Send mails in after_create_commit hook

[vangberg]

#262

The AsyncAdapter will run jobs immediately. When a mail is sent via perform_later in an after_create hook, the job could run before the record exists in the database, since after_create hooks are executed before the transaction is completed:

1. Contact.create opens a new transaction.
2. after_create is run with the transaction still open.
3. If the job runs before the transaction is committed, the Contact record does not exist yet.

By changing to an after_create_commit hook, we ensure that the Contact actually exists. Same goes for Notification.

I can reproduce this consistently in the production console:

original = Contact.find(30)

Contact.transaction do
  c = original.dup
  c.subject = "ASYNC BAD #{Time.now}"
  c.message = original.message.body.to_html
  c.save!

  puts "created #{c.id}; holding transaction open"
  sleep 1
end

This never sends an email. If I manually switch out the hooks and run the above block again, it reliably sends emails:

  Contact.skip_callback(:create, :after, :send_message)
  Contact.set_callback(:commit, :after, :send_message, on: :create)

[lmrodriguezr]

Excellent! That makes perfect sense, thanks!