feat: add accounts in-memory cache (#1086)

crates/common_utils/src/errors.rs

@@ -33,7 +33,7 @@ pub enum ParsingError {
 
 /// Validation errors.
 #[allow(missing_docs)] // Only to prevent warnings about struct fields not being documented
-#[derive(Debug, thiserror::Error)]
+#[derive(Debug, thiserror::Error, Clone)]
 pub enum ValidationError {
     /// The provided input is missing a required field.
     #[error("Missing required field: {field_name}")]

crates/redis_interface/src/errors.rs

@@ -58,4 +58,6 @@ pub enum RedisError {
     SubscribeError,
     #[error("Failed to publish to a channel")]
     PublishError,
+    #[error("Failed while receiving message from publisher")]
+    OnMessageError,
 }

crates/redis_interface/src/types.rs

@@ -5,9 +5,36 @@
 
 use common_utils::errors::CustomResult;
 use error_stack::IntoReport;
+use fred::types::RedisValue as FredRedisValue;
 
 use crate::errors;
 
+pub struct RedisValue {
+    inner: FredRedisValue,
+}
+
+impl std::ops::Deref for RedisValue {
+    type Target = FredRedisValue;
+
+    fn deref(&self) -> &Self::Target {
+        &self.inner
+    }
+}
+
+impl RedisValue {
+    pub fn new(value: FredRedisValue) -> Self {
+        Self { inner: value }
+    }
+    pub fn into_inner(self) -> FredRedisValue {
+        self.inner
+    }
+    pub fn from_string(value: String) -> Self {
+        Self {
+            inner: FredRedisValue::String(value.into()),
+        }
+    }
+}
+
 #[derive(Debug, serde::Deserialize, Clone)]
 #[serde(default)]
 pub struct RedisSettings {

crates/router/src/cache.rs

@@ -1,8 +1,18 @@
-use std::{any::Any, sync::Arc};
+use std::{any::Any, borrow::Cow, sync::Arc};
 
 use dyn_clone::DynClone;
+use error_stack::Report;
 use moka::future::Cache as MokaCache;
 use once_cell::sync::Lazy;
+use redis_interface::RedisValue;
+
+use crate::core::errors;
+
+/// Prefix for config cache key
+const CONFIG_CACHE_PREFIX: &str = "config";
+
+/// Prefix for accounts cache key
+const ACCOUNTS_CACHE_PREFIX: &str = "accounts";
 
 /// Time to live 30 mins
 const CACHE_TTL: u64 = 30 * 60;
@@ -10,14 +20,56 @@ const CACHE_TTL: u64 = 30 * 60;
 /// Time to idle 10 mins
 const CACHE_TTI: u64 = 10 * 60;
 
+/// Max Capacity of Cache in MB
+const MAX_CAPACITY: u64 = 30;
+
 /// Config Cache with time_to_live as 30 mins and time_to_idle as 10 mins.
-pub static CONFIG_CACHE: Lazy<Cache> = Lazy::new(|| Cache::new(CACHE_TTL, CACHE_TTI));
+pub static CONFIG_CACHE: Lazy<Cache> = Lazy::new(|| Cache::new(CACHE_TTL, CACHE_TTI, None));
+
+/// Accounts cache with time_to_live as 30 mins and size limit
+pub static ACCOUNTS_CACHE: Lazy<Cache> =
+    Lazy::new(|| Cache::new(CACHE_TTL, CACHE_TTI, Some(MAX_CAPACITY)));
 
 /// Trait which defines the behaviour of types that's gonna be stored in Cache
 pub trait Cacheable: Any + Send + Sync + DynClone {
     fn as_any(&self) -> &dyn Any;
 }
 
