Create cache directories if they do not already exist (#105)

host/src/lib.rs

@@ -51,8 +51,9 @@ pub fn save_receipt<T: serde::Serialize>(receipt_label: &String, receipt_data: &
 }
 
 fn zkp_cache_path(receipt_label: &String) -> String {
-    Path::new("cache_zkp")
-        .join(format!("{}.zkp", receipt_label))
+    let dir = Path::new("cache_zkp");
+    std::fs::create_dir_all(&dir).expect("Could not create directory");
+    dir.join(format!("{}.zkp", receipt_label))
         .to_str()
         .unwrap()
         .to_string()

lib/src/host/mod.rs

@@ -24,10 +24,9 @@ pub mod rpc_db;
 pub mod verify;
 
 pub fn cache_file_path(cache_path: &Path, network: &str, block_no: u64, ext: &str) -> PathBuf {
-    cache_path
-        .join(network)
-        .join(block_no.to_string())
-        .with_extension(ext)
+    let dir = cache_path.join(network);
+    std::fs::create_dir_all(&dir).expect("Could not create directory");
+    dir.join(block_no.to_string()).with_extension(ext)
 }
 
 #[derive(Clone)]

lib/src/host/rpc_db.rs

@@ -12,7 +12,7 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-use std::path::{Path, PathBuf};
+use std::path::PathBuf;
 
 use anyhow::Context;
 use zeth_primitives::{
@@ -22,21 +22,17 @@ use zeth_primitives::{
 };
 
 use crate::{
-    host::provider::{new_provider, BlockQuery},
+    host::{
+        cache_file_path,
+        provider::{new_provider, BlockQuery},
+    },
     optimism::{
         batcher_db::{BatcherDb, BlockInput, MemDb},
         config::ChainConfig,
         deposits, system_config,
     },
 };
 
-fn cache_file_path(cache_path: &Path, network: &str, block_no: u64, ext: &str) -> PathBuf {
-    cache_path
-        .join(network)
-        .join(block_no.to_string())
-        .with_extension(ext)
-}
-
 fn eth_cache_path(cache: &Option<PathBuf>, block_no: u64) -> Option<PathBuf> {
     cache
         .as_ref()