src/hotspot/share/runtime/jniHandles.cpp
author erikj
Tue, 12 Sep 2017 19:03:39 +0200
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parent 46703 hotspot/src/share/vm/runtime/jniHandles.cpp@f152b500376e
child 47649 12623954920e
permissions -rw-r--r--
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/*
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 * Copyright (c) 1998, 2017, Oracle and/or its affiliates. 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 Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 * or visit www.oracle.com if you need additional information or have any
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 * questions.
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 *
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 */
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#include "precompiled.hpp"
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#include "classfile/systemDictionary.hpp"
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#include "logging/log.hpp"
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#include "memory/iterator.hpp"
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#include "oops/oop.inline.hpp"
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#include "prims/jvmtiExport.hpp"
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#include "runtime/jniHandles.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "runtime/thread.inline.hpp"
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#include "utilities/align.hpp"
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#if INCLUDE_ALL_GCS
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#include "gc/g1/g1SATBCardTableModRefBS.hpp"
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#endif
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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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  assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC");
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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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  assert(!Universe::heap()->is_gc_active(), "can't extend the root set during GC");
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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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    {
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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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    }
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    // Add weak tag.
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    assert(is_aligned(res, weak_tag_alignment), "invariant");
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    char* tptr = reinterpret_cast<char*>(res) + weak_tag_value;
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    res = reinterpret_cast<jobject>(tptr);
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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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template<bool external_guard>
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oop JNIHandles::resolve_jweak(jweak handle) {
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  assert(is_jweak(handle), "precondition");
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  oop result = jweak_ref(handle);
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  result = guard_value<external_guard>(result);
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#if INCLUDE_ALL_GCS
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  if (result != NULL && UseG1GC) {
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    G1SATBCardTableModRefBS::enqueue(result);
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  }
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#endif // INCLUDE_ALL_GCS
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  return result;
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}
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template oop JNIHandles::resolve_jweak<true>(jweak);
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template oop JNIHandles::resolve_jweak<false>(jweak);
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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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    jobject_ref(handle) = deleted_handle();
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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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    jweak_ref(handle) = deleted_handle();
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  }
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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::weak_oops_do(OopClosure* f) {
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  AlwaysTrueClosure always_true;
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  weak_oops_do(&always_true, 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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  Klass* k      = SystemDictionary::Object_klass();
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  _deleted_handle = InstanceKlass::cast(k)->allocate_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 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* ooph) {
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    if (*ooph != JNIHandles::deleted_handle()) {
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      _count++;
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    }
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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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  oops_do(&global_handle_count);
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  weak_oops_do(&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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  oops_do(&verify_handle);
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  weak_oops_do(&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 (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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  block->_planned_capacity = block_size_in_oops;
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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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    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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    // Add original freelist to end of chain
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    if ( freelist != NULL ) {
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      while ( block->_next != NULL ) block = block->_next;
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      block->_next = freelist;
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    }
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    block = NULL;
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  }
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  if (block != NULL) {
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    // Return blocks to free list
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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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    while (block != NULL) {
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      if (ZapJNIHandleArea) block->zap();
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      JNIHandleBlock* next = block->_next;
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      block->_next = _block_free_list;
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      _block_free_list = block;
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      block = next;
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    }
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  }
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diff changeset
   365
  if (pop_frame_link != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   366
    // As a sanity check we release blocks pointed to by the pop_frame_link.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   367
    // This should never happen (only if PopLocalFrame is not called the
489c9b5090e2 Initial load
duke
parents:
diff changeset
   368
    // correct number of times).
