feat: new background work process

This removes all previous dependencies on RabbitMQ and the need to run separate cron and requeueing processes.

app/models/queued_message.rb

@@ -29,33 +29,18 @@
 class QueuedMessage < ApplicationRecord
 
   include HasMessage
+  include HasLocking
 
   belongs_to :server
   belongs_to :ip_address, optional: true
   belongs_to :user, optional: true
 
   before_create :allocate_ip_address
-  after_commit :queue, on: :create
 
-  scope :unlocked, -> { where(locked_at: nil) }
-  scope :retriable, -> { where("retry_after IS NULL OR retry_after < ?", Time.now) }
-  scope :requeueable, -> { where("retry_after IS NULL OR retry_after < ?", 30.seconds.ago) }
+  scope :ready_with_delayed_retry, -> { where("retry_after IS NULL OR retry_after < ?", 30.seconds.ago) }
 
-  def retriable?
-    retry_after.nil? || retry_after < Time.now
-  end
-
-  def queue
-    UnqueueMessageJob.queue(queue_name, id: id)
-  end
-
-  def queue!
-    update_column(:retry_after, nil)
-    queue
-  end
-
-  def queue_name
-    ip_address ? :"outgoing-#{ip_address.id}" : :main
+  def retry_now
+    update(retry_after: nil)
   end
 
   def send_bounce
@@ -70,40 +55,6 @@ class QueuedMessage < ApplicationRecord
     self.ip_address = pool.ip_addresses.select_by_priority
   end
 
-  def acquire_lock
-    time = Time.now
-    locker = Postal.locker_name
-    rows = self.class.where(id: id, locked_by: nil, locked_at: nil).update_all(locked_by: locker, locked_at: time)
-    if rows == 1
-      self.locked_by = locker
-      self.locked_at = time
-      true
-    else
-      false
-    end
-  end
-
-  def retry_later(time = nil)
-    retry_time = time || self.class.calculate_retry_time(attempts, 5.minutes)
-    self.locked_by = nil
-    self.locked_at = nil
-    update_columns(locked_by: nil, locked_at: nil, retry_after: Time.now + retry_time, attempts: attempts + 1)
-  end
-
-  def unlock
-    self.locked_by = nil
-    self.locked_at = nil
-    update_columns(locked_by: nil, locked_at: nil)
-  end
-
-  def self.calculate_retry_time(attempts, initial_period)
-    (1.3**attempts) * initial_period
-  end
-
-  def locked?
-    locked_at.present?
-  end
-
   def batchable_messages(limit = 10)
     unless locked?
       raise Postal::Error, "Must lock current message before locking any friends"
@@ -114,13 +65,9 @@ class QueuedMessage < ApplicationRecord
     else
       time = Time.now
       locker = Postal.locker_name
-      self.class.retriable.where(batch_key: batch_key, ip_address_id: ip_address_id, locked_by: nil, locked_at: nil).limit(limit).update_all(locked_by: locker, locked_at: time)
+      self.class.ready.where(batch_key: batch_key, ip_address_id: ip_address_id, locked_by: nil, locked_at: nil).limit(limit).update_all(locked_by: locker, locked_at: time)
       QueuedMessage.where(batch_key: batch_key, ip_address_id: ip_address_id, locked_by: locker, locked_at: time).where.not(id: id)
     end
   end
 
-  def self.requeue_all
-    unlocked.requeueable.each(&:queue)
-  end
-
 end