Module: Simple::SQL::Transactions

Included in:
Simple::SQL
Defined in:
lib/simple/sql/transactions.rb

Overview

private

Constant Summary collapse

SELF = 
self

Class Method Summary collapse

Instance Method Summary collapse

Class Method Details

.nesting_level ⇒ Object 



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# File 'lib/simple/sql/transactions.rb', line 5

def self.nesting_level
  Thread.current[:nesting_level] ||= 0
end

.nesting_level=(nesting_level) ⇒ Object 



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# File 'lib/simple/sql/transactions.rb', line 9

def self.nesting_level=(nesting_level)
  Thread.current[:nesting_level] = nesting_level
end

Instance Method Details

#transaction(&block) ⇒ Object 



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# File 'lib/simple/sql/transactions.rb', line 13

def transaction(&block)
  # Notes: by using "ensure" (as opposed to rescue) we are rolling back 
  # both when an exception was raised and when a value was thrown. This 
  # also means we have to track whether or not to rollback. i.e. do roll
  # back when we yielded to &block but not otherwise.
  #
  # Also the transaction support is a bit limited: you cannot rollback.
  # Rolling back from inside a nested transaction would require SAVEPOINT
  # support; without the code is simpler at least :)
  if SELF.nesting_level == 0
    transaction_started = true
    ask "BEGIN"
  end

  SELF.nesting_level += 1

  return_value = yield

  # Only commit if we started a transaction here.
  if transaction_started
    ask "COMMIT"
    transaction_committed = true
  end

  return_value
ensure
  SELF.nesting_level -= 1
  if transaction_started && !transaction_committed
    ask "ROLLBACK"
  end
end