489c9b5090e2 Initial load
duke
parents:
diff changeset
   369
    release_block(pop_frame_link, thread);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   370
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   371
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   372
489c9b5090e2 Initial load
duke
parents:
diff changeset
   373
489c9b5090e2 Initial load
duke
parents:
diff changeset
   374
void JNIHandleBlock::oops_do(OopClosure* f) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   375
  JNIHandleBlock* current_chain = this;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   376
  // Iterate over chain of blocks, followed by chains linked through the
489c9b5090e2 Initial load
duke
parents:
diff changeset
   377
  // pop frame links.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   378
  while (current_chain != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   379
    for (JNIHandleBlock* current = current_chain; current != NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   380
         current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   381
      assert(current == current_chain || current->pop_frame_link() == NULL,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   382
        "only blocks first in chain should have pop frame link set");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   383
      for (int index = 0; index < current->_top; index++) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   384
        oop* root = &(current->_handles)[index];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   385
        oop value = *root;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   386
        // traverse heap pointers only, not deleted handles or free list
489c9b5090e2 Initial load
duke
parents:
diff changeset
   387
        // pointers
489c9b5090e2 Initial load
duke
parents:
diff changeset
   388
        if (value != NULL && Universe::heap()->is_in_reserved(value)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   389
          f->do_oop(root);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   390
        }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   391
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   392
      // the next handle block is valid only if current block is full
489c9b5090e2 Initial load
duke
parents:
diff changeset
   393
      if (current->_top < block_size_in_oops) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   394
        break;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   395
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   396
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   397
    current_chain = current_chain->pop_frame_link();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   398
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   399
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   400
489c9b5090e2 Initial load
duke
parents:
diff changeset
   401
32817
acc2744fd84b 8136627: Backout JDK-8133818 Additional number of processed references printed with -XX:+PrintReferenceGC after JDK-8047125
kbarrett
parents: 32607
diff changeset
   402
void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive,
acc2744fd84b 8136627: Backout JDK-8133818 Additional number of processed references printed with -XX:+PrintReferenceGC after JDK-8047125
kbarrett
parents: 32607
diff changeset
   403
                                  OopClosure* f) {
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   404
  for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   405
    assert(current->pop_frame_link() == NULL,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   406
      "blocks holding weak global JNI handles should not have pop frame link set");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   407
    for (int index = 0; index < current->_top; index++) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   408
      oop* root = &(current->_handles)[index];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   409
      oop value = *root;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   410
      // traverse heap pointers only, not deleted handles or free list pointers
489c9b5090e2 Initial load
duke
parents:
diff changeset
   411
      if (value != NULL && Universe::heap()->is_in_reserved(value)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   412
        if (is_alive->do_object_b(value)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   413
          // The weakly referenced object is alive, update pointer
489c9b5090e2 Initial load
duke
parents:
diff changeset
   414
          f->do_oop(root);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   415
        } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   416
          // The weakly referenced object is not alive, clear the reference by storing NULL
35061
be6025ebffea 8145092: Use Unified Logging for the GC logging
brutisso
parents: 33148
diff changeset
   417
          log_develop_trace(gc, ref)("Clearing JNI weak reference (" INTPTR_FORMAT ")", p2i(root));
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   418
          *root = NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   419
        }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   420
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   421
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   422
    // the next handle block is valid only if current block is full
489c9b5090e2 Initial load
duke
parents:
diff changeset
   423
    if (current->_top < block_size_in_oops) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   424
      break;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   425
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   426
  }
7896
08aadd7aa3ee 6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents: 7397
diff changeset
   427
08aadd7aa3ee 6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents: 7397
diff changeset
   428
  /*
7918
ce1e4ae77aea 7012505: BreakpointWithFullGC.sh fails with Internal Error (src/share/vm/oops/methodOop.cpp:220)
kamg
parents: 7896
diff changeset
   429
   * JVMTI data structures may also contain weak oops.  The iteration of them
ce1e4ae77aea 7012505: BreakpointWithFullGC.sh fails with Internal Error (src/share/vm/oops/methodOop.cpp:220)
kamg
parents: 7896
diff changeset
   430
   * is placed here so that we don't need to add it to each of the collectors.
7896
08aadd7aa3ee 6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents: 7397
diff changeset
   431
   */
32817
acc2744fd84b 8136627: Backout JDK-8133818 Additional number of processed references printed with -XX:+PrintReferenceGC after JDK-8047125
kbarrett
parents: 32607
diff changeset
   432
  JvmtiExport::weak_oops_do(is_alive, f);
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   433
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   434
489c9b5090e2 Initial load
duke
parents:
diff changeset
   435
489c9b5090e2 Initial load
duke
parents:
diff changeset
   436
jobject JNIHandleBlock::allocate_handle(oop obj) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   437
  assert(Universe::heap()->is_in_reserved(obj), "sanity check");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   438
  if (_top == 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   439
    // This is the first allocation or the initial block got zapped when
489c9b5090e2 Initial load
duke
parents:
diff changeset
   440
    // entering a native function. If we have any following blocks they are
489c9b5090e2 Initial load
duke
parents:
diff changeset
   441
    // not valid anymore.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   442
    for (JNIHandleBlock* current = _next; current != NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   443
         current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   444
      assert(current->_last == NULL, "only first block should have _last set");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   445
      assert(current->_free_list == NULL,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   446
             "only first block should have _free_list set");
46703
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   447
      if (current->_top == 0) {
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   448
        // All blocks after the first clear trailing block are already cleared.
