Module: Transaction::Simple

### Home Classes Methods

### In Files

- lib/transaction/simple.rb

### Namespace

- MODULE Transaction::Simple::ThreadSafe
- CLASS Transaction::Simple::Group

### Methods

- ::debug
- ::debug_io
- ::debug_io=
- ::debugging?
- ::start
- ::start_named
- #abort_transaction
- #commit_transaction
- #rewind_transaction
- #start_transaction
- #transaction
- #transaction_exclusions
- #transaction_name
- #transaction_open?

### Files

- History.rdoc
- Manifest.txt
- README.rdoc

### Class/Module Index

Quicksearch

- Transaction
- Transaction::Simple
- Transaction::Simple::Group
- Transaction::Simple::ThreadSafe
- Transaction::Simple::ThreadSafe::Group
- Transaction::TransactionAborted
- Transaction::TransactionCommitted
- Transaction::TransactionError
- Transaction::TransactionThreadError

No matching classes.

# Transaction::Simple

### Constants

SKIP_TRANSACTION_VARS
VERSION

### Attributes

debug_with_checkpoint[RW]

Set to `true` if you want the checkpoint printed with debugging messages where it matters.

### Public Class Methods

debug(format, *args) click to toggle source

Fast debugging.

    # File lib/transaction/simple.rb, line 77
    def debug(format, *args)
      return unless debugging?
      debug_io << (format % args)
    end

debug_io() click to toggle source

Returns the Transaction::Simple debug object. It must respond to #<<.

    # File lib/transaction/simple.rb, line 71
    def debug_io
      @tdi ||= ""
      @tdi
    end

debug_io=(io) click to toggle source

Sets the Transaction::Simple debug object. It must respond to #<<. Debugging will be performed automatically if there's a debug object.

    # File lib/transaction/simple.rb, line 50
    def debug_io=(io)
      if io.nil?
        @tdi        = nil
        @debugging  = false
      else
        raise Transaction::TransactionError, Transaction::Messages[:bad_debug_object] unless io.respond_to?(:<<)
        @tdi = io
        @debugging = true
      end
    end

debugging?() click to toggle source

Returns `true` if we are debugging.

    # File lib/transaction/simple.rb, line 66
    def debugging?
      defined? @debugging and @debugging
    end

start(*vars, &block) click to toggle source

Start a named transaction in a block. The transaction will auto-commit when the block finishes.

    # File lib/transaction/simple.rb, line 446
    def start(*vars, &block)
      __common_start(nil, vars, &block)
    end

start_named(name, *vars, &block) click to toggle source

Start a named transaction in a block. The transaction will auto-commit when the block finishes.

    # File lib/transaction/simple.rb, line 440
    def start_named(name, *vars, &block)
      __common_start(name, vars, &block)
    end

### Public Instance Methods

abort_transaction(name = nil) click to toggle source

Aborts the transaction. Rewinds the object state to what it was before the transaction was started and closes the transaction. If `name` is specified, then the intervening transactions and the named transaction will be aborted. Otherwise, only the current transaction is aborted.

See rewind_transaction for information about dealing with complex self-referential object graphs.

If the current or named transaction has been started by a block (Transaction::Simple.start), then the execution of the block will be halted with `break` `self`.

    # File lib/transaction/simple.rb, line 268
    def abort_transaction(name = nil)
      raise Transaction::TransactionError, ___tmessage[:cannot_abort_no_transaction] if @__transaction_checkpoint__.nil?

      # Check to see if we are trying to abort a transaction that is outside
      # of the current transaction block. Otherwise, raise TransactionAborted
      # if they are the same.
      defined? @__transaction_block__ or @__transaction_block__ = nil
      if @__transaction_block__ and name
        nix = @__transaction_names__.index(name) + 1
        raise Transaction::TransactionError, ___tmessage[:cannot_abort_transaction_before_block] if nix < @__transaction_block__
        raise Transaction::TransactionAborted if @__transaction_block__ == nix
      end

      raise Transaction::TransactionAborted if @__transaction_block__ == @__transaction_level__

      if name.nil?
        __abort_transaction(name)
      else
        raise Transaction::TransactionError, ___tmessage[:cannot_abort_named_transaction] % name.inspect unless @__transaction_names__.include?(name)
        __abort_transaction(name) while @__transaction_names__.include?(name)
      end

      self
    end

commit_transaction(name = nil) click to toggle source

If `name` is `nil` (default), the current transaction level is closed out and the changes are committed.

