Support for the sparse-index RFC

.gitignore

@@ -22,6 +22,9 @@ crates/*/target
 # file for saving processes from `persist`
 /persist-dump.json
 
+# miscellaneous ignored folder
+/ignored
+
 # alexandrie local testing folders
 /app-data
 /crate-index

crates/alexandrie-index/src/index/cli.rs

@@ -5,7 +5,7 @@ use semver::{Version, VersionReq};
 
 use crate::error::Error;
 use crate::tree::Tree;
-use crate::{CrateVersion, Indexer};
+use crate::{ConfigFile, CrateVersion, Indexer};
 
 /// The 'command-line' crate index management strategy type.
 ///
@@ -39,6 +39,10 @@ impl Indexer for CommandLineIndex {
         self.repo.commit_and_push(msg)
     }
 
+    fn configuration(&self) -> Result<ConfigFile, Error> {
+        self.tree.configuration()
+    }
+
     fn match_record(&self, name: &str, req: VersionReq) -> Result<CrateVersion, Error> {
         self.tree.match_record(name, req)
     }

crates/alexandrie-index/src/index/git2.rs

@@ -5,7 +5,7 @@ use semver::{Version, VersionReq};
 
 use crate::error::Error;
 use crate::tree::Tree;
-use crate::{CrateVersion, Indexer};
+use crate::{ConfigFile, CrateVersion, Indexer};
 
 /// The 'git2' crate index management strategy type.
 ///
@@ -135,6 +135,10 @@ impl Indexer for Git2Index {
         Ok(())
     }
 
+    fn configuration(&self) -> Result<ConfigFile, Error> {
+        self.tree.configuration()
+    }
+
     fn match_record(&self, name: &str, req: VersionReq) -> Result<CrateVersion, Error> {
         self.tree.match_record(name, req)
     }

crates/alexandrie-index/src/lib.rs

@@ -1,4 +1,5 @@
 use semver::{Version, VersionReq};
+use serde::{Deserialize, Serialize};
 
 pub mod config;
 pub mod error;
@@ -7,8 +8,8 @@ mod index;
 mod models;
 mod tree;
 
-pub use index::*;
-pub use models::{CrateDependency, CrateDependencyKind, CrateVersion};
+pub use crate::index::*;
+pub use crate::models::{CrateDependency, CrateDependencyKind, CrateVersion};
 
 use crate::cli::CommandLineIndex;
 use crate::error::Error;
@@ -28,20 +29,34 @@ pub enum Index {
     Git2(Git2Index),
 }
 
+/// Represents the index's configuration file.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+#[serde(rename_all = "kebab-case")]
+pub struct ConfigFile {
+    /// The download link format for crates.
+    pub dl: String,
+    /// The base URL where the API for this index's registry can be found.
+    pub api: String,
+    /// The URLs to the other registries that crates in this index are allowed to have dependencies on.
+    pub allowed_registries: Vec<String>,
+}
+
 /// The required trait that any crate index management type must implement.
 pub trait Indexer {
     /// Gives back the URL of the managed crate index.
     fn url(&self) -> Result<String, Error>;
     /// Refreshes the managed crate index (in case another instance made modification to it).
     fn refresh(&self) -> Result<(), Error>;
+    /// Commits and pushes changes upstream.
+    fn commit_and_push(&self, msg: &str) -> Result<(), Error>;
+    /// Retrieves the index's current configuration file.
+    fn configuration(&self) -> Result<ConfigFile, Error>;
     /// Retrieves all the version records of a crate.
     fn all_records(&self, name: &str) -> Result<Vec<CrateVersion>, Error>;
     /// Retrieves the latest version record of a crate.
     fn latest_record(&self, name: &str) -> Result<CrateVersion, Error>;
     /// Retrieves the latest crate version record that matches the given name and version requirement.
     fn match_record(&self, name: &str, req: VersionReq) -> Result<CrateVersion, Error>;
-    /// Commits and pushes changes upstream.
-    fn commit_and_push(&self, msg: &str) -> Result<(), Error>;
     /// Adds a new crate record into the index.
     fn add_record(&self, record: CrateVersion) -> Result<(), Error>;
     /// Alters an index's crate version record with the passed-in function.
@@ -83,6 +98,14 @@ impl Indexer for Index {
         }
     }
 
+    fn configuration(&self) -> Result<ConfigFile, Error> {
+        match self {
+            Index::CommandLine(idx) => idx.configuration(),
+            #[cfg(feature = "git2")]
+            Index::Git2(idx) => idx.configuration(),
+        }
+    }
+
     fn all_records(&self, name: &str) -> Result<Vec<CrateVersion>, Error> {
         match self {
             Index::CommandLine(idx) => idx.all_records(name),

crates/alexandrie-index/src/tree.rs

@@ -7,7 +7,7 @@ use semver::{Version, VersionReq};
 
 use crate::error::IndexError;
 use crate::models::CrateVersion;
-use crate::Error;
+use crate::{ConfigFile, Error};
 