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   449
#ifdef ASSERT
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   450
        for (current = current->_next; current != NULL; current = current->_next) {
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   451
          assert(current->_top == 0, "trailing blocks must already be cleared");
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   452
        }
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   453
#endif
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   454
        break;
f152b500376e 8175318: Performance issue regarding local JNI references
kbarrett
parents: 46625
diff changeset
   455
      }
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   456
      current->_top = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   457
      if (ZapJNIHandleArea) current->zap();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   458
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   459
    // Clear initial block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   460
    _free_list = NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   461
    _allocate_before_rebuild = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   462
    _last = this;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   463
    if (ZapJNIHandleArea) zap();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   464
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   465
489c9b5090e2 Initial load
duke
parents:
diff changeset
   466
  // Try last block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   467
  if (_last->_top < block_size_in_oops) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   468
    oop* handle = &(_last->_handles)[_last->_top++];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   469
    *handle = obj;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   470
    return (jobject) handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   471
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   472
489c9b5090e2 Initial load
duke
parents:
diff changeset
   473
  // Try free list
489c9b5090e2 Initial load
duke
parents:
diff changeset
   474
  if (_free_list != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   475
    oop* handle = _free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   476
    _free_list = (oop*) *_free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   477
    *handle = obj;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   478
    return (jobject) handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   479
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   480
  // Check if unused block follow last
489c9b5090e2 Initial load
duke
parents:
diff changeset
   481
  if (_last->_next != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   482
    // update last and retry
489c9b5090e2 Initial load
duke
parents:
diff changeset
   483
    _last = _last->_next;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   484
    return allocate_handle(obj);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   485
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   486
489c9b5090e2 Initial load
duke
parents:
diff changeset
   487
  // No space available, we have to rebuild free list or expand
489c9b5090e2 Initial load
duke
parents:
diff changeset
   488
  if (_allocate_before_rebuild == 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   489
      rebuild_free_list();        // updates _allocate_before_rebuild counter
489c9b5090e2 Initial load
duke
parents:
diff changeset
   490
  } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   491
    // Append new block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   492
    Thread* thread = Thread::current();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   493
    Handle obj_handle(thread, obj);
22551
9bf46d16dcc6 8025856: Fix typos in the GC code
jwilhelm
parents: 22234
diff changeset
   494
    // This can block, so we need to preserve obj across call.
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   495
    _last->_next = JNIHandleBlock::allocate_block(thread);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   496
    _last = _last->_next;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   497
    _allocate_before_rebuild--;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   498
    obj = obj_handle();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   499
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   500
  return allocate_handle(obj);  // retry
489c9b5090e2 Initial load
duke
parents:
diff changeset
   501
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   502
36508
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   503
void JNIHandleBlock::release_handle(jobject h) {
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   504
  if (h != NULL) {
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   505
    assert(chain_contains(h), "does not contain the JNI handle");
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   506
    // Mark the handle as deleted, allocate will reuse it
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   507
    *((oop*)h) = JNIHandles::deleted_handle();
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   508
  }
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   509
}
5f9eee6b383b 8142968: Module System implementation
alanb
parents: 36398
diff changeset
   510
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   511
489c9b5090e2 Initial load
duke
parents:
diff changeset
   512
void JNIHandleBlock::rebuild_free_list() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   513
  assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   514
  int free = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   515
  int blocks = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   516
  for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   517
    for (int index = 0; index < current->_top; index++) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   518
      oop* handle = &(current->_handles)[index];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   519
      if (*handle ==  JNIHandles::deleted_handle()) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   520
        // this handle was cleared out by a delete call, reuse it
489c9b5090e2 Initial load
duke
parents:
diff changeset
   521
        *handle = (oop) _free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   522
        _free_list = handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   523
        free++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   524
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   525
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   526
    // we should not rebuild free list if there are unused handles at the end
489c9b5090e2 Initial load
duke
parents:
diff changeset
   527
    assert(current->_top == block_size_in_oops, "just checking");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   528
    blocks++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   529
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   530
  // Heuristic: if more than half of the handles are free we rebuild next time
489c9b5090e2 Initial load
duke
parents:
diff changeset
   531
  // as well, otherwise we append a corresponding number of new blocks before
489c9b5090e2 Initial load
duke
parents:
diff changeset
   532
  // attempting a free list rebuild again.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   533
  int total = blocks * block_size_in_oops;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   534
  int extra = total - 2*free;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   535
  if (extra > 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   536
    // Not as many free handles as we would like - compute number of new blocks to append
489c9b5090e2 Initial load
duke
parents:
diff changeset
