method

transaction

v1_9_1_378 - Show latest stable - 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 318
  def transaction(read_only = false, &block)  # :yields:  pstore
    value = nil
    raise PStore::Error, "nested transaction" if @transaction
    @lock.synchronize do
      @rdonly = read_only
      @transaction = true
      @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 if !file.closed?
        end
      else
        # This can only occur if read_only == true.
        @table = {}
        catch(:pstore_abort_transaction) do
          value = yield(self)
        end
      end
    end
    value
  ensure
    @transaction = false
  end

transaction

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