attic: Allow disabling tokio

Not needed at all for parsing usecases.

attic/Cargo.toml

@@ -28,6 +28,7 @@ cxx = { version = "1.0", optional = true }
 
 [dependencies.tokio]
 version = "1.23.0"
+optional = true
 features = [
 	"fs",
 	"io-util",
@@ -45,9 +46,14 @@ cxx-build = { version = "1.0", optional = true }
 pkg-config = "0.3.26"
 
 [features]
-default = [ "nix_store" ]
+default = [ "nix_store", "tokio" ]
 
 # Native libnixstore bindings.
 #
 # When disabled, the native Rust portions of nix_store can still be used.
-nix_store = [ "cxx", "bindgen", "cxx-build" ]
+nix_store = [ "dep:cxx", "dep:bindgen", "dep:cxx-build" ]
+
+# Tokio.
+#
+# When disabled, any part depending on tokio is unavailable.
+tokio = [ "dep:tokio" ]

attic/src/lib.rs

@@ -22,8 +22,10 @@ pub mod hash;
 pub mod mime;
 pub mod nix_store;
 pub mod signing;
+#[cfg(feature = "tokio")]
 pub mod stream;
 pub mod testing;
+#[cfg(feature = "tokio")]
 pub mod util;
 
 pub use error::{AtticError, AtticResult};

server/Cargo.toml

@@ -19,7 +19,7 @@ path = "src/adm/main.rs"
 doc = false
 
 [dependencies]
-attic = { path = "../attic", default-features = false }
+attic = { path = "../attic", default-features = false, features = [ "tokio" ] }
 attic-token = { path = "../token" }
 
 anyhow = "1.0.68"