Ensure Action Mailbox processes an email only once when received multiple times

This also adds a new column, message_checksum, to the action_mailbox_inbound_emails table
for storing SHA1 digest of the email source. Additionally, it makes generating the missing
message id deterministic and adds a unique index on message_checksum and message_id to
detect duplicate emails.

1 files changed, 4 insertions, 1 deletions

diff --git a/actionmailbox/db/migrate/20180917164000_create_action_mailbox_tables.rb b/actionmailbox/db/migrate/20180917164000_create_action_mailbox_tables.rb
index 8cf621d7e3..e697748f82 100644
--- a/actionmailbox/db/migrate/20180917164000_create_action_mailbox_tables.rb
+++ b/actionmailbox/db/migrate/20180917164000_create_action_mailbox_tables.rb
@@ -2,10 +2,13 @@ class CreateActionMailboxTables < ActiveRecord::Migration[6.0]
   def change
     create_table :action_mailbox_inbound_emails do |t|
       t.integer :status, default: 0, null: false
-      t.string  :message_id
+      t.string  :message_id, null: false
+      t.string  :message_checksum, null: false
 
       t.datetime :created_at, precision: 6, null: false
       t.datetime :updated_at, precision: 6, null: false
+
+      t.index [ :message_id, :message_checksum ], unique: true
     end
   end
 end