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Content addressing and adding to store cleanup #9325

Merged
merged 2 commits into from
Dec 19, 2023
Merged

Content addressing and adding to store cleanup #9325

merged 2 commits into from
Dec 19, 2023

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Ericson2314
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@Ericson2314 Ericson2314 commented Nov 9, 2023 •
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Motivation

Organize content addressing

We now better distinguish ways to:

  • Content address a store object (to CA store path):
    • Text
    • Flat
    • NAR
    • (someday soon) Git
  • Content-address a file system object (to hash):
    • Text
    • Flat
    • NAR
    • (someday soon) Git

The former has a new underlying method to give the method it uses for the latter.

Use SourceAccessor with Store::addToStore

This helps promote SourceAccessor --- eventually (I think) we want just about all file system access to go directly through it and not use native operations directly. This will help us with in-memory story (good for unit tests!) and dovetails with #9278.

Remove now-redundant text-hashing store methods

addTextToStore and computeStorePathFromDump are now redundant because the other methods are upgraded to take a ContentAddressMethod not FileIngestionMethod --- we have a single suite of methods that works with all types store object content adressing, and we don't need any additional methods for the Text case.

Context

I was reminded how much duplicated code we had working on #8918. This is a long standing issue and it's high time we clean it up. Cleaning it up first will also make it easier to review git hashing support to libstore.

Priorities

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@Ericson2314 Ericson2314 changed the title content addressing and adding to store cleanup Content addressing and adding to store cleanup Nov 9, 2023
@github-actions github-actions bot added new-cli Relating to the "nix" command store Issues and pull requests concerning the Nix store fetching Networking with the outside (non-Nix) world, input locking labels Nov 9, 2023
edolstra
edolstra reviewed Nov 9, 2023
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src/libfetchers/input-accessor.cc
@@ -3,31 +3,6 @@

namespace nix {

StorePath InputAccessor::fetchToStore(
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Just to note but some of this code is here to minimize the diff with lazy-trees. So if we start changing this, it will increases the lazy-trees diff again.

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@edolstra happy to fix that merge conflict :)

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Right now there is a conflict in lazy trees from #8848 that is very domain-specific on both side. I can't help with that so much, but I am happy to do all the other conflicts!

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fetchToStore stays non-virtual on lazy-trees so I think there is no issue here. This PR makes Store able to consume SourceAccessors directly so we just use that. Anything in an InputAcessor beyond the underlying SourceAccessor Store::addToStore won't care about anyways.

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@Ericson2314 Ericson2314 Nov 10, 2023 •
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For the fingerprinting, Sure that method could go back, but we could also flip around the logic so the SourceAccesor itself has a maybeLstat-like method to try to cheaply content-address file system object, and the InputAccesor implementations do the getCache() to look this up.

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On lazy-trees, InputAccessor::fetchToStore() implements a SQLite cache for SourcePath -> StorePath mappings that I want to backport to master. It optimizes stuff like src = <some big tree>. That's why it's important not to get rid of fetchToStore().

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OK I'll put it back

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It is now put back (not sure why this thread isn't marked outdated).

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Not on a red or green line, is probably why.

@Ericson2314 Ericson2314 marked this pull request as ready for review November 9, 2023 22:21
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Fixed the bug!

@Ericson2314 Ericson2314 force-pushed the accessor-add-to-store branch 2 times, most recently from 23b70f2 to 395e3c3 Compare November 10, 2023 13:15
roberth
roberth reviewed Nov 10, 2023
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Just one suggestion.
Great stuff: less code, more consistent use of fewer interfaces, progress towards in-memory store.

Ok to merge after the suggestion and resolving the work priority inversion. It seems that you can't help @edolstra with lazy-trees until the existing conflict is resolved.

src/libstore/content-address.cc Outdated Show resolved Hide resolved
@Ericson2314 Ericson2314 mentioned this pull request Nov 10, 2023
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@Ericson2314 Ericson2314 mentioned this pull request Nov 15, 2023
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@amjoseph-nixpkgs BTW this addresses some duplication you brought up a while back :)

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This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2023-11-17-nix-team-meeting-minutes-104/35753/1

@Ericson2314 Ericson2314 mentioned this pull request Nov 20, 2023
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Just rebased this fixing conflicts. it would be very good to get it reviewed @edolstra so I can continue with the rest of the git hashing stuff!

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This pull request has been mentioned on NixOS Discourse. There might be relevant details there:

https://discourse.nixos.org/t/2023-11-27-nix-team-meeting-minutes-107/36112/1

@roberth roberth assigned roberth and edolstra and unassigned edolstra and roberth Dec 18, 2023
@Ericson2314 @roberth
Organize content addressing, use SourceAccessor with `Store::addToS…
dfc8765 
…tore`

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
@Ericson2314 @roberth
Remove now-redundant text-hashing store methods
ed26b18 
`addTextToStore` and `computeStorePathFromDump` are now redundant.

Co-authored-by: Robert Hensing <roberth@users.noreply.github.com>
@edolstra edolstra merged commit 7cfd6c0 into master Dec 19, 2023
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@edolstra edolstra deleted the accessor-add-to-store branch December 19, 2023 14:10
@Ericson2314 Ericson2314 mentioned this pull request Dec 22, 2023
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@theoparis theoparis mentioned this pull request Jan 21, 2024
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@Ericson2314 Ericson2314 added this to the git-hashing stabilisation milestone Mar 22, 2024
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@edolstra edolstra edolstra left review comments

@thufschmitt thufschmitt Awaiting requested review from thufschmitt

@fricklerhandwerk fricklerhandwerk Awaiting requested review from fricklerhandwerk fricklerhandwerk is a code owner

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Labels
fetching Networking with the outside (non-Nix) world, input locking new-cli Relating to the "nix" command store Issues and pull requests concerning the Nix store
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@Ericson2314 @nixos-discourse @roberth @edolstra