# Copyright (c) 2005 Jamis Buck
#
# Permission is hereby granted, free of charge, to any person obtaining
# a copy of this software and associated documentation files (the
# "Software"), to deal in the Software without restriction, including
# without limitation the rights to use, copy, modify, merge, publish,
# distribute, sublicense, and/or sell copies of the Software, and to
# permit persons to whom the Software is furnished to do so, subject to
# the following conditions:
#
# The above copyright notice and this permission notice shall be
# included in all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
module DeadlockRetry
  def self.append_features(base)
    super
    base.extend(ClassMethods)
    base.class_eval do
      class <<self
        alias_method :transaction_without_deadlock_handling, :transaction
        alias_method :transaction, :transaction_with_deadlock_handling
      end
    end
  end

  module ClassMethods
    DEADLOCK_ERROR_MESSAGES = [
      "Deadlock found when trying to get lock",
      "Lock wait timeout exceeded",
      "deadlock detected"
    ]

    MAXIMUM_RETRIES_ON_DEADLOCK = 3

    def transaction_with_deadlock_handling(*objects, &block)
      retry_count = 0

      begin
        transaction_without_deadlock_handling(*objects, &block)
      rescue ActiveRecord::StatementInvalid => error
        raise unless connection.open_transactions.zero?
        if DEADLOCK_ERROR_MESSAGES.any? { |msg| error.message =~ /#{Regexp.escape(msg)}/ }
          raise if retry_count >= MAXIMUM_RETRIES_ON_DEADLOCK
          retry_count += 1
          logger.info "Deadlock detected on retry #{retry_count}, restarting transaction"
          retry
        else
          raise
        end
      end
    end
  end
end