hotspot/src/share/vm/runtime/jniHandles.cpp
author pliden
Fri, 11 Apr 2014 12:29:24 +0200
changeset 24094 5dbf1f44de18
parent 22556 a17351e8c2c2
child 24424 2658d7834c6e
permissions -rw-r--r--
8039147: Cleanup SuspendibleThreadSet Reviewed-by: brutisso, tschatzl, mgerdin
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/*
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 * Copyright (c) 1998, 2014, 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 "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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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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    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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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::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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  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 AlwaysAliveClosure: public BoolObjectClosure {
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public:
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  bool do_object_b(oop obj) { return true; }
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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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  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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    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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   322
    if ( freelist != NULL ) {
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   323
      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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   327
  }
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   328
  if (block != NULL) {
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   329
    // Return blocks to free list
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   330
    // locking with safepoint checking introduces a potential deadlock:
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   331
    // - we would hold JNIHandleBlockFreeList_lock and then Threads_lock
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   332
    // - another would hold Threads_lock (jni_AttachCurrentThread) and then
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   333
    //   JNIHandleBlockFreeList_lock (JNIHandleBlock::allocate_block)
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   334
    MutexLockerEx ml(JNIHandleBlockFreeList_lock,
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   335
                     Mutex::_no_safepoint_check_flag);
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   336
    while (block != NULL) {
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   337
      if (ZapJNIHandleArea) block->zap();
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   338
      JNIHandleBlock* next = block->_next;
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   339
      block->_next = _block_free_list;
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      _block_free_list = block;
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   341
      block = next;
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   342
    }
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   343
  }
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   344
  if (pop_frame_link != NULL) {
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   345
    // As a sanity check we release blocks pointed to by the pop_frame_link.
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   346
    // This should never happen (only if PopLocalFrame is not called the
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   347
    // correct number of times).
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   348
    release_block(pop_frame_link, thread);
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   349
  }
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}
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   351
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   352
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   353
void JNIHandleBlock::oops_do(OopClosure* f) {
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   354
  JNIHandleBlock* current_chain = this;
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   355
  // Iterate over chain of blocks, followed by chains linked through the
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   356
  // pop frame links.
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   357
  while (current_chain != NULL) {
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   358
    for (JNIHandleBlock* current = current_chain; current != NULL;
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   359
         current = current->_next) {
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   360
      assert(current == current_chain || current->pop_frame_link() == NULL,
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   361
        "only blocks first in chain should have pop frame link set");
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   362
      for (int index = 0; index < current->_top; index++) {
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   363
        oop* root = &(current->_handles)[index];
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   364
        oop value = *root;
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   365
        // traverse heap pointers only, not deleted handles or free list
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   366
        // pointers
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   367
        if (value != NULL && Universe::heap()->is_in_reserved(value)) {
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   368
          f->do_oop(root);
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   369
        }
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   370
      }
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   371
      // the next handle block is valid only if current block is full
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   372
      if (current->_top < block_size_in_oops) {
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   373
        break;
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   374
      }
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   375
    }
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   376
    current_chain = current_chain->pop_frame_link();
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   377
  }
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   378
}
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   379
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   380
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   381
void JNIHandleBlock::weak_oops_do(BoolObjectClosure* is_alive,
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   382
                                  OopClosure* f) {
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   383
  for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
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   384
    assert(current->pop_frame_link() == NULL,
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   385
      "blocks holding weak global JNI handles should not have pop frame link set");
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   386
    for (int index = 0; index < current->_top; index++) {
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   387
      oop* root = &(current->_handles)[index];
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   388
      oop value = *root;
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   389
      // traverse heap pointers only, not deleted handles or free list pointers
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   390
      if (value != NULL && Universe::heap()->is_in_reserved(value)) {
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   391
        if (is_alive->do_object_b(value)) {
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parents:
diff changeset
   392
