diff options
author | Florian Klink <flokli@flokli.de> | 2024-05-12T17·34+0200 |
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committer | clbot <clbot@tvl.fyi> | 2024-05-13T22·05+0000 |
commit | adb42959a373f9084456cfaef665a07f27dd75f3 (patch) | |
tree | 3a445c77924a5d9fb6f23c68412eafb2d2126303 /tvix | |
parent | 30995a099068a5ffa9113625b985a25c0ac83f3f (diff) |
feat(tvix/store/pathinfo): add a Cache combinator r/8144
This allows querying two PathInfoService implementations sequentially, and inserts into the "near" one if it's not there yet. There is no negative cache, and put / listing is not implemented (for now). Change-Id: I24c3d0e0c3c2f0524a6cc7b2f3cbc33eb20cf92b Reviewed-on: https://cl.tvl.fyi/c/depot/+/11636 Autosubmit: flokli <flokli@flokli.de> Tested-by: BuildkiteCI Reviewed-by: Connor Brewster <cbrewster@hey.com>
Diffstat (limited to '')
-rw-r--r-- | tvix/store/src/pathinfoservice/combinators.rs | 111 | ||||
-rw-r--r-- | tvix/store/src/pathinfoservice/mod.rs | 2 |
2 files changed, 113 insertions, 0 deletions
diff --git a/tvix/store/src/pathinfoservice/combinators.rs b/tvix/store/src/pathinfoservice/combinators.rs new file mode 100644 index 000000000000..664144ef494b --- /dev/null +++ b/tvix/store/src/pathinfoservice/combinators.rs @@ -0,0 +1,111 @@ +use crate::proto::PathInfo; +use futures::stream::BoxStream; +use nix_compat::nixbase32; +use tonic::async_trait; +use tracing::{debug, instrument}; +use tvix_castore::Error; + +use super::PathInfoService; + +/// Asks near first, if not found, asks far. +/// If found in there, returns it, and *inserts* it into +/// near. +/// There is no negative cache. +/// Inserts and listings are not implemented for now. +pub struct Cache<PS1, PS2> { + near: PS1, + far: PS2, +} + +impl<PS1, PS2> Cache<PS1, PS2> { + pub fn new(near: PS1, far: PS2) -> Self { + Self { near, far } + } +} + +#[async_trait] +impl<PS1, PS2> PathInfoService for Cache<PS1, PS2> +where + PS1: PathInfoService, + PS2: PathInfoService, +{ + #[instrument(level = "trace", skip_all, fields(path_info.digest = nixbase32::encode(&digest)))] + async fn get(&self, digest: [u8; 20]) -> Result<Option<PathInfo>, Error> { + match self.near.get(digest).await? { + Some(path_info) => { + debug!("serving from cache"); + Ok(Some(path_info)) + } + None => { + debug!("not found in near, asking remote…"); + match self.far.get(digest).await? { + None => Ok(None), + Some(path_info) => { + debug!("found in remote, adding to cache"); + self.near.put(path_info.clone()).await?; + Ok(Some(path_info)) + } + } + } + } + } + + async fn put(&self, _path_info: PathInfo) -> Result<PathInfo, Error> { + Err(Error::StorageError("unimplemented".to_string())) + } + + fn list(&self) -> BoxStream<'static, Result<PathInfo, Error>> { + Box::pin(tokio_stream::once(Err(Error::StorageError( + "unimplemented".to_string(), + )))) + } +} + +#[cfg(test)] +mod test { + use std::num::NonZeroUsize; + + use crate::{ + pathinfoservice::{LruPathInfoService, MemoryPathInfoService, PathInfoService}, + tests::fixtures::PATH_INFO_WITH_NARINFO, + }; + + const PATH_INFO_DIGEST: [u8; 20] = [0; 20]; + + /// Helper function setting up an instance of a "far" and "near" + /// PathInfoService. + async fn create_pathinfoservice() -> super::Cache<LruPathInfoService, MemoryPathInfoService> { + // Create an instance of a "far" PathInfoService. + let far = MemoryPathInfoService::default(); + + // … and an instance of a "near" PathInfoService. + let near = LruPathInfoService::with_capacity(NonZeroUsize::new(1).unwrap()); + + // create a Pathinfoservice combining the two and return it. + super::Cache::new(near, far) + } + + /// Getting from the far backend is gonna insert it into the near one. + #[tokio::test] + async fn test_populate_cache() { + let svc = create_pathinfoservice().await; + + // query the PathInfo, things should not be there. + assert!(svc.get(PATH_INFO_DIGEST).await.unwrap().is_none()); + + // insert it into the far one. + svc.far.put(PATH_INFO_WITH_NARINFO.clone()).await.unwrap(); + + // now try getting it again, it should succeed. + assert_eq!( + Some(PATH_INFO_WITH_NARINFO.clone()), + svc.get(PATH_INFO_DIGEST).await.unwrap() + ); + + // peek near, it should now be there. + assert_eq!( + Some(PATH_INFO_WITH_NARINFO.clone()), + svc.near.get(PATH_INFO_DIGEST).await.unwrap() + ); + } +} diff --git a/tvix/store/src/pathinfoservice/mod.rs b/tvix/store/src/pathinfoservice/mod.rs index 5f5da2bff296..574bcc0b8b88 100644 --- a/tvix/store/src/pathinfoservice/mod.rs +++ b/tvix/store/src/pathinfoservice/mod.rs @@ -1,3 +1,4 @@ +mod combinators; mod from_addr; mod grpc; mod lru; @@ -17,6 +18,7 @@ use tvix_castore::Error; use crate::proto::PathInfo; +pub use self::combinators::Cache as CachePathInfoService; pub use self::from_addr::from_addr; pub use self::grpc::GRPCPathInfoService; pub use self::lru::LruPathInfoService; |