From 4d3b851b2c140ba5aa7a39b28e4ae10000912130 Mon Sep 17 00:00:00 2001
From: Bryan Stitt <bryan@satoshiandkin.com>
Date: Tue, 26 Apr 2022 17:03:38 +0000
Subject: [PATCH] decrement even if error

---
 src/main.rs | 52 +++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 35 insertions(+), 17 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 4bdbad58..f2f0fd2f 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -26,13 +26,22 @@ static APP_USER_AGENT: &str = concat!(
     env!("CARGO_PKG_VERSION"),
 );
 
-// TODO: i tried to use Box<dyn Provider>, but hit https://github.com/gakonst/ethers-rs/issues/592
+type RpcRateLimiter =
+    RateLimiter<NotKeyed, InMemoryState, QuantaClock, NoOpMiddleware<QuantaInstant>>;
+
+type BlockMap = RwLock<HashMap<String, Block<TxHash>>>;
+type RateLimiterMap = RwLock<HashMap<String, RpcRateLimiter>>;
+// TODO: include the ethers client on this map
+type ConnectionsMap = RwLock<HashMap<String, EthersConnection>>;
+
+// TODO: instead of an enum, I tried to use Box<dyn Provider>, but hit https://github.com/gakonst/ethers-rs/issues/592
 #[derive(From)]
 enum EthersProvider {
     Http(ethers::providers::Provider<ethers::providers::Http>),
     Ws(ethers::providers::Provider<ethers::providers::Ws>),
 }
 
+/// Forward functions to the inner ethers::providers::Provider
 impl EthersProvider {
     /// Send a web3 request
     pub async fn request(
@@ -91,6 +100,7 @@ impl EthersProvider {
     }
 }
 
+/// An active connection to a Web3Rpc
 struct EthersConnection {
     /// keep track of currently open requests. We sort on this
     active_requests: u32,
@@ -98,6 +108,7 @@ struct EthersConnection {
 }
 
 impl EthersConnection {
+    /// Connect to a web3 rpc and subscribe to new heads
     async fn try_new(
         url_str: String,
         http_client: Option<reqwest::Client>,
@@ -141,11 +152,11 @@ impl EthersConnection {
         })
     }
 
-    fn inc(&mut self) {
+    fn inc_active_requests(&mut self) {
         self.active_requests += 1;
     }
 
-    fn dec(&mut self) {
+    fn dec_active_requests(&mut self) {
         self.active_requests -= 1;
     }
 }
@@ -164,22 +175,17 @@ impl PartialOrd for EthersConnection {
     }
 }
 
+/// note that this is just comparing the active requests. two providers with different rpc urls are equal!
 impl PartialEq for EthersConnection {
     fn eq(&self, other: &Self) -> bool {
         self.active_requests == other.active_requests
     }
 }
 
-type BlockMap = RwLock<HashMap<String, Block<TxHash>>>;
-type RateLimiterMap = RwLock<HashMap<String, RpcRateLimiter>>;
-// TODO: include the ethers client on this map
-type ConnectionsMap = RwLock<HashMap<String, EthersConnection>>;
-
-type RpcRateLimiter =
-    RateLimiter<NotKeyed, InMemoryState, QuantaClock, NoOpMiddleware<QuantaInstant>>;
-
-/// Load balance to the least-connection rpc
+/// Load balance to the rpc
 struct RpcTier {
+    /// RPC urls sorted by
+    /// TODO: what type?
     rpcs: RwLock<Vec<String>>,
     connections: Arc<ConnectionsMap>,
     ratelimits: RateLimiterMap,
@@ -325,7 +331,7 @@ impl RpcTier {
                 .await
                 .get_mut(selected_rpc)
                 .unwrap()
-                .inc();
+                .inc_active_requests();
 
             // return the selected RPC
             return Ok(selected_rpc.clone());
@@ -382,7 +388,7 @@ impl RpcTier {
                 .await
                 .get_mut(selected_rpc)
                 .unwrap()
-                .inc();
+                .inc_active_requests();
 
             // this is rpc should work
             selected_rpcs.push(selected_rpc.clone());
@@ -402,9 +408,14 @@ impl RpcTier {
     }
 }
 
+/// Application state
 struct Web3ProxyState {
+    /// clock used for rate limiting
+    /// TODO: use tokio's clock (will require a different ratelimiting crate)
     clock: QuantaClock,
+    /// Send requests to the best server available
     balanced_rpc_tiers: Arc<Vec<RpcTier>>,
+    /// Send private requests (like eth_sendRawTransaction) to all these servers
     private_rpcs: Option<Arc<RpcTier>>,
     /// write lock on these when all rate limits are hit
     balanced_rpc_ratelimiter_lock: RwLock<()>,
@@ -518,6 +529,7 @@ impl Web3ProxyState {
             // this is not a private transaction (or no private relays are configured)
             // try to send to each tier, stopping at the first success
             loop {
+                // TODO: i'm not positive that this locking is correct
                 let read_lock = self.balanced_rpc_ratelimiter_lock.read().await;
 
                 // there are multiple tiers. save the earliest not_until (if any). if we don't return, we will sleep until then and then try again
@@ -625,10 +637,16 @@ impl Web3ProxyState {
                 // get the client for this rpc server
                 let provider = connections.read().await.get(&rpc).unwrap().provider.clone();
 
-                // TODO: there has to be a better way to attach the url to the result
-                let mut response = provider.request(&method, params).await?;
+                let response = provider.request(&method, params).await;
 
-                connections.write().await.get_mut(&rpc).unwrap().dec();
+                connections
+                    .write()
+                    .await
+                    .get_mut(&rpc)
+                    .unwrap()
+                    .dec_active_requests();
+
+                let mut response = response?;
 
                 if let Some(response_id) = response.get_mut("id") {
                     *response_id = incoming_id;