Very WIP (i.e broken) start of SQLite storage in server

sync-server/Cargo.toml

@@ -10,12 +10,15 @@ edition = "2018"
 uuid = { version = "^0.8.2", features = ["serde", "v4"] }
 actix-web = "^3.3.2"
 anyhow = "1.0"
+thiserror = "1.0"
 futures = "^0.3.8"
 serde = "^1.0.125"
+serde_json = "^1.0"
 kv = {version = "^0.10.0", features = ["msgpack-value"]}
 clap = "^2.33.0"
 log = "^0.4.14"
 env_logger = "^0.8.3"
+rusqlite = { version = "0.25", features = ["bundled"] }
 
 [dev-dependencies]
 actix-rt = "^2.2.0"

sync-server/src/storage/mod.rs

@@ -6,6 +6,9 @@ mod inmemory;
 #[cfg(test)]
 pub(crate) use inmemory::InMemoryStorage;
 
+mod sqlite;
+pub(crate) use self::sqlite::SqliteStorage;
+
 mod kv;
 pub(crate) use self::kv::KvStorage;
 

sync-server/src/storage/sqlite.rs

@@ -0,0 +1,270 @@
+use super::{Client, Storage, StorageTxn, Uuid, Version};
+use rusqlite::types::{FromSql, ToSql};
+use rusqlite::{params, Connection, OptionalExtension};
+use std::path::Path;
+use std::sync::{Arc, Mutex};
+use anyhow::Context;
+
+#[derive(Debug, thiserror::Error)]
+enum SqliteError {
+    #[error("SQLite transaction already committted")]
+    TransactionAlreadyCommitted,
+}
+
+
+/// Newtype to allow implementing `FromSql` for foreign `uuid::Uuid`
+struct StoredUuid(Uuid);
+
+/// Conversion from Uuid stored as a string (rusqlite's uuid feature stores as binary blob)
+impl FromSql for StoredUuid {
+    fn column_result(value: rusqlite::types::ValueRef<'_>) -> rusqlite::types::FromSqlResult<Self> {
+        let u = Uuid::parse_str(value.as_str()?)
+            .map_err(|_| rusqlite::types::FromSqlError::InvalidType)?;
+        Ok(StoredUuid(u))
+    }
+}
+
+/// Store Uuid as string in database
+impl ToSql for StoredUuid {
+    fn to_sql(&self) -> rusqlite::Result<rusqlite::types::ToSqlOutput<'_>> {
+        let s = self.0.to_string();
+        Ok(s.into())
+    }
+}
+
+/// Stores [`Client`] in SQLite
+impl FromSql for Client {
+    fn column_result(value: rusqlite::types::ValueRef<'_>) -> rusqlite::types::FromSqlResult<Self> {
+        let o: Client = serde_json::from_str(value.as_str()?)
+            .map_err(|_| rusqlite::types::FromSqlError::InvalidType)?;
+        Ok(o)
+    }
+}
+
+/// Parsers Operation stored as JSON in string column
+impl ToSql for Client {
+    fn to_sql(&self) -> rusqlite::Result<rusqlite::types::ToSqlOutput<'_>> {
+        let s = serde_json::to_string(&self)
+            .map_err(|e| rusqlite::Error::ToSqlConversionFailure(Box::new(e)))?;
+        Ok(s.into())
+    }
+}
+
+
+
+/// DB Key for versions: concatenation of client_key and parent_version_id
+type VersionDbKey = [u8; 32];
+
+fn version_db_key(client_key: Uuid, parent_version_id: Uuid) -> VersionDbKey {
+    let mut key = [0u8; 32];
+    key[..16].clone_from_slice(client_key.as_bytes());
+    key[16..].clone_from_slice(parent_version_id.as_bytes());
+    key
+}
+
+/// Key for clients: just the client_key
+type ClientDbKey = [u8; 16];
+
+fn client_db_key(client_key: Uuid) -> ClientDbKey {
+    *client_key.as_bytes()
+}
+
+/// An on-disk storage backend which uses SQLite
+pub(crate) struct SqliteStorage {
+    db_file: std::path::PathBuf,
+}
+
+impl SqliteStorage {
+    fn new_connection(&self) -> anyhow::Result<Connection> {
+        Ok(Connection::open(&self.db_file)?)
+    }
+
+    pub fn new<P: AsRef<Path>>(directory: P) -> anyhow::Result<SqliteStorage> {
+        let db_file = directory.as_ref().join("taskchampion-sync-server.sqlite3");
+
+        let o = SqliteStorage { db_file };
+
+        {
+            let mut con = o.new_connection()?;
+            let txn = con.transaction()?;
+
+            let queries = vec![
+                "CREATE TABLE IF NOT EXISTS clients (id INTEGER PRIMARY KEY AUTOINCREMENT, data STRING);",
+            ];
+            for q in queries {
+                txn.execute(q, []).context("Creating table")?;
+            }
+            txn.commit()?;
+        }
+
+        Ok(o)
+    }
+}
+
+impl Storage for SqliteStorage {
+    fn txn<'a>(&'a self) -> anyhow::Result<Box<dyn StorageTxn + 'a>> {
+        let mut con = self.new_connection()?;
+        let mut t = Txn{con, txn: None};
+        Ok(Box::new(t))
+    }
+}
+
+struct Txn<'t> {
+    con: Connection,
+    txn: Option<&'t rusqlite::Transaction<'t>>,
+}
+
+impl <'t>Txn<'t> {
+    fn get_txn(&mut self) -> Result<&'t rusqlite::Transaction, SqliteError> {
+        Ok(&self.con.transaction().unwrap())
