➕ update: add ArcSwap to update gauges lock-free

Cargo.lock

@@ -46,6 +46,12 @@ version = "1.0.35"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "2c0df63cb2955042487fad3aefd2c6e3ae7389ac5dc1beb28921de0b69f779d4"
 
+[[package]]
+name = "arc-swap"
+version = "1.1.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ec5a4539a733493f412c4d0bb962748ea1f90f3dfdba9ff3ee18acbefc3b33f0"
+
 [[package]]
 name = "arrayref"
 version = "0.3.6"
@@ -1636,6 +1642,7 @@ name = "ptth_file_server"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "arc-swap",
  "handlebars",
  "http",
  "hyper",
@@ -1682,6 +1689,7 @@ dependencies = [
  "aho-corasick",
  "always_equal",
  "anyhow",
+ "arc-swap",
  "base64 0.12.3",
  "blake3",
  "chrono",

crates/ptth_file_server_bin/Cargo.toml

@@ -9,6 +9,7 @@ license = "AGPL-3.0"
 [dependencies]
 
 anyhow = "1.0.34"
+arc-swap = "1.1.0"
 handlebars = "3.5.1"
 http = "0.2.1"
 hyper = "0.13.8"

crates/ptth_file_server_bin/src/main.rs

@@ -6,6 +6,7 @@ use std::{
 	sync::Arc,
 };
 
+use arc_swap::ArcSwap;
 use hyper::{
 	Body,
 	Request,
@@ -98,7 +99,26 @@ async fn main () -> Result <(), anyhow::Error> {
 		config_file.name.unwrap_or_else (|| "PTTH File Server".to_string ())
 	);
 	
-	let gauges = metrics::Gauges::new ().await?;
+	let metrics_gauge = Arc::new (ArcSwap::from_pointee (None));
+	
+	let gauge_writer = Arc::clone (&metrics_gauge);
+	
+	tokio::spawn (async move {
+		let mut interval = tokio::time::interval (std::time::Duration::from_secs (2));
+		loop {
+			interval.tick ().await;
+			
+			let new_gauges = match file_server::metrics::Gauges::new ().await {
+				Err (e) => {
+					error! ("Failed to update gauge metrics: {:?}", e);
+					continue;
+				},
+				Ok (x) => x,
+			};
+			let new_gauges = Arc::new (Some (new_gauges));
+			gauge_writer.store (new_gauges);
+		}
+	});
 	
 	let state = Arc::new (State {
 		config: file_server::Config {
@@ -106,6 +126,7 @@ async fn main () -> Result <(), anyhow::Error> {
 		},
 		handlebars,
 		metrics_startup,
+		metrics_gauge,
 		hidden_path: Some (path),
 	});
 	

crates/ptth_server/Cargo.toml

@@ -10,6 +10,7 @@ license = "AGPL-3.0"
 
 aho-corasick = "0.7.14"
 anyhow = "1.0.34"
+arc-swap = "1.1.0"
 base64 = "0.12.3"
 blake3 = "0.3.7"
 chrono = {version = "0.4.19", features = ["serde"]}

crates/ptth_server/src/file_server/metrics.rs

@@ -35,6 +35,7 @@ pub struct Startup {
 
 #[derive (Debug, serde::Serialize)]
 pub struct Gauges {
+	pub utc: DateTime <Utc>,
 	pub rss_mib: u64,
 }
 
@@ -48,6 +49,7 @@ impl Gauges {
 		let rss_mib = mem.rss ().get::<mebibyte> ();
 		
 		let x = Gauges {
+			utc: Utc::now (),
 			rss_mib,
 		};
 		

crates/ptth_server/src/file_server/mod.rs

@@ -12,8 +12,10 @@ use std::{
 		Path,
 		PathBuf,
 	},
+	sync::Arc,
 };
 
+use arc_swap::ArcSwap;
 use handlebars::Handlebars;
 use serde::Serialize;
 use tokio::{
@@ -57,6 +59,7 @@ pub struct State {
 	pub config: Config,
 	pub handlebars: handlebars::Handlebars <'static>,
 	pub metrics_startup: metrics::Startup,
+	pub metrics_gauge: Arc <ArcSwap <Option <metrics::Gauges>>>,
 	pub hidden_path: Option <PathBuf>,
 }
 

crates/ptth_server/src/lib.rs

@@ -53,7 +53,6 @@ pub fn password_is_bad (mut password: String) -> bool {
 struct State {
 	file_server: file_server::State,
 	config: Config,
-	gauges: RwLock <file_server::metrics::Gauges>,
 	client: Client,
 }
 
@@ -179,8 +178,11 @@ pub async fn run_server (
 )
 -> Result <(), ServerError> 
 {
-	use std::convert::TryInto;
+	use std::{
+		convert::TryInto,
+	};
 	
+	use arc_swap::ArcSwap;
 	use http::status::StatusCode;
 	
 	let asset_root = asset_root.unwrap_or_else (PathBuf::new);
@@ -202,6 +204,7 @@ pub async fn run_server (
 	let handlebars = file_server::load_templates (&asset_root)?;
 	
 	let metrics_startup = file_server::metrics::Startup::new (config_file.name);
+	let metrics_gauge = Arc::new (ArcSwap::from_pointee (None));
 	
 	let state = Arc::new (State {
 		file_server: file_server::State {
@@ -210,12 +213,12 @@ pub async fn run_server (
 			},
 			handlebars,
 			metrics_startup,
+			metrics_gauge,
 			hidden_path,
 		},
 		config: Config {
 			relay_url: config_file.relay_url,
 		},
-		gauges: RwLock::new (file_server::metrics::Gauges::new ().await?),
 		client,
 	});