Serializza gli invii SMTP su una coda unica per non far chiudere Aruba.

Co-authored-by: Cursor <cursoragent@cursor.com>

app/services/mailings/outbound_queue.rb

@@ -0,0 +1,98 @@
+class Mailings::OutboundQueue
+  LOCK_PATH = Rails.root.join("tmp/outbound_smtp.lock")
+  STAMP_PATH = Rails.root.join("tmp/outbound_last_sent")
+
+  class << self
+    attr_accessor :min_interval
+
+    def enqueue(recipient)
+      recipient.with_lock do
+        return false unless recipient.mailing.sending?
+        return false unless recipient.pending?
+
+        recipient.update!(status: "queued", error_message: nil)
+        true
+      end
+    end
+
+    def drain_one!
+      File.open(lock_path, File::RDWR | File::CREAT, 0o644) do |file|
+        return :busy unless file.flock(File::LOCK_EX | File::LOCK_NB)
+
+        wait = seconds_until_next_slot
+        return :wait if wait.positive?
+
+        recipient = next_queued
+        return :empty if recipient.nil?
+        return :closed unless Mailings::SendClock.new(recipient.mailing).open?
+
+        begin
+          CampaignMailer.raise_delivery_errors = true
+          outcome = recipient.deliver_queued!
+          stamp!
+          outcome == :sent ? :sent : :deferred
+        ensure
+          CampaignMailer.raise_delivery_errors = false if Rails.env.development?
+        end
+      end
+    end
+
+    def exclusive
+      File.open(lock_path, File::RDWR | File::CREAT, 0o644) do |file|
+        file.flock(File::LOCK_EX)
+        yield
+      end
+    end
+
+    def next_queued
+      queued_scope.order(:updated_at, :id).first
+    end
+
+    def queued_scope
+      MailingRecipient.queued.joins(:mailing).merge(Mailing.sending)
+    end
+
+    def seconds_until_next_slot
+      return 0 if min_interval.to_f <= 0
+
+      last = last_sent_at
+      return 0 if last.nil?
+
+      remaining = min_interval - (Time.current - last)
+      remaining.positive? ? remaining : 0
+    end
+
+    def reset!
+      @last_sent_at = nil
+      File.delete(stamp_path) if File.exist?(stamp_path)
+    rescue Errno::ENOENT
+      nil
+    end
+
+    def stamp!
+      @last_sent_at = Time.current
+      File.write(stamp_path, @last_sent_at.to_f.to_s)
+    end
+
+    def last_sent_at
+      return @last_sent_at if @last_sent_at
+      return unless File.exist?(stamp_path)
+
+      @last_sent_at = Time.zone.at(Float(File.read(stamp_path)))
+    rescue ArgumentError, TypeError, Errno::ENOENT
+      nil
+    end
+
+    private
+
+    def lock_path
+      LOCK_PATH
+    end
+
+    def stamp_path
+      STAMP_PATH
+    end
+  end
+
+  self.min_interval = Rails.env.test? ? 0.0 : 180.0
+end