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.

actionpack/lib/action_controller/railtie.rb

@@ -123,7 +123,7 @@ module ActionController
         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 @@ module ActiveJob
         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 @@ module ActiveRecord
       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 @@ module ActiveRecord
       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 @@ module ActiveRecord
         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 @@ To keep using the current cache store, you can turn off cache versioning entirel
       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 @@ class QueryLogsTest < ActiveRecord::TestCase
     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 @@ class QueryLogsTest < ActiveRecord::TestCase
 
   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