Don't query adapter in ensure blocks when connection is closed

Trilogy closes its connection when it encounters a timeout. Active
Record doesn't always account for this, and can query the adapter in
ensure blocks of certain adapter methods. Instead, we need to preface
these queries with active checks to make sure we don't swallow the
timeout and raise an adapter error instead.

Co-authored-by: Adrianna Chang <[email protected]>

Author: gmcgibbon

activerecord/lib/active_record/connection_adapters/abstract/transaction.rb

@@ -350,7 +350,7 @@ def restart
 
       def rollback
         unless @state.invalidated?
-          connection.rollback_to_savepoint(savepoint_name) if materialized?
+          connection.rollback_to_savepoint(savepoint_name) if materialized? && connection.active?
         end
         @state.rollback!
         @instrumenter.finish(:rollback) if materialized?

activerecord/lib/active_record/connection_adapters/abstract_mysql_adapter.rb

@@ -218,7 +218,7 @@ def disable_referential_integrity # :nodoc:
           update("SET FOREIGN_KEY_CHECKS = 0")
           yield
         ensure
-          update("SET FOREIGN_KEY_CHECKS = #{old}")
+          update("SET FOREIGN_KEY_CHECKS = #{old}") if active?
         end
       end
 

activerecord/lib/active_record/connection_adapters/trilogy/database_statements.rb

@@ -96,7 +96,7 @@ def with_multi_statements
 
               yield
             ensure
-              conn.set_server_option(::Trilogy::SET_SERVER_MULTI_STATEMENTS_OFF)
+              conn.set_server_option(::Trilogy::SET_SERVER_MULTI_STATEMENTS_OFF) if active?
             end
           end
       end

activerecord/test/cases/adapters/trilogy/trilogy_adapter_test.rb

@@ -4,6 +4,7 @@
 require "support/ddl_helper"
 require "models/book"
 require "models/post"
+require "timeout"
 
 class TrilogyAdapterTest < ActiveRecord::TrilogyTestCase
   setup do
@@ -17,6 +18,40 @@ class TrilogyAdapterTest < ActiveRecord::TrilogyTestCase
     assert_kind_of ActiveRecord::ConnectionAdapters::NullPool, error.connection_pool
   end
 
+  test "timeout in transaction doesnt query closed connection" do
+    assert_raises(Timeout::Error) do
+      Timeout.timeout(0.1) do
+        @conn.transaction do
+          @conn.execute("SELECT SLEEP(1)")
+        end
+      end
+    end
+  end
+
+  test "timeout in fixture set insertion doesnt query closed connection" do
+    fixtures = [
+      ["traffic_lights", [
+        { "location" => "US", "state" => ["NY"], "long_state" => ["a"] },
+      ]]
+    ] * 1000
+
+    assert_raises(Timeout::Error) do
+      Timeout.timeout(0.1) do
+        @conn.insert_fixtures_set(fixtures)
+      end
+    end
+  end
+
+  test "timeout without referential integrity doesnt query closed connection" do
+    assert_raises(Timeout::Error) do
+      Timeout.timeout(0.1) do
+        @conn.disable_referential_integrity do
+          @conn.execute("SELECT SLEEP(1)")
+        end
+      end
+    end
+  end
+
   test "#explain for one query" do
     explain = @conn.explain("select * from posts")
     assert_match %(possible_keys), explain