From 5be1e20eb4c0b6e7a9286bed606711b0f73f46f0 Mon Sep 17 00:00:00 2001
From: Charles Hall <charles@computer.surgery>
Date: Mon, 21 Oct 2024 11:25:08 -0700
Subject: [PATCH] call maximize_fd_limit at top of main

This way we don't shoot ourselves in the foot by forgetting to do it for
other subcommands (e.g. that manipulate the database) in the future.
---
 src/cli/serve.rs | 29 -----------------------------
 src/main.rs      | 30 ++++++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 29 deletions(-)

diff --git a/src/cli/serve.rs b/src/cli/serve.rs
index 69d5eb2b..310c97a2 100644
--- a/src/cli/serve.rs
+++ b/src/cli/serve.rs
@@ -78,17 +78,6 @@ pub(crate) async fn run(args: ServeArgs) -> Result<(), error::ServeCommand> {
 
     let (_guard, reload_handles) = observability::init(&config)?;
 
-    // This is needed for opening lots of file descriptors, which tends to
-    // happen more often when using RocksDB and making lots of federation
-    // connections at startup. The soft limit is usually 1024, and the hard
-    // limit is usually 512000; I've personally seen it hit >2000.
-    //
-    // * https://www.freedesktop.org/software/systemd/man/systemd.exec.html#id-1.12.2.1.17.6
-    // * https://github.com/systemd/systemd/commit/0abf94923b4a95a7d89bc526efc84e7ca2b71741
-    #[cfg(unix)]
-    maximize_fd_limit()
-        .expect("should be able to increase the soft limit to the hard limit");
-
     info!("Loading database");
     let db = Box::leak(Box::new(
         KeyValueDatabase::load_or_create(&config)
@@ -908,21 +897,3 @@ fn method_to_filter(method: Method) -> MethodFilter {
         m => panic!("Unsupported HTTP method: {m:?}"),
     }
 }
-
-#[cfg(unix)]
-#[tracing::instrument(err)]
-fn maximize_fd_limit() -> Result<(), nix::errno::Errno> {
-    use nix::sys::resource::{getrlimit, setrlimit, Resource};
-
-    let res = Resource::RLIMIT_NOFILE;
-
-    let (soft_limit, hard_limit) = getrlimit(res)?;
-
-    debug!(soft_limit, "Current nofile soft limit");
-
-    setrlimit(res, hard_limit, hard_limit)?;
-
-    debug!(hard_limit, "Increased nofile soft limit to the hard limit");
-
-    Ok(())
-}
diff --git a/src/main.rs b/src/main.rs
index 2726b4bd..8f4268a1 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -84,6 +84,17 @@ fn set_application_state(state: ApplicationState) {
 
 #[tokio::main]
 async fn main() -> ExitCode {
+    // This is needed for opening lots of file descriptors, which tends to
+    // happen more often when using RocksDB and making lots of federation
+    // connections at startup. The soft limit is usually 1024, and the hard
+    // limit is usually 512000; I've personally seen it hit >2000.
+    //
+    // * https://www.freedesktop.org/software/systemd/man/systemd.exec.html#id-1.12.2.1.17.6
+    // * https://github.com/systemd/systemd/commit/0abf94923b4a95a7d89bc526efc84e7ca2b71741
+    #[cfg(unix)]
+    maximize_fd_limit()
+        .expect("should be able to increase the soft limit to the hard limit");
+
     let args = cli::Args::parse();
     let Err(e) = args.run().await else {
         return ExitCode::SUCCESS;
@@ -99,3 +110,22 @@ async fn main() -> ExitCode {
 
     ExitCode::FAILURE
 }
+
+#[cfg(unix)]
+#[tracing::instrument(err)]
+fn maximize_fd_limit() -> Result<(), nix::errno::Errno> {
+    use nix::sys::resource::{getrlimit, setrlimit, Resource};
+    use tracing::debug;
+
+    let res = Resource::RLIMIT_NOFILE;
+
+    let (soft_limit, hard_limit) = getrlimit(res)?;
+
+    debug!(soft_limit, "Current nofile soft limit");
+
+    setrlimit(res, hard_limit, hard_limit)?;
+
+    debug!(hard_limit, "Increased nofile soft limit to the hard limit");
+
+    Ok(())
+}