refactor(tvix/store): use composition in tvix_store crate

Change-Id: Ie6290b296baba2b987f1a61c9bb4c78549ac11f1
Reviewed-on: https://cl.tvl.fyi/c/depot/+/11983
Reviewed-by: flokli <flokli@flokli.de>
Autosubmit: yuka <yuka@yuka.dev>
Tested-by: BuildkiteCI

tvix/store/src/pathinfoservice/bigtable.rs

@@ -10,15 +10,17 @@ use nix_compat::nixbase32;
 use prost::Message;
 use serde::{Deserialize, Serialize};
 use serde_with::{serde_as, DurationSeconds};
+use std::sync::Arc;
 use tonic::async_trait;
 use tracing::{instrument, trace};
+use tvix_castore::composition::{CompositionContext, ServiceBuilder};
 use tvix_castore::Error;
 
 /// There should not be more than 10 MiB in a single cell.
 /// https://cloud.google.com/bigtable/docs/schema-design#cells
 const CELL_SIZE_LIMIT: u64 = 10 * 1024 * 1024;
 
-/// Provides a [DirectoryService] implementation using
+/// Provides a [PathInfoService] implementation using
 /// [Bigtable](https://cloud.google.com/bigtable/docs/)
 /// as an underlying K/V store.
 ///
@@ -44,57 +46,6 @@ pub struct BigtablePathInfoService {
     emulator: std::sync::Arc<(tempfile::TempDir, async_process::Child)>,
 }
 
-/// Represents configuration of [BigtablePathInfoService].
-/// This currently conflates both connect parameters and data model/client
-/// behaviour parameters.
-#[serde_as]
-#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
-pub struct BigtableParameters {
-    project_id: String,
-    instance_name: String,
-    #[serde(default)]
-    is_read_only: bool,
-    #[serde(default = "default_channel_size")]
-    channel_size: usize,
-
-    #[serde_as(as = "Option<DurationSeconds<String>>")]
-    #[serde(default = "default_timeout")]
-    timeout: Option<std::time::Duration>,
-    table_name: String,
-    family_name: String,
-
-    #[serde(default = "default_app_profile_id")]
-    app_profile_id: String,
-}
-
-impl BigtableParameters {
-    #[cfg(test)]
-    pub fn default_for_tests() -> Self {
-        Self {
-            project_id: "project-1".into(),
-            instance_name: "instance-1".into(),
-            is_read_only: false,
-            channel_size: default_channel_size(),
-            timeout: default_timeout(),
-            table_name: "table-1".into(),
-            family_name: "cf1".into(),
-            app_profile_id: default_app_profile_id(),
-        }
-    }
-}
-
-fn default_app_profile_id() -> String {
-    "default".to_owned()
-}
-
-fn default_channel_size() -> usize {
-    4
-}
-
-fn default_timeout() -> Option<std::time::Duration> {
-    Some(std::time::Duration::from_secs(4))
-}
-
 impl BigtablePathInfoService {
     #[cfg(not(test))]
     pub async fn connect(params: BigtableParameters) -> Result<Self, bigtable::Error> {
@@ -412,3 +363,88 @@ impl PathInfoService for BigtablePathInfoService {
         Box::pin(stream)
     }
 }
+
+/// Represents configuration of [BigtablePathInfoService].
+/// This currently conflates both connect parameters and data model/client
+/// behaviour parameters.
+#[serde_as]
+#[derive(Clone, Debug, PartialEq, Deserialize, Serialize)]
+pub struct BigtableParameters {
+    project_id: String,
+    instance_name: String,
+    #[serde(default)]
+    is_read_only: bool,
+    #[serde(default = "default_channel_size")]
+    channel_size: usize,
+
+    #[serde_as(as = "Option<DurationSeconds<String>>")]
+    #[serde(default = "default_timeout")]
+    timeout: Option<std::time::Duration>,
+    table_name: String,
+    family_name: String,
+
+    #[serde(default = "default_app_profile_id")]
+    app_profile_id: String,
+}
+
+impl BigtableParameters {
+    #[cfg(test)]
+    pub fn default_for_tests() -> Self {
+        Self {
+            project_id: "project-1".into(),
+            instance_name: "instance-1".into(),
+            is_read_only: false,
+            channel_size: default_channel_size(),
+            timeout: default_timeout(),
+            table_name: "table-1".into(),
+            family_name: "cf1".into(),
+            app_profile_id: default_app_profile_id(),
+        }
+    }
+}
+
+fn default_app_profile_id() -> String {
+    "default".to_owned()
+}
+
+fn default_channel_size() -> usize {
+    4
+}
+
+fn default_timeout() -> Option<std::time::Duration> {
+    Some(std::time::Duration::from_secs(4))
+}
+
+#[async_trait]
+impl ServiceBuilder for BigtableParameters {
+    type Output = dyn PathInfoService;
+    async fn build<'a>(
+        &'a self,
+        _instance_name: &str,
+        _context: &CompositionContext,
+    ) -> Result<Arc<dyn PathInfoService>, Box<dyn std::error::Error + Send + Sync>> {
+        Ok(Arc::new(
+            BigtablePathInfoService::connect(self.clone()).await?,
+        ))
+    }
+}
+
+impl TryFrom<url::Url> for BigtableParameters {
+    type Error = Box<dyn std::error::Error + Send + Sync>;
+    fn try_from(mut url: url::Url) -> Result<Self, Self::Error> {
+        // parse the instance name from the hostname.
+        let instance_name = url
+            .host_str()
+            .ok_or_else(|| Error::StorageError("instance name missing".into()))?
+            .to_string();
+
+        // … but add it to the query string now, so we just need to parse that.
+        url.query_pairs_mut()
+            .append_pair("instance_name", &instance_name);
+
+        let params: BigtableParameters = serde_qs::from_str(url.query().unwrap_or_default())
+            .map_err(|e| Error::InvalidRequest(format!("failed to parse parameters: {}", e)))?;
+
+        Ok(params)
+    }
+}