feat(rust): scaffold redis cache crate

Co-Authored-By: Devin AI <158243242+devin-ai-integration[bot]@users.noreply.github.com>

litellm-rust/Cargo.lock

@@ -70,6 +70,12 @@ dependencies = [
  "rustversion",
 ]
 
+[[package]]
+name = "arcstr"
+version = "1.2.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "03918c3dbd7701a85c6b9887732e2921175f26c350b4563841d0958c21d57e6d"
+
 [[package]]
 name = "async-compression"
 version = "0.4.46"
@@ -1915,6 +1921,15 @@ dependencies = [
  "tokio",
 ]
 
+[[package]]
+name = "litellm-cache-redis"
+version = "0.1.0"
+dependencies = [
+ "litellm-cache",
+ "redis",
+ "serde_json",
+]
+
 [[package]]
 name = "litellm-core"
 version = "0.1.0"
@@ -2140,6 +2155,16 @@ dependencies = [
  "minimal-lexical",
 ]
 
+[[package]]
+name = "num-bigint"
+version = "0.5.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "93e7820bc0a80a0238e650327316f929ba18d5be054b647490a3a6a339f3e7c0"
+dependencies = [
+ "num-integer",
+ "num-traits",
+]
+
 [[package]]
 name = "num-conv"
 version = "0.2.2"
@@ -2656,6 +2681,24 @@ dependencies = [
  "crossbeam-utils",
 ]
 
+[[package]]
+name = "redis"
+version = "1.7.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2acbc41a996f7652b2ddd9dfd98cc4ff602cfd742ae35382f07f608405ab50ed"
+dependencies = [
+ "arcstr",
+ "combine",
+ "itoa",
+ "num-bigint",
+ "percent-encoding",
+ "ryu",
+ "sha1_smol",
+ "socket2 0.6.5",
+ "url",
+ "xxhash-rust",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.5.18"
@@ -3096,6 +3139,12 @@ dependencies = [
  "digest 0.10.7",
 ]
 
+[[package]]
+name = "sha1_smol"
+version = "1.0.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "bbfa15b3dddfee50a0fff136974b3e1bde555604ba463834a7eb7deb6417705d"
+
 [[package]]
 name = "sha2"
 version = "0.10.9"
@@ -4182,6 +4231,12 @@ version = "0.13.6"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "66fee0b777b0f5ac1c69bb06d361268faafa61cd4682ae064a171c16c433e9e4"
 
+[[package]]
+name = "xxhash-rust"
+version = "0.8.18"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "aee1b19627c7c60102ab80d3a9cbe18de90bfe03bfa6c3715447681f0e8c8af6"
+
 [[package]]
 name = "yoke"
 version = "0.8.3"

litellm-rust/Cargo.toml

@@ -23,6 +23,7 @@ pyo3 = "0.29.2"
 pyo3-async-runtimes = { version = "0.29.0", features = ["tokio-runtime"] }
 pythonize = "0.29.0"
 rand = "0.8"
+redis = "1.7.0"
 reqwest = { version = "0.12", default-features = false, features = ["blocking", "json", "multipart", "rustls-tls", "http2", "stream"] }
 rstest = "0.26.1"
 rustls = { version = "0.23", default-features = false, features = ["ring", "std", "tls12"] }

litellm-rust/crates/cache-redis/Cargo.toml

@@ -0,0 +1,11 @@
+[package]
+name = "litellm-cache-redis"
+version = "0.1.0"
+edition.workspace = true
+license.workspace = true
+repository.workspace = true
+
+[dependencies]
+litellm-cache.workspace = true
+redis.workspace = true
+serde_json.workspace = true

