From 360ae996c5366c6ab03b476ffc903728acebb58a Mon Sep 17 00:00:00 2001
From: Jose Quintana <joseluisquintana20@gmail.com>
Date: Wed, 20 Jan 2021 01:20:45 +0100
Subject: [PATCH] feat: worker threads multiplier option --threads-multiplier

A new -t, --threads-multiplier <threads-multiplier> option which
represent a number of worker threads multiplier that'll be multiplied
by the number of system CPUs using the formula:
worker threads = number of CPUs * n
where `n` is the value that changes with this option.
When the multiplier value is 0 or 1 then the `number of CPUs` is only used.
The number of worker threads result should be a number between 1 and
32,768 though it is advised to keep this value on the smaller side.
---
 src/bin/server.rs  | 22 +++++++++++++++++++---
 src/core/config.rs | 12 ++++++++++++
 2 files changed, 31 insertions(+), 3 deletions(-)

diff --git a/src/bin/server.rs b/src/bin/server.rs
index 994c579..8d0292f 100644
--- a/src/bin/server.rs
+++ b/src/bin/server.rs
@@ -93,9 +93,25 @@ async fn server(opts: config::Options) -> Result {
     Ok(())
 }
 
-#[tokio::main(max_threads = 10_000)]
-async fn main() -> Result {
-    server(config::Options::from_args()).await?;
+fn main() -> Result {
+    let opts = config::Options::from_args();
+    let n = if opts.threads_multiplier == 0 {
+        1
+    } else {
+        opts.threads_multiplier
+    };
+    let threads = num_cpus::get() * n;
+
+    tokio::runtime::Builder::new_multi_thread()
+        .worker_threads(threads)
+        .enable_all()
+        .build()?
+        .block_on(async {
+            let r = server(opts).await;
+            if r.is_err() {
+                panic!("Server error: {:?}", r.unwrap_err())
+            }
+        });
 
     Ok(())
 }
diff --git a/src/core/config.rs b/src/core/config.rs
index 43a5914..63e9f23 100644
--- a/src/core/config.rs
+++ b/src/core/config.rs
@@ -11,6 +11,18 @@ pub struct Options {
     /// Host port
     pub port: u16,
 
+    #[structopt(
+        long,
+        short = "t",
+        default_value = "8",
+        env = "SERVER_THREADS_MULTIPLIER"
+    )]
+    /// Number of worker threads multiplier that'll be multiplied by the number of system CPUs
+    /// using the formula: `worker threads = number of CPUs * n` where `n` is the value that changes here.
+    /// When multiplier value is 0 or 1 then the `number of CPUs` is used.
+    /// Number of worker threads result should be a number between 1 and 32,768 though it is advised to keep this value on the smaller side.
+    pub threads_multiplier: usize,
+
     #[structopt(long, short = "r", default_value = "./public", env = "SERVER_ROOT")]
     /// Root directory path of static files
     pub root: String,
--
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