implement git store sync (maybe)

.gitignore

@@ -1 +1,2 @@
 /target
+.cargo

Cargo.toml

@@ -8,3 +8,8 @@ edition = "2021"
 [dependencies]
 sha2 = "0.10.6"
 hex = "0.4.3"
+gix = { version = "0.44.1", features = [
+    "blocking-network-client",
+    "blocking-http-transport-reqwest-rust-tls",
+]}
+tempdir = "0.3.7"

flake.lock

@@ -35,16 +35,16 @@
     },
     "nixpkgs_2": {
       "locked": {
-        "lastModified": 1683020768,
-        "narHash": "sha256-ZyZl6k9NWS5QPwD3NoAVz/eSgodQDvl+y+fu8MVbrHc=",
+        "lastModified": 1683103914,
+        "narHash": "sha256-Mbrst3sLaiL55eOlZOEL8kB+XTWffaQVfcI03YWiryg=",
         "owner": "NixOS",
         "repo": "nixpkgs",
-        "rev": "44f30edf5661d86fb3a95841c35127f3d0ea8b0f",
+        "rev": "54495a4eafe99c537695a87fe04cb50bf17e651d",
         "type": "github"
       },
       "original": {
         "owner": "NixOS",
-        "ref": "nixpkgs-unstable",
+        "ref": "nixos-22.11",
         "repo": "nixpkgs",
         "type": "github"
       }

flake.nix

@@ -1,7 +1,7 @@
 {
   inputs = {
     naersk.url = "github:nix-community/naersk/master";
-    nixpkgs.url = "github:NixOS/nixpkgs/nixpkgs-unstable";
+    nixpkgs.url = "github:NixOS/nixpkgs/nixos-22.11";
     utils.url = "github:numtide/flake-utils";
   };
 
@@ -16,6 +16,9 @@
         devShell = with pkgs; mkShell {
           buildInputs = [ cargo rustc rustfmt pre-commit rustPackages.clippy ];
           RUST_SRC_PATH = rustPlatform.rustLibSrc;
+          shellHook = ''
+            export CARGO_HOME=$(pwd)/.cargo
+          '';
         };
       });
 }

src/lib.rs

@@ -0,0 +1 @@
+pub mod origin;

src/main.rs

@@ -1,13 +0,0 @@
-mod origin;
-
-use crate::origin::Descr;
-
-fn main() {
-
-    let d = Descr::Git{
-        url: "foo",
-        branch: "bar",
-    };
-
-    println!("{}", d.id());
-}

src/origin.rs

@@ -1,44 +1,10 @@
-use sha2::{Sha256, Digest};
-use hex::ToHex;
+mod descr;
+pub use self::descr::Descr;
 
-/// A unique description of an origin, from where a domain might be served.
-pub enum Descr<'a> {
-    Git{url: &'a str, branch: &'a str},
+pub mod store;
+
+/// A View of an origin is used to read the files of that origin at a particular point in time. A
+/// single instance of a View should remain consistent across its lifetime.
+pub trait View {
+    fn open(&self, path: &str) -> &dyn std::io::Read;
 }
-
-impl<'a> Descr<'a> {
-
-    /// Returns a globally unique string for the Descr.
-    pub fn id(&'a self) -> String {
-
-        let mut h = Sha256::new();
-
-        let mut h_update = |b: &str| {
-            h.update(b);
-            h.update("\n");
-        };
-
-        match self {
-            Descr::Git{url, branch} => {
-                h_update("git");
-                h_update(url);
-                h_update(branch);
-            }
-        }
-
-        h.finalize().encode_hex::<String>()
-    }
-}
-
-#[cfg(test)]
-mod descr_tests {
-
-    #[test]
-    fn id() {
-
-        assert_eq!(
-            super::Descr::Git{url:"foo", branch:"bar"}.id(),
-            "424130b9e6c1675c983b4b97579877e16d8a6377e4fe10970e6d210811c3b7ac",
-        )
-    }
-//}

src/origin/descr.rs

@@ -1,9 +1,10 @@
 use sha2::{Sha256, Digest};
 use hex::ToHex;
 
+#[derive(Clone,Copy)]
 /// A unique description of an origin, from where a domain might be served.
 pub enum Descr<'a> {
-    Git{url: &'a str, branch: &'a str},
+    Git{url: &'a str, branch_name: &'a str},
 }
 
 impl<'a> Descr<'a> {
@@ -19,10 +20,10 @@ impl<'a> Descr<'a> {
         };
 
         match self {
-            Descr::Git{url, branch} => {
+            Descr::Git{url, branch_name} => {
                 h_update("git");
                 h_update(url);
-                h_update(branch);
+                h_update(branch_name);
             }
         }
 
