Fix query cache for multiple connections

Currently the query cache is only aware of one handler so once we added
multiple databases switching on the handler we broke query cache for
those reading connections.

While #34054 is the proper fix, that fix is not straight forward and I
want to make sure that the query cache isn't just broken for all other
connections not in the main handler.

1 files changed, 11 insertions, 4 deletions

diff --git a/activerecord/lib/active_record/query_cache.rb b/activerecord/lib/active_record/query_cache.rb
index 28194c7c46..43a21e629e 100644
--- a/activerecord/lib/active_record/query_cache.rb
+++ b/activerecord/lib/active_record/query_cache.rb
@@ -26,15 +26,22 @@ module ActiveRecord
     end
 
     def self.run
-      ActiveRecord::Base.connection_handler.connection_pool_list.
-        reject { |p| p.query_cache_enabled }.each { |p| p.enable_query_cache! }
+      pools = []
+
+      ActiveRecord::Base.connection_handlers.each do |key, handler|
+        pools << handler.connection_pool_list.reject { |p| p.query_cache_enabled }.each { |p| p.enable_query_cache! }
+      end
+
+      pools.flatten
     end
 
     def self.complete(pools)
       pools.each { |pool| pool.disable_query_cache! }
 
-      ActiveRecord::Base.connection_handler.connection_pool_list.each do |pool|
-        pool.release_connection if pool.active_connection? && !pool.connection.transaction_open?
+      ActiveRecord::Base.connection_handlers.each do |_, handler|
+        handler.connection_pool_list.each do |pool|
+          pool.release_connection if pool.active_connection? && !pool.connection.transaction_open?
+        end
       end
     end