+pub enum CacheKind<'a> {
+    Config(Cow<'a, str>),
+    Accounts(Cow<'a, str>),
+}
+
+impl<'a> From<CacheKind<'a>> for RedisValue {
+    fn from(kind: CacheKind<'a>) -> Self {
+        let value = match kind {
+            CacheKind::Config(s) => format!("{CONFIG_CACHE_PREFIX},{s}"),
+            CacheKind::Accounts(s) => format!("{ACCOUNTS_CACHE_PREFIX},{s}"),
+        };
+        Self::from_string(value)
+    }
+}
+
+impl<'a> TryFrom<RedisValue> for CacheKind<'a> {
+    type Error = Report<errors::ValidationError>;
+    fn try_from(kind: RedisValue) -> Result<Self, Self::Error> {
+        let validation_err = errors::ValidationError::InvalidValue {
+            message: "Invalid publish key provided in pubsub".into(),
+        };
+        let kind = kind.as_string().ok_or(validation_err.clone())?;
+        let mut split = kind.split(',');
+        match split.next().ok_or(validation_err.clone())? {
+            ACCOUNTS_CACHE_PREFIX => Ok(Self::Accounts(Cow::Owned(
+                split.next().ok_or(validation_err)?.to_string(),
+            ))),
+            CONFIG_CACHE_PREFIX => Ok(Self::Config(Cow::Owned(
+                split.next().ok_or(validation_err)?.to_string(),
+            ))),
+            _ => Err(validation_err.into()),
+        }
+    }
+}
+
 impl<T> Cacheable for T
 where
     T: Any + Clone + Send + Sync,
@@ -45,13 +97,19 @@ impl Cache {
     ///
     /// `time_to_live`: Time in seconds before an object is stored in a caching system before it’s deleted
     /// `time_to_idle`: Time in seconds before a `get` or `insert` operation an object is stored in a caching system before it's deleted
-    pub fn new(time_to_live: u64, time_to_idle: u64) -> Self {
-        Self {
-            inner: MokaCache::builder()
+    /// `max_capacity`: Max size in MB's that the cache can hold
+    pub fn new(time_to_live: u64, time_to_idle: u64, max_capacity: Option<u64>) -> Self {
+        let mut cache_builder = MokaCache::builder()
             .eviction_listener_with_queued_delivery_mode(|_, _, _| {})
             .time_to_live(std::time::Duration::from_secs(time_to_live))
-                .time_to_idle(std::time::Duration::from_secs(time_to_idle))
-                .build(),
+            .time_to_idle(std::time::Duration::from_secs(time_to_idle));
+
+        if let Some(capacity) = max_capacity {
+            cache_builder = cache_builder.max_capacity(capacity * 1024 * 1024);
+        }
+
+        Self {
+            inner: cache_builder.build(),
         }
     }
 
@@ -71,8 +129,23 @@ mod cache_tests {
 
     #[tokio::test]
     async fn construct_and_get_cache() {
-        let cache = Cache::new(1800, 1800);
+        let cache = Cache::new(1800, 1800, None);
         cache.push("key".to_string(), "val".to_string()).await;
         assert_eq!(cache.get_val::<String>("key"), Some(String::from("val")));
     }
+
+    #[tokio::test]
+    async fn eviction_on_time_test() {
+        let cache = Cache::new(2, 2, None);
+        cache.push("key".to_string(), "val".to_string()).await;
+        tokio::time::sleep(std::time::Duration::from_secs(3)).await;
+        assert_eq!(cache.get_val::<String>("key"), None);
+    }
+
+    #[tokio::test]
+    async fn eviction_on_size_test() {
+        let cache = Cache::new(2, 2, Some(0));
+        cache.push("key".to_string(), "val".to_string()).await;
+        assert_eq!(cache.get_val::<String>("key"), None);
+    }
 }

crates/router/src/db/cache.rs

@@ -87,9 +87,9 @@ where
     Ok(data)
 }
 
-pub async fn publish_and_redact<T, F, Fut>(
+pub async fn publish_and_redact<'a, T, F, Fut>(
     store: &Store,
-    key: &str,
+    key: cache::CacheKind<'a>,
     fun: F,
 ) -> CustomResult<T, errors::StorageError>
 where

crates/router/src/db/configs.rs

@@ -2,7 +2,7 @@ use error_stack::IntoReport;
 
 use super::{cache, MockDb, Store};
 use crate::{
-    cache::CONFIG_CACHE,
+    cache::{CacheKind, CONFIG_CACHE},
     connection, consts,
     core::errors::{self, CustomResult},
     services::PubSubInterface,
@@ -78,7 +78,10 @@ impl ConfigInterface for Store {
         key: &str,
         config_update: storage::ConfigUpdate,
     ) -> CustomResult<storage::Config, errors::StorageError> {
-        cache::publish_and_redact(self, key, || self.update_config_by_key(key, config_update)).await
+        cache::publish_and_redact(self, CacheKind::Config(key.into()), || {
+            self.update_config_by_key(key, config_update)
+        })
+        .await
     }
 
     async fn find_config_by_key_cached(
@@ -98,7 +101,7 @@ impl ConfigInterface for Store {
 
