tidy and document recent changes

app/controllers/file_controller.rb

@@ -61,7 +61,7 @@ def check_download
 
   def check_version
     version = @file.inv_version
-    obj = version.inv_object
+    version.inv_object
   end
 
   def not_found_obj

app/lib/merritt_retry_mixin.rb

@@ -4,6 +4,11 @@ class RetryException < RuntimeError; end
 
   RETRY_LIMIT = 3
 
+  # Merritt UI was encountering 500 errors on database connections that were no longer active.
+  # The first solution that I tried was to wrap frequent query blocks with the following retry logic.
+  # This significantly decreased the number of 500 errors.
+  # In Jan 2024, I also began setting "idle_timeout=0".  Hopefully, this will address the underlying issue.
+  # For each retry block that is invoked, there is an RSpec test that forces the code into the retry logic.
   def merritt_retry_block
     retries = 0
     begin

config/database.yml

@@ -14,6 +14,9 @@ default: &default
   host: "{!SSM: inv/db-host}"
   database: "{!SSM: inv/db-name}"
   pool: 25
+  # Merritt UI encountered 500 errors when mysql connections were no longer active.
+  # Jan 2024 - adding this setting to see if it prevents inactive connections.
+  # See https://api.rubyonrails.org/classes/ActiveRecord/ConnectionAdapters/ConnectionPool.html
   idle_timeout: 0
   port: 3306
   username: "{!SSM: inv/readwrite/db-user}"