          // The weakly referenced object is alive, update pointer
489c9b5090e2 Initial load
duke
parents:
diff changeset
   393
          f->do_oop(root);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   394
        } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   395
          // The weakly referenced object is not alive, clear the reference by storing NULL
489c9b5090e2 Initial load
duke
parents:
diff changeset
   396
          if (TraceReferenceGC) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   397
            tty->print_cr("Clearing JNI weak reference (" INTPTR_FORMAT ")", root);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   398
          }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   399
          *root = NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   400
        }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   401
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   402
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   403
    // the next handle block is valid only if current block is full
489c9b5090e2 Initial load
duke
parents:
diff changeset
   404
    if (current->_top < block_size_in_oops) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   405
      break;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   406
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   407
  }
7896
08aadd7aa3ee 6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents: 7397
diff changeset
   408
08aadd7aa3ee 6458402: 3 jvmti tests fail with CMS and +ExplicitGCInvokesConcurrent
kamg
parents: 7397
diff changeset
   409
  /*
7918
ce1e4ae77aea 7012505: BreakpointWithFullGC.sh fails with Internal Error (src/share/vm/oops/methodOop.cpp:220)
kamg
parents: 7896
diff changeset
   410
   * 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
   411
   * 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
   412
   */
7918
ce1e4ae77aea 7012505: BreakpointWithFullGC.sh fails with Internal Error (src/share/vm/oops/methodOop.cpp:220)
kamg
parents: 7896
diff changeset
   413
  JvmtiExport::weak_oops_do(is_alive, f);
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   414
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   415
489c9b5090e2 Initial load
duke
parents:
diff changeset
   416
489c9b5090e2 Initial load
duke
parents:
diff changeset
   417
jobject JNIHandleBlock::allocate_handle(oop obj) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   418
  assert(Universe::heap()->is_in_reserved(obj), "sanity check");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   419
  if (_top == 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   420
    // This is the first allocation or the initial block got zapped when
489c9b5090e2 Initial load
duke
parents:
diff changeset
   421
    // entering a native function. If we have any following blocks they are
489c9b5090e2 Initial load
duke
parents:
diff changeset
   422
    // not valid anymore.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   423
    for (JNIHandleBlock* current = _next; current != NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   424
         current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   425
      assert(current->_last == NULL, "only first block should have _last set");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   426
      assert(current->_free_list == NULL,
489c9b5090e2 Initial load
duke
parents:
diff changeset
   427
             "only first block should have _free_list set");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   428
      current->_top = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   429
      if (ZapJNIHandleArea) current->zap();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   430
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   431
    // Clear initial block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   432
    _free_list = NULL;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   433
    _allocate_before_rebuild = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   434
    _last = this;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   435
    if (ZapJNIHandleArea) zap();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   436
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   437
489c9b5090e2 Initial load
duke
parents:
diff changeset
   438
  // Try last block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   439
  if (_last->_top < block_size_in_oops) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   440
    oop* handle = &(_last->_handles)[_last->_top++];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   441
    *handle = obj;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   442
    return (jobject) handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   443
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   444
489c9b5090e2 Initial load
duke
parents:
diff changeset
   445
  // Try free list
489c9b5090e2 Initial load
duke
parents:
diff changeset
   446
  if (_free_list != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   447
    oop* handle = _free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   448
    _free_list = (oop*) *_free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   449
    *handle = obj;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   450
    return (jobject) handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   451
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   452
  // Check if unused block follow last
489c9b5090e2 Initial load
duke
parents:
diff changeset
   453
  if (_last->_next != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   454
    // update last and retry
489c9b5090e2 Initial load
duke
parents:
diff changeset
   455
    _last = _last->_next;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   456
    return allocate_handle(obj);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   457
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   458
489c9b5090e2 Initial load
duke
parents:
diff changeset
   459
  // No space available, we have to rebuild free list or expand
489c9b5090e2 Initial load
duke
parents:
diff changeset
   460
  if (_allocate_before_rebuild == 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   461
      rebuild_free_list();        // updates _allocate_before_rebuild counter
489c9b5090e2 Initial load
duke
parents:
diff changeset
   462
  } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   463
    // Append new block
489c9b5090e2 Initial load
duke
parents:
diff changeset
   464
    Thread* thread = Thread::current();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   465
    Handle obj_handle(thread, obj);
22551
9bf46d16dcc6 8025856: Fix typos in the GC code
jwilhelm
parents: 22234
diff changeset
   466
    // This can block, so we need to preserve obj across call.
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   467
    _last->_next = JNIHandleBlock::allocate_block(thread);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   468
    _last = _last->_next;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   469
    _allocate_before_rebuild--;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   470
    obj = obj_handle();
489c9b5090e2 Initial load
duke
parents:
diff changeset
   471
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   472
  return allocate_handle(obj);  // retry
489c9b5090e2 Initial load
duke
parents:
diff changeset
   473
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   474
489c9b5090e2 Initial load
duke
parents:
diff changeset
   475
489c9b5090e2 Initial load
duke
parents:
diff changeset
   476
void JNIHandleBlock::rebuild_free_list() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   477
  assert(_allocate_before_rebuild == 0 && _free_list == NULL, "just checking");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   478
  int free = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   479
  int blocks = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   480
  for (JNIHandleBlock* current = this; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   481
    for (int index = 0; index < current->_top; index++) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   482
      oop* handle = &(current->_handles)[index];
