Support "near" parameter in prepared query service block #2137
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| sortFrom = args.Origin | ||
| } | ||
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| // Perform the distance sort |
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Do we want to memoize this value for ~60s or whatever the interval is for the tomography calcs? I seem to recall someone saying this calc was "expensive," but if it's not, disregard. DNS can set a TTL, so maybe this isn't a huge issue, but that depends on the level of DNS caching at a given site.
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It's not too bad - I'd probably leave as-is since this can be DNS TTL-ed and read-scaled with staleness across the servers.
| // is executing the query on behalf of the client. It is taken | ||
| // as a QuerySource so that it can be used directly for queries | ||
| // relating to the agent servicing the request. | ||
| Origin QuerySource |
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Did you take a look at the existing Source parameter right after this one? I think it was originally intended to do what Origin does.
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Pretty close yeah. I originally tried to use that, but I switched to this because in the HTTP/DNS api code at the agent, you can't be sure what the prepared query actually does, so the agent can't be sure if it should pass its own name + datacenter, or the user's provided ?near and/or ?dc value. This just makes it so we can send both and decide outside of the agent.
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@ryanuber took a look through and added some comments - this is looking good! I think the |
| // Build the query source. This can be provided by the client, or by | ||
| // the prepared query. Client-specified takes priority. | ||
| qs := args.Source | ||
| if qs.Datacenter == "" { |
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DC should always be supplied by parseDC but this is fine and defensive.
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@ryanuber looks good! I still think we need to revert the |
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Allows the use of the
Nearparameter in a prepared query definition. This parameter works just like the?near=fooHTTP API parameter, only it is baked into the query, allowing it to be used from the DNS interface.This enables some interesting functionality and opens up additional useful prepared query features when using DNS as the query mechanism.
/cc @slackpad