?
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  Handle obj = (Handle)mh;
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  oop* jobj = (oop*)jmid;
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  *jobj = obj();
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}
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void JNIHandles::destroy_global(jobject handle) {
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  if (handle != NULL) {
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    assert(is_global_handle(handle), "Invalid delete of global JNI handle");
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    *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
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  }
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}
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void JNIHandles::destroy_weak_global(jobject handle) {
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  if (handle != NULL) {
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    assert(!CheckJNICalls || is_weak_global_handle(handle), "Invalid delete of weak global JNI handle");
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    *((oop*)handle) = deleted_handle(); // Mark the handle as deleted, allocate will reuse it
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  }
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}
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void JNIHandles::destroy_jmethod_id(jmethodID mid) {
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  destroy_weak_global((jobject)mid);
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}
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void JNIHandles::oops_do(OopClosure* f) {
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  f->do_oop(&_deleted_handle);
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  _global_handles->oops_do(f);
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}
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void JNIHandles::weak_oops_do(BoolObjectClosure* is_alive, OopClosure* f) {
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  _weak_global_handles->weak_oops_do(is_alive, f);
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}
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void JNIHandles::initialize() {
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  _global_handles      = JNIHandleBlock::allocate_block();
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  _weak_global_handles = JNIHandleBlock::allocate_block();
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  EXCEPTION_MARK;
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  // We will never reach the CATCH below since Exceptions::_throw will cause
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  // the VM to exit if an exception is thrown during initialization
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  klassOop k      = SystemDictionary::object_klass();
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  _deleted_handle = instanceKlass::cast(k)->allocate_permanent_instance(CATCH);
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}
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bool JNIHandles::is_local_handle(Thread* thread, jobject handle) {
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  JNIHandleBlock* block = thread->active_handles();
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  // Look back past possible native calls to jni_PushLocalFrame.
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  while (block != NULL) {
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    if (block->chain_contains(handle)) {
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      return true;
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    }
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    block = block->pop_frame_link();
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  }
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  return false;
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}
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// Determine if the handle is somewhere in the current thread's stack.
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// We easily can't isolate any particular stack frame the handle might
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// come from, so we'll check the whole stack.
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bool JNIHandles::is_frame_handle(JavaThread* thr, jobject obj) {
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  // If there is no java frame, then this must be top level code, such
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  // as the java command executable, in which case, this type of handle
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  // is not permitted.
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  return (thr->has_last_Java_frame() &&
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         (void*)obj < (void*)thr->stack_base() &&
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         (void*)obj >= (void*)thr->last_Java_sp());
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}
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bool JNIHandles::is_global_handle(jobject handle) {
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  return _global_handles->chain_contains(handle);
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}
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bool JNIHandles::is_weak_global_handle(jobject handle) {
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  return _weak_global_handles->chain_contains(handle);
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}
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long JNIHandles::global_handle_memory_usage() {
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  return _global_handles->memory_usage();
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}
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long JNIHandles::weak_global_handle_memory_usage() {
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  return _weak_global_handles->memory_usage();
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}
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class AlwaysAliveClosure: public BoolObjectClosure {
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public:
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  bool do_object_b(oop obj) { return true; }
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  void do_object(oop obj) { assert(false, "Don't call"); }
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};
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class CountHandleClosure: public OopClosure {
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private:
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  int _count;
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public:
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  CountHandleClosure(): _count(0) {}
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  virtual void do_oop(oop* unused) {
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    _count++;
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  }
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  virtual void do_oop(narrowOop* unused) { ShouldNotReachHere(); }
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  int count() { return _count; }
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};
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// We assume this is called at a safepoint: no lock is needed.