         self.redis_conn()
             .map_err(Into::<errors::StorageError>::into)?
-            .publish(consts::PUB_SUB_CHANNEL, key)
+            .publish(consts::PUB_SUB_CHANNEL, CacheKind::Config(key.into()))
             .await
             .map_err(Into::<errors::StorageError>::into)?;
 

crates/router/src/db/merchant_account.rs

@@ -1,6 +1,8 @@
 use error_stack::IntoReport;
 
 use super::{MockDb, Store};
+#[cfg(feature = "accounts_cache")]
+use crate::cache::{self, ACCOUNTS_CACHE};
 use crate::{
     connection,
     core::errors::{self, CustomResult},
@@ -75,7 +77,8 @@ impl MerchantAccountInterface for Store {
 
         #[cfg(feature = "accounts_cache")]
         {
-            super::cache::get_or_populate_redis(self, merchant_id, fetch_func).await
+            super::cache::get_or_populate_in_memory(self, merchant_id, fetch_func, &ACCOUNTS_CACHE)
+                .await
         }
     }
 
@@ -100,7 +103,12 @@ impl MerchantAccountInterface for Store {
 
         #[cfg(feature = "accounts_cache")]
         {
-            super::cache::redact_cache(self, &_merchant_id, update_func, None).await
+            super::cache::publish_and_redact(
+                self,
+                cache::CacheKind::Accounts(_merchant_id.into()),
+                update_func,
+            )
+            .await
         }
     }
 

crates/router/src/services.rs

@@ -6,13 +6,13 @@ pub mod logger;
 use std::sync::{atomic, Arc};
 
 use error_stack::{IntoReport, ResultExt};
-use redis_interface::{errors as redis_errors, PubsubInterface};
+use redis_interface::{errors as redis_errors, PubsubInterface, RedisValue};
 use tokio::sync::oneshot;
 
 pub use self::{api::*, encryption::*};
 use crate::{
     async_spawn,
-    cache::CONFIG_CACHE,
+    cache::{CacheKind, ACCOUNTS_CACHE, CONFIG_CACHE},
     configs::settings,
     connection::{diesel_make_pg_pool, PgPool},
     consts,
@@ -26,10 +26,10 @@ pub trait PubSubInterface {
         channel: &str,
     ) -> errors::CustomResult<usize, redis_errors::RedisError>;
 
-    async fn publish(
+    async fn publish<'a>(
         &self,
         channel: &str,
-        key: &str,
+        key: CacheKind<'a>,
     ) -> errors::CustomResult<usize, redis_errors::RedisError>;
 
     async fn on_message(&self) -> errors::CustomResult<(), redis_errors::RedisError>;
@@ -50,13 +50,13 @@ impl PubSubInterface for redis_interface::RedisConnectionPool {
     }
 
     #[inline]
-    async fn publish(
+    async fn publish<'a>(
         &self,
         channel: &str,
-        key: &str,
+        key: CacheKind<'a>,
     ) -> errors::CustomResult<usize, redis_errors::RedisError> {
         self.publisher
-            .publish(channel, key)
+            .publish(channel, RedisValue::from(key).into_inner())
             .await
             .into_report()
             .change_context(redis_errors::RedisError::SubscribeError)
@@ -66,13 +66,19 @@ impl PubSubInterface for redis_interface::RedisConnectionPool {
     async fn on_message(&self) -> errors::CustomResult<(), redis_errors::RedisError> {
         let mut rx = self.subscriber.on_message();
         while let Ok(message) = rx.recv().await {
-            let key = message
-                .value
-                .as_string()
-                .ok_or::<redis_errors::RedisError>(redis_errors::RedisError::DeleteFailed)?;
-
-            self.delete_key(&key).await?;
-            CONFIG_CACHE.invalidate(&key).await;
+            let key: CacheKind<'_> = RedisValue::new(message.value)
+                .try_into()
+                .change_context(redis_errors::RedisError::OnMessageError)?;
+            match key {
+                CacheKind::Config(key) => {
+                    self.delete_key(key.as_ref()).await?;
+                    CONFIG_CACHE.invalidate(key.as_ref()).await;
+                }
+                CacheKind::Accounts(key) => {
+                    self.delete_key(key.as_ref()).await?;
+                    ACCOUNTS_CACHE.invalidate(key.as_ref()).await;
+                }
+            }
         }
         Ok(())
     }