[pbs-devel] [PATCH proxmox-backup 1/1] backup-proxy and parallel_handler: Improved errors when panics occur and the panic message is a formatted (not static) string. This worked already for &str literals, but not for Strings.

[Laurențiu Leahu-Vlăducu]

Downcasting to both &str and String is also done by the Rust Standard
Library in the default panic handler. See:
https://github.com/rust-lang/rust/blob/b605c65b6eb5fa71783f8e26df69975f9f1680ee/library/std/src/panicking.rs#L777

Signed-off-by: Laurențiu Leahu-Vlăducu <l.leahu-vladucu at proxmox.com>
---
 src/bin/proxmox-backup-proxy.rs | 5 ++++-
 src/tools/parallel_handler.rs   | 8 +++++++-
 2 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/bin/proxmox-backup-proxy.rs b/src/bin/proxmox-backup-proxy.rs
index ce1be1c0..a7dab4ac 100644
--- a/src/bin/proxmox-backup-proxy.rs
+++ b/src/bin/proxmox-backup-proxy.rs
@@ -424,7 +424,10 @@ async fn run_task_scheduler() {
         match schedule_tasks().catch_unwind().await {
             Err(panic) => match panic.downcast::<&str>() {
                 Ok(msg) => eprintln!("task scheduler panic: {msg}"),
-                Err(_) => eprintln!("task scheduler panic - unknown type"),
+                Err(panic) => match panic.downcast::<String>() {
+                    Ok(msg) => eprintln!("task scheduler panic: {msg}"),
+                    Err(_) => eprintln!("task scheduler panic - cannot show error message due to unknown error type")
+                }
             },
             Ok(Err(err)) => eprintln!("task scheduler failed - {err:?}"),
             Ok(Ok(_)) => {}
diff --git a/src/tools/parallel_handler.rs b/src/tools/parallel_handler.rs
index 17f70179..429a1f8b 100644
--- a/src/tools/parallel_handler.rs
+++ b/src/tools/parallel_handler.rs
@@ -140,7 +140,13 @@ impl<I: Send + 'static> ParallelHandler<I> {
                         "thread {} ({}) panicked: {}",
                         self.name, i, panic_msg
                     )),
-                    Err(_) => msg_list.push(format!("thread {} ({}) panicked", self.name, i)),
+                    Err(panic) => match panic.downcast::<String>() {
+                        Ok(panic_msg) => msg_list.push(format!(
+                            "thread {} ({}) panicked: {}",
+                                self.name, i, panic_msg
+                        )),
+                        Err(_) => msg_list.push(format!("thread {} ({}) panicked", self.name, i))
+                    },
                 }
             }
             i += 1;
-- 
2.39.5