PStore ^(Class)

# File pstore.rb, line 22
  def initialize(file)
    dir = File::dirname(file)
    unless File::directory? dir
      raise PStore::Error, format("directory %s does not exist", dir)
    end
    if File::exist? file and not File::readable? file
      raise PStore::Error, format("file %s not readable", file)
    end
    @transaction = false
    @filename = file
    @abort = false
  end

# File pstore.rb, line 40
  def [](name)
    in_transaction
    @table[name]
  end

# File pstore.rb, line 54
  def []=(name, value)
    in_transaction
    @table[name] = value
  end

# File pstore.rb, line 80
  def abort
    in_transaction
    @abort = true
    throw :pstore_abort_transaction
  end

# File pstore.rb, line 75
  def commit
    in_transaction
    @abort = false
    throw :pstore_abort_transaction
  end

# File pstore.rb, line 58
  def delete(name)
    in_transaction
    @table.delete name
  end

# File pstore.rb, line 44
  def fetch(name, default=PStore::Error)
    unless @table.key? name
      if default==PStore::Error
        raise PStore::Error, format("undefined root name `%s'", name)
      else
        default
      end
    end
    self[name]
  end

# File pstore.rb, line 71
  def path
    @filename
  end

# File pstore.rb, line 67
  def root?(name)
    in_transaction
    @table.key? name
  end

# File pstore.rb, line 63
  def roots
    in_transaction
    @table.keys
  end

# File pstore.rb, line 86
  def transaction(read_only=false)
    raise PStore::Error, "nested transaction" if @transaction
    begin
      @transaction = true
      value = nil
      backup = @filename+"~"
      begin
        file = File::open(@filename, read_only ? "rb" : "rb+")
        orig = true
      rescue Errno::ENOENT
        raise if read_only
        file = File::open(@filename, "wb+")
      end
      file.flock(read_only ? File::LOCK_SH : File::LOCK_EX)
      if read_only
        @table = Marshal::load(file)
      elsif orig and (content = file.read) != ""
        @table = Marshal::load(content)
        size = content.size
        md5 = Digest::MD5.digest(content)
        content = nil          # unreference huge data

      else
        @table = {}
      end
      begin
        catch(:pstore_abort_transaction) do
          value = yield(self)
        end
      rescue Exception
        @abort = true
        raise
      ensure
        if !read_only and !@abort
          file.rewind
          content = Marshal::dump(@table)
          if !md5 || size != content.size || md5 != Digest::MD5.digest(content)
            File::copy @filename, backup
            begin
              file.write(content)
              file.truncate(file.pos)
              content = nil            # unreference huge data

            rescue
              File::rename backup, @filename if File::exist?(backup)
              raise
            end
          end
        end
        if @abort and !orig
          File.unlink(@filename)
        end
        @abort = false
      end
    ensure
      @table = nil
      @transaction = false
      file.close if file
    end
    value
  end