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void JNIHandles::print_on(outputStream* st) {
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  assert(SafepointSynchronize::is_at_safepoint(), "must be at safepoint");
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  assert(_global_handles != NULL && _weak_global_handles != NULL,
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         "JNIHandles not initialized");
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  CountHandleClosure global_handle_count;
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  AlwaysAliveClosure always_alive;
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  oops_do(&global_handle_count);
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  weak_oops_do(&always_alive, &global_handle_count);
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  st->print_cr("JNI global references: %d", global_handle_count.count());
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  st->cr();
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  st->flush();
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}
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class VerifyHandleClosure: public OopClosure {
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public:
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  virtual void do_oop(oop* root) {
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    (*root)->verify();
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  }
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  virtual void do_oop(narrowOop* root) { ShouldNotReachHere(); }
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};
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void JNIHandles::verify() {
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  VerifyHandleClosure verify_handle;
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  AlwaysAliveClosure always_alive;
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  oops_do(&verify_handle);
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  weak_oops_do(&always_alive, &verify_handle);
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}
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void jni_handles_init() {
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  JNIHandles::initialize();
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}
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int             JNIHandleBlock::_blocks_allocated     = 0;
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JNIHandleBlock* JNIHandleBlock::_block_free_list      = NULL;
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#ifndef PRODUCT
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JNIHandleBlock* JNIHandleBlock::_block_list           = NULL;
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#endif
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void JNIHandleBlock::zap() {
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  // Zap block values
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  _top  = 0;
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  for (int index = 0; index < block_size_in_oops; index++) {
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    _handles[index] = badJNIHandle;
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  }
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}
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JNIHandleBlock* JNIHandleBlock::allocate_block(Thread* thread)  {
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  assert(thread == NULL || thread == Thread::current(), "sanity check");
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  JNIHandleBlock* block;
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  // Check the thread-local free list for a block so we don't
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  // have to acquire a mutex.
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  if (thread != NULL && thread->free_handle_block() != NULL) {
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    block = thread->free_handle_block();
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    thread->set_free_handle_block(block->_next);
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  }
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  else {
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    // locking with safepoint checking introduces a potential deadlock:
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    // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock
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    // - another would hold Threads_lock (jni_AttachCurrentThread) and then
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    //   JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block)
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    MutexLockerEx ml(JNIHandleBlockFreeList_lock,
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                     Mutex::_no_safepoint_check_flag);
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    if (_block_free_list == NULL) {
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      // Allocate new block
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      block = new JNIHandleBlock();
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      _blocks_allocated++;
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      if (TraceJNIHandleAllocation) {
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        tty->print_cr("JNIHandleBlock " INTPTR_FORMAT " allocated (%d total blocks)",
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                      block, _blocks_allocated);
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      }
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      if (ZapJNIHandleArea) block->zap();
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      #ifndef PRODUCT
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      // Link new block to list of all allocated blocks
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      block->_block_list_link = _block_list;
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      _block_list = block;
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      #endif
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    } else {
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      // Get block from free list
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      block = _block_free_list;
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      _block_free_list = _block_free_list->_next;
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    }
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  }
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  block->_top  = 0;
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  block->_next = NULL;
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  block->_pop_frame_link = NULL;
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  // _last, _free_list & _allocate_before_rebuild initialized in allocate_handle
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  debug_only(block->_last = NULL);
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  debug_only(block->_free_list = NULL);
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  debug_only(block->_allocate_before_rebuild = -1);
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  return block;
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}
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void JNIHandleBlock::release_block(JNIHandleBlock* block, Thread* thread) {
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  assert(thread == NULL || thread == Thread::current(), "sanity check");
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  JNIHandleBlock* pop_frame_link = block->pop_frame_link();
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  // Put returned block at the beginning of the thread-local free list.
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  // Note that if thread == NULL, we use it as an implicit argument that
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  // we _don't_ want the block to be kept on the free_handle_block.
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  // See for instance JavaThread::exit().