If `name` is specified and `name` is in the list of named transactions, then all transactions are closed and committed until the named transaction is reached.

    # File lib/transaction/simple.rb, line 299
    def commit_transaction(name = nil)
      raise Transaction::TransactionError, ___tmessage[:cannot_commit_no_transaction] if @__transaction_checkpoint__.nil?
      @__transaction_block__ ||= nil

      # Check to see if we are trying to commit a transaction that is outside
      # of the current transaction block. Otherwise, raise
      # TransactionCommitted if they are the same.
      if @__transaction_block__ and name
        nix = @__transaction_names__.index(name) + 1
        raise Transaction::TransactionError, ___tmessage[:cannot_commit_transaction_before_block] if nix < @__transaction_block__

        raise Transaction::TransactionCommitted if @__transaction_block__ == nix
      end

      raise Transaction::TransactionCommitted if @__transaction_block__ == @__transaction_level__

      if name.nil?
        ___tdebug "<", "%s(%s)", ___tmessage[:commit_transaction], name.inspect
        __commit_transaction
      else
        raise Transaction::TransactionError, ___tmessage[:cannot_commit_named_transaction] % name.inspect unless @__transaction_names__.include?(name)

        while @__transaction_names__.last != name
          ___tdebug "<", "%s(%s)", ___tmessage[:commit_transaction], name.inspect
          __commit_transaction
          ___tdebug_checkpoint
        end

        ___tdebug "<", "%s(%s)", ___tmessage[:commit_transaction], name.inspect
        __commit_transaction
      end

      ___tdebug_checkpoint

      self
    end

rewind_transaction(name = nil) click to toggle source

Rewinds the transaction. If `name` is specified, then the intervening transactions will be aborted and the named transaction will be rewound. Otherwise, only the current transaction is rewound.

After each level of transaction is rewound, if the callback method #_post_transaction_rewind is defined, it will be called. It is intended to allow a complex self-referential graph to fix itself. The simplest way to explain this is with an example.

    class Child
      attr_accessor :parent
    end

    class Parent
      include Transaction::Simple

      attr_reader :children
      def initialize
        @children = []
      end

      def << child
        child.parent = self
        @children << child
      end

      def valid?
        @children.all? { |child| child.parent == self }
      end
    end

    parent = Parent.new
    parent << Child.new
    parent.start_transaction
    parent << Child.new
    parent.abort_transaction
    puts parent.valid? # => false

This problem can be fixed by modifying the Parent class to include the #_post_transaction_rewind callback.

    class Parent
      # Reconnect the restored children to me, instead of to the bogus me
      # that was restored to them by Marshal::load.
      def _post_transaction_rewind
        @children.each { |child| child.parent = self }
      end
    end

    parent = Parent.new
    parent << Child.new
    parent.start_transaction
    parent << Child.new
    parent.abort_transaction
    puts parent.valid? # => true

    # File lib/transaction/simple.rb, line 220
    def rewind_transaction(name = nil)
      raise Transaction::TransactionError, ___tmessage[:cannot_rewind_no_transaction] if @__transaction_checkpoint__.nil?

      # Check to see if we are trying to rewind a transaction that is outside
      # of the current transaction block.
      defined? @__transaction_block__ or @__transaction_block__ = nil
      if @__transaction_block__ and name
        nix = @__transaction_names__.index(name) + 1
        raise Transaction::TransactionError, ___tmessage[:cannot_rewind_transaction_before_block] if nix < @__transaction_block__
      end

      if name.nil?
        checkpoint = @__transaction_checkpoint__
        __rewind_this_transaction
        @__transaction_checkpoint__ = checkpoint
      else
        raise Transaction::TransactionError, ___tmessage[:cannot_rewind_named_transaction] % name.inspect unless @__transaction_names__.include?(name)

        while @__transaction_names__.last != name
          ___tdebug_checkpoint
          @__transaction_checkpoint__ = __rewind_this_transaction
          ___tdebug '<', ___tmessage[:rewind_transaction], name
          @__transaction_level__ -= 1
          @__transaction_names__.pop
        end

        checkpoint = @__transaction_checkpoint__
        __rewind_this_transaction
        @__transaction_checkpoint__ = checkpoint
      end

