diff options
| -rw-r--r-- | synapse/rest/client/transactions.py | 22 | ||||
| -rw-r--r-- | tests/rest/client/test_transactions.py | 54 |
2 files changed, 67 insertions, 9 deletions
diff --git a/synapse/rest/client/transactions.py b/synapse/rest/client/transactions.py index fceca2edeb..93ce0f5348 100644 --- a/synapse/rest/client/transactions.py +++ b/synapse/rest/client/transactions.py @@ -87,19 +87,23 @@ class HttpTransactionCache(object): deferred = fn(*args, **kwargs) - # if the request fails with a Twisted failure, remove it - # from the transaction map. This is done to ensure that we don't - # cache transient errors like rate-limiting errors, etc. + observable = ObservableDeferred(deferred, consumeErrors=False) + self.transactions[txn_key] = (observable, self.clock.time_msec()) + + # if the request fails with an exception, remove it from the + # transaction map. This is done to ensure that we don't cache + # transient errors like rate-limiting errors, etc. + # + # (make sure we add this errback *after* adding the key above, in case + # the deferred has already failed and is running errbacks + # synchronously) def remove_from_map(err): self.transactions.pop(txn_key, None) - return err + # we deliberately do not propagate the error any further, as we + # expect the observers to have reported it. + deferred.addErrback(remove_from_map) - # We don't add any other errbacks to the raw deferred, so we ask - # ObservableDeferred to swallow the error. This is fine as the error will - # still be reported to the observers. - observable = ObservableDeferred(deferred, consumeErrors=True) - self.transactions[txn_key] = (observable, self.clock.time_msec()) return observable.observe() def _cleanup(self): diff --git a/tests/rest/client/test_transactions.py b/tests/rest/client/test_transactions.py index d7cea30260..b650a7772b 100644 --- a/tests/rest/client/test_transactions.py +++ b/tests/rest/client/test_transactions.py @@ -2,6 +2,8 @@ from synapse.rest.client.transactions import HttpTransactionCache from synapse.rest.client.transactions import CLEANUP_PERIOD_MS from twisted.internet import defer from mock import Mock, call + +from synapse.util.logcontext import LoggingContext from tests import unittest from tests.utils import MockClock @@ -40,6 +42,58 @@ class HttpTransactionCacheTestCase(unittest.TestCase): cb.assert_called_once_with("some_arg", keyword="arg", changing_args=0) @defer.inlineCallbacks + def test_does_not_cache_exceptions(self): + """Checks that, if the callback throws an exception, it is called again + for the next request. + """ + called = [False] + + def cb(): + if called[0]: + # return a valid result the second time + return defer.succeed(self.mock_http_response) + + called[0] = True + raise Exception("boo") + + with LoggingContext("test") as test_context: + try: + yield self.cache.fetch_or_execute(self.mock_key, cb) + except Exception as e: + self.assertEqual(e.message, "boo") + self.assertIs(LoggingContext.current_context(), test_context) + + res = yield self.cache.fetch_or_execute(self.mock_key, cb) + self.assertEqual(res, self.mock_http_response) + self.assertIs(LoggingContext.current_context(), test_context) + + @defer.inlineCallbacks + def test_does_not_cache_failures(self): + """Checks that, if the callback returns a failure, it is called again + for the next request. + """ + called = [False] + + def cb(): + if called[0]: + # return a valid result the second time + return defer.succeed(self.mock_http_response) + + called[0] = True + return defer.fail(Exception("boo")) + + with LoggingContext("test") as test_context: + try: + yield self.cache.fetch_or_execute(self.mock_key, cb) + except Exception as e: + self.assertEqual(e.message, "boo") + self.assertIs(LoggingContext.current_context(), test_context) + + res = yield self.cache.fetch_or_execute(self.mock_key, cb) + self.assertEqual(res, self.mock_http_response) + self.assertIs(LoggingContext.current_context(), test_context) + + @defer.inlineCallbacks def test_cleans_up(self): cb = Mock( return_value=defer.succeed(self.mock_http_response) |