feat(tvix/store/blobsvc): add from_addr

This allows constructing blob stores with a URL syntax at runtime,
by passing the --blob-service-addr arg.

We probably still want to have some builder pattern here, to allow
additional schemes to be registered.

Change-Id: Ie588ff7a7c6fb64c9474dfbd2e4bc5f168dfd778
Reviewed-on: https://cl.tvl.fyi/c/depot/+/8742
Reviewed-by: tazjin <tazjin@tvl.su>
Tested-by: BuildkiteCI

tvix/store/src/blobservice/from_addr.rs

@@ -0,0 +1,31 @@
+use std::sync::Arc;
+use url::Url;
+
+use super::{BlobService, GRPCBlobService, MemoryBlobService, SledBlobService};
+
+/// Constructs a new instance of a [BlobService] from an URI.
+///
+/// The following schemes are supported by the following services:
+/// - `memory://` ([MemoryBlobService])
+/// - `sled://` ([SledBlobService])
+/// - `grpc+*://` ([GRPCBlobService])
+///
+/// See their [from_url] methods for more details about their syntax.
+pub async fn from_addr(uri: &str) -> Result<Arc<dyn BlobService>, crate::Error> {
+    let url = Url::parse(uri).map_err(|e| {
+        crate::Error::StorageError(format!("unable to parse url: {}", e.to_string()))
+    })?;
+
+    Ok(if url.scheme() == "memory" {
+        Arc::new(MemoryBlobService::from_url(&url)?)
+    } else if url.scheme() == "sled" {
+        Arc::new(SledBlobService::from_url(&url)?)
+    } else if url.scheme().starts_with("grpc+") {
+        Arc::new(GRPCBlobService::from_url(&url)?)
+    } else {
+        Err(crate::Error::StorageError(format!(
+            "unknown scheme: {}",
+            url.scheme()
+        )))?
+    })
+}