Avoid isValidPath(), use queryPathInfo() instead#157
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edolstra merged 2 commits intodetsys-mainfrom Jul 28, 2025
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Since recently we call isValidPath() a lot from the evaluator, specifically from LocalStoreAccessor::requireStoreObject(). Unfortunately, isValidPath() uses but does not populate the in-memory path info cache; only queryPathInfo() does that. So isValidPath() is fast *if* we happened to call queryPathInfo() on the same path previously. This is not the case when lazy-trees is enabled, so we got a lot of superfluous, high-latency calls to the daemon (which show up in verbose output as `performing daemon worker op: 1`). Similarly, `fetchToStore()` called `isValidPath()` as well. The fix is to use `queryPathInfo()`, which for one particular eval reduced the number of daemon calls from 15246 to 2324. This may cause Nix to fetch some unnecessary information from the daemon, but that probably doesn't matter much given the high latency.
cole-h
approved these changes
Jul 28, 2025
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Motivation
Since recently we call
isValidPath()a lot from the evaluator, specifically fromLocalStoreAccessor::requireStoreObject(). Unfortunately,isValidPath()uses but does not populate the in-memory path info cache; onlyqueryPathInfo()does that. SoisValidPath()is fast if we happened to callqueryPathInfo()on the same path previously. This is not the case when lazy-trees is enabled, so we got a lot of superfluous, high-latency calls to the daemon (which show up in verbose output asperforming daemon worker op: 1).Similarly,
fetchToStore()calledisValidPath()as well.The fix is to use
queryPathInfo(), which for one particular eval reduced the number of daemon calls from 15246 to 2324. This may cause Nix to fetch some unnecessary information from the daemon, but that probably doesn't matter much given the high latency.Context