Mercurial > hg > graal-jvmci-8
view src/share/vm/runtime/reflectionUtils.hpp @ 1716:be3f9c242c9d
6948538: CMS: BOT walkers can fall into object allocation and initialization cracks
Summary: GC workers now recognize an intermediate transient state of blocks which are allocated but have not yet completed initialization. blk_start() calls do not attempt to determine the size of a block in the transient state, rather waiting for the block to become initialized so that it is safe to query its size. Audited and ensured the order of initialization of object fields (klass, free bit and size) to respect block state transition protocol. Also included some new assertion checking code enabled in debug mode.
Reviewed-by: chrisphi, johnc, poonam
author | ysr |
---|---|
date | Mon, 16 Aug 2010 15:58:42 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
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/* * Copyright (c) 1999, 2005, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ // A KlassStream is an abstract stream for streaming over self, superclasses // and (super)interfaces. Streaming is done in reverse order (subclasses first, // interfaces last). // // for (KlassStream st(k, false, false); !st.eos(); st.next()) { // klassOop k = st.klass(); // ... // } class KlassStream VALUE_OBJ_CLASS_SPEC { protected: instanceKlassHandle _klass; // current klass/interface iterated over objArrayHandle _interfaces; // transitive interfaces for initial class int _interface_index; // current interface being processed bool _local_only; // process initial class/interface only bool _classes_only; // process classes only (no interfaces) int _index; virtual int length() const = 0; public: // constructor KlassStream(instanceKlassHandle klass, bool local_only, bool classes_only); // testing bool eos(); // iterating virtual void next() = 0; // accessors instanceKlassHandle klass() const { return _klass; } int index() const { return _index; } }; // A MethodStream streams over all methods in a class, superclasses and (super)interfaces. // Streaming is done in reverse order (subclasses first, methods in reverse order) // Usage: // // for (MethodStream st(k, false, false); !st.eos(); st.next()) { // methodOop m = st.method(); // ... // } class MethodStream : public KlassStream { private: int length() const { return methods()->length(); } objArrayOop methods() const { return _klass->methods(); } public: MethodStream(instanceKlassHandle klass, bool local_only, bool classes_only) : KlassStream(klass, local_only, classes_only) { _index = length(); next(); } void next() { _index--; } methodOop method() const { return methodOop(methods()->obj_at(index())); } }; // A FieldStream streams over all fields in a class, superclasses and (super)interfaces. // Streaming is done in reverse order (subclasses first, fields in reverse order) // Usage: // // for (FieldStream st(k, false, false); !st.eos(); st.next()) { // symbolOop field_name = st.name(); // ... // } class FieldStream : public KlassStream { private: int length() const { return fields()->length(); } constantPoolOop constants() const { return _klass->constants(); } protected: typeArrayOop fields() const { return _klass->fields(); } public: FieldStream(instanceKlassHandle klass, bool local_only, bool classes_only) : KlassStream(klass, local_only, classes_only) { _index = length(); next(); } void next() { _index -= instanceKlass::next_offset; } // Accessors for current field AccessFlags access_flags() const { AccessFlags flags; flags.set_flags(fields()->ushort_at(index() + instanceKlass::access_flags_offset)); return flags; } symbolOop name() const { int name_index = fields()->ushort_at(index() + instanceKlass::name_index_offset); return constants()->symbol_at(name_index); } symbolOop signature() const { int signature_index = fields()->ushort_at(index() + instanceKlass::signature_index_offset); return constants()->symbol_at(signature_index); } // missing: initval() int offset() const { return _klass->offset_from_fields( index() ); } }; class FilteredField { private: klassOop _klass; int _field_offset; public: FilteredField(klassOop klass, int field_offset) { _klass = klass; _field_offset = field_offset; } klassOop klass() { return _klass; } oop* klass_addr() { return (oop*) &_klass; } int field_offset() { return _field_offset; } }; class FilteredFieldsMap : AllStatic { private: static GrowableArray<FilteredField *> *_filtered_fields; public: static void initialize(); static bool is_filtered_field(klassOop klass, int field_offset) { for (int i=0; i < _filtered_fields->length(); i++) { if (klass == _filtered_fields->at(i)->klass() && field_offset == _filtered_fields->at(i)->field_offset()) { return true; } } return false; } static int filtered_fields_count(klassOop klass, bool local_only) { int nflds = 0; for (int i=0; i < _filtered_fields->length(); i++) { if (local_only && klass == _filtered_fields->at(i)->klass()) { nflds++; } else if (klass->klass_part()->is_subtype_of(_filtered_fields->at(i)->klass())) { nflds++; } } return nflds; } // GC support. static void klasses_oops_do(OopClosure* f) { for (int i = 0; i < _filtered_fields->length(); i++) { f->do_oop((oop*)_filtered_fields->at(i)->klass_addr()); } } }; // A FilteredFieldStream streams over all fields in a class, superclasses and // (super)interfaces. Streaming is done in reverse order (subclasses first, // fields in reverse order) // // Usage: // // for (FilteredFieldStream st(k, false, false); !st.eos(); st.next()) { // symbolOop field_name = st.name(); // ... // } class FilteredFieldStream : public FieldStream { private: int _filtered_fields_count; bool has_filtered_field() { return (_filtered_fields_count > 0); } public: FilteredFieldStream(instanceKlassHandle klass, bool local_only, bool classes_only) : FieldStream(klass, local_only, classes_only) { _filtered_fields_count = FilteredFieldsMap::filtered_fields_count((klassOop)klass(), local_only); } int field_count(); void next() { _index -= instanceKlass::next_offset; if (has_filtered_field()) { while (_index >=0 && FilteredFieldsMap::is_filtered_field((klassOop)_klass(), offset())) { _index -= instanceKlass::next_offset; } } } };