      ___tdebug '|', "%s(%s)", ___tmessage[:rewind_transaction], name.inspect
      ___tdebug_checkpoint

      self
    end

start_transaction(name = nil) click to toggle source

Starts a transaction. Stores the current object state. If a transaction name is specified, the transaction will be named. Transaction names must be unique. Transaction names of `nil` will be treated as unnamed transactions.

    # File lib/transaction/simple.rb, line 146
    def start_transaction(name = nil)
      @__transaction_level__ ||= 0
      @__transaction_names__ ||= []

      name = name.dup.freeze if name.kind_of?(String)

      raise Transaction::TransactionError, ___tmessage[:unique_names] if name and @__transaction_names__.include?(name)

      @__transaction_names__ << name
      @__transaction_level__ += 1

      ___tdebug '>', "%s(%s)", ___tmessage[:start_transaction], name.inspect
      ___tdebug_checkpoint

      checkpoint = Marshal.dump(self)

      @__transaction_checkpoint__ = Marshal.dump(self)
    end

transaction(action = nil, name = nil) click to toggle source

Alternative method for calling the transaction methods. An optional name can be specified for named transaction support. This method is deprecated and will be removed in Transaction::Simple 2.0.

transaction(:start) | start_transaction
transaction(:rewind) | rewind_transaction
transaction(:abort) | abort_transaction
transaction(:commit) | commit_transaction
transaction(:name) | transaction_name
transaction | transaction_open?

    # File lib/transaction/simple.rb, line 346
    def transaction(action = nil, name = nil)
      _method = case action
                when :start then :start_transaction
                when :rewind then :rewind_transaction
                when :abort then :abort_transaction
                when :commit then :commit_transaction
                when :name then :transaction_name
                when nil then :transaction_open?
                else nil
                end

      if _method
        warn "The #transaction method has been deprecated. Use #{_method} instead."
      else
        warn "The #transaction method has been deprecated."
      end

      case _method
      when :transaction_name
        __send__ _method
      when nil
        nil
      else
        __send__ _method, name
      end
    end

transaction_exclusions() click to toggle source

Allows specific variables to be excluded from transaction support. Must be done after extending the object but before starting the first transaction on the object.

    vv.transaction_exclusions << "@io"

    # File lib/transaction/simple.rb, line 378
    def transaction_exclusions
      @transaction_exclusions ||= []
    end

transaction_name() click to toggle source

Returns the current name of the transaction. Transactions not explicitly named are named `nil`.

    # File lib/transaction/simple.rb, line 128
    def transaction_name
      raise Transaction::TransactionError, ___tmessage[:no_transaction_open] if @__transaction_checkpoint__.nil?

      name = @__transaction_names__.last

      ___tdebug '|', "%s(%s)", ___tmessage[:transaction_name], name.inspect

      if name.kind_of?(String)
        name.dup
      else
        name
      end
    end

transaction_open?(name = nil) click to toggle source

If `name` is `nil` (default), then returns `true` if there is currently a transaction open. If `name` is specified, then returns `true` if there is currently a transaction known as `name` open.

    # File lib/transaction/simple.rb, line 109
    def transaction_open?(name = nil)
      defined? @__transaction_checkpoint__ or @__transaction_checkpoint__ = nil

      has_t = nil

      if name.nil?
        has_t = (not @__transaction_checkpoint__.nil?)
      else
        has_t = ((not @__transaction_checkpoint__.nil?) and
                 @__transaction_names__.include?(name))
      end

      ___tdebug '>', "%s [%s]", ___tmessage[:transaction], ___tmessage[has_t ? :opened : :closed]

      has_t
    end

[Validate]

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