alvinalexander.com | career | drupal | java | mac | mysql | perl | scala | uml | unix  

Java example source code file (filemap.hpp)

This example Java source code file (filemap.hpp) is included in the alvinalexander.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" TM.

Learn more about this Java project at its project page.

Java - Java tags/keywords

cds_only, filemapheader, filemapinfo, jvm_arch_max, jvm_ident_max, jvm_shared_jars_max, metaspace, not_cds_return_, number, objectalignmentinbytes, reservedspace, share_vm_memory_filemap_hpp, sharedmisccodesize, sharedmiscdatasize

The filemap.hpp Java example source code

/*
 * Copyright (c) 2003, 2013, 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.
 *
 */

#ifndef SHARE_VM_MEMORY_FILEMAP_HPP
#define SHARE_VM_MEMORY_FILEMAP_HPP

#include "memory/metaspaceShared.hpp"
#include "memory/metaspace.hpp"

// Layout of the file:
//  header: dump of archive instance plus versioning info, datestamp, etc.
//   [magic # = 0xF00BABA2]
//  ... padding to align on page-boundary
//  read-write space from CompactingPermGenGen
//  read-only space from CompactingPermGenGen
//  misc data (block offset table, string table, symbols, dictionary, etc.)
//  tag(666)

static const int JVM_SHARED_JARS_MAX = 128;
static const int JVM_SPACENAME_MAX = 128;
static const int JVM_IDENT_MAX = 256;
static const int JVM_ARCH_MAX = 12;


class Metaspace;

class FileMapInfo : public CHeapObj<mtInternal> {
private:
  enum {
    _invalid_version = -1,
    _current_version = 1
  };

  bool  _file_open;
  int   _fd;
  long  _file_offset;

  // FileMapHeader describes the shared space data in the file to be
  // mapped.  This structure gets written to a file.  It is not a class, so
  // that the compilers don't add any compiler-private data to it.

  struct FileMapHeader {
    int    _magic;                    // identify file type.
    int    _version;                  // (from enum, above.)
    size_t _alignment;                // how shared archive should be aligned
    int    _obj_alignment;            // value of ObjectAlignmentInBytes

    struct space_info {
      int    _file_offset;   // sizeof(this) rounded to vm page size
      char*  _base;          // copy-on-write base address
      size_t _capacity;      // for validity checking
      size_t _used;          // for setting space top on read
      bool   _read_only;     // read only space?
      bool   _allow_exec;    // executable code in space?
    } _space[MetaspaceShared::n_regions];

    // The following fields are all sanity checks for whether this archive
    // will function correctly with this JVM and the bootclasspath it's
    // invoked with.
    char  _arch[JVM_ARCH_MAX];            // architecture
    char  _jvm_ident[JVM_IDENT_MAX];      // identifier for jvm
    int   _num_jars;              // Number of jars in bootclasspath

    // Per jar file data:  timestamp, size.

    struct {
      time_t _timestamp;          // jar timestamp.
      long   _filesize;           // jar file size.
    } _jar[JVM_SHARED_JARS_MAX];
  } _header;
  const char* _full_path;

  static FileMapInfo* _current_info;

  bool  init_from_file(int fd);
  void  align_file_position();

public:
  FileMapInfo() {
    _file_offset = 0;
    _file_open = false;
    _header._version = _invalid_version;
  }

  static int current_version()        { return _current_version; }
  void   populate_header(size_t alignment);
  bool   validate();
  void   invalidate();
  int    version()                    { return _header._version; }
  size_t alignment()                  { return _header._alignment; }
  size_t space_capacity(int i)        { return _header._space[i]._capacity; }
  char*  region_base(int i)           { return _header._space[i]._base; }
  struct FileMapHeader* header()      { return &_header; }

  static void set_current_info(FileMapInfo* info) {
    CDS_ONLY(_current_info = info;)
  }

  static FileMapInfo* current_info() {
    CDS_ONLY(return _current_info;)
    NOT_CDS(return NULL;)
  }

  static void assert_mark(bool check);

  // File manipulation.
  bool  initialize() NOT_CDS_RETURN_(false);
  bool  open_for_read();
  void  open_for_write();
  void  write_header();
  void  write_space(int i, Metaspace* space, bool read_only);
  void  write_region(int region, char* base, size_t size,
                     size_t capacity, bool read_only, bool allow_exec);
  void  write_bytes(const void* buffer, int count);
  void  write_bytes_aligned(const void* buffer, int count);
  char* map_region(int i);
  void  unmap_region(int i);
  void  close();
  bool  is_open() { return _file_open; }
  ReservedSpace reserve_shared_memory();

  // JVM/TI RedefineClasses() support:
  // Remap the shared readonly space to shared readwrite, private.
  bool  remap_shared_readonly_as_readwrite();

  // Errors.
  static void fail_stop(const char *msg, ...);
  void fail_continue(const char *msg, ...);

  // Return true if given address is in the mapped shared space.
  bool is_in_shared_space(const void* p) NOT_CDS_RETURN_(false);
  void print_shared_spaces() NOT_CDS_RETURN;

  static size_t shared_spaces_size() {
    return align_size_up(SharedReadOnlySize + SharedReadWriteSize +
                         SharedMiscDataSize + SharedMiscCodeSize,
                         os::vm_allocation_granularity());
  }

  // Stop CDS sharing and unmap CDS regions.
  static void stop_sharing_and_unmap(const char* msg);
};

#endif // SHARE_VM_MEMORY_FILEMAP_HPP

Other Java examples (source code examples)

Here is a short list of links related to this Java filemap.hpp source code file:

... this post is sponsored by my books ...

#1 New Release!

FP Best Seller

 

new blog posts

 

Copyright 1998-2021 Alvin Alexander, alvinalexander.com
All Rights Reserved.

A percentage of advertising revenue from
pages under the /java/jwarehouse URI on this website is
paid back to open source projects.