   537
    _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   538
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   539
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   540
489c9b5090e2 Initial load
duke
parents:
diff changeset
   541
489c9b5090e2 Initial load
duke
parents:
diff changeset
   542
bool JNIHandleBlock::contains(jobject handle) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   543
  return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   544
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   545
489c9b5090e2 Initial load
duke
parents:
diff changeset
   546
489c9b5090e2 Initial load
duke
parents:
diff changeset
   547
bool JNIHandleBlock::chain_contains(jobject handle) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   548
  for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   549
    if (current->contains(handle)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   550
      return true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   551
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   552
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   553
  return false;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   554
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   555
489c9b5090e2 Initial load
duke
parents:
diff changeset
   556
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   557
int JNIHandleBlock::length() const {
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   558
  int result = 1;
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   559
  for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) {
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   560
    result++;
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   561
  }
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   562
  return result;
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parents:
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   563
}
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   564
25058
4542f853c2ac 8043224: -Xcheck:jni improvements to exception checking and excessive local refs
dsimms
parents: 24424
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   565
const size_t JNIHandleBlock::get_number_of_live_handles() {
4542f853c2ac 8043224: -Xcheck:jni improvements to exception checking and excessive local refs
dsimms
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   566
  CountHandleClosure counter;
4542f853c2ac 8043224: -Xcheck:jni improvements to exception checking and excessive local refs
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   567
  oops_do(&counter);
4542f853c2ac 8043224: -Xcheck:jni improvements to exception checking and excessive local refs
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parents: 24424
diff changeset
   568
  return counter.count();
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dsimms
parents: 24424
diff changeset
   569
}
4542f853c2ac 8043224: -Xcheck:jni improvements to exception checking and excessive local refs
dsimms
parents: 24424
diff changeset
   570
22551
9bf46d16dcc6 8025856: Fix typos in the GC code
jwilhelm
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   571
// This method is not thread-safe, i.e., must be called while holding a lock on the
1
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   572
// structure.
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   573
long JNIHandleBlock::memory_usage() const {
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   574
  return length() * sizeof(JNIHandleBlock);
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   575
}
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   576
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   577
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   578
#ifndef PRODUCT
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   579
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   580
bool JNIHandleBlock::any_contains(jobject handle) {
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   581
  for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) {
489c9b5090e2 Initial load
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   582
    if (current->contains(handle)) {
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   583
      return true;
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   584
    }
489c9b5090e2 Initial load
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   585
  }
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   586
  return false;
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   587
}
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   588
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   589
void JNIHandleBlock::print_statistics() {
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   590
  int used_blocks = 0;
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parents:
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   591
  int free_blocks = 0;
489c9b5090e2 Initial load
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parents:
diff changeset
   592
  int used_handles = 0;
489c9b5090e2 Initial load
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parents:
diff changeset
   593
  int free_handles = 0;
489c9b5090e2 Initial load
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parents:
diff changeset
   594
  JNIHandleBlock* block = _block_list;
489c9b5090e2 Initial load
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parents:
diff changeset
   595
  while (block != NULL) {
489c9b5090e2 Initial load
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parents:
diff changeset
   596
    if (block->_top > 0) {
489c9b5090e2 Initial load
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parents:
diff changeset
   597
      used_blocks++;
489c9b5090e2 Initial load
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parents:
diff changeset
   598
    } else {
489c9b5090e2 Initial load
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parents:
diff changeset
   599
      free_blocks++;
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parents:
diff changeset
   600
    }
489c9b5090e2 Initial load
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parents:
diff changeset
   601
    used_handles += block->_top;
489c9b5090e2 Initial load
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parents:
diff changeset
   602
    free_handles += (block_size_in_oops - block->_top);
489c9b5090e2 Initial load
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parents:
diff changeset
   603
    block = block->_block_list_link;
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parents:
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   604
  }
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parents:
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   605
  tty->print_cr("JNIHandleBlocks statistics");
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parents:
diff changeset
   606
  tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks);
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parents:
diff changeset
   607
  tty->print_cr("- blocks in use:    %d", used_blocks);
489c9b5090e2 Initial load
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parents:
diff changeset
   608
  tty->print_cr("- blocks free:      %d", free_blocks);
489c9b5090e2 Initial load
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parents:
diff changeset
   609
  tty->print_cr("- handles in use:   %d", used_handles);
489c9b5090e2 Initial load
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parents:
diff changeset
   610
  tty->print_cr("- handles free:     %d", free_handles);
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parents:
diff changeset
   611
}
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   612
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parents:
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   613
#endif