don't cache nulls

Cargo.lock

@@ -7219,7 +7219,7 @@ dependencies = [
 
 [[package]]
 name = "web3_proxy"
-version = "1.42.0"
+version = "1.42.1"
 dependencies = [
  "anyhow",
  "arc-swap",

web3_proxy/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "web3_proxy"
-version = "1.42.0"
+version = "1.42.1"
 edition = "2021"
 default-run = "web3_proxy_cli"
 

web3_proxy/src/app/mod.rs

@@ -1731,10 +1731,16 @@ impl Web3ProxyApp {
                                 // return all the errors now. moka will not cache Err results
                                 Err(err)
                             } else {
+                                // convert jsonrpc errors into JsonRpcResponseEnum, but leave the rest as errors
                                 let response_data: JsonRpcResponseEnum<Arc<RawValue>> = response_data.try_into()?;
 
-                                // TODO: response data should maybe be Arc<JsonRpcResponseEnum<Box<RawValue>>>, but that's more work
+                                if response_data.is_null() {
-                                Ok(response_data)
+                                    // don't ever cache "null" as a success. its too likely to be a problem
+                                    Err(Web3ProxyError::NullJsonRpcResult)
+                                } else {
+                                    // TODO: response data should maybe be Arc<JsonRpcResponseEnum<Box<RawValue>>>, but that's more work
+                                    Ok(response_data)
+                                }
                             }
                         }).await?
                 } else {

web3_proxy/src/errors.rs

@@ -124,6 +124,8 @@ pub enum Web3ProxyError {
     #[from(ignore)]
     NotImplemented(Cow<'static, str>),
     NoVolatileRedisDatabase,
+    /// make it easy to skip caching null results
+    NullJsonRpcResult,
     OriginRequired,
     #[error(ignore)]
     #[from(ignore)]
@@ -759,6 +761,9 @@ impl Web3ProxyError {
                     },
                 )
             }
+            Self::NullJsonRpcResult => {
+                return (StatusCode::OK, JsonRpcResponseEnum::NullResult);
+            }
             Self::OriginRequired => {
                 trace!("OriginRequired");
                 (

web3_proxy/src/jsonrpc.rs

@@ -366,6 +366,10 @@ impl JsonRpcForwardedResponse {
 
     pub fn from_response_data(data: JsonRpcResponseEnum<Arc<RawValue>>, id: Box<RawValue>) -> Self {
         match data {
+            JsonRpcResponseEnum::NullResult => {
+                let x: Box<RawValue> = Default::default();
+                Self::from_raw_response(x.into(), id)
+            }
             JsonRpcResponseEnum::Result { value, .. } => Self::from_raw_response(value, id),
             JsonRpcResponseEnum::RpcError {
                 error_data: value, ..

web3_proxy/src/response_cache.rs

@@ -89,6 +89,7 @@ pub type JsonRpcResponseCache = Cache<u64, JsonRpcResponseEnum<Arc<RawValue>>>;
 /// TODO: we might need one that holds RawValue and one that holds serde_json::Value
 #[derive(Clone, Debug)]
 pub enum JsonRpcResponseEnum<R> {
+    NullResult,
     Result {
         value: R,
         num_bytes: u32,
@@ -103,12 +104,29 @@ pub enum JsonRpcResponseEnum<R> {
 impl<R> JsonRpcResponseEnum<R> {
     pub fn num_bytes(&self) -> u32 {
         match self {
+            Self::NullResult => 1,
             Self::Result { num_bytes, .. } => *num_bytes,
             Self::RpcError { num_bytes, .. } => *num_bytes,
         }
     }
 }
 
+impl<R> JsonRpcResponseEnum<Option<R>> {
+    pub fn is_null(&self) -> bool {
+        matches!(self, Self::NullResult | Self::Result { value: None, .. })
+    }
+}
+
+impl JsonRpcResponseEnum<Arc<RawValue>> {
+    pub fn is_null(&self) -> bool {
+        match self {
+            Self::NullResult => true,
+            Self::Result { value, .. } => value.get() == "null",
+            _ => false,
+        }
+    }
+}
+
 impl From<serde_json::Value> for JsonRpcResponseEnum<Arc<RawValue>> {
     fn from(value: serde_json::Value) -> Self {
         let value = RawValue::from_string(value.to_string()).unwrap();