From 5b8dfa5dc88de8420f09dd7590952b7693b0ca3d Mon Sep 17 00:00:00 2001
From: Thomas Alton <thomas.alton@gmail.com>
Date: Wed, 14 Sep 2022 20:53:28 -0500
Subject: [PATCH] Use Arc wrapper for ConnectOptions to reduce lock contention

---
 sqlx-core/src/mysql/testing/mod.rs    | 7 ++++++-
 sqlx-core/src/pool/inner.rs           | 6 +++---
 sqlx-core/src/pool/mod.rs             | 9 +++------
 sqlx-core/src/postgres/testing/mod.rs | 7 ++++++-
 4 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/sqlx-core/src/mysql/testing/mod.rs b/sqlx-core/src/mysql/testing/mod.rs
index 5f476e74a2..c31c868dee 100644
--- a/sqlx-core/src/mysql/testing/mod.rs
+++ b/sqlx-core/src/mysql/testing/mod.rs
@@ -1,4 +1,5 @@
 use std::fmt::Write;
+use std::ops::Deref;
 use std::str::FromStr;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::Duration;
@@ -152,7 +153,11 @@ async fn test_context(args: &TestArgs) -> Result<TestContext<MySql>, Error> {
             // Close connections ASAP if left in the idle queue.
             .idle_timeout(Some(Duration::from_secs(1)))
             .parent(master_pool.clone()),
-        connect_opts: master_pool.connect_options().clone().database(&new_db_name),
+        connect_opts: master_pool
+            .connect_options()
+            .deref()
+            .clone()
+            .database(&new_db_name),
         db_name: new_db_name,
     })
 }
diff --git a/sqlx-core/src/pool/inner.rs b/sqlx-core/src/pool/inner.rs
index f7655f5503..2a48ac6347 100644
--- a/sqlx-core/src/pool/inner.rs
+++ b/sqlx-core/src/pool/inner.rs
@@ -20,7 +20,7 @@ use futures_util::FutureExt;
 use std::time::{Duration, Instant};
 
 pub(crate) struct PoolInner<DB: Database> {
-    pub(super) connect_options: RwLock<<DB::Connection as Connection>::Options>,
+    pub(super) connect_options: RwLock<Arc<<DB::Connection as Connection>::Options>>,
     pub(super) idle_conns: ArrayQueue<Idle<DB>>,
     pub(super) semaphore: Semaphore,
     pub(super) size: AtomicU32,
@@ -47,7 +47,7 @@ impl<DB: Database> PoolInner<DB> {
         };
 
         let pool = Self {
-            connect_options: RwLock::new(connect_options),
+            connect_options: RwLock::new(Arc::new(connect_options)),
             idle_conns: ArrayQueue::new(capacity),
             semaphore: Semaphore::new(options.fair, semaphore_capacity),
             size: AtomicU32::new(0),
@@ -292,7 +292,7 @@ impl<DB: Database> PoolInner<DB> {
         loop {
             let timeout = deadline_as_timeout::<DB>(deadline)?;
 
-            // clone the connect options so they can be used without holding the RwLockReadGuard
+            // clone the connect options arc so it can be used without holding the RwLockReadGuard
             // across an async await point
             let connect_options = self
                 .connect_options
diff --git a/sqlx-core/src/pool/mod.rs b/sqlx-core/src/pool/mod.rs
index 64b43c4260..91ac3b8dfb 100644
--- a/sqlx-core/src/pool/mod.rs
+++ b/sqlx-core/src/pool/mod.rs
@@ -491,7 +491,7 @@ impl<DB: Database> Pool<DB> {
     }
 
     /// Gets a clone of the connection options for this pool
-    pub fn connect_options(&self) -> <DB::Connection as Connection>::Options {
+    pub fn connect_options(&self) -> Arc<<DB::Connection as Connection>::Options> {
         self.0
             .connect_options
             .read()
@@ -501,10 +501,7 @@ impl<DB: Database> Pool<DB> {
 
     /// Updates the connection options this pool will use when opening any future connections.  Any
     /// existing open connection in the pool will be left as-is.
-    pub fn with_connect_options(
-        &self,
-        mut connect_options: <DB::Connection as Connection>::Options,
-    ) {
+    pub fn set_connect_options(&self, connect_options: <DB::Connection as Connection>::Options) {
         // technically write() could also panic if the current thread already holds the lock,
         // but because this method can't be re-entered by the same thread that shouldn't be a problem
         let mut guard = self
@@ -512,7 +509,7 @@ impl<DB: Database> Pool<DB> {
             .connect_options
             .write()
             .expect("write-lock holder panicked");
-        std::mem::swap(guard.deref_mut(), &mut connect_options);
+        std::mem::swap(guard.deref_mut(), &mut Arc::new(connect_options));
     }
 
     /// Get the options for this pool
diff --git a/sqlx-core/src/postgres/testing/mod.rs b/sqlx-core/src/postgres/testing/mod.rs
index e3640b3bed..b566725a51 100644
--- a/sqlx-core/src/postgres/testing/mod.rs
+++ b/sqlx-core/src/postgres/testing/mod.rs
@@ -1,4 +1,5 @@
 use std::fmt::Write;
+use std::ops::Deref;
 use std::str::FromStr;
 use std::sync::atomic::{AtomicBool, Ordering};
 use std::time::Duration;
@@ -159,7 +160,11 @@ async fn test_context(args: &TestArgs) -> Result<TestContext<Postgres>, Error> {
             // Close connections ASAP if left in the idle queue.
             .idle_timeout(Some(Duration::from_secs(1)))
             .parent(master_pool.clone()),
-        connect_opts: master_pool.connect_options().clone().database(&new_db_name),
+        connect_opts: master_pool
+            .connect_options()
+            .deref()
+            .clone()
+            .database(&new_db_name),
         db_name: new_db_name,
     })
 }