From 6b18eb443054087c4a8153b19b3cc4d3b731d324 Mon Sep 17 00:00:00 2001 From: Sean Quah <8349537+squahtx@users.noreply.github.com> Date: Tue, 12 Oct 2021 11:23:46 +0100 Subject: [PATCH] Fix opentracing and Prometheus metrics for replication requests (#10996) This commit fixes two bugs to do with decorators not instrumenting `ReplicationEndpoint`'s `send_request` correctly. There are two decorators on `send_request`: Prometheus' `Gauge.track_inprogress()` and Synapse's `opentracing.trace`. `Gauge.track_inprogress()` does not have any support for async functions when used as a decorator. Since async functions behave like regular functions that return coroutines, only the creation of the coroutine was covered by the metric and none of the actual body of `send_request`. `Gauge.track_inprogress()` returns a regular, non-async function wrapping `send_request`, which is the source of the next bug. The `opentracing.trace` decorator would normally handle async functions correctly, but since the wrapped `send_request` is a non-async function, the decorator ends up suffering from the same issue as `Gauge.track_inprogress()`: the opentracing span only measures the creation of the coroutine and none of the actual function body. Using `Gauge.track_inprogress()` as a context manager instead of a decorator resolves both bugs. --- changelog.d/10996.misc | 1 + synapse/logging/opentracing.py | 8 ++ synapse/replication/http/_base.py | 148 +++++++++++++++--------------- 3 files changed, 84 insertions(+), 73 deletions(-) create mode 100644 changelog.d/10996.misc diff --git a/changelog.d/10996.misc b/changelog.d/10996.misc new file mode 100644 index 000000000..c830d7ec2 --- /dev/null +++ b/changelog.d/10996.misc @@ -0,0 +1 @@ +Fix a bug introduced in Synapse 1.21.0 that causes opentracing and Prometheus metrics for replication requests to be measured incorrectly. diff --git a/synapse/logging/opentracing.py b/synapse/logging/opentracing.py index 5276c4bfc..20d23a426 100644 --- a/synapse/logging/opentracing.py +++ b/synapse/logging/opentracing.py @@ -807,6 +807,14 @@ def trace(func=None, opname=None): result.addCallbacks(call_back, err_back) else: + if inspect.isawaitable(result): + logger.error( + "@trace may not have wrapped %s correctly! " + "The function is not async but returned a %s.", + func.__qualname__, + type(result).__name__, + ) + scope.__exit__(None, None, None) return result diff --git a/synapse/replication/http/_base.py b/synapse/replication/http/_base.py index f1b78d09f..e047ec74d 100644 --- a/synapse/replication/http/_base.py +++ b/synapse/replication/http/_base.py @@ -182,85 +182,87 @@ class ReplicationEndpoint(metaclass=abc.ABCMeta): ) @trace(opname="outgoing_replication_request") - @outgoing_gauge.track_inprogress() async def send_request(*, instance_name="master", **kwargs): - if instance_name == local_instance_name: - raise Exception("Trying to send HTTP request to self") - if instance_name == "master": - host = master_host - port = master_port - elif instance_name in instance_map: - host = instance_map[instance_name].host - port = instance_map[instance_name].port - else: - raise Exception( - "Instance %r not in 'instance_map' config" % (instance_name,) + with outgoing_gauge.track_inprogress(): + if instance_name == local_instance_name: + raise Exception("Trying to send HTTP request to self") + if instance_name == "master": + host = master_host + port = master_port + elif instance_name in instance_map: + host = instance_map[instance_name].host + port = instance_map[instance_name].port + else: + raise Exception( + "Instance %r not in 'instance_map' config" % (instance_name,) + ) + + data = await cls._serialize_payload(**kwargs) + + url_args = [ + urllib.parse.quote(kwargs[name], safe="") for name in cls.PATH_ARGS + ] + + if cls.CACHE: + txn_id = random_string(10) + url_args.append(txn_id) + + if cls.METHOD == "POST": + request_func = client.post_json_get_json + elif cls.METHOD == "PUT": + request_func = client.put_json + elif cls.METHOD == "GET": + request_func = client.get_json + else: + # We have already asserted in the constructor that a + # compatible was picked, but lets be paranoid. + raise Exception( + "Unknown METHOD on %s replication endpoint" % (cls.NAME,) + ) + + uri = "http://%s:%s/_synapse/replication/%s/%s" % ( + host, + port, + cls.NAME, + "/".join(url_args), ) - data = await cls._serialize_payload(**kwargs) + try: + # We keep retrying the same request for timeouts. This is so that we + # have a good idea that the request has either succeeded or failed + # on the master, and so whether we should clean up or not. + while True: + headers: Dict[bytes, List[bytes]] = {} + # Add an authorization header, if configured. + if replication_secret: + headers[b"Authorization"] = [ + b"Bearer " + replication_secret + ] + opentracing.inject_header_dict(headers, check_destination=False) + try: + result = await request_func(uri, data, headers=headers) + break + except RequestTimedOutError: + if not cls.RETRY_ON_TIMEOUT: + raise - url_args = [ - urllib.parse.quote(kwargs[name], safe="") for name in cls.PATH_ARGS - ] + logger.warning("%s request timed out; retrying", cls.NAME) - if cls.CACHE: - txn_id = random_string(10) - url_args.append(txn_id) + # If we timed out we probably don't need to worry about backing + # off too much, but lets just wait a little anyway. + await clock.sleep(1) + except HttpResponseException as e: + # We convert to SynapseError as we know that it was a SynapseError + # on the main process that we should send to the client. (And + # importantly, not stack traces everywhere) + _outgoing_request_counter.labels(cls.NAME, e.code).inc() + raise e.to_synapse_error() + except Exception as e: + _outgoing_request_counter.labels(cls.NAME, "ERR").inc() + raise SynapseError(502, "Failed to talk to main process") from e - if cls.METHOD == "POST": - request_func = client.post_json_get_json - elif cls.METHOD == "PUT": - request_func = client.put_json - elif cls.METHOD == "GET": - request_func = client.get_json - else: - # We have already asserted in the constructor that a - # compatible was picked, but lets be paranoid. - raise Exception( - "Unknown METHOD on %s replication endpoint" % (cls.NAME,) - ) - - uri = "http://%s:%s/_synapse/replication/%s/%s" % ( - host, - port, - cls.NAME, - "/".join(url_args), - ) - - try: - # We keep retrying the same request for timeouts. This is so that we - # have a good idea that the request has either succeeded or failed on - # the master, and so whether we should clean up or not. - while True: - headers: Dict[bytes, List[bytes]] = {} - # Add an authorization header, if configured. - if replication_secret: - headers[b"Authorization"] = [b"Bearer " + replication_secret] - opentracing.inject_header_dict(headers, check_destination=False) - try: - result = await request_func(uri, data, headers=headers) - break - except RequestTimedOutError: - if not cls.RETRY_ON_TIMEOUT: - raise - - logger.warning("%s request timed out; retrying", cls.NAME) - - # If we timed out we probably don't need to worry about backing - # off too much, but lets just wait a little anyway. - await clock.sleep(1) - except HttpResponseException as e: - # We convert to SynapseError as we know that it was a SynapseError - # on the main process that we should send to the client. (And - # importantly, not stack traces everywhere) - _outgoing_request_counter.labels(cls.NAME, e.code).inc() - raise e.to_synapse_error() - except Exception as e: - _outgoing_request_counter.labels(cls.NAME, "ERR").inc() - raise SynapseError(502, "Failed to talk to main process") from e - - _outgoing_request_counter.labels(cls.NAME, 200).inc() - return result + _outgoing_request_counter.labels(cls.NAME, 200).inc() + return result return send_request