From b6245bcf4be9e78fe04a784667faa679961fff6e Mon Sep 17 00:00:00 2001
From: Jiahao XU <Jiahao_XU@outlook.com>
Date: Tue, 7 Jun 2022 16:13:38 +1000
Subject: [PATCH] Spawn `entry()` in `main` to improve parallelism

Using `rt.block_on`, the future returned by `entry` can only be run on
the main thread.

Buf if we use `tokio::spawn`, then it can be run on any thread.

Signed-off-by: Jiahao XU <Jiahao_XU@outlook.com>
---
 src/main.rs | 23 ++++++++++++++++-------
 1 file changed, 16 insertions(+), 7 deletions(-)

diff --git a/src/main.rs b/src/main.rs
index 5c913dc5..87f63063 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -11,7 +11,7 @@ use miette::{miette, IntoDiagnostic, Result, WrapErr};
 use simplelog::{ColorChoice, ConfigBuilder, TermLogger, TerminalMode};
 use structopt::StructOpt;
 use tempfile::TempDir;
-use tokio::{process::Command, runtime::Runtime};
+use tokio::{process::Command, runtime::Runtime, task::JoinError};
 
 use cargo_binstall::{
     bins,
@@ -84,6 +84,7 @@ enum MainExit {
     Success(Duration),
     Error(BinstallError),
     Report(miette::Report),
+    JoinErr(JoinError),
 }
 
 impl Termination for MainExit {
@@ -99,6 +100,11 @@ impl Termination for MainExit {
                 eprintln!("{err:?}");
                 ExitCode::from(16)
             }
+            Self::JoinErr(err) => {
+                error!("Fatal error:");
+                eprintln!("{err:?}");
+                ExitCode::from(16)
+            }
         }
     }
 }
@@ -107,19 +113,22 @@ fn main() -> MainExit {
     let start = Instant::now();
 
     let rt = Runtime::new().unwrap();
-    let result = rt.block_on(entry());
+    let handle = rt.spawn(entry());
+    let result = rt.block_on(handle);
     drop(rt);
 
     let done = start.elapsed();
     debug!("run time: {done:?}");
 
     result
-        .map(|_| MainExit::Success(done))
-        .unwrap_or_else(|err| {
-            err.downcast::<BinstallError>()
-                .map(MainExit::Error)
-                .unwrap_or_else(MainExit::Report)
+        .map(|res| {
+            res.map(|_| MainExit::Success(done)).unwrap_or_else(|err| {
+                err.downcast::<BinstallError>()
+                    .map(MainExit::Error)
+                    .unwrap_or_else(MainExit::Report)
+            })
         })
+        .unwrap_or_else(MainExit::JoinErr)
 }
 
 async fn entry() -> Result<()> {