Freeze modifications to ActiveRecord::QueryLogs

Tags and taggings build a cache when they are assigned, which means we
cannot support them being mutated. This freezes tags and taggings to
ensure they aren't changed after assignment.

This may not cover all cases, and per the previous PR we intend this to
be configured mostly via application.config, but it covers a case we
were making in our test suite and so should hopefully cover a mistake
users are somewhat likely to make.

Author: jhawthorn

actionpack/lib/action_controller/railtie.rb

@@ -123,7 +123,7 @@ class Railtie < Rails::Railtie # :nodoc:
         app.config.active_record.query_log_tags |= [:action]
 
         ActiveSupport.on_load(:active_record) do
-          ActiveRecord::QueryLogs.taggings.merge!(
+          ActiveRecord::QueryLogs.taggings = ActiveRecord::QueryLogs.taggings.merge(
             controller:            ->(context) { context[:controller]&.controller_name },
             action:                ->(context) { context[:controller]&.action_name },
             namespaced_controller: ->(context) {

activejob/lib/active_job/railtie.rb

@@ -93,7 +93,9 @@ class Railtie < Rails::Railtie # :nodoc:
         app.config.active_record.query_log_tags |= [:job]
 
         ActiveSupport.on_load(:active_record) do
-          ActiveRecord::QueryLogs.taggings[:job] = ->(context) { context[:job].class.name if context[:job] }
+          ActiveRecord::QueryLogs.taggings = ActiveRecord::QueryLogs.taggings.merge(
+            job: ->(context) { context[:job].class.name if context[:job] }
+          )
         end
       end
     end

activerecord/lib/active_record/query_logs.rb

@@ -102,8 +102,8 @@ def call(_context)
       end
     end
 
-    @taggings = {}
-    @tags = [ :application ]
+    @taggings = {}.freeze
+    @tags = [ :application ].freeze
     @prepend_comment = false
     @cache_query_log_tags = false
     @tags_formatter = false
@@ -115,17 +115,16 @@ class << self
       attr_accessor :prepend_comment, :cache_query_log_tags # :nodoc:
 
       def taggings=(taggings) # :nodoc:
-        @taggings = taggings
+        @taggings = taggings.freeze
         @handlers = rebuild_handlers
       end
 
       def tags=(tags) # :nodoc:
-        @tags = tags
+        @tags = tags.freeze
         @handlers = rebuild_handlers
       end
 
       def tags_formatter=(format) # :nodoc:
-        @tags_formatter = format
         @formatter = case format
         when :legacy
           LegacyFormatter
@@ -134,6 +133,7 @@ def tags_formatter=(format) # :nodoc:
         else
           raise ArgumentError, "Formatter is unsupported: #{format}"
         end
+        @tags_formatter = format
       end
 
       def call(sql, connection) # :nodoc:

activerecord/lib/active_record/railtie.rb

@@ -385,7 +385,7 @@ class Railtie < Rails::Railtie # :nodoc:
       config.after_initialize do
         if app.config.active_record.query_log_tags_enabled
           ActiveRecord.query_transformers << ActiveRecord::QueryLogs
-          ActiveRecord::QueryLogs.taggings.merge!(
+          ActiveRecord::QueryLogs.taggings = ActiveRecord::QueryLogs.taggings.merge(
             application:  Rails.application.class.name.split("::").first,
             pid:          -> { Process.pid.to_s },
             socket:       ->(context) { context[:connection].pool.db_config.socket },

activerecord/test/cases/query_logs_test.rb

@@ -20,8 +20,8 @@ def setup
     ActiveRecord::QueryLogs.prepend_comment = false
     ActiveRecord::QueryLogs.cache_query_log_tags = false
     ActiveRecord::QueryLogs.cached_comment = nil
-    ActiveRecord::QueryLogs.taggings[:application] = -> {
-      "active_record"
+    ActiveRecord::QueryLogs.taggings = {
+      application: -> { "active_record" }
     }
   end
 
@@ -185,7 +185,7 @@ def test_empty_comments_are_not_added
 
   def test_sql_commenter_format
     ActiveRecord::QueryLogs.tags_formatter = :sqlcommenter
-    ActiveRecord::QueryLogs.tags = [:application, {}]
+    ActiveRecord::QueryLogs.tags = [:application]
 
     assert_queries_match(%r{/\*application='active_record'\*/}) do
       Dashboard.first