From 42e36ba5e8413738a40fab795a8d7f392b2a51db Mon Sep 17 00:00:00 2001
From: Conrad Ludgate <conradludgate@gmail.com>
Date: Wed, 16 Apr 2025 15:25:59 +0100
Subject: [PATCH] simplify generics more

---
 proxy/src/serverless/backend.rs        | 11 +++++------
 proxy/src/serverless/conn_pool.rs      |  2 +-
 proxy/src/serverless/conn_pool_lib.rs  | 23 ++++++++++------------
 proxy/src/serverless/http_conn_pool.rs | 27 ++++++++++----------------
 4 files changed, 26 insertions(+), 37 deletions(-)

diff --git a/proxy/src/serverless/backend.rs b/proxy/src/serverless/backend.rs
index 81cf37a996..a72e319081 100644
--- a/proxy/src/serverless/backend.rs
+++ b/proxy/src/serverless/backend.rs
@@ -42,10 +42,9 @@ use crate::rate_limiter::EndpointRateLimiter;
 use crate::types::{EndpointId, Host, LOCAL_PROXY_SUFFIX};
 
 pub(crate) struct PoolingBackend {
-    pub(crate) http_conn_pool: Arc<GlobalConnPool<Send, HttpConnPool>>,
+    pub(crate) http_conn_pool: Arc<GlobalConnPool<HttpConnPool>>,
     pub(crate) local_pool: Arc<LocalConnPool<postgres_client::Client>>,
-    pub(crate) pool:
-        Arc<GlobalConnPool<postgres_client::Client, EndpointConnPool<postgres_client::Client>>>,
+    pub(crate) pool: Arc<GlobalConnPool<EndpointConnPool<postgres_client::Client>>>,
 
     pub(crate) config: &'static ProxyConfig,
     pub(crate) auth_backend: &'static crate::auth::Backend<'static, ()>,
@@ -248,7 +247,7 @@ impl PoolingBackend {
         conn_info: ConnInfo,
     ) -> Result<http_conn_pool::Client<Send>, HttpConnError> {
         debug!("pool: looking for an existing connection");
-        if let Ok(Some(client)) = self.http_conn_pool.get(ctx, &conn_info) {
+        if let Some(client) = self.http_conn_pool.get(ctx, &conn_info) {
             return Ok(client);
         }
 
@@ -532,7 +531,7 @@ impl ShouldRetryWakeCompute for LocalProxyConnError {
 }
 
 struct TokioMechanism {
-    pool: Arc<GlobalConnPool<postgres_client::Client, EndpointConnPool<postgres_client::Client>>>,
+    pool: Arc<GlobalConnPool<EndpointConnPool<postgres_client::Client>>>,
     conn_info: ConnInfo,
     conn_id: uuid::Uuid,
 
@@ -593,7 +592,7 @@ impl ConnectMechanism for TokioMechanism {
 }
 
 struct HyperMechanism {
-    pool: Arc<GlobalConnPool<Send, HttpConnPool>>,
+    pool: Arc<GlobalConnPool<HttpConnPool>>,
     conn_info: ConnInfo,
     conn_id: uuid::Uuid,
 
diff --git a/proxy/src/serverless/conn_pool.rs b/proxy/src/serverless/conn_pool.rs
index 87176ff7d6..6df8d0d1b5 100644
--- a/proxy/src/serverless/conn_pool.rs
+++ b/proxy/src/serverless/conn_pool.rs
@@ -57,7 +57,7 @@ impl fmt::Display for ConnInfo {
 }
 
 pub(crate) fn poll_client<C: ClientInnerExt>(
-    global_pool: Arc<GlobalConnPool<C, EndpointConnPool<C>>>,
+    global_pool: Arc<GlobalConnPool<EndpointConnPool<C>>>,
     ctx: &RequestContext,
     conn_info: ConnInfo,
     client: C,
diff --git a/proxy/src/serverless/conn_pool_lib.rs b/proxy/src/serverless/conn_pool_lib.rs
index 42a3ea17a2..b191399f45 100644
--- a/proxy/src/serverless/conn_pool_lib.rs
+++ b/proxy/src/serverless/conn_pool_lib.rs
@@ -1,5 +1,4 @@
 use std::collections::HashMap;
-use std::marker::PhantomData;
 use std::ops::Deref;
 use std::sync::atomic::{self, AtomicUsize};
 use std::sync::{Arc, Weak};
@@ -326,12 +325,15 @@ impl<C: ClientInnerExt> DbUserConn<C> for DbUserConnPool<C> {
     }
 }
 
-pub(crate) trait EndpointConnPoolExt<C: ClientInnerExt> {
+pub(crate) trait EndpointConnPoolExt {
+    type Client;
     fn clear_closed(&mut self) -> usize;
     fn total_conns(&self) -> usize;
 }
 
-impl<C: ClientInnerExt> EndpointConnPoolExt<C> for EndpointConnPool<C> {
+impl<C: ClientInnerExt> EndpointConnPoolExt for EndpointConnPool<C> {
+    type Client = Client<C>;
+
     fn clear_closed(&mut self) -> usize {
         let mut clients_removed: usize = 0;
         for db_pool in self.pools.values_mut() {
@@ -345,10 +347,9 @@ impl<C: ClientInnerExt> EndpointConnPoolExt<C> for EndpointConnPool<C> {
     }
 }
 
