tahoe-lafs/trac-2024-07-25

The interface for the client-side storage plugin web resource has a one-to-many conflict #3258

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opened 2019-10-03 13:56:17 +00:00 by exarkun · 1 comment

exarkun commented

2019-10-03 13:56:17 +00:00

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Storage plugins can contribute to the web interface on client nodes. They do this by implementing IFoolscapStoragePlugin.get_client_resource. This is somewhat awkward to implement because it does not receive all of the same information that IFoolscapStoragePlugin.get_storage_client receives and collecting that information where get_client_resource needs to be called is challenging to implement.

This divergence in available information is caused by the following conflict. get_client_resource is expected to return a single resource which represents "the plugin". However, get_storage_client is called on a per-server basis to get an IStorageServer provider specifically for that single server. Since a Tahoe-LAFS client can be connected to many servers, this call may be made many times to create many objects.

I don't see any way to easily simultaneously accommodate both of these constraints.

Storage plugins can contribute to the web interface on client nodes. They do this by implementing `IFoolscapStoragePlugin.get_client_resource`. This is somewhat awkward to implement because it does not receive all of the same information that `IFoolscapStoragePlugin.get_storage_client` receives and collecting that information where `get_client_resource` needs to be called is challenging to implement. This divergence in available information is caused by the following conflict. `get_client_resource` is expected to return a single resource which represents "the plugin". However, `get_storage_client` is called on a per-server basis to get an `IStorageServer` provider specifically for that single server. Since a Tahoe-LAFS client can be connected to many servers, this call may be made many times to create many objects. I don't see any way to easily simultaneously accommodate both of these constraints.

tahoe-lafs added the

labels 2019-10-03 13:56:17 +00:00

tahoe-lafs added this to the storage economics plugins milestone 2019-10-03 13:56:17 +00:00

tahoe-lafs changed title from ~~Get the client-side web resource for storage plugins from the storage object itself~~ to The interface for the client-side storage plugin web resource has a one-to-many conflict

2019-10-03 16:33:24 +00:00

exarkun commented

2019-10-03 16:35:43 +00:00

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For the time being, I think I can get by with the interface as-is - by imposing some additional constraints on the plugin I am implementing outside of Tahoe-LAFS. At some point I will want to revisit this, though, and almost certainly make interface changes here.

I've edited the ticket description to more directly describe the problem instead of my hypothesized solution.

Originally I thought that there was a solution to this that involved making a web resource per-storage-server as well. This may indeed end up being a solution but it is more involved than I thought. There still very likely needs to be a per-plugin resource that can act as some kind of container for the per-storage-server resources. For the time being, I think I can get by with the interface as-is - by imposing some additional constraints on the plugin I am implementing outside of Tahoe-LAFS. At some point I will want to revisit this, though, and almost certainly make interface changes here. I've edited the ticket description to more directly describe the problem instead of my hypothesized solution.