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view src/share/vm/runtime/atomic.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 |
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date | Mon, 16 Aug 2010 15:58:42 -0700 |
parents | c18cbe5936b8 |
children | f95d63e2154a |
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/* * Copyright (c) 1999, 2009, 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. * */ class Atomic : AllStatic { public: // Atomically store to a location static void store (jbyte store_value, jbyte* dest); static void store (jshort store_value, jshort* dest); static void store (jint store_value, jint* dest); static void store (jlong store_value, jlong* dest); static void store_ptr(intptr_t store_value, intptr_t* dest); static void store_ptr(void* store_value, void* dest); static void store (jbyte store_value, volatile jbyte* dest); static void store (jshort store_value, volatile jshort* dest); static void store (jint store_value, volatile jint* dest); static void store (jlong store_value, volatile jlong* dest); static void store_ptr(intptr_t store_value, volatile intptr_t* dest); static void store_ptr(void* store_value, volatile void* dest); static jlong load(volatile jlong* src); // Atomically add to a location, return updated value static jint add (jint add_value, volatile jint* dest); static intptr_t add_ptr(intptr_t add_value, volatile intptr_t* dest); static void* add_ptr(intptr_t add_value, volatile void* dest); // Atomically increment location static void inc (volatile jint* dest); static void inc_ptr(volatile intptr_t* dest); static void inc_ptr(volatile void* dest); // Atomically decrement a location static void dec (volatile jint* dest); static void dec_ptr(volatile intptr_t* dest); static void dec_ptr(volatile void* dest); // Performs atomic exchange of *dest with exchange_value. Returns old prior value of *dest. static jint xchg(jint exchange_value, volatile jint* dest); static unsigned int xchg(unsigned int exchange_value, volatile unsigned int* dest); static intptr_t xchg_ptr(intptr_t exchange_value, volatile intptr_t* dest); static void* xchg_ptr(void* exchange_value, volatile void* dest); // Performs atomic compare of *dest and compare_value, and exchanges *dest with exchange_value // if the comparison succeeded. Returns prior value of *dest. Guarantees a two-way memory // barrier across the cmpxchg. I.e., it's really a 'fence_cmpxchg_acquire'. static jbyte cmpxchg (jbyte exchange_value, volatile jbyte* dest, jbyte compare_value); static jint cmpxchg (jint exchange_value, volatile jint* dest, jint compare_value); static jlong cmpxchg (jlong exchange_value, volatile jlong* dest, jlong compare_value); static unsigned int cmpxchg(unsigned int exchange_value, volatile unsigned int* dest, unsigned int compare_value); static intptr_t cmpxchg_ptr(intptr_t exchange_value, volatile intptr_t* dest, intptr_t compare_value); static void* cmpxchg_ptr(void* exchange_value, volatile void* dest, void* compare_value); };