method

retrieve_connection_pool

v4.2.7 - Show latest stable - 0 notes - Class: ActiveRecord::ConnectionAdapters::ConnectionHandler

retrieve_connection_pool(klass) public

Retrieving the connection pool happens a lot so we cache it in @class_to_pool. This makes retrieving the connection pool O(1) once the process is warm. When a connection is established or removed, we invalidate the cache.

Ideally we would use #fetch here, as class_to_pool[klass] may sometimes be nil. However, benchmarking (gist.github.com/jonleighton/3552829) showed that #fetch is significantly slower than #[]. So in the nil case, no caching will take place, but that’s ok since the nil case is not the common one that we wish to optimise for.

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# File activerecord/lib/active_record/connection_adapters/abstract/connection_pool.rb, line 605
      def retrieve_connection_pool(klass)
        class_to_pool[klass.name] ||= begin
          until pool = pool_for(klass)
            klass = klass.superclass
            break unless klass <= Base
          end

          class_to_pool[klass.name] = pool
        end
      end

retrieve_connection_pool

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