From dc8d8ccd8850566276e00d9f7fddf31d54c9c378 Mon Sep 17 00:00:00 2001
From: Jiahao XU <Jiahao_XU@outlook.com>
Date: Thu, 21 Jul 2022 13:06:34 +1000
Subject: [PATCH] Optimize `MultiFetcher`: Start `check`ing ASAP

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>
---
 src/fetchers.rs | 27 +++++++++------------------
 1 file changed, 9 insertions(+), 18 deletions(-)

diff --git a/src/fetchers.rs b/src/fetchers.rs
index 237a2b85..dc60dfc6 100644
--- a/src/fetchers.rs
+++ b/src/fetchers.rs
@@ -47,30 +47,21 @@ pub struct Data {
     pub meta: PkgMeta,
 }
 
+type FetcherJoinHandle = AutoAbortJoinHandle<Result<bool, BinstallError>>;
+
 #[derive(Default)]
-pub struct MultiFetcher {
-    fetchers: Vec<Arc<dyn Fetcher>>,
-}
+pub struct MultiFetcher(Vec<(Arc<dyn Fetcher>, FetcherJoinHandle)>);
 
 impl MultiFetcher {
     pub fn add(&mut self, fetcher: Arc<dyn Fetcher>) {
-        self.fetchers.push(fetcher);
+        self.0.push((
+            fetcher.clone(),
+            AutoAbortJoinHandle::new(tokio::spawn(async move { fetcher.check().await })),
+        ));
     }
 
-    pub async fn first_available(&self) -> Option<Arc<dyn Fetcher>> {
-        let handles: Vec<_> = self
-            .fetchers
-            .iter()
-            .cloned()
-            .map(|fetcher| {
-                (
-                    fetcher.clone(),
-                    AutoAbortJoinHandle::new(tokio::spawn(async move { fetcher.check().await })),
-                )
-            })
-            .collect();
-
-        for (fetcher, handle) in handles {
+    pub async fn first_available(self) -> Option<Arc<dyn Fetcher>> {
+        for (fetcher, handle) in self.0 {
             match handle.await {
                 Ok(Ok(true)) => return Some(fetcher),
                 Ok(Ok(false)) => (),