From c95258c98d15bab317ca8955fbfca37df30da655 Mon Sep 17 00:00:00 2001
From: Fabian Freyer <fabian.freyer@physik.tu-berlin.de>
Date: Mon, 20 Feb 2023 22:56:51 +0100
Subject: [PATCH 1/3] Implement UnwindSafe by never returning on panic

Don't return objects to the pool on panic, since we can't be sure
whether they were the source of the panic.

See-also: #139
---
 src/managed/mod.rs   | 15 +++++++++++++++
 src/unmanaged/mod.rs |  7 +++++++
 2 files changed, 22 insertions(+)

diff --git a/src/managed/mod.rs b/src/managed/mod.rs
index d6ebd4e3..97178d7a 100644
--- a/src/managed/mod.rs
+++ b/src/managed/mod.rs
@@ -71,6 +71,7 @@ use std::{
     future::Future,
     marker::PhantomData,
     ops::{Deref, DerefMut},
+    panic::{RefUnwindSafe, UnwindSafe},
     sync::{
         atomic::{AtomicUsize, Ordering},
         Arc, Mutex, Weak,
@@ -615,6 +616,20 @@ impl<M: Manager, W: From<Object<M>>> Pool<M, W> {
     }
 }
 
+impl<M: Manager, W: From<Object<M>>> UnwindSafe for Pool<M, W>
+where
+    M: UnwindSafe,
+    W: UnwindSafe,
+{
+}
+
+impl<M: Manager, W: From<Object<M>>> RefUnwindSafe for Pool<M, W>
+where
+    M: UnwindSafe,
+    W: UnwindSafe,
+{
+}
+
 struct PoolInner<M: Manager> {
     manager: M,
     slots: Mutex<Slots<ObjectInner<M>>>,
diff --git a/src/unmanaged/mod.rs b/src/unmanaged/mod.rs
index 7b899322..a6f6f219 100644
--- a/src/unmanaged/mod.rs
+++ b/src/unmanaged/mod.rs
@@ -78,6 +78,13 @@ impl<T> Object<T> {
 
 impl<T> Drop for Object<T> {
     fn drop(&mut self) {
+        // If we're panicking, there is no way to determine whether the object
+        // we are dropping is the source of the panic. Therefore, always discard
+        // the object on a panic, and do not return it to the pool.
+        if std::thread::panicking() {
+            return;
+        }
+
         if let Some(obj) = self.obj.take() {
             if let Some(pool) = self.pool.upgrade() {
                 {

From 5b6cf55fc1ce8e48233235f633484a24ac0a0e1e Mon Sep 17 00:00:00 2001
From: Fabian Freyer <fabian.freyer@physik.tu-berlin.de>
Date: Tue, 21 Feb 2023 00:16:23 +0100
Subject: [PATCH 2/3] postgres: Manager is UnwindSafe

---
 postgres/src/lib.rs | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/postgres/src/lib.rs b/postgres/src/lib.rs
index bb716933..a44c565b 100644
--- a/postgres/src/lib.rs
+++ b/postgres/src/lib.rs
@@ -154,6 +154,8 @@ impl managed::Manager for Manager {
     }
 }
 
+impl std::panic::UnwindSafe for Manager {}
+
 #[async_trait]
 trait Connect: Sync + Send {
     async fn connect(&self, pg_config: &PgConfig) -> Result<(PgClient, JoinHandle<()>), Error>;

From e001940aa3a90c1a9a7b398f53d3d187466c9f32 Mon Sep 17 00:00:00 2001
From: Fabian Freyer <fabian.freyer@physik.tu-berlin.de>
Date: Tue, 21 Feb 2023 00:16:55 +0100
Subject: [PATCH 3/3] Unwind Safety: Don't require for W

---
 src/managed/mod.rs | 2 --
 1 file changed, 2 deletions(-)

diff --git a/src/managed/mod.rs b/src/managed/mod.rs
index 97178d7a..3a300467 100644
--- a/src/managed/mod.rs
+++ b/src/managed/mod.rs
@@ -619,14 +619,12 @@ impl<M: Manager, W: From<Object<M>>> Pool<M, W> {
 impl<M: Manager, W: From<Object<M>>> UnwindSafe for Pool<M, W>
 where
     M: UnwindSafe,
-    W: UnwindSafe,
 {
 }
 
 impl<M: Manager, W: From<Object<M>>> RefUnwindSafe for Pool<M, W>
 where
     M: UnwindSafe,
-    W: UnwindSafe,
 {
 }