BinaryCacheStore::narFromPath(): Fix unreachable code#14643
Merged
Conversation
When this function is called as a coroutine (e.g. when it's called by `copyStorePath()`), the code after `decompressor->finish()` is never reached because the coroutine is destroyed when the caller reaches the end of the NAR. So put that code in a `LambdaSink` destructor.
github-actions
bot
added
the
store
Ericson2314
approved these changes
Nov 25, 2025
Member
Ericson2314
left a comment
Ericson2314
left a comment
There was a problem hiding this comment.
This looks good to me, but I would like @xokdvium to give it a quick glance
xokdvium
reviewed
Nov 25, 2025
| stats.narRead++; | ||
| // stats.narReadCompressedBytes += nar->size(); // FIXME | ||
| stats.narReadBytes += narSize.length; | ||
| // Note: don't do anything here because it's never reached if we're called as a coroutine. |
Contributor
There was a problem hiding this comment.
But if this code doesn't run then how is the destructor (for LambdaSink) being run? Would be nice to add a unit test for the issue so it's more clear what's being fixed
Member
Author
There was a problem hiding this comment.
Boost unwinds the coroutine stack by throwing an exception of type boost::context::detail::forced_unwind. So destructors of stack variables do get executed.
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
3 participants
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
Motivation
When this function is called as a coroutine (e.g. when it's called by
copyStorePath()), the code afterdecompressor->finish()is never reached because the coroutine is destroyed when the caller reaches the end of the NAR. So put that code in aLambdaSinkdestructor.Context
Noticed while doing DeterminateSystems#279.
Add 👍 to pull requests you find important.
The Nix maintainer team uses a GitHub project board to schedule and track reviews.