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openvstorage / volumedriver

The Open vStorage VolumeDriver is the core of the Open vStorage solution: a high performance distributed block layer. It converts block storage into objects (Storage Container Objects).
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Differentiate between real runtimerrors and client timeout errors #349

Closed JeffreyDevloo closed 6 years ago

JeffreyDevloo commented 7 years ago

Problem description

Certain volumedriver calls have a set timeout within the framework but the framework is unable to differentiate between a real problem and a timeout due to the fact that they both raise a runtime errors with an xmlrpc message

I'd suggest raising a timeout exception that the framework can import and check upon

redlicha commented 7 years ago

Differentiation is already possible (but code inspection suggests a bug): if the node does not respond (= not running, or on timeout), a ClusterNotReachableException or a NodeNotReachableException is raised. The latter is however not correctly translated from C++ to Python (to be fixed as part of this ticket? Please let me know if you want this) which means it's currently reported as a RuntimeError "failed to send XMLRPC request". At the moment there is no distinction possible between timeout and e.g. voldrv not running (the library used does not offer this).

wimpers commented 7 years ago

I assume fixing the bug will allow Framework to know it is a timeout in https://github.com/openvstorage/framework/issues/1557 and act accordingly?

redlicha commented 7 years ago

Yes. For now / backward compatibility it might be a good idea to identify connection / timeout issues reported via the "failed to send XMLRPC request" message of a RuntimeError.

JeffreyDevloo commented 7 years ago

So all "failed to send" are timeouts? We could work with that but having a cleaner option (like a custom exception) would be better

redlicha commented 7 years ago

Timeouts or a problem contacting the node (differentiation of these requires changes to the library used / using another library). Mind, this is just to work around the bug in the C++ -> Python exception translation / to get the functionality with old volumedriver instances; fixing the exception translation should still be done of course.

wimpers commented 6 years ago

Milestone closed.