From 02c48f660668be83bc3c0bac14692a2a5f4fc793 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Domen=20Ko=C5=BEar?= <domen@dev.si>
Date: Wed, 13 Mar 2024 10:54:12 +0000
Subject: [PATCH] --cores defaults to 2, --max-jobs defaults to num_cpu/2

---
 devenv.lock           | 16 ++++++++--------
 devenv/src/command.rs |  3 +++
 devenv/src/main.rs    | 27 +++++++++++++++++++++++----
 tests/cli/.test.sh    |  4 +---
 4 files changed, 35 insertions(+), 15 deletions(-)

diff --git a/devenv.lock b/devenv.lock
index 0e55f63a0..b5dc8416e 100644
--- a/devenv.lock
+++ b/devenv.lock
@@ -109,17 +109,17 @@
     },
     "nixpkgs": {
       "locked": {
-        "lastModified": 1710222005,
-        "owner": "NixOS",
-        "repo": "nixpkgs",
-        "rev": "9a9a7552431c4f1a3b2eee9398641babf7c30d0e",
-        "treeHash": "f86a6354c1b9536fd6eec80186c371c5b09c0be8",
+        "lastModified": 1710236354,
+        "owner": "cachix",
+        "repo": "devenv-nixpkgs",
+        "rev": "829e73affeadfb4198a7105cbe3a03153d13edc9",
+        "treeHash": "c92d1301b904a3d47027cca315d4de397f711280",
         "type": "github"
       },
       "original": {
-        "owner": "NixOS",
-        "ref": "nixpkgs-unstable",
-        "repo": "nixpkgs",
+        "owner": "cachix",
+        "ref": "rolling",
+        "repo": "devenv-nixpkgs",
         "type": "github"
       }
     },
diff --git a/devenv/src/command.rs b/devenv/src/command.rs
index 99f47d9af..e583b2e34 100644
--- a/devenv/src/command.rs
+++ b/devenv/src/command.rs
@@ -109,6 +109,9 @@ impl App {
     ) -> Result<std::process::Command> {
         let cmd = if command.starts_with("nix") {
             let mut flags = NIX_FLAGS.to_vec();
+            flags.push("--max-jobs");
+            let max_jobs = self.cli.max_jobs.to_string();
+            flags.push(&max_jobs);
 
             // handle --nix-option key value
             for chunk in self.cli.nix_option.chunks_exact(2) {
diff --git a/devenv/src/main.rs b/devenv/src/main.rs
index 5144e5ab2..66e0079e5 100644
--- a/devenv/src/main.rs
+++ b/devenv/src/main.rs
@@ -34,6 +34,17 @@ struct Cli {
     #[arg(short, long, help = "Enable debug log level.")]
     verbose: bool,
 
+    #[arg(short = 'j', long, help = "Maximum number of Nix builds at any time.", default_value_t = max_jobs())]
+    max_jobs: u8,
+
+    #[arg(
+        short = 'j',
+        long,
+        help = "Maximum number CPU cores being used by a single build..",
+        default_value = "2"
+    )]
+    cores: u8,
+
     #[arg(short, long, default_value_t = default_system())]
     system: String,
 
@@ -376,7 +387,7 @@ impl App {
         for filename in REQUIRED_FILES {
             let file_path = target.join(filename);
             if file_path.exists() {
-                panic!("File already exists {}", file_path.display());
+                bail!("File already exists {}", file_path.display());
             }
         }
 
@@ -404,10 +415,10 @@ impl App {
             if !status.success() {
                 match status.code() {
                     Some(code) => {
-                        panic!("direnv allow failed with code: {code}!");
+                        bail!("direnv allow failed with code: {code}!");
                     }
                     None => {
-                        panic!("direnv allow failed!");
+                        bail!("direnv allow failed!");
                     }
                 }
             }
@@ -1034,7 +1045,7 @@ impl App {
 
     fn assemble(&mut self) -> Result<()> {
         if !PathBuf::from("devenv.nix").exists() {
-            panic!(indoc::indoc! {"
+            bail!(indoc::indoc! {"
             File devenv.nix does not exist. To get started, run:
 
                 $ devenv init
@@ -1233,3 +1244,11 @@ fn cleanup_symlinks(root: &Path) -> (Vec<PathBuf>, Vec<PathBuf>) {
 
     (to_gc, removed_symlinks)
 }
+
+fn max_jobs() -> u8 {
+    let num_cpus = std::thread::available_parallelism().unwrap_or_else(|e| {
+        eprintln!("Failed to get number of logical CPUs: {}", e);
+        std::num::NonZeroUsize::new(1).unwrap()
+    });
+    (num_cpus.get() / 2).try_into().unwrap()
+}
diff --git a/tests/cli/.test.sh b/tests/cli/.test.sh
index 3c52a0920..bd6e5d0da 100755
--- a/tests/cli/.test.sh
+++ b/tests/cli/.test.sh
@@ -1,8 +1,6 @@
 set -xe 
 
-# TODO: provide devenv cli via inputs
-export PATH=$(pwd)/../../result/bin:$PATH
-
+rm devenv.yaml || true
 devenv build languages.python.package
 devenv shell ls -- -la | grep ".test.sh" 
 devenv shell ls ../ | grep "cli"