method

transaction

Ruby latest stable (v2_5_5) - 0 notes - Class: PStore

transaction(read_only = false) public

Opens a new transaction for the data store. Code executed inside a block passed to this method may read and write data to and from the data store file.

At the end of the block, changes are committed to the data store automatically. You may exit the transaction early with a call to either PStore#commit or PStore#abort. See those methods for details about how changes are handled. Raising an uncaught Exception in the block is equivalent to calling PStore#abort.

If read_only is set to true, you will only be allowed to read from the data store during the transaction and any attempts to change the data will raise a PStore::Error.

Note that PStore does not support nested transactions.

Show source

# File lib/pstore.rb, line 311
  def transaction(read_only = false)  # :yields:  pstore
    value = nil
    if !@thread_safe
      raise PStore::Error, "nested transaction" unless @lock.try_lock
    else
      begin
        @lock.lock
      rescue ThreadError
        raise PStore::Error, "nested transaction"
      end
    end
    begin
      @rdonly = read_only
      @abort = false
      file = open_and_lock_file(@filename, read_only)
      if file
        begin
          @table, checksum, original_data_size = load_data(file, read_only)

          catch(:pstore_abort_transaction) do
            value = yield(self)
          end

          if !@abort && !read_only
            save_data(checksum, original_data_size, file)
          end
        ensure
          file.close
        end
      else
        # This can only occur if read_only == true.
        @table = {}
        catch(:pstore_abort_transaction) do
          value = yield(self)
        end
      end
    ensure
      @lock.unlock
    end
    value
  end

transaction

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