Module: Transaction::Simple

Included in:
ThreadSafe
Defined in:
lib/transaction/simple.rb

Defined Under Namespace

Modules: ThreadSafe Classes: Group

Constant Summary collapse

VERSION =
TRANSACTION_SIMPLE_VERSION = '1.4.0.2'
SKIP_TRANSACTION_VARS =
%w(@__transaction_checkpoint__ @__transaction_level__)

Class Attribute Summary collapse

Class Method Summary collapse

Instance Method Summary collapse

Class Attribute Details

.debug_with_checkpointObject

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


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# File 'lib/transaction/simple.rb', line 64

def debug_with_checkpoint
  @debug_with_checkpoint
end

Class Method Details

.__common_start(name, vars, &block) ⇒ Object


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# File 'lib/transaction/simple.rb', line 384

def __common_start(name, vars, &block)
  raise Transaction::TransactionError, ___tmessage[:cannot_start_empty_block_transaction] if vars.empty?

  if block
    begin
      vlevel = {}

      vars.each do |vv|
        vv.extend(Transaction::Simple)
        vv.start_transaction(name)
        vlevel[vv.__id__] = vv.instance_variable_get(:@__transaction_level__)
        vv.instance_variable_set(:@__transaction_block__, vlevel[vv.__id__])
      end

      yield(*vars)
    rescue Transaction::TransactionAborted
      vars.each do |vv|
        if name.nil? and vv.transaction_open?
          loop do
            tlevel = vv.instance_variable_get(:@__transaction_level__) || -1
            vv.instance_variable_set(:@__transaction_block__, -1)
            break if tlevel < vlevel[vv.__id__]
            vv.abort_transaction if vv.transaction_open?
          end
        elsif vv.transaction_open?(name)
          vv.instance_variable_set(:@__transaction_block__, -1)
          vv.abort_transaction(name)
        end
      end
    rescue Transaction::TransactionCommitted
      nil
    ensure
      vars.each do |vv|
        if name.nil? and vv.transaction_open?
          loop do
            tlevel = vv.instance_variable_get(:@__transaction_level__) || -1
            break if tlevel < vlevel[vv.__id__]
            vv.instance_variable_set(:@__transaction_block__, -1)
            vv.commit_transaction if vv.transaction_open?
          end
        elsif vv.transaction_open?(name)
          vv.instance_variable_set(:@__transaction_block__, -1)
          vv.commit_transaction(name)
        end
      end
    end
  else
    vars.each do |vv|
      vv.extend(Transaction::Simple)
      vv.start_transaction(name)
    end
  end
end

.debug(format, *args) ⇒ Object

Fast debugging.


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# File 'lib/transaction/simple.rb', line 78

def debug(format, *args)
  return unless debugging?
  debug_io << (format % args)
end

.debug_ioObject

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


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# File 'lib/transaction/simple.rb', line 72

def debug_io
  @tdi ||= ""
  @tdi
end

.debug_io=(io) ⇒ Object

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


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# File 'lib/transaction/simple.rb', line 51

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?Boolean

Returns true if we are debugging.

Returns:

  • (Boolean)

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# File 'lib/transaction/simple.rb', line 67

def debugging?
  defined? @debugging and @debugging
end

.start(*vars, &block) ⇒ Object

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


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# File 'lib/transaction/simple.rb', line 447

def start(*vars, &block)
  __common_start(nil, vars, &block)
end

.start_named(name, *vars, &block) ⇒ Object

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


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# File 'lib/transaction/simple.rb', line 441

def start_named(name, *vars, &block)
  __common_start(name, vars, &block)
end

Instance Method Details

#abort_transaction(name = nil) ⇒ Object

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.


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# File 'lib/transaction/simple.rb', line 269

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) ⇒ Object

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.


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# File 'lib/transaction/simple.rb', line 300

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) ⇒ Object

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

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# File 'lib/transaction/simple.rb', line 221

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) ⇒ Object

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.


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# File 'lib/transaction/simple.rb', line 147

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) ⇒ Object

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?


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# File 'lib/transaction/simple.rb', line 347

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_exclusionsObject

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"

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# File 'lib/transaction/simple.rb', line 379

def transaction_exclusions
  @transaction_exclusions ||= []
end

#transaction_nameObject

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


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# File 'lib/transaction/simple.rb', line 129

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) ⇒ Boolean

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.

Returns:

  • (Boolean)

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# File 'lib/transaction/simple.rb', line 110

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