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  if (thread != NULL ) {
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    if (ZapJNIHandleArea) block->zap();
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   326
    JNIHandleBlock* freelist = thread->free_handle_block();
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    block->_pop_frame_link = NULL;
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    thread->set_free_handle_block(block);
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   329
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   330
    // Add original freelist to end of chain
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   331
    if ( freelist != NULL ) {
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   332
      while ( block->_next != NULL ) block = block->_next;
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   333
      block->_next = freelist;
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   334
    }
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   335
    block = NULL;
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   336
  }
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   337
  if (block != NULL) {
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   338
    // Return blocks to free list
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   339
    // locking with safepoint checking introduces a potential deadlock:
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   340
    // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock
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   341
    // - another would hold Threads_lock (jni_AttachCurrentThread) and then
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   342
    //   JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block)
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   343
    MutexLockerEx ml(JNIHandleBlockFreeList_lock,
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   344
                     Mutex::_no_safepoint_check_flag);
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   345
    while (block != NULL) {
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   346
      if (ZapJNIHandleArea) block->zap();
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   347
      JNIHandleBlock* next = block->_next;
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   348
      block->_next = _block_free_list;
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   349
      _block_free_list = block;
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   350
      block = next;
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   351
    }
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   352
  }
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   353
  if (pop_frame_link != NULL) {
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   354
    // As a sanity check we release blocks pointed to by the pop_frame_link.
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   355
    // This should never happen (only if PopLocalFrame is not called the
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   356
    // correct number of times).
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   357
    release_block(pop_frame_link, thread);
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   358
  }
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   359
}
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   360
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   361
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   362
void JNIHandleBlock::oops_do(OopClosure* f) {
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   363
  JNIHandleBlock* current_chain = this;
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   364
  // Iterate over chain of blocks, followed by chains linked through the
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   365
  // pop frame links.
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   366
  while (current_chain != NULL) {
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   367
    for (JNIHandleBlock* current = current_chain; current != NULL;
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   368
         current = current->_next) {
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   369
      assert(current == current_chain || current->pop_frame_link() == NULL,
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   370
        "only blocks first in chain should have pop frame link set");
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   371
      for (int index = 0; index < current->_top; index++) {
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   372
        oop* root = &(current->_handles)[index];
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   373
        oop value = *root;
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   374
        // traverse heap pointers only, not deleted handles or free list
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   375
        // pointers
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   376
        if (value != NULL && Universe::heap()->is_in_reserved(value)) {
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   377
          f->do_oop(root);
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   378
        }
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   379
      }
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   380
      // the next handle block is valid only if current block is full
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   381
      if (current->_top < block_size_in_oops) {
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   382
        break;
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   383
      }
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   384
    }
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   385
    current_chain = current_chain->pop_frame_link();
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   386
  }
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   387
}
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   388
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   389
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   390
void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive,
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   391
                                  OopClosure* f) {
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   392
  for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
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diff changeset
   393
    assert(current->pop_frame_link() == NULL,
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   394
      "blocks holding weak global JNI handles should not have pop frame link set");
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diff changeset
   395
    for (int index = 0; index < current->_top; index++) {
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diff changeset
   396
      oop* root = &(current->_handles)[index];
489c9b5090e2 Initial load
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diff changeset
   397
      oop value = *root;
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diff changeset
   398
      // traverse heap pointers only, not deleted handles or free list pointers
489c9b5090e2 Initial load
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diff changeset
   399
      if (value != NULL && Universe::heap()->is_in_reserved(value)) {
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diff changeset
