feat(tvix/store): add directoryservice r/5912

This adds a DirectoryService trait, and an implementation for it using
sled, and one using a HashMap.

Change-Id: Ida61524b2ca949e1b3a78089a5aa7d9f9800c8d7
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8093
Tested-by: BuildkiteCI
Reviewed-by: raitobezarius <tvl@lahfa.xyz>

1 files changed, 76 insertions, 0 deletions

diff --git a/tvix/store/src/directoryservice/memory.rs b/tvix/store/src/directoryservice/memory.rs
new file mode 100644
index 000000000000..34ee45203320
--- /dev/null
+++ b/tvix/store/src/directoryservice/memory.rs
@@ -0,0 +1,76 @@
+use crate::{proto, Error};
+use data_encoding::BASE64;
+use std::collections::HashMap;
+use std::sync::{Arc, RwLock};
+use tracing::{instrument, warn};
+
+use super::DirectoryService;
+
+#[derive(Clone)]
+pub struct MemoryDirectoryService {
+    db: Arc<RwLock<HashMap<Vec<u8>, proto::Directory>>>,
+}
+
+impl MemoryDirectoryService {
+    pub fn new() -> Self {
+        let db = Arc::new(RwLock::new(HashMap::default()));
+
+        Self { db }
+    }
+}
+
+impl DirectoryService for MemoryDirectoryService {
+    // TODO: change api to only be by digest
+    #[instrument(skip(self, by_what))]
+    fn get(
+        &self,
+        by_what: &proto::get_directory_request::ByWhat,
+    ) -> Result<Option<proto::Directory>, Error> {
+        match by_what {
+            proto::get_directory_request::ByWhat::Digest(digest) => {
+                let db = self.db.read()?;
+
+                match db.get(digest) {
+                    // The directory was not found, return
+                    None => Ok(None),
+
+                    // The directory was found, try to parse the data as Directory message
+                    Some(directory) => {
+                        // Validate the retrieved Directory indeed has the
+                        // digest we expect it to have, to detect corruptions.
+                        let actual_digest = directory.digest();
+                        if actual_digest.as_slice() != digest {
+                            return Err(Error::StorageError(format!(
+                                "requested directory with digest {}, but got {}",
+                                BASE64.encode(digest),
+                                BASE64.encode(&actual_digest)
+                            )));
+                        }
+
+                        Ok(Some(directory.clone()))
+                    }
+                }
+            }
+        }
+    }
+
+    #[instrument(skip(self, directory), fields(directory.digest = BASE64.encode(&directory.digest())))]
+    fn put(&self, directory: proto::Directory) -> Result<Vec<u8>, Error> {
+        let digest = directory.digest();
+
+        // validate the directory itself.
+        if let Err(e) = directory.validate() {
+            return Err(Error::InvalidRequest(format!(
+                "directory {} failed validation: {}",
+                BASE64.encode(&digest),
+                e,
+            )));
+        }
+
+        // store it
+        let mut db = self.db.write()?;
+        db.insert(digest.clone(), directory);
+
+        Ok(digest)
+    }
+}