489c9b5090e2 Initial load
duke
parents:
diff changeset
   483
      if (*handle ==  JNIHandles::deleted_handle()) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   484
        // this handle was cleared out by a delete call, reuse it
489c9b5090e2 Initial load
duke
parents:
diff changeset
   485
        *handle = (oop) _free_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   486
        _free_list = handle;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   487
        free++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   488
      }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   489
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   490
    // we should not rebuild free list if there are unused handles at the end
489c9b5090e2 Initial load
duke
parents:
diff changeset
   491
    assert(current->_top == block_size_in_oops, "just checking");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   492
    blocks++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   493
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   494
  // Heuristic: if more than half of the handles are free we rebuild next time
489c9b5090e2 Initial load
duke
parents:
diff changeset
   495
  // as well, otherwise we append a corresponding number of new blocks before
489c9b5090e2 Initial load
duke
parents:
diff changeset
   496
  // attempting a free list rebuild again.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   497
  int total = blocks * block_size_in_oops;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   498
  int extra = total - 2*free;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   499
  if (extra > 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   500
    // Not as many free handles as we would like - compute number of new blocks to append
489c9b5090e2 Initial load
duke
parents:
diff changeset
   501
    _allocate_before_rebuild = (extra + block_size_in_oops - 1) / block_size_in_oops;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   502
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   503
  if (TraceJNIHandleAllocation) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   504
    tty->print_cr("Rebuild free list JNIHandleBlock " INTPTR_FORMAT " blocks=%d used=%d free=%d add=%d",
489c9b5090e2 Initial load
duke
parents:
diff changeset
   505
      this, blocks, total-free, free, _allocate_before_rebuild);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   506
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   507
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   508
489c9b5090e2 Initial load
duke
parents:
diff changeset
   509
489c9b5090e2 Initial load
duke
parents:
diff changeset
   510
bool JNIHandleBlock::contains(jobject handle) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   511
  return ((jobject)&_handles[0] <= handle && handle<(jobject)&_handles[_top]);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   512
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   513
489c9b5090e2 Initial load
duke
parents:
diff changeset
   514
489c9b5090e2 Initial load
duke
parents:
diff changeset
   515
bool JNIHandleBlock::chain_contains(jobject handle) const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   516
  for (JNIHandleBlock* current = (JNIHandleBlock*) this; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   517
    if (current->contains(handle)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   518
      return true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   519
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   520
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   521
  return false;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   522
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   523
489c9b5090e2 Initial load
duke
parents:
diff changeset
   524
489c9b5090e2 Initial load
duke
parents:
diff changeset
   525
int JNIHandleBlock::length() const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   526
  int result = 1;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   527
  for (JNIHandleBlock* current = _next; current != NULL; current = current->_next) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   528
    result++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   529
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   530
  return result;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   531
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   532
22551
9bf46d16dcc6 8025856: Fix typos in the GC code
jwilhelm
parents: 22234
diff changeset
   533
// This method is not thread-safe, i.e., must be called while holding a lock on the
1
489c9b5090e2 Initial load
duke
parents:
diff changeset
   534
// structure.
489c9b5090e2 Initial load
duke
parents:
diff changeset
   535
long JNIHandleBlock::memory_usage() const {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   536
  return length() * sizeof(JNIHandleBlock);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   537
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   538
489c9b5090e2 Initial load
duke
parents:
diff changeset
   539
489c9b5090e2 Initial load
duke
parents:
diff changeset
   540
#ifndef PRODUCT
489c9b5090e2 Initial load
duke
parents:
diff changeset
   541
489c9b5090e2 Initial load
duke
parents:
diff changeset
   542
bool JNIHandleBlock::any_contains(jobject handle) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   543
  for (JNIHandleBlock* current = _block_list; current != NULL; current = current->_block_list_link) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   544
    if (current->contains(handle)) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   545
      return true;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   546
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   547
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   548
  return false;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   549
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   550
489c9b5090e2 Initial load
duke
parents:
diff changeset
   551
void JNIHandleBlock::print_statistics() {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   552
  int used_blocks = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   553
  int free_blocks = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   554
  int used_handles = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   555
  int free_handles = 0;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   556
  JNIHandleBlock* block = _block_list;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   557
  while (block != NULL) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   558
    if (block->_top > 0) {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   559
      used_blocks++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   560
    } else {
489c9b5090e2 Initial load
duke
parents:
diff changeset
   561
      free_blocks++;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   562
    }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   563
    used_handles += block->_top;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   564
    free_handles += (block_size_in_oops - block->_top);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   565
    block = block->_block_list_link;
489c9b5090e2 Initial load
duke
parents:
diff changeset
   566
  }
489c9b5090e2 Initial load
duke
parents:
diff changeset
   567
  tty->print_cr("JNIHandleBlocks statistics");
489c9b5090e2 Initial load
duke
parents:
diff changeset
   568
  tty->print_cr("- blocks allocated: %d", used_blocks + free_blocks);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   569
  tty->print_cr("- blocks in use:    %d", used_blocks);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   570
  tty->print_cr("- blocks free:      %d", free_blocks);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   571
  tty->print_cr("- handles in use:   %d", used_handles);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   572
  tty->print_cr("- handles free:     %d", free_handles);
489c9b5090e2 Initial load
duke
parents:
diff changeset
   573
}
489c9b5090e2 Initial load
duke
parents:
diff changeset
   574
489c9b5090e2 Initial load
duke
parents:
diff changeset
   575
#endif