 #[derive(Debug, Clone, PartialEq)]
 pub struct Tree {
@@ -28,6 +28,13 @@ impl Tree {
         }
     }
 
+    pub fn configuration(&self) -> Result<ConfigFile, Error> {
+        let path = self.path.join("config.json");
+        let bytes = fs::read(&path)?;
+        let config = json::from_slice(&bytes)?;
+        Ok(config)
+    }
+
     pub fn match_record(&self, name: &str, req: VersionReq) -> Result<CrateVersion, Error> {
         let path = self.compute_record_path(name);
         let file = fs::File::open(path).map_err(|err| match err.kind() {
@@ -96,14 +103,10 @@ impl Tree {
             }),
             _ => Error::from(err),
         })?;
-        let mut krates: Vec<CrateVersion> = {
-            let mut out = Vec::new();
-            for line in io::BufReader::new(file).lines() {
-                let krate = json::from_str(line?.as_str())?;
-                out.push(krate);
-            }
-            out
-        };
+        let mut krates: Vec<CrateVersion> = io::BufReader::new(file)
+            .lines()
+            .map(|line| Ok(json::from_str(line?.as_str())?))
+            .collect::<Result<_, Error>>()?;
         let found = krates
             .iter_mut()
             .find(|krate| krate.vers == version)

crates/alexandrie/src/api/mod.rs

@@ -4,3 +4,5 @@ pub mod account;
 pub mod categories;
 /// Crate-related endpoints (eg. "/api/v1/crates/*").
 pub mod crates;
+/// Sparse index endpoints (eg. "/api/v1/sparse/se/rd/serde").
+pub mod sparse;

crates/alexandrie/src/api/sparse/mod.rs

@@ -0,0 +1,62 @@
+use std::sync::Arc;
+
+use axum::extract::{Path, State};
+use axum::Json;
+use serde::{Deserialize, Serialize};
+
+use alexandrie_index::{ConfigFile, Indexer};
+
+use crate::config::AppState;
+use crate::error::ApiError;
+
+/// Response body for this route.
+#[derive(Debug, Clone, PartialEq, Eq, Serialize, Deserialize)]
+pub struct PathParams {
+    /// The crate's name.
+    pub fst: String,
+    /// The crate's description.
+    pub snd: String,
+    /// The crate's repository link.
+    #[serde(rename = "crate")]
+    pub krate: Option<String>,
+}
+
+/// Route to sparsly access index entries for a crate.
+pub async fn get(
+    State(state): State<Arc<AppState>>,
+    Path(params): Path<PathParams>,
+) -> Result<String, ApiError> {
+    let (fst, snd, krate) = match params.krate.as_deref() {
+        Some(krate) => (params.fst.as_str(), Some(params.snd.as_str()), krate),
+        None => (params.fst.as_str(), None, params.snd.as_str()),
+    };
+
+    let maybe_expected = match krate.len() {
+        0 => None,
+        1 => Some(("1", None)),
+        2 => Some(("2", None)),
+        3 => Some(("3", Some(&krate[..1]))),
+        _ => Some((&krate[..2], Some(&krate[2..4]))),
+    };
+
+    if maybe_expected.map_or(true, |it| it != (fst, snd)) {
+        return Err(ApiError::msg("the crate could not be found"));
+    }
+
+    let records = state.index.all_records(krate)?;
+
+    let mut output = String::default();
+    for record in records {
+        let record = json::to_string(&record)?;
+        output.push_str(&record);
+        output.push('\n');
+    }
+
+    Ok(output)
+}
+
+/// Route to sparsly access the index's configuration.
+pub async fn get_config(State(state): State<Arc<AppState>>) -> Result<Json<ConfigFile>, ApiError> {
+    let config = state.index.configuration()?;
+    Ok(Json(config))
+}

crates/alexandrie/src/main.rs

@@ -31,6 +31,8 @@ use clap::Parser;
 use diesel_migrations::MigrationHarness;
 use tower_http::trace::{self, TraceLayer};
 use tracing::Level;
+use tracing_subscriber::filter::LevelFilter;
+use tracing_subscriber::EnvFilter;
 
 #[cfg(feature = "frontend")]
 use axum::http::StatusCode;
@@ -40,8 +42,6 @@ use tower_http::services::ServeDir;
 use tower_sessions::cookie::SameSite;
 #[cfg(feature = "frontend")]
 use tower_sessions::SessionManagerLayer;
-use tracing_subscriber::filter::LevelFilter;
-use tracing_subscriber::EnvFilter;
 
 /// API endpoints definitions.
 pub mod api;
@@ -185,6 +185,9 @@ fn api_routes() -> Router<Arc<AppState>> {
             "/crates/:name/:version/download",
             get(api::crates::download::get),
         )
+        .route("/sparse/:fst/:snd/:crate", get(api::sparse::get))
+        .route("/sparse/:fst/:snd", get(api::sparse::get))
+        .route("/sparse/config.json", get(api::sparse::get_config))
 }
 
 #[derive(Debug, Parser)]