object_store: Add enabled-by-default "fs" feature

Author: Turbo87

object_store/Cargo.toml

@@ -41,7 +41,7 @@ percent-encoding = "2.1"
 snafu = { version = "0.8", default-features = false, features = ["std", "rust_1_61"] }
 tracing = { version = "0.1" }
 url = "2.2"
-walkdir = "2"
+walkdir = { version = "2", optional = true }
 
 # Cloud storage support
 base64 = { version = "0.22", default-features = false, features = ["std"], optional = true }
@@ -60,8 +60,10 @@ md-5 = { version = "0.10.6", default-features = false, optional = true }
 nix = { version = "0.29.0", features = ["fs"] }
 
 [features]
+default = ["fs"]
 cloud = ["serde", "serde_json", "quick-xml", "hyper", "reqwest", "reqwest/json", "reqwest/stream", "chrono/serde", "base64", "rand", "ring"]
 azure = ["cloud"]
+fs = ["walkdir"]
 gcp = ["cloud", "rustls-pemfile"]
 aws = ["cloud", "md-5"]
 http = ["cloud"]

object_store/src/lib.rs

@@ -70,6 +70,10 @@
 //!
 //! Feature flags are used to enable support for other implementations:
 //!
+#![cfg_attr(
+    feature = "fs",
+    doc = "* Local filesystem: [`LocalFileSystem`](local::LocalFileSystem)"
+)]
 #![cfg_attr(
     feature = "gcp",
     doc = "* [`gcp`]: [Google Cloud Storage](https://cloud.google.com/storage/) support. See [`GoogleCloudStorageBuilder`](gcp::GoogleCloudStorageBuilder)"
@@ -513,7 +517,7 @@ pub mod gcp;
 #[cfg(feature = "http")]
 pub mod http;
 pub mod limit;
-#[cfg(not(target_arch = "wasm32"))]
+#[cfg(all(feature = "fs", not(target_arch = "wasm32")))]
 pub mod local;
 pub mod memory;
 pub mod path;
@@ -1047,7 +1051,7 @@ impl GetResult {
     pub async fn bytes(self) -> Result<Bytes> {
         let len = self.range.end - self.range.start;
         match self.payload {
-            #[cfg(not(target_arch = "wasm32"))]
+            #[cfg(all(feature = "fs", not(target_arch = "wasm32")))]
             GetResultPayload::File(mut file, path) => {
                 maybe_spawn_blocking(move || {
                     file.seek(SeekFrom::Start(self.range.start as _))
@@ -1087,7 +1091,7 @@ impl GetResult {
     /// no additional complexity or overheads
     pub fn into_stream(self) -> BoxStream<'static, Result<Bytes>> {
         match self.payload {
-            #[cfg(not(target_arch = "wasm32"))]
+            #[cfg(all(feature = "fs", not(target_arch = "wasm32")))]
             GetResultPayload::File(file, path) => {
                 const CHUNK_SIZE: usize = 8 * 1024;
                 local::chunked_stream(file, path, self.range, CHUNK_SIZE)