Add Celery config option to ignore expected exceptions

Author: mervync

docs/integrations/celery.rst

@@ -16,14 +16,19 @@ Celery error handling::
     # register a custom filter to filter out duplicate logs
     register_logger_signal(client)
 
-    # hook into the Celery error handler
-    register_signal(client)
-
     # The register_logger_signal function can also take an optional argument
     # `loglevel` which is the level used for the handler created.
     # Defaults to `logging.ERROR`
     register_logger_signal(client, loglevel=logging.INFO)
 
+    # hook into the Celery error handler
+    register_signal(client)
+
+    # The register_signal function can also take an optional argument
+    # `ignore_expected` which causes exception classes specified in Task.throws
+    # to be ignored
+    register_signal(client, ignore_expected=True)
+
 A more complex version to encapsulate behavior:
 
 .. code-block:: python

raven/contrib/celery/__init__.py

@@ -24,8 +24,11 @@ def filter(self, record):
         return extra_data.get('internal', record.funcName != '_log_error')
 
 
-def register_signal(client):
+def register_signal(client, ignore_expected=False):
     def process_failure_signal(sender, task_id, args, kwargs, einfo, **kw):
+        if ignore_expected and isinstance(einfo.exception, sender.throws):
+            return
+
         # This signal is fired inside the stack so let raven do its magic
         if isinstance(einfo.exception, SoftTimeLimitExceeded):
             fingerprint = ['celery', 'SoftTimeLimitExceeded', sender]