...

scout/lua/reserve.lua

@@ -0,0 +1,12 @@
+local resource = KEYS[1]
+local claim = ARGV[1]
+local current = redis.call('GET', resource)
+if not current then
+    -- Freshly reserved
+    redis.call('SET', resource, claim)
+    return 1
+elseif current == claim then
+    -- Already reserved
+    return 0
+end
+return {err='BadClaim'}

scout/src/test/lua.rs

@@ -1,5 +1,85 @@
 use super::*;
 
+
+#[cfg(test)]
+mod reserve {
+    use super::*;
+
+    const SCRIPT: &'static str = include_str!("../../lua/reserve.lua");
+
+    #[test]
+    fn load() {
+        let mut client = redis::Client::open("redis://127.0.0.1:6379").unwrap();
+        let hash: String = redis::cmd("SCRIPT")
+            .arg("LOAD")
+            .arg(SCRIPT)
+            .query(&mut client)
+            .unwrap();
+        assert_eq!(hash.len(), 40);
+    }
+
+    #[test]
+    fn freshly_reserved() {
+        let resource = Uuid::new_v4().to_string();
+        let claim = Uuid::new_v4().to_string();
+        let key = rk::claim(&resource);
+        let mut client = redis::Client::open("redis://127.0.0.1:6379").unwrap();
+        let reserved: bool = redis::cmd("EVAL")
+            .arg(SCRIPT)
+            .arg(1)
+            .arg(&key)
+            .arg(&claim)
+            .query(&mut client)
+            .unwrap();
+        assert!(reserved);
+    }
+
+    #[test]
+    fn already_reserved() {
+        let resource = Uuid::new_v4().to_string();
+        let claim = Uuid::new_v4().to_string();
+        let key = rk::claim(&resource);
+        let mut client = redis::Client::open("redis://127.0.0.1:6379").unwrap();
+        let reserved: bool = redis::cmd("EVAL")
+            .arg(SCRIPT)
+            .arg(1)
+            .arg(&key)
+            .arg(&claim)
+            .query(&mut client)
+            .unwrap();
+        assert!(reserved);
+        let reserved: bool = redis::cmd("EVAL")
+            .arg(SCRIPT)
+            .arg(1)
+            .arg(&key)
+            .arg(&claim)
+            .query(&mut client)
+            .unwrap();
+        assert!(!reserved);
+    }
+
+    #[test]
+    fn err_bad_claim() {
+        let resource = Uuid::new_v4().to_string();
+        let claim = Uuid::new_v4().to_string();
+        let key = rk::claim(&resource);
+        let mut client = redis::Client::open("redis://127.0.0.1:6379").unwrap();
+        let _: () = redis::cmd("SET")
+            .arg(&key)
+            .arg("foobarbaz")
+            .query(&mut client)
+            .unwrap();
+        let err = redis::cmd("EVAL")
+            .arg(SCRIPT)
+            .arg(1)
+            .arg(&key)
+            .arg(&claim)
+            .query::<bool>(&mut client)
+            .unwrap_err();
+        assert_eq!(err.code().unwrap(), "BadClaim");
+    }
+}
+
 #[cfg(test)]
 mod release {
     use super::*;