store: Do not cache calls that return 0x (#6187)

Signed-off-by: Maksim Dimitrov <dimitrov.maksim@gmail.com>

Author: dimitrovmaksim

store/postgres/src/chain_store.rs

@@ -2839,13 +2839,20 @@ impl EthereumCallCache for ChainStore {
         block: BlockPtr,
         return_value: call::Retval,
     ) -> Result<(), Error> {
-        let call::Retval::Value(return_value) = return_value else {
-            // We do not want to cache unsuccessful calls as some RPC nodes
-            // have weird behavior near the chain head. The details are lost
-            // to time, but we had issues with some RPC clients in the past
-            // where calls first failed and later succeeded
-            return Ok(());
+        let return_value = match return_value {
+            call::Retval::Value(return_value) if !return_value.is_empty() => return_value,
+            _ => {
+                // We do not want to cache unsuccessful calls as some RPC nodes
+                // have weird behavior near the chain head. The details are lost
+                // to time, but we had issues with some RPC clients in the past
+                // where calls first failed and later succeeded
+                // Also in some cases RPC nodes may return empty ("0x") values
+                // which in the context of graph-node most likely means an issue
+                // with the RPC node rather than a successful call.
+                return Ok(());
+            }
         };
+
         let id = contract_call_id(&call, &block);
         let conn = &mut *self.get_conn()?;
         conn.transaction(|conn| {

store/test-store/tests/postgres/chain_head.rs

@@ -475,6 +475,7 @@ fn eth_call_cache() {
             .unwrap();
         assert_eq!(&new_return_value, ret.as_slice());
 
+        // Reverted calls should not be cached
         store
             .set_call(
                 &logger,
@@ -486,6 +487,19 @@ fn eth_call_cache() {
         let ret = store.get_call(&call, BLOCK_THREE.block_ptr()).unwrap();
         assert_eq!(None, ret);
 
+        // Empty return values should not be cached
+        let return_value: [u8; 0] = [];
+        store
+            .set_call(
+                &logger,
+                call.cheap_clone(),
+                BLOCK_FOUR.block_ptr(),
+                ccr(&return_value),
+            )
+            .unwrap();
+        let ret = store.get_call(&call, BLOCK_FOUR.block_ptr()).unwrap();
+        assert_eq!(None, ret);
+
         Ok(())
     })
 }