   400
        if (is_alive->do_object_b(value)) {
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diff changeset
   401
          // The weakly referenced object is alive, update pointer
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duke
parents:
diff changeset
   402
          f->do_oop(root);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   403
        } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   404
          // The weakly referenced object is not alive, clear the reference by storing NULL
489c9b5090e2 Initial load
duke
parents:
diff changeset
   405
          if (TraceReferenceGC) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   406
            tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", root);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   407
          }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   408
          *root = NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   409
        }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   410
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   411
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   412
    // the next handle block is valid only if current block is full
489c9b5090e2 Initial load
duke
parents:
diff changeset
   413
    if (current->_top < block_size_in_oops) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   414
      break;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   415
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   416
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   417
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   418
489c9b5090e2 Initial load
duke
parents:
diff changeset
   419
489c9b5090e2 Initial load
duke
parents:
diff changeset
   420
jobject JNIHandleBlock::allocate_handle(oop obj) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   421
  assert(Universe::heap()->is_in_reserved(obj), "sanity check");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   422
  if (_top == 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   423
    // This is the first allocation or the initial block got zapped when
489c9b5090e2 Initial load
duke
parents:
diff changeset
   424
    // entering a native function. If we have any following blocks they are
489c9b5090e2 Initial load
duke
parents:
diff changeset
   425
    // not valid anymore.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   426
    for (JNIHandleBlock* current = _next; current != NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   427
         current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   428
      assert(current->_last == NULL, "only first block should have _last set");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   429
      assert(current->_free_list == NULL,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   430
             "only first block should have _free_list set");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   431
      current->_top = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   432
      if (ZapJNIHandleArea) current->zap();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   433
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   434
    // Clear initial block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   435
    _free_list = NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   436
    _allocate_before_rebuild = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   437
    _last = this;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   438
    if (ZapJNIHandleArea) zap();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   439
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   440
489c9b5090e2 Initial load
duke
parents:
diff changeset
   441
  // Try last block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   442
  if (_last->_top < block_size_in_oops) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   443
    oop* handle = &(_last->_handles)[_last->_top++];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   444
    *handle = obj;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   445
    return (jobject) handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   446
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   447
489c9b5090e2 Initial load
duke
parents:
diff changeset
   448
  // Try free list
489c9b5090e2 Initial load
duke
parents:
diff changeset
   449
  if (_free_list != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   450
    oop* handle = _free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   451
    _free_list = (oop*) *_free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   452
    *handle = obj;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   453
    return (jobject) handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   454
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   455
  // Check if unused block follow last
489c9b5090e2 Initial load
duke
parents:
diff changeset
   456
  if (_last->_next != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   457
    // update last and retry
489c9b5090e2 Initial load
duke
parents:
diff changeset
   458
    _last = _last->_next;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   459
    return allocate_handle(obj);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   460
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   461
489c9b5090e2 Initial load
duke
parents:
diff changeset
   462
  // No space available, we have to rebuild free list or expand
489c9b5090e2 Initial load
duke
parents:
diff changeset
   463
  if (_allocate_before_rebuild == 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   464
      rebuild_free_list();        // updates _allocate_before_rebuild counter
489c9b5090e2 Initial load
duke
parents:
diff changeset
   465
  } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   466
    // Append new block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   467
    Thread* thread = Thread::current();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   468
    Handle obj_handle(thread, obj);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   469
    // This can block, so we need to preserve obj accross call.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   470
    _last->_next = JNIHandleBlock::allocate_block(thread);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   471
    _last = _last->_next;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   472
    _allocate_before_rebuild--;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   473
    obj = obj_handle();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   474
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   475
  return allocate_handle(obj);  // retry
489c9b5090e2 Initial load
duke
parents:
diff changeset
   476
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   477
489c9b5090e2 Initial load
duke
parents:
diff changeset
   478
489c9b5090e2 Initial load
duke
parents:
diff changeset
   479
void JNIHandleBlock::rebuild_free_list() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   480
  assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   481
  int free = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   482
  int blocks = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   483
  for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   484
    for (int index = 0; index < current->_top; index++) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   485
      oop* handle = &(current->_handles)[index];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   486