@@ -37,7 +38,7 @@ mod descr_tests {
     fn id() {
 
         assert_eq!(
-            super::Descr::Git{url:"foo", branch:"bar"}.id(),
+            super::Descr::Git{url:"foo", branch_name:"bar"}.id(),
             "424130b9e6c1675c983b4b97579877e16d8a6377e4fe10970e6d210811c3b7ac",
         )
     }

src/origin/store.rs

@@ -0,0 +1,138 @@
+use std::error::Error;
+
+use super::Descr;
+use super::View;
+
+#[derive(Clone,Copy)]
+pub struct Limits {}
+
+pub enum GetViewError {
+    TODO,
+    Unexpected(Box<dyn Error>),
+}
+
+#[derive(Debug)]
+pub enum SyncError {
+    InvalidURL,
+    InvalidBranchName,
+    Unexpected(Box<dyn Error>),
+}
+
+pub trait Store {
+    fn get_view(&self, descr: Descr) -> Result<&dyn View, GetViewError>;
+    fn sync(&self, descr: Descr, limits: Limits) -> Result<(), SyncError>;
+}
+
+pub mod git {
+
+    use std::path::Path;
+    use super::{Store as originStore, *};
+
+    use gix::clone::Error as gixCloneErr;
+    use gix::progress::Discard;
+
+    // Catching error from gix::prepare_clone_bare
+    impl From<gixCloneErr> for SyncError {
+        fn from(e: gixCloneErr) -> SyncError {
+            match e {
+                gixCloneErr::Init(gix::init::Error::InvalidBranchName{..}) =>
+                    SyncError::InvalidBranchName,
+                gixCloneErr::UrlParse(_) |
+                gixCloneErr::CanonicalizeUrl{..} =>
+                    SyncError::InvalidURL,
+                _ =>
+                    SyncError::Unexpected(Box::from(e)),
+            }
+        }
+    }
+
+    pub struct Store<'a> {
+        dir_path: &'a Path,
+    }
+
+    impl<'a> Store<'a> {
+
+        pub fn new(dir_path: &Path) -> std::io::Result<Store> {
+            std::fs::create_dir_all(dir_path)?;
+            println!("{}", &dir_path.display());
+            Ok(Store{dir_path})
+        }
+    }
+
+    impl<'a> originStore for Store<'a> {
+
+        fn sync(&self, descr: Descr, _limits: Limits) -> Result<(), SyncError> {
+
+            let should_interrupt = &core::sync::atomic::AtomicBool::new(false);
+
+            let Descr::Git{url, ..} = descr;
+
+            let path = &self.dir_path.clone().join(descr.id());
+
+            // if the path doesn't exist then use the gix clone feature to clone it into the
+            // directory.
+            if std::fs::read_dir(path).is_err() {
+
+                std::fs::create_dir_all(path)
+                    .map_err(|e| SyncError::Unexpected(Box::from(e)))?;
+
+                gix::prepare_clone_bare(url, path)?
+                    .fetch_only(Discard, should_interrupt)
+                    .map_err(|_| SyncError::InvalidURL)?;
+
+                return Ok(());
+            }
+
+            let direction = gix::remote::Direction::Fetch;
+
+            let repo = gix::open(path)
+                .map_err(|e| SyncError::Unexpected(Box::from(e)))?;
+
+            let remote = repo.find_default_remote(direction)
+                .ok_or(SyncError::Unexpected(Box::from("no default configured")))?
+                .map_err(|e| SyncError::Unexpected(Box::from(e)))?;
+
+            remote
+                .connect(direction)
+                .map_err(|e| SyncError::Unexpected(Box::from(e)))?
+                .prepare_fetch(Discard, Default::default())
+                .map_err(|e| SyncError::Unexpected(Box::from(e)))?
+                .receive(Discard, should_interrupt)
+                .map_err(|e| SyncError::Unexpected(Box::from(e)))?;
+
+            Ok(())
+        }
+
+        fn get_view(&self, _descr: Descr) -> Result<&dyn View, GetViewError> {
+            Err(GetViewError::TODO)
+        }
+
+    }
+
+    #[cfg(test)]
+    mod tests {
+
+        use super::Descr;
+        use super::super::Store;
+
+        use tempdir::TempDir;
+
+        #[test]
+        fn sync() {
+
+            let tmp_dir = TempDir::new("origin_store_git").unwrap();
+
+            let descr = Descr::Git{
+                url: "https://github.com/mediocregopher/priority-finder.git",
+                branch_name: "master",
+            };
+
+            let limits = super::Limits{};
+
+            let store = super::Store::new(tmp_dir.path()).expect("store created");
+
+            store.sync(descr, limits).expect("sync should succeed");
+            store.sync(descr, limits).expect("second sync should succeed");
+        }
+    }
+}