add a shared pool of bonus concurrency (#218)

web3_proxy/src/app/mod.rs

@@ -99,6 +99,9 @@ pub struct Web3ProxyApp {
         Option<DeferredRateLimiter<RegisteredUserRateLimitKey>>,
     /// concurrent/parallel request limits for anonymous users
     pub ip_semaphores: Cache<IpAddr, Arc<Semaphore>>,
+    /// give some bonus capacity to public users
+    pub bonus_ip_concurrency: Arc<Semaphore>,
+    /// the /debug/ rpc endpoints send detailed logging to kafka
     pub kafka_producer: Option<rdkafka::producer::FutureProducer>,
     /// rate limit the login endpoint
     /// we do this because each pending login is a row in the database
@@ -114,6 +117,8 @@ pub struct Web3ProxyApp {
     pub user_balance_cache: UserBalanceCache,
     /// concurrent/parallel RPC request limits for authenticated users
     pub user_semaphores: Cache<(NonZeroU64, IpAddr), Arc<Semaphore>>,
+    /// give some bonus capacity to premium users
+    pub bonus_user_concurrency: Arc<Semaphore>,
     /// volatile cache used for rate limits
     /// TODO: i think i might just delete this entirely. instead use local-only concurrency limits.
     pub vredis_pool: Option<RedisPool>,
@@ -488,8 +493,15 @@ impl Web3ProxyApp {
             .ok()
             .and_then(|x| x.to_str().map(|x| x.to_string()));
 
+        // TODO: get the size out of the config
+        let bonus_ip_concurrency = Arc::new(Semaphore::new(top_config.app.bonus_ip_concurrency));
+        let bonus_user_concurrency =
+            Arc::new(Semaphore::new(top_config.app.bonus_user_concurrency));
+
         let app = Self {
             balanced_rpcs,
+            bonus_ip_concurrency,
+            bonus_user_concurrency,
             bundler_4337_rpcs,
             config: top_config.app.clone(),
             frontend_ip_rate_limiter,

web3_proxy/src/config.rs

@@ -83,6 +83,13 @@ pub struct AppConfig {
     #[serde_inline_default(90_000u64)]
     pub archive_depth: u64,
 
+    /// pool of extra connections allowed for authenticated users
+    #[serde_inline_default(0usize)]
+    pub bonus_user_concurrency: usize,
+    /// pool of extra connections allowed for anonymous users
+    #[serde_inline_default(0usize)]
+    pub bonus_ip_concurrency: usize,
+
     /// EVM chain id. 1 for ETH
     /// TODO: better type for chain_id? max of `u64::MAX / 2 - 36` <https://github.com/ethereum/EIPs/issues/2294>
     #[serde_inline_default(1u64)]

web3_proxy/src/frontend/authorization.rs

@@ -955,7 +955,16 @@ impl Web3ProxyApp {
                 })
                 .await;
 
-            let semaphore_permit = semaphore.acquire_owned().await?;
+            let semaphore_permit = tokio::select! {
+                biased;
+
+                p = semaphore.acquire_owned() => {
+                    p
+                }
+                p = self.bonus_ip_concurrency.clone().acquire_owned() => {
+                    p
+                }
+            }?;
 
             Ok(Some(semaphore_permit))
         } else {
@@ -984,7 +993,19 @@ impl Web3ProxyApp {
                 })
                 .await;
 
-            let semaphore_permit = semaphore.acquire_owned().await?;
+            let semaphore_permit = tokio::select! {
+                biased;
+
+                p = semaphore.acquire_owned() => {
+                    p
+                }
+                p = self.bonus_user_concurrency.clone().acquire_owned() => {
+                    p
+                }
+                p = self.bonus_ip_concurrency.clone().acquire_owned() => {
+                    p
+                }
+            }?;
 
             Ok(Some(semaphore_permit))
         } else {