modules/direnv/pre-cache: Remove `nix build` from hot path

1 files changed, 16 insertions, 8 deletions

diff --git a/modules/by-name/di/direnv/pre-cache.sh b/modules/by-name/di/direnv/pre-cache.sh
index 8c43a556..d2174f98 100755
--- a/modules/by-name/di/direnv/pre-cache.sh
+++ b/modules/by-name/di/direnv/pre-cache.sh
@@ -50,24 +50,32 @@ _pre_cache_build_shells() {
     installables=""
 
     for lang in "$@"; do
-        new_part="$REPO#devShells.$system.$lang"
+        lang_cache="$final_cache/$lang"
 
-        if [ -z "$installables" ]; then
-            installables="$new_part"
-        else
-            installables="$installables $new_part"
+        if ! [ -f "$lang_cache" ]; then
+            new_part="$REPO#devShells.$system.$lang"
+
+            if [ -z "$installables" ]; then
+                installables="$new_part"
+            else
+                installables="$installables $new_part"
+            fi
         fi
     done
 
-    # We want shell-spliting
-    # shellcheck disable=SC2086
-    _nix build --no-link $installables
+    if [ -n "$installables" ]; then
+        _pre_cache_log "Building '$installables'..."
 
+        # We want shell-spliting
+        # shellcheck disable=SC2086
+        _nix build --no-link $installables
+    fi
 }
 
 pre_cache_load() {
     _pre_cache_preflight
 
+    # Build all not-yet build shells concurrently. That speeds up the initial load.
     _pre_cache_build_shells "$@"
 
     for lan in "$@"; do