Don't fail lock release if the connection was disconnected

If the connection is broken, then the lock was released because
the session is aborted. Thus there is no need to fail.

Author: fsateler

lib/with_advisory_lock/postgresql.rb

@@ -14,6 +14,8 @@ def release_lock
       pg_function = "pg_advisory_unlock#{shared ? '_shared' : ''}"
       execute_successful?(pg_function)
     rescue ActiveRecord::StatementInvalid => e
+      # If something goes real bad, pg will close the connection. in that case the lock is no longer held
+      return if e.message =~ /PG::ConnectionBad:/
       raise unless e.message =~ / ERROR: +current transaction is aborted,/
 
       begin

test/lock_test.rb

@@ -56,6 +56,12 @@
 
       thread_with_lock.kill
     end
+
+    it 'handles lost connection gracefully' do
+      Tag.with_advisory_lock(lock_name) { Tag.connection.disconnect! }
+
+      assert_nil(Tag.current_advisory_lock)
+    end
   end
 
   describe '.with_advisory_lock!' do

test/test_helper.rb

@@ -37,6 +37,7 @@ def env_db
 module MiniTest
   class Spec
     before do
+      ActiveRecord::Base.establish_connection
       ENV['FLOCK_DIR'] = Dir.mktmpdir
       Tag.delete_all
       TagAudit.delete_all