litellm-rust/crates/cache-redis/src/cache.rs

@@ -0,0 +1,127 @@
+use std::sync::Mutex;
+use std::time::Duration;
+
+use litellm_cache::{
+    BaseCache, CacheConnectionResult, CacheConnectionStatus, CacheEntry, CacheFuture, CacheKwargs,
+    Error,
+};
+use redis::Commands;
+
+const DEFAULT_TTL: Duration = Duration::from_secs(600);
+
+pub struct RedisCache {
+    connection: Mutex<redis::Connection>,
+    default_ttl: Duration,
+}
+
+impl RedisCache {
+    pub fn new(url: &str, default_ttl: Option<Duration>) -> Result<Self, Error> {
+        let client = redis::Client::open(url).map_err(|_| Error::Unavailable)?;
+        let connection = client.get_connection().map_err(|_| Error::Unavailable)?;
+        Ok(Self {
+            connection: Mutex::new(connection),
+            default_ttl: default_ttl.unwrap_or(DEFAULT_TTL),
+        })
+    }
+
+    fn connection(&self) -> Result<std::sync::MutexGuard<'_, redis::Connection>, Error> {
+        self.connection.lock().map_err(|_| Error::Unavailable)
+    }
+
+    fn encode(value: &CacheEntry) -> Result<Vec<u8>, Error> {
+        serde_json::to_vec(value).map_err(|_| Error::InvalidEntry)
+    }
+
+    fn decode(value: Vec<u8>) -> Result<CacheEntry, Error> {
+        serde_json::from_slice(&value).map_err(|_| Error::InvalidEntry)
+    }
+
+    fn ttl_seconds(ttl: Duration) -> u64 {
+        ttl.as_secs().max(1)
+    }
+}
+
+impl BaseCache for RedisCache {
+    type Value = CacheEntry;
+
+    fn default_ttl(&self) -> Duration {
+        self.default_ttl
+    }
+
+    fn set_cache(&self, key: &str, value: Self::Value, kwargs: CacheKwargs) -> Result<(), Error> {
+        let payload = Self::encode(&value)?;
+        let ttl = Self::ttl_seconds(self.get_ttl(&kwargs));
+        self.connection()?
+            .set_ex::<_, _, ()>(key, payload, ttl)
+            .map_err(|_| Error::Unavailable)
+    }
+
+    fn get_cache(&self, key: &str, _: &CacheKwargs) -> Result<Option<Self::Value>, Error> {
+        self.connection()?
+            .get::<_, Option<Vec<u8>>>(key)
+            .map_err(|_| Error::Unavailable)?
+            .map(Self::decode)
+            .transpose()
+    }
+
+    fn delete_cache(&self, key: &str) -> Result<(), Error> {
+        self.connection()?
+            .del::<_, ()>(key)
+            .map_err(|_| Error::Unavailable)
+    }
+
+    fn flush_cache(&self) -> Result<(), Error> {
+        self.connection()?
+            .flushdb::<()>()
+            .map_err(|_| Error::Unavailable)
+    }
+
+    fn disconnect(&self) -> CacheFuture<'_, ()> {
+        Box::pin(async { Ok(()) })
+    }
+
+    fn test_connection(&self) -> CacheFuture<'_, CacheConnectionResult> {
+        Box::pin(async {
+            let mut connection = self.connection()?;
+            redis::cmd("PING")
+                .query::<String>(&mut *connection)
+                .map_err(|_| Error::Unavailable)?;
+            Ok(CacheConnectionResult {
+                status: CacheConnectionStatus::Success,
+                message: "Redis cache connection test successful".into(),
+                error: None,
+            })
+        })
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::RedisCache;
+    use litellm_cache::CacheEntry;
+    use serde_json::json;
+    use std::time::Duration;
+
+    #[test]
+    fn cache_entries_round_trip_through_json() {
+        let entry = CacheEntry {
+            timestamp: 123.0,
+            response: json!({"choices": [{"text": "cached"}]}),
+        };
+
+        let encoded = RedisCache::encode(&entry).unwrap();
+        assert_eq!(RedisCache::decode(encoded).unwrap(), entry);
+    }
+
+    #[test]
+    fn invalid_json_is_rejected() {
+        assert!(RedisCache::decode(b"not json".to_vec()).is_err());
+    }
+
+    #[test]
+    fn ttl_seconds_keeps_redis_expiration_positive() {
+        assert_eq!(RedisCache::ttl_seconds(Duration::ZERO), 1);
+        assert_eq!(RedisCache::ttl_seconds(Duration::from_millis(1500)), 1);
+        assert_eq!(RedisCache::ttl_seconds(Duration::from_secs(15)), 15);
+    }
+}

litellm-rust/crates/cache-redis/src/lib.rs

@@ -0,0 +1,3 @@
+mod cache;
+
+pub use cache::RedisCache;

litellm-rust/crates/cache-redis/tests/cache.rs

@@ -0,0 +1,6 @@
+use litellm_cache_redis::RedisCache;
+
+#[test]
+fn constructor_rejects_invalid_urls() {
+    assert!(RedisCache::new("not a redis url", None).is_err());
+}