+    }
+}
+
+
+impl <'t>StorageTxn for Txn<'t> {
+    fn get_client(&mut self, client_key: Uuid) -> anyhow::Result<Option<Client>> {
+        let t = self.get_txn()?;
+        let result: Option<Client> = t
+            .query_row(
+                "SELECT data FROM clients WHERE client_key = ? LIMIT 1",
+                [&StoredUuid(client_key)],
+                |r| r.get("data"),
+            )
+            .optional()?;
+
+        Ok(result)
+    }
+
+    fn new_client(&mut self, client_key: Uuid, latest_version_id: Uuid) -> anyhow::Result<()> {
+        let t = self.get_txn()?;
+
+        let client = Client{ latest_version_id };
+        t.execute(
+            "INSERT OR REPLACE INTO clients (client_key, latest_version_id) VALUES (?, ?)",
+            params![&StoredUuid(latest_version_id), &client],
+        )
+        .context("Create client query")?;
+        Ok(())
+    }
+
+    fn set_client_latest_version_id(
+        &mut self,
+        client_key: Uuid,
+        latest_version_id: Uuid,
+    ) -> anyhow::Result<()> {
+        // Implementation is same as new_client
+        self.new_client(client_key, latest_version_id)
+    }
+
+    fn get_version_by_parent(
+        &mut self,
+        client_key: Uuid,
+        parent_version_id: Uuid,
+    ) -> anyhow::Result<Option<Version>> {
+        todo!()
+    }
+
+    fn add_version(
+        &mut self,
+        client_key: Uuid,
+        version_id: Uuid,
+        parent_version_id: Uuid,
+        history_segment: Vec<u8>,
+    ) -> anyhow::Result<()> {
+        let version = Version {
+            version_id,
+            parent_version_id,
+            history_segment,
+        };
+        todo!();
+        Ok(())
+    }
+
+    fn commit(&mut self) -> anyhow::Result<()> {
+        let t = self
+            .txn
+            .take()
+            .ok_or(SqliteError::TransactionAlreadyCommitted)?;
+        t.commit().context("Committing transaction")?;
+        Ok(())
+    }
+}
+
+#[cfg(test)]
+mod test {
+    use super::*;
+    use tempfile::TempDir;
+
+    #[test]
+    fn test_get_client_empty() -> anyhow::Result<()> {
+        let tmp_dir = TempDir::new()?;
+        let storage = SqliteStorage::new(&tmp_dir.path())?;
+        let mut txn = storage.txn()?;
+        let maybe_client = txn.get_client(Uuid::new_v4())?;
+        assert!(maybe_client.is_none());
+        Ok(())
+    }
+
+    #[test]
+    fn test_client_storage() -> anyhow::Result<()> {
+        let tmp_dir = TempDir::new()?;
+        let storage = SqliteStorage::new(&tmp_dir.path())?;
+        let mut txn = storage.txn()?;
+
+        let client_key = Uuid::new_v4();
+        let latest_version_id = Uuid::new_v4();
+        txn.new_client(client_key, latest_version_id)?;
+
+        let client = txn.get_client(client_key)?.unwrap();
+        assert_eq!(client.latest_version_id, latest_version_id);
+
+        let latest_version_id = Uuid::new_v4();
+        txn.set_client_latest_version_id(client_key, latest_version_id)?;
+
+        let client = txn.get_client(client_key)?.unwrap();
+        assert_eq!(client.latest_version_id, latest_version_id);
+
+        Ok(())
+    }
+
+    #[test]
+    fn test_gvbp_empty() -> anyhow::Result<()> {
+        let tmp_dir = TempDir::new()?;
+        let storage = SqliteStorage::new(&tmp_dir.path())?;
+        let mut txn = storage.txn()?;
+        let maybe_version = txn.get_version_by_parent(Uuid::new_v4(), Uuid::new_v4())?;
+        assert!(maybe_version.is_none());
+        Ok(())
+    }
+
+    #[test]
+    fn test_add_version_and_gvbp() -> anyhow::Result<()> {
+        let tmp_dir = TempDir::new()?;
+        let storage = SqliteStorage::new(&tmp_dir.path())?;
+        let mut txn = storage.txn()?;
+
+        let client_key = Uuid::new_v4();
+        let version_id = Uuid::new_v4();
+        let parent_version_id = Uuid::new_v4();
+        let history_segment = b"abc".to_vec();
+        txn.add_version(
+            client_key,
+            version_id,
+            parent_version_id,
+            history_segment.clone(),
+        )?;
+        let version = txn
+            .get_version_by_parent(client_key, parent_version_id)?
+            .unwrap();
+
+        assert_eq!(
+            version,
+            Version {
+                version_id,
+                parent_version_id,
+                history_segment,
+            }
+        );
+        Ok(())
+    }
+}