view src/share/vm/utilities/defaultStream.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) 2003, 2004, 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 defaultStream : public xmlTextStream {
  friend void ostream_abort();
 public:
  enum { NO_WRITER = -1 };
 private:
  bool         _inited;
  fileStream*  _log_file;  // XML-formatted file shared by all threads
  static int   _output_fd;
  static int   _error_fd;
  static FILE* _output_stream;
  static FILE* _error_stream;

  void init();
  void init_log();
  void finish_log();
  void finish_log_on_error(char *buf, int buflen);
 public:
  // must defer time stamp due to the fact that os::init() hasn't
  // yet been called and os::elapsed_counter() may not be valid
  defaultStream() {
    _log_file = NULL;
    _inited = false;
    _writer = -1;
    _last_writer = -1;
  }

  ~defaultStream() {
    if (has_log_file())  finish_log();
  }

  static inline FILE* output_stream() {
    return DisplayVMOutputToStderr ? _error_stream : _output_stream;
  }
  static inline FILE* error_stream() {
    return DisplayVMOutputToStdout ? _output_stream : _error_stream;
  }
  static inline int output_fd() {
    return DisplayVMOutputToStderr ? _error_fd : _output_fd;
  }
  static inline int error_fd() {
    return DisplayVMOutputToStdout ? _output_fd : _error_fd;
  }

  virtual void write(const char* s, size_t len);

  void flush() {
    // once we can determine whether we are in a signal handler, we
    // should add the following assert here:
    // assert(xxxxxx, "can not flush buffer inside signal handler");
    xmlTextStream::flush();
    fflush(output_stream());
    if (has_log_file()) _log_file->flush();
  }

  // advisory lock/unlock of _writer field:
 private:
  intx _writer;    // thread_id with current rights to output
  intx _last_writer;
 public:
  intx hold(intx writer_id);
  void release(intx holder);
  intx writer() { return _writer; }
  bool has_log_file();

  static defaultStream* instance;  // sole instance
};