      if (*handle ==  JNIHandles::deleted_handle()) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   487
        // this handle was cleared out by a delete call, reuse it
489c9b5090e2 Initial load
duke
parents:
diff changeset
   488
        *handle = (oop) _free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   489
        _free_list = handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   490
        free++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   491
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   492
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   493
    // we should not rebuild free list if there are unused handles at the end
489c9b5090e2 Initial load
duke
parents:
diff changeset
   494
    assert(current->_top == block_size_in_oops, "just checking");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   495
    blocks++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   496
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   497
  // Heuristic: if more than half of the handles are free we rebuild next time
489c9b5090e2 Initial load
duke
parents:
diff changeset
   498
  // as well, otherwise we append a corresponding number of new blocks before
489c9b5090e2 Initial load
duke
parents:
diff changeset
   499
  // attempting a free list rebuild again.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   500
  int total = blocks * block_size_in_oops;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   501
  int extra = total - 2*free;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   502
  if (extra > 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   503
    // Not as many free handles as we would like - compute number of new blocks to append
489c9b5090e2 Initial load
duke
parents:
diff changeset
   504
    _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   505
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   506
  if (TraceJNIHandleAllocation) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   507
    tty->print_cr("Rebuild free list JNIHandleBlock " INTPTR_FORMAT " blocks=%d used=%d free=%d add=%d",
489c9b5090e2 Initial load
duke
parents:
diff changeset
   508
      this, blocks, total-free, free, _allocate_before_rebuild);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   509
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   510
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   511
489c9b5090e2 Initial load
duke
parents:
diff changeset
   512
489c9b5090e2 Initial load
duke
parents:
diff changeset
   513
bool JNIHandleBlock::contains(jobject handle) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   514
  return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   515
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   516
489c9b5090e2 Initial load
duke
parents:
diff changeset
   517
489c9b5090e2 Initial load
duke
parents:
diff changeset
   518
bool JNIHandleBlock::chain_contains(jobject handle) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   519
  for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   520
    if (current->contains(handle)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   521
      return true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   522
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   523
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   524
  return false;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   525
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   526
489c9b5090e2 Initial load
duke
parents:
diff changeset
   527
489c9b5090e2 Initial load
duke
parents:
diff changeset
   528
int JNIHandleBlock::length() const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   529
  int result = 1;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   530
  for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   531
    result++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   532
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   533
  return result;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   534
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   535
489c9b5090e2 Initial load
duke
parents:
diff changeset
   536
// This method is not thread-safe, i.e., must be called whule holding a lock on the
489c9b5090e2 Initial load
duke
parents:
diff changeset
   537
// structure.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   538
long JNIHandleBlock::memory_usage() const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   539
  return length() * sizeof(JNIHandleBlock);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   540
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   541
489c9b5090e2 Initial load
duke
parents:
diff changeset
   542
489c9b5090e2 Initial load
duke
parents:
diff changeset
   543
#ifndef PRODUCT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   544
489c9b5090e2 Initial load
duke
parents:
diff changeset
   545
bool JNIHandleBlock::any_contains(jobject handle) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   546
  for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   547
    if (current->contains(handle)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   548
      return true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   549
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   550
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   551
  return false;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   552
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   553
489c9b5090e2 Initial load
duke
parents:
diff changeset
   554
void JNIHandleBlock::print_statistics() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   555
  int used_blocks = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   556
  int free_blocks = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   557
  int used_handles = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   558
  int free_handles = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   559
  JNIHandleBlock* block = _block_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   560
  while (block != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   561
    if (block->_top > 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   562
      used_blocks++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   563
    } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   564
      free_blocks++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   565
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   566
    used_handles += block->_top;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   567
    free_handles += (block_size_in_oops - block->_top);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   568
    block = block->_block_list_link;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   569
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   570
  tty->print_cr("JNIHandleBlocks statistics");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   571
  tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   572
  tty->print_cr("- blocks in use:    %d", used_blocks);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   573
  tty->print_cr("- blocks free:      %d", free_blocks);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   574
  tty->print_cr("- handles in use:   %d", used_handles);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   575
  tty->print_cr("- handles free:     %d", free_handles);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   576
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   577
489c9b5090e2 Initial load
duke
parents:
diff changeset
   578
#endif