chore: fix caching issue for conditional merchant creation (#68)

Author: NishantJoshi00

src/error.rs

@@ -59,6 +59,8 @@ pub enum StorageError {
     DecryptionError,
     #[error("Error while encrypting the payload")]
     EncryptionError,
+    #[error("Element not found in storage")]
+    NotFoundError,
 }
 
 #[derive(Debug, Copy, Clone, thiserror::Error)]

src/error/container.rs

@@ -1,7 +1,7 @@
 use std::error::Error;
 
 pub struct ContainerError<E> {
-    pub(super) error: error_stack::Report<E>,
+    pub(crate) error: error_stack::Report<E>,
 }
 
 impl<T> std::fmt::Debug for ContainerError<T> {

src/error/custom_error.rs

@@ -10,6 +10,8 @@ pub enum MerchantDBError {
     DBFilterError,
     #[error("Error while inserting element in the database")]
     DBInsertError,
+    #[error("Element not found in database")]
+    NotFoundError,
     #[error("Unpredictable error occurred")]
     UnknownError,
 }
@@ -43,3 +45,13 @@ pub enum HashDBError {
     #[error("Unpredictable error occurred")]
     UnknownError,
 }
+
+pub trait NotFoundError {
+    fn is_not_found(&self) -> bool;
+}
+
+impl NotFoundError for super::ContainerError<MerchantDBError> {
+    fn is_not_found(&self) -> bool {
+        matches!(self.error.current_context(), MerchantDBError::NotFoundError)
+    }
+}

src/error/transforms.rs

@@ -40,6 +40,7 @@ impl<'a> From<&'a super::StorageError> for super::MerchantDBError {
             | super::StorageError::EncryptionError
             | super::StorageError::DeleteError => Self::UnknownError,
             super::StorageError::InsertError => Self::DBInsertError,
+            super::StorageError::NotFoundError => Self::NotFoundError,
         }
     }
 }
@@ -57,6 +58,7 @@ impl<'a> From<&'a super::StorageError> for super::LockerDBError {
             }
             super::StorageError::InsertError => Self::DBInsertError,
             super::StorageError::DeleteError => Self::DBDeleteError,
+            super::StorageError::NotFoundError => Self::DBFilterError,
         }
     }
 }
@@ -73,6 +75,7 @@ impl<'a> From<&'a super::StorageError> for super::HashDBError {
             | super::StorageError::EncryptionError
             | super::StorageError::DeleteError => Self::UnknownError,
             super::StorageError::InsertError => Self::DBInsertError,
+            super::StorageError::NotFoundError => Self::DBFilterError,
         }
     }
 }
@@ -103,6 +106,7 @@ impl<'a> From<&'a super::MerchantDBError> for super::ApiError {
                                                          // occur because of master key failure
             super::MerchantDBError::DBError |
             super::MerchantDBError::DBFilterError |
+            super::MerchantDBError::NotFoundError |
             super::MerchantDBError::DBInsertError=> Self::MerchantError,
             super::MerchantDBError::UnknownError => Self::UnknownError
         }

src/storage/caching/hash_table.rs

@@ -38,3 +38,42 @@ where
         Ok(output)
     }
 }
+
+#[async_trait::async_trait]
+impl<T> storage::MerchantInterface for super::Caching<T, types::HashTable>
+where
+    T: storage::MerchantInterface + storage::Cacheable<types::HashTable> + Sync,
+{
+    type Algorithm = T::Algorithm;
+    type Error = T::Error;
+
+    async fn find_by_merchant_id(
+        &self,
+        merchant_id: &str,
+        tenant_id: &str,
+        key: &Self::Algorithm,
+    ) -> Result<types::Merchant, ContainerError<Self::Error>> {
+        self.inner
+            .find_by_merchant_id(merchant_id, tenant_id, key)
+            .await
+    }
+
+    async fn find_or_create_by_merchant_id(
+        &self,
+        merchant_id: &str,
+        tenant_id: &str,
+        key: &Self::Algorithm,
+    ) -> Result<types::Merchant, ContainerError<Self::Error>> {
+        self.inner
+            .find_or_create_by_merchant_id(merchant_id, tenant_id, key)
+            .await
+    }
+
+    async fn insert_merchant(
+        &self,
+        new: types::MerchantNew<'_>,
+        key: &Self::Algorithm,
+    ) -> Result<types::Merchant, ContainerError<Self::Error>> {
+        self.inner.insert_merchant(new, key).await
+    }
+}

src/storage/caching/merchant.rs

@@ -1,5 +1,8 @@
+use futures_util::TryFutureExt;
+
 use crate::{
-    error::ContainerError,
+    crypto::aes::generate_aes256_key,
+    error::{ContainerError, NotFoundError},
     storage::{self, types},
 };
 
@@ -10,6 +13,7 @@ where
         + storage::Cacheable<types::Merchant, Key = (String, String), Value = types::Merchant>
         + Sync
         + Send,
+    ContainerError<<T as storage::MerchantInterface>::Error>: NotFoundError,
 {
     type Algorithm = T::Algorithm;
     type Error = T::Error;
@@ -46,8 +50,23 @@ where
         tenant_id: &str,
         key: &Self::Algorithm,
     ) -> Result<types::Merchant, ContainerError<Self::Error>> {
-        self.inner
-            .find_or_create_by_merchant_id(merchant_id, tenant_id, key)
+        self.find_by_merchant_id(merchant_id, tenant_id, key)
+            .or_else(|err| async {
+                match err.is_not_found() {
+                    false => Err(err),
+                    true => {
+                        self.insert_merchant(
+                            types::MerchantNew {
+                                merchant_id,
+                                tenant_id,
+                                enc_key: generate_aes256_key().to_vec().into(),
+                            },
+                            key,
+                        )
+                        .await
+                    }
+                }
+            })
             .await
     }
 
@@ -64,3 +83,25 @@ where
         Ok(output)
     }
 }
+
+#[async_trait::async_trait]
+impl<T> storage::HashInterface for super::Caching<T, types::Merchant>
+where
+    T: storage::HashInterface + storage::Cacheable<types::Merchant> + Sync,
+{
+    type Error = T::Error;
+
+    async fn find_by_data_hash(
+        &self,
+        data_hash: &[u8],
+    ) -> Result<Option<types::HashTable>, ContainerError<Self::Error>> {
+        self.inner.find_by_data_hash(data_hash).await
+    }
+
+    async fn insert_hash(
+        &self,
+        data_hash: Vec<u8>,
+    ) -> Result<types::HashTable, ContainerError<Self::Error>> {
+        self.inner.insert_hash(data_hash).await
+    }
+}

src/storage/db.rs

@@ -33,12 +33,13 @@ impl MerchantInterface for Storage {
                 .get_result(&mut conn)
                 .await;
         output
-            .change_error(error::StorageError::FindError)
-            .map_err(From::from)
-            .and_then(|inner| {
-                Ok(inner.decrypt(key)?)
-                // .change_context(error::StorageError::DecryptionError)
+            .map_err(|error| match error {
+                diesel::result::Error::NotFound => error::StorageError::NotFoundError,
+                _ => error::StorageError::FindError,
             })
+            .map_err(error::ContainerError::from)
+            .map_err(From::from)
+            .and_then(|inner| Ok(inner.decrypt(key)?))
     }
 
     async fn find_or_create_by_merchant_id(