-pub(crate) struct GlobalConnPool<C, P>
+pub(crate) struct GlobalConnPool<P>
 where
-    C: ClientInnerExt,
-    P: EndpointConnPoolExt<C>,
+    P: EndpointConnPoolExt,
 {
     // endpoint -> per-endpoint connection pool
     //
@@ -367,8 +368,6 @@ where
     pub(crate) global_connections_count: Arc<AtomicUsize>,
 
     pub(crate) config: &'static crate::config::HttpConfig,
-
-    _marker: PhantomData<C>,
 }
 
 #[derive(Debug, Clone, Copy)]
@@ -391,10 +390,9 @@ pub struct GlobalConnPoolOptions {
     pub max_total_conns: usize,
 }
 
-impl<C, P> GlobalConnPool<C, P>
+impl<P> GlobalConnPool<P>
 where
-    C: ClientInnerExt,
-    P: EndpointConnPoolExt<C>,
+    P: EndpointConnPoolExt,
 {
     pub(crate) fn new(config: &'static crate::config::HttpConfig) -> Arc<Self> {
         let shards = config.pool_options.pool_shards;
@@ -403,7 +401,6 @@ where
             global_pool_size: AtomicUsize::new(0),
             config,
             global_connections_count: Arc::new(AtomicUsize::new(0)),
-            _marker: PhantomData,
         })
     }
 
@@ -492,7 +489,7 @@ where
     }
 }
 
-impl<C: ClientInnerExt> GlobalConnPool<C, EndpointConnPool<C>> {
+impl<C: ClientInnerExt> GlobalConnPool<EndpointConnPool<C>> {
     pub(crate) fn get(
         self: &Arc<Self>,
         ctx: &RequestContext,
diff --git a/proxy/src/serverless/http_conn_pool.rs b/proxy/src/serverless/http_conn_pool.rs
index f233294009..79072cd85d 100644
--- a/proxy/src/serverless/http_conn_pool.rs
+++ b/proxy/src/serverless/http_conn_pool.rs
@@ -9,7 +9,6 @@ use smol_str::ToSmolStr;
 use tracing::{Instrument, debug, error, info, info_span};
 
 use super::AsyncRW;
-use super::backend::HttpConnError;
 use super::conn_pool_lib::{
     ClientDataEnum, ClientInnerCommon, ClientInnerExt, ConnInfo, ConnPoolEntry,
     EndpointConnPoolExt, GlobalConnPool,
@@ -85,7 +84,9 @@ impl HttpConnPool {
     }
 }
 
-impl EndpointConnPoolExt<Send> for HttpConnPool {
+impl EndpointConnPoolExt for HttpConnPool {
+    type Client = Client<Send>;
+
     fn clear_closed(&mut self) -> usize {
         let Self { conns, .. } = self;
         let old_len = conns.len();
@@ -114,23 +115,15 @@ impl Drop for HttpConnPool {
     }
 }
 
-impl GlobalConnPool<Send, HttpConnPool> {
-    #[expect(unused_results)]
+impl GlobalConnPool<HttpConnPool> {
     pub(crate) fn get(
         self: &Arc<Self>,
         ctx: &RequestContext,
         conn_info: &ConnInfo,
-    ) -> Result<Option<Client<Send>>, HttpConnError> {
-        let result: Result<Option<Client<Send>>, HttpConnError>;
-        let Some(endpoint) = conn_info.endpoint_cache_key() else {
-            result = Ok(None);
-            return result;
-        };
-        let endpoint_pool = self.get_or_create_endpoint_pool(&endpoint);
-        let Some(client) = endpoint_pool.write().get_conn_entry() else {
-            result = Ok(None);
-            return result;
-        };
+    ) -> Option<Client<Send>> {
+        let endpoint = conn_info.endpoint_cache_key()?;
+        let endpoint_pool = self.global_pool.get(&endpoint)?.clone();
+        let client = endpoint_pool.write().get_conn_entry()?;
 
         tracing::Span::current().record("conn_id", tracing::field::display(client.conn.conn_id));
         debug!(
@@ -140,7 +133,7 @@ impl GlobalConnPool<Send, HttpConnPool> {
         ctx.set_cold_start_info(ColdStartInfo::HttpPoolHit);
         ctx.success();
 
-        Ok(Some(Client::new(client.conn.clone())))
+        Some(Client::new(client.conn.clone()))
     }
 
     fn get_or_create_endpoint_pool(
@@ -186,7 +179,7 @@ impl GlobalConnPool<Send, HttpConnPool> {
 }
 
 pub(crate) fn poll_http2_client(
-    global_pool: Arc<GlobalConnPool<Send, HttpConnPool>>,
+    global_pool: Arc<GlobalConnPool<HttpConnPool>>,
     ctx: &RequestContext,
     conn_info: &ConnInfo,
     client: Send,