add justknobs stub

Reviewed By: mitrandir77, RajivTS

Differential Revision: D50264249

fbshipit-source-id: 56d624c97fcde323e3f7525349052ef3e41b11f7

Cargo.toml

@@ -51,6 +51,7 @@ members = [
   "shed/hash_memo",
   "shed/hostcaps",
   "shed/hostname",
+  "shed/justknobs_stub",
   "shed/limited_async_read",
   "shed/lock_ext",
   "shed/memcache_stub",

shed/justknobs_stub/Cargo.toml

@@ -0,0 +1,14 @@
+# @generated by autocargo
+
+[package]
+name = "justknobs"
+version = "0.1.0"
+authors = ["Facebook <[email protected]>"]
+edition = "2021"
+description = "Client for accessing JustKnobs. Noop crate for now"
+readme = "../../README.md"
+repository = "https://github.com/facebookexperimental/rust-shed/"
+license = "MIT OR Apache-2.0"
+
+[dependencies]
+anyhow = "=1.0.72"

shed/justknobs_stub/src/lib.rs

@@ -0,0 +1,38 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under both the MIT license found in the
+ * LICENSE-MIT file in the root directory of this source tree and the Apache
+ * License, Version 2.0 found in the LICENSE-APACHE file in the root directory
+ * of this source tree.
+ */
+
+//! This crate provides a client for accessing JustKnobs. The version on GitHub
+//! is no-op for now.
+
+use anyhow as _;
+#[cfg(fbcode_build)]
+pub use fb_justknobs::*;
+#[cfg(not(fbcode_build))]
+pub use stub::*;
+
+#[cfg(not(fbcode_build))]
+mod stub {
+    use anyhow::Result;
+
+    pub fn eval(_name: &str, _hash_val: Option<&str>, _switch_val: Option<&str>) -> Result<bool> {
+        Ok(false)
+    }
+
+    pub fn get(_name: &str, _switch_val: Option<&str>) -> Result<i64> {
+        Ok(0)
+    }
+
+    pub fn get_as<T>(_name: &str, _switch_val: Option<&str>) -> Result<T>
+    where
+        T: TryFrom<i64>,
+        <T as TryFrom<i64>>::Error: std::error::Error + Send + Sync + 'static,
+    {
+        Ok(0